Biochmical et Biophysica Acta - General Subjects
Alpha-lipoic acid supplementation protects enzymes from damage by nitrosative and oxidative stress
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Sylvia Hiller, Robert DeKroon, Eric D. Hamlett, Longquan Xu, Cristina Osorio, Jennifer Robinette, Witold Winnik, Stephen Simington, Nobuyo Maeda, Oscar Alzate, Xianwen Yi
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Sylvia Hiller, Robert DeKroon, Eric D. Hamlett, Longquan Xu, Cristina Osorio, Jennifer Robinette, Witold Winnik, Stephen Simington, Nobuyo Maeda, Oscar Alzate, Xianwen Yi
Interaction of α-crystallin with some small molecules and its effect on its structure and function
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): A. Biswas, S. Karmakar, A. Chowdhury, K.P. Das
Background α-Crystallin acts like a molecular chaperone by interacting with its substrate proteins and thus prevents their aggregation. It also interacts with various kinds of small molecules that affect its structure and function. Scope of review In this article we will present a review of work done with respect to the interaction of ATP, peptide generated from lens crystallin and other proteins and some bivalent metal ions with α-crystallin and discuss the role of these interactions on its structure and function and cataract formation. We will also discuss the interaction of some hydrophobic fluorescence probes and surface active agents with α-crystallin. Major conclusions Small molecule interaction controls the structure and function of α-crystallin. ATP and Zn+2 stabilize its structure and enhance chaperone function. Therefore the depletion of these small molecules can be detrimental to maintenance of lens transparency. However, the accumulation of small peptides due to protease activity in the lens can also be harmful as the interaction of these peptides with α-crystallin and other crystallin proteins in the lens promotes aggregation and loss of lens transparency. The use of hydrophobic probe has led to a wealth of information regarding the location of substrate binding site and nature of chaperone–substrate interaction. Interaction of surface active agents with α-crystallin has helped us to understand the structural stability and oligomeric dissociation in α-crystallin. General significance These interactions are very helpful in understanding the mechanistic details of the structural changes and chaperone function of α-crystallin. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): A. Biswas, S. Karmakar, A. Chowdhury, K.P. Das
Background α-Crystallin acts like a molecular chaperone by interacting with its substrate proteins and thus prevents their aggregation. It also interacts with various kinds of small molecules that affect its structure and function. Scope of review In this article we will present a review of work done with respect to the interaction of ATP, peptide generated from lens crystallin and other proteins and some bivalent metal ions with α-crystallin and discuss the role of these interactions on its structure and function and cataract formation. We will also discuss the interaction of some hydrophobic fluorescence probes and surface active agents with α-crystallin. Major conclusions Small molecule interaction controls the structure and function of α-crystallin. ATP and Zn+2 stabilize its structure and enhance chaperone function. Therefore the depletion of these small molecules can be detrimental to maintenance of lens transparency. However, the accumulation of small peptides due to protease activity in the lens can also be harmful as the interaction of these peptides with α-crystallin and other crystallin proteins in the lens promotes aggregation and loss of lens transparency. The use of hydrophobic probe has led to a wealth of information regarding the location of substrate binding site and nature of chaperone–substrate interaction. Interaction of surface active agents with α-crystallin has helped us to understand the structural stability and oligomeric dissociation in α-crystallin. General significance These interactions are very helpful in understanding the mechanistic details of the structural changes and chaperone function of α-crystallin. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Identification of a neuropeptide precursor protein that gives rise to a “cocktail” of peptides that bind Cu(II) and generate metal-linked dimers
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Christopher E. Jones, Meet Zandawala, Dean C. Semmens, Sarah Anderson, Graeme R. Hanson, Daniel A. Janies, Maurice R. Elphick
Background Neuropeptides with an Amino Terminal Cu(II), Ni(II) Binding (ATCUN) motif (H2N-xxH) bind Cu(II)/Ni(II) ions. Here we report the novel discovery of a neuropeptide precursor that gives rise to a “cocktail” of peptides that bind Cu(II)/Ni(II) and form ternary complexes — the L-type SALMFamide precursor in the starfish Asterias rubens. Methods Echinoderm transcriptome sequence data were analysed to identify transcripts encoding precursors of SALMFamide-type neuropeptides. The sequence of the L-type SALMFamide precursor in the starfish Asterias rubens was confirmed by cDNA sequencing and peptides derived from this precursor (e.g. AYHSALPF-NH2, GYHSGLPF-NH2 and LHSALPF-NH2) were synthesized. The ability of these peptides to bind metals was investigated using UV/Vis, NMR, circular dichroism and EPR spectroscopy. Results AYHSALPF-NH2 and GYHSGLPF-NH2 bind Cu(II) and Ni(II) and generate metal-linked dimers to form ternary complexes with LHSALPF-NH2. Investigation of the evolutionary history of the histidine residue that confers these properties revealed that it can be traced to the common ancestor of echinoderms, which is estimated to have lived ~500million years ago. However, L-type precursors comprising multiple SALMFamides with the histidine residue forming an ATCUN motif appears to be a feature that has evolved uniquely in starfish (Asteroidea). General Significance The discovery of a SALMFamide-type neuropeptide precursor protein that gives rise to a “cocktail” of peptides that bind metal ions and generate metal-linked dimers provides a new insight on ATCUN motif-containing neuropeptides. This property of L-type SALMFamides in the Asteroidea may be associated with a role in regulation of the unusual extra-oral feeding behaviour of starfish.
Graphical abstract
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Christopher E. Jones, Meet Zandawala, Dean C. Semmens, Sarah Anderson, Graeme R. Hanson, Daniel A. Janies, Maurice R. Elphick
Background Neuropeptides with an Amino Terminal Cu(II), Ni(II) Binding (ATCUN) motif (H2N-xxH) bind Cu(II)/Ni(II) ions. Here we report the novel discovery of a neuropeptide precursor that gives rise to a “cocktail” of peptides that bind Cu(II)/Ni(II) and form ternary complexes — the L-type SALMFamide precursor in the starfish Asterias rubens. Methods Echinoderm transcriptome sequence data were analysed to identify transcripts encoding precursors of SALMFamide-type neuropeptides. The sequence of the L-type SALMFamide precursor in the starfish Asterias rubens was confirmed by cDNA sequencing and peptides derived from this precursor (e.g. AYHSALPF-NH2, GYHSGLPF-NH2 and LHSALPF-NH2) were synthesized. The ability of these peptides to bind metals was investigated using UV/Vis, NMR, circular dichroism and EPR spectroscopy. Results AYHSALPF-NH2 and GYHSGLPF-NH2 bind Cu(II) and Ni(II) and generate metal-linked dimers to form ternary complexes with LHSALPF-NH2. Investigation of the evolutionary history of the histidine residue that confers these properties revealed that it can be traced to the common ancestor of echinoderms, which is estimated to have lived ~500million years ago. However, L-type precursors comprising multiple SALMFamides with the histidine residue forming an ATCUN motif appears to be a feature that has evolved uniquely in starfish (Asteroidea). General Significance The discovery of a SALMFamide-type neuropeptide precursor protein that gives rise to a “cocktail” of peptides that bind metal ions and generate metal-linked dimers provides a new insight on ATCUN motif-containing neuropeptides. This property of L-type SALMFamides in the Asteroidea may be associated with a role in regulation of the unusual extra-oral feeding behaviour of starfish.
Graphical abstract
Multidimensional significance of crystallin protein–protein interactions and their implications in various human diseases
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Kumarasamy Anbarasu, Jeyarajan Sivakumar
Background Crystallins are the important structural and functional proteins in the eye lens responsible for refractive index. Post-translational modifications (PTMs) and mutations are major causative factors that affect crystallin structural conformation and functional characteristics thus playing a vital role in the etiology of cataractogenesis. Scope of review The significance of crystallin protein–protein interactions (PPIs) in the lens and non-lenticular tissues is summarized. Major conclusions Aberrancy of PPIs between crystallin, its associated protein and metal ions has been accomplished in various human diseases including cataract. A detailed account on multidimensional structural and functional significance of crystallin PPI in humans must be brought into limelight, in order to understand the biochemical and molecular basis augmenting the aberrancies of such interaction. In this scenario, the present review is focused to shed light on studies which will aid to expand our present understanding on disease pathogenesis related to loss of PPI thereby paving the way for putative future therapeutic targets to curb such diseases. General significance The interactions with α-crystallins always aid to protect their structural and functional characteristics. The up-regulation of αB-crystallin in the non-lenticular tissues always decodes as biomarker for various stress related disorders. For better understanding and treatment of various diseases, PPI studies provide overall outline about the structural and functional characteristics of the proteins. This information not only helps to find out the route of cataractogenesis but also aid to identify potential molecules to inhibit/prevent the further development of such complicated phenomenon. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Kumarasamy Anbarasu, Jeyarajan Sivakumar
Background Crystallins are the important structural and functional proteins in the eye lens responsible for refractive index. Post-translational modifications (PTMs) and mutations are major causative factors that affect crystallin structural conformation and functional characteristics thus playing a vital role in the etiology of cataractogenesis. Scope of review The significance of crystallin protein–protein interactions (PPIs) in the lens and non-lenticular tissues is summarized. Major conclusions Aberrancy of PPIs between crystallin, its associated protein and metal ions has been accomplished in various human diseases including cataract. A detailed account on multidimensional structural and functional significance of crystallin PPI in humans must be brought into limelight, in order to understand the biochemical and molecular basis augmenting the aberrancies of such interaction. In this scenario, the present review is focused to shed light on studies which will aid to expand our present understanding on disease pathogenesis related to loss of PPI thereby paving the way for putative future therapeutic targets to curb such diseases. General significance The interactions with α-crystallins always aid to protect their structural and functional characteristics. The up-regulation of αB-crystallin in the non-lenticular tissues always decodes as biomarker for various stress related disorders. For better understanding and treatment of various diseases, PPI studies provide overall outline about the structural and functional characteristics of the proteins. This information not only helps to find out the route of cataractogenesis but also aid to identify potential molecules to inhibit/prevent the further development of such complicated phenomenon. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Ligand tunnels in T. brucei and human CYP51: Insights for parasite-specific drug design
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Xiaofeng Yu, Prajwal Nandekar, Ghulam Mustafa, Vlad Cojocaru, Galina I. Lepesheva, Rebecca C. Wade
Background Cytochrome P450 sterol 14α-demethylase (CYP51) is an essential enzyme for sterol biosynthesis and a target for anti-parasitic drug design. However, the design of parasite-specific drugs that inhibit parasitic CYP51 without severe side effects remains challenging. The active site of CYP51 is situated in the interior of the protein. Here, we characterize the potential ligand egress routes and mechanisms in Trypanosoma brucei and human CYP51 enzymes. Methods We performed Random Acceleration Molecular Dynamics simulations of the egress of four different ligands from the active site of models of soluble and membrane-bound T. brucei CYP51 and of soluble human CYP51. Results In the simulations, tunnel 2f, which leads to the membrane, was found to be the predominant ligand egress tunnel for all the ligands studied. Tunnels S, 1 and W, which lead to the cytosol, were also used in T. brucei CYP51, whereas tunnel 1 was the only other tunnel used significantly in human CYP51. The common tunnels found previously in other CYPs were barely used. The ligand egress times were shorter for human than T. brucei CYP51, suggesting lower barriers to ligand passage. Two gating residues, F105 and M460, in T. brucei CYP51 that modulate the opening of tunnels 2f and S were identified. Conclusions Although the main egress tunnel was the same, differences in the tunnel-lining residues, ligand passage and tunnel usage were found between T. brucei and human CYP51s. General Significance The results provide a basis for the design of selective anti-parasitic agents targeting the ligand tunnels.
Graphical abstract
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Xiaofeng Yu, Prajwal Nandekar, Ghulam Mustafa, Vlad Cojocaru, Galina I. Lepesheva, Rebecca C. Wade
Background Cytochrome P450 sterol 14α-demethylase (CYP51) is an essential enzyme for sterol biosynthesis and a target for anti-parasitic drug design. However, the design of parasite-specific drugs that inhibit parasitic CYP51 without severe side effects remains challenging. The active site of CYP51 is situated in the interior of the protein. Here, we characterize the potential ligand egress routes and mechanisms in Trypanosoma brucei and human CYP51 enzymes. Methods We performed Random Acceleration Molecular Dynamics simulations of the egress of four different ligands from the active site of models of soluble and membrane-bound T. brucei CYP51 and of soluble human CYP51. Results In the simulations, tunnel 2f, which leads to the membrane, was found to be the predominant ligand egress tunnel for all the ligands studied. Tunnels S, 1 and W, which lead to the cytosol, were also used in T. brucei CYP51, whereas tunnel 1 was the only other tunnel used significantly in human CYP51. The common tunnels found previously in other CYPs were barely used. The ligand egress times were shorter for human than T. brucei CYP51, suggesting lower barriers to ligand passage. Two gating residues, F105 and M460, in T. brucei CYP51 that modulate the opening of tunnels 2f and S were identified. Conclusions Although the main egress tunnel was the same, differences in the tunnel-lining residues, ligand passage and tunnel usage were found between T. brucei and human CYP51s. General Significance The results provide a basis for the design of selective anti-parasitic agents targeting the ligand tunnels.
Graphical abstract
Autophagy and UPR in alpha-crystallin mutant knock-in mouse models of hereditary cataracts
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Usha P. Andley, Joshua W. Goldman
Background Knock-in mice provide useful models of congenital and age-related cataracts caused by α-crystallin mutations. R49C αA-crystallin and R120G αB-crystallin mutations are linked with hereditary cataracts. Knock-in αA-R49C+/− heterozygotes develop cataracts by 1–2months, whereas homozygote mice have cataracts at birth. The R49C mutation drastically reduces lens protein water solubility and causes cell death in knock-in mouse lenses. Mutant crystallin cannot function as a chaperone, which leads to protein aggregation and lens opacity. Protein aggregation disrupts the lens fiber cell structure and normal development and causes cell death in epithelial and fiber cells. We determined what aspects of the wild-type phenotype are age-dependently altered in the mutant lens. Methods Wild-type, heterozygote (αA-R49C+/−), and homozygote (αA-R49C+/+) mouse lenses were assessed pre- and postnatally for lens morphology (electron microscopy, immunohistochemistry), and autophagy or unfolded protein response markers (immunoblotting). Results Morphology was altered by embryonic day 17 in R49C+/+ lenses; R49C+/− lens morphology was unaffected at this stage. Active autophagy in the lens epithelium of mutant lenses was indicated by the presence of autophagosomes using electron microscopy. Protein p62 levels, which are degraded specifically by autophagy, increased in αA-R49C mutant versus wild-type lenses, suggesting autophagy inhibition in the mutant lenses. The unfolded protein response marker XBP-1 was upregulated in adult lenses of αB-R120G+/+ mice, suggesting its role in lens opacification. Conclusions Mutated crystallins alter lens morphology, autophagy, and stress responses. General significance Therapeutic modulation of autophagic pathways may improve protein degradation in cataractous lenses and reduce lens opacity. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Usha P. Andley, Joshua W. Goldman
Background Knock-in mice provide useful models of congenital and age-related cataracts caused by α-crystallin mutations. R49C αA-crystallin and R120G αB-crystallin mutations are linked with hereditary cataracts. Knock-in αA-R49C+/− heterozygotes develop cataracts by 1–2months, whereas homozygote mice have cataracts at birth. The R49C mutation drastically reduces lens protein water solubility and causes cell death in knock-in mouse lenses. Mutant crystallin cannot function as a chaperone, which leads to protein aggregation and lens opacity. Protein aggregation disrupts the lens fiber cell structure and normal development and causes cell death in epithelial and fiber cells. We determined what aspects of the wild-type phenotype are age-dependently altered in the mutant lens. Methods Wild-type, heterozygote (αA-R49C+/−), and homozygote (αA-R49C+/+) mouse lenses were assessed pre- and postnatally for lens morphology (electron microscopy, immunohistochemistry), and autophagy or unfolded protein response markers (immunoblotting). Results Morphology was altered by embryonic day 17 in R49C+/+ lenses; R49C+/− lens morphology was unaffected at this stage. Active autophagy in the lens epithelium of mutant lenses was indicated by the presence of autophagosomes using electron microscopy. Protein p62 levels, which are degraded specifically by autophagy, increased in αA-R49C mutant versus wild-type lenses, suggesting autophagy inhibition in the mutant lenses. The unfolded protein response marker XBP-1 was upregulated in adult lenses of αB-R120G+/+ mice, suggesting its role in lens opacification. Conclusions Mutated crystallins alter lens morphology, autophagy, and stress responses. General significance Therapeutic modulation of autophagic pathways may improve protein degradation in cataractous lenses and reduce lens opacity. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
De novo lipogenesis in Atlantic salmon adipocytes
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Marta Bou, Marijana Todorčević, Jacob Torgersen, Stanko Škugor, Isabel Navarro, Bente Ruyter
Background Carnivorous teleost fish utilize glucose poorly, and the reason for this is not known. It is possible that the capacity of adipocytes to synthesize lipids from carbohydrate precursors through a process known as “de novo lipogenesis” (DNL) is one of the factors that contributes to glucose intolerance in Atlantic salmon. Methods Primary adipocytes from Atlantic salmon differentiated in vitro were incubated with radiolabelled glucose in order to explore the capacity of salmon adipocytes to synthesize and deposit lipids from glucose through DNL. The lipid-storage capacity of adipocytes incubated with glucose was compared with that of cells incubated with the fatty acid palmitic acid. Quantitative PCR and immunohistochemistry were used to assess changes of genes and proteins involved in glucose and lipid transport and metabolism. Results Less than 0.1% of the radiolabelled glucose was metabolized to the fatty acids 16:0 and the stearoyl-CoA desaturase products 16:1 and 18:1 by DNL, whereas approximately 40% was converted to glycerol to form the triacylglycerol backbone of lipids. Transcriptional analysis indicated that adipocytes ensure the availability of necessary cofactors and other substrates for lipid synthesis and storage from glycolysis, the pentose phosphate pathway and glyceroneogenesis. Conclusions We have shown for the first time that the DNL pathway is active in fish adipocytes. The capacity of the pathway to convert glucose into cellular lipids for storage is relatively low. General significance The limited capacity of adipocytes to utilize glucose as a substrate for lipid deposition may contribute to glucose intolerance in salmonids.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Marta Bou, Marijana Todorčević, Jacob Torgersen, Stanko Škugor, Isabel Navarro, Bente Ruyter
Background Carnivorous teleost fish utilize glucose poorly, and the reason for this is not known. It is possible that the capacity of adipocytes to synthesize lipids from carbohydrate precursors through a process known as “de novo lipogenesis” (DNL) is one of the factors that contributes to glucose intolerance in Atlantic salmon. Methods Primary adipocytes from Atlantic salmon differentiated in vitro were incubated with radiolabelled glucose in order to explore the capacity of salmon adipocytes to synthesize and deposit lipids from glucose through DNL. The lipid-storage capacity of adipocytes incubated with glucose was compared with that of cells incubated with the fatty acid palmitic acid. Quantitative PCR and immunohistochemistry were used to assess changes of genes and proteins involved in glucose and lipid transport and metabolism. Results Less than 0.1% of the radiolabelled glucose was metabolized to the fatty acids 16:0 and the stearoyl-CoA desaturase products 16:1 and 18:1 by DNL, whereas approximately 40% was converted to glycerol to form the triacylglycerol backbone of lipids. Transcriptional analysis indicated that adipocytes ensure the availability of necessary cofactors and other substrates for lipid synthesis and storage from glycolysis, the pentose phosphate pathway and glyceroneogenesis. Conclusions We have shown for the first time that the DNL pathway is active in fish adipocytes. The capacity of the pathway to convert glucose into cellular lipids for storage is relatively low. General significance The limited capacity of adipocytes to utilize glucose as a substrate for lipid deposition may contribute to glucose intolerance in salmonids.
Functional sequences in human alphaB crystallin
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): John I. Clark
Background Human alphaB crystallin (HspB5) contains the alpha crystallin core domain, a series of antiparallel beta-strands organized into the characteristic beta sandwich of small heat shock proteins (sHsps). The full 3-dimensional structure for alpha crystallin has not been determined and the mechanism for the biological activity remains elusive because sHsps participate in multiple interactions with a broad range of target proteins that favor self-assembly of polydisperse fibrils and complexes. We selected human alphaB crystallin to study interactive sequences because it is involved in many human condensation, amyloid, and aggregation diseases and it is very sensitive to the destabilization of unfolding proteins. Sophisticated methods are being used to analyze and complete the structure of alphaB crystallin with the expectation of understanding sHsp function. This review considers the identification of interactive sites on the surface of the alphaB crystallin, which may be the key to understanding the multifunctional activity of human alphaB crystallin. Scope of review This review summarizes the research on the identification of the bioactive interactive sequences responsible for the function of human alphaB crystallin, an sHsp with chaperone-like activity. Major conclusions The multifunctional activity of human alphaB crystallin results from the interactive peptide sequences exposed on the surface of the molecule. The multiple, non-covalent, interactive sequences can account for the selectivity and sensitivity of alphaB crystallin to the initiation of protein unfolding. General significance Human alphaB crystallin may be an important part of an endogenous protective mechanism in aging cells and tissues. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): John I. Clark
Background Human alphaB crystallin (HspB5) contains the alpha crystallin core domain, a series of antiparallel beta-strands organized into the characteristic beta sandwich of small heat shock proteins (sHsps). The full 3-dimensional structure for alpha crystallin has not been determined and the mechanism for the biological activity remains elusive because sHsps participate in multiple interactions with a broad range of target proteins that favor self-assembly of polydisperse fibrils and complexes. We selected human alphaB crystallin to study interactive sequences because it is involved in many human condensation, amyloid, and aggregation diseases and it is very sensitive to the destabilization of unfolding proteins. Sophisticated methods are being used to analyze and complete the structure of alphaB crystallin with the expectation of understanding sHsp function. This review considers the identification of interactive sites on the surface of the alphaB crystallin, which may be the key to understanding the multifunctional activity of human alphaB crystallin. Scope of review This review summarizes the research on the identification of the bioactive interactive sequences responsible for the function of human alphaB crystallin, an sHsp with chaperone-like activity. Major conclusions The multifunctional activity of human alphaB crystallin results from the interactive peptide sequences exposed on the surface of the molecule. The multiple, non-covalent, interactive sequences can account for the selectivity and sensitivity of alphaB crystallin to the initiation of protein unfolding. General significance Human alphaB crystallin may be an important part of an endogenous protective mechanism in aging cells and tissues. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Proton pump inhibitors drastically modify triosephosphate isomerase from Giardia lamblia at functional and structural levels, providing molecular leads in the design of new antigiardiasic drugs
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Itzhel García-Torres, Ignacio de la Mora-de la Mora, Jaime Marcial-Quino, Saúl Gómez-Manzo, América Vanoye-Carlo, Gabriel Navarrete-Vázquez, Blanca Colín-Lozano, Pedro Gutiérrez-Castrellón, Edgar Sierra-Palacios, Gabriel López-Velázquez, Sergio Enríquez-Flores
Background Proton pump inhibitors (PPIs) are extensively used in clinical practice because of their effectiveness and safety. Omeprazole is one of the best-selling drugs worldwide and, with other PPIs, has been proposed to be potential drugs for the treatment of several diseases. We demonstrated that omeprazole shows cytotoxic effects in Giardia and concomitantly inactivates giardial triosephosphate isomerase (GlTIM). Therefore, we evaluated the efficiency of commercially available PPIs to inactivate this enzyme. Methods We assayed the effect of PPIs on the GlTIM WT, single Cys mutants, and the human counterpart, following enzyme activity, thermal stability, exposure of hydrophobic regions, and susceptibility to limited proteolysis. Results PPIs efficiently inactivated GlTIM; however, rabeprazole was the best inactivating drug and was nearly ten times more effective. The mechanism of inactivation by PPIs was through the modification of the Cys 222 residue. Moreover, there are important changes at the structural level, the thermal stability of inactivated-GlTIM was drastically diminished and the structural rigidity was lost, as observed by the exposure of hydrophobic regions and their susceptibility to limited proteolysis. Conclusions Our results demonstrate that rabeprazole is the most potent PPI for GlTIM inactivation and that all PPIs tested have substantial abilities to alter GITIM at the structural level, causing serious damage. General significance. This is the first report demonstrating the effectiveness of commercial PPIs on a glycolytic parasitic enzyme, with structural features well known. This study is a step forward in the use and understanding the implicated mechanisms of new antigiardiasic drugs safe in humans.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Itzhel García-Torres, Ignacio de la Mora-de la Mora, Jaime Marcial-Quino, Saúl Gómez-Manzo, América Vanoye-Carlo, Gabriel Navarrete-Vázquez, Blanca Colín-Lozano, Pedro Gutiérrez-Castrellón, Edgar Sierra-Palacios, Gabriel López-Velázquez, Sergio Enríquez-Flores
Background Proton pump inhibitors (PPIs) are extensively used in clinical practice because of their effectiveness and safety. Omeprazole is one of the best-selling drugs worldwide and, with other PPIs, has been proposed to be potential drugs for the treatment of several diseases. We demonstrated that omeprazole shows cytotoxic effects in Giardia and concomitantly inactivates giardial triosephosphate isomerase (GlTIM). Therefore, we evaluated the efficiency of commercially available PPIs to inactivate this enzyme. Methods We assayed the effect of PPIs on the GlTIM WT, single Cys mutants, and the human counterpart, following enzyme activity, thermal stability, exposure of hydrophobic regions, and susceptibility to limited proteolysis. Results PPIs efficiently inactivated GlTIM; however, rabeprazole was the best inactivating drug and was nearly ten times more effective. The mechanism of inactivation by PPIs was through the modification of the Cys 222 residue. Moreover, there are important changes at the structural level, the thermal stability of inactivated-GlTIM was drastically diminished and the structural rigidity was lost, as observed by the exposure of hydrophobic regions and their susceptibility to limited proteolysis. Conclusions Our results demonstrate that rabeprazole is the most potent PPI for GlTIM inactivation and that all PPIs tested have substantial abilities to alter GITIM at the structural level, causing serious damage. General significance. This is the first report demonstrating the effectiveness of commercial PPIs on a glycolytic parasitic enzyme, with structural features well known. This study is a step forward in the use and understanding the implicated mechanisms of new antigiardiasic drugs safe in humans.
Alpha-crystallin-derived peptides as therapeutic chaperones
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Murugesan Raju, Puttur Santhoshkumar, K. Krishna Sharma
Background The demonstration of chaperone-like activity in peptides (mini-chaperones) derived from α-crystallin's chaperone region has generated significant interest in exploring the therapeutic potential of peptide chaperones in diseases of protein aggregation. Recent studies in experimental animals show that mini-chaperones could reach intended targets and alter the disease phenotype. Although mini-chaperones show potential benefits against protein aggregation diseases, they do tend to form aggregates on storage. There is thus a need to fine-tune peptide chaperones to increase their solubility, pharmacokinetics, and biological efficacy. Scope of review This review summarizes the properties and the potential therapeutic roles of mini-chaperones in protein aggregation diseases and highlights some of the refinements needed to increase the stability and biological efficacy of mini-chaperones while maintaining or enhancing their chaperone-like activity against precipitation of unfolding proteins. Major conclusions Mini-chaperones suppress the aggregation of proteins, block amyloid fibril formation, stabilize mutant proteins, sequester metal ions, and exhibit antiapoptotic properties. Much work must be done to fine-tune mini-chaperones and increase their stability and biological efficacy. Peptide chaperones could have a great therapeutic value in diseases associated with protein aggregation and apoptosis. General significance Accumulation of misfolded proteins is a primary cause for many age-related diseases, including cataract, macular degeneration, and various neurological diseases. Stabilization of native proteins is a logical therapeutic approach for such diseases. Mini-chaperones, with their inherent antiaggregation and antiapoptotic properties, may represent an effective therapeutic molecule to prevent the cascade of protein conformational disorders. Future studies will further uncover the therapeutic potential of mini-chaperones. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Murugesan Raju, Puttur Santhoshkumar, K. Krishna Sharma
Background The demonstration of chaperone-like activity in peptides (mini-chaperones) derived from α-crystallin's chaperone region has generated significant interest in exploring the therapeutic potential of peptide chaperones in diseases of protein aggregation. Recent studies in experimental animals show that mini-chaperones could reach intended targets and alter the disease phenotype. Although mini-chaperones show potential benefits against protein aggregation diseases, they do tend to form aggregates on storage. There is thus a need to fine-tune peptide chaperones to increase their solubility, pharmacokinetics, and biological efficacy. Scope of review This review summarizes the properties and the potential therapeutic roles of mini-chaperones in protein aggregation diseases and highlights some of the refinements needed to increase the stability and biological efficacy of mini-chaperones while maintaining or enhancing their chaperone-like activity against precipitation of unfolding proteins. Major conclusions Mini-chaperones suppress the aggregation of proteins, block amyloid fibril formation, stabilize mutant proteins, sequester metal ions, and exhibit antiapoptotic properties. Much work must be done to fine-tune mini-chaperones and increase their stability and biological efficacy. Peptide chaperones could have a great therapeutic value in diseases associated with protein aggregation and apoptosis. General significance Accumulation of misfolded proteins is a primary cause for many age-related diseases, including cataract, macular degeneration, and various neurological diseases. Stabilization of native proteins is a logical therapeutic approach for such diseases. Mini-chaperones, with their inherent antiaggregation and antiapoptotic properties, may represent an effective therapeutic molecule to prevent the cascade of protein conformational disorders. Future studies will further uncover the therapeutic potential of mini-chaperones. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Using solution X-ray scattering to determine the high-resolution structure and morphology of PEGylated liposomal doxorubicin nanodrugs
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Y. Schilt, T. Berman, X. Wei, Y. Barenholz, U. Raviv
Background Among nanodrugs, PEGylated nanoliposomes loaded with an active agent are of major importance. In this paper we studied the structures and morphology of PEGylated nanoliposomes before and after remote loading with doxorubicin. Methods High-resolution structures were obtained by solution X-ray scattering combined with our advanced analysis tools. We studied the PEGylated liposomal doxorubicin (PLD) product Doxil®, and its generics, where remote doxorubicin loading is performed by a gradient of ammonium sulfate, and LC100, a novel PLD under development, where remote loading was done by a gradient of ammonium methanesulfonate. The PLD structures were compared with drug-free nanoliposomes having identical composition. Results We determined the membrane electron density profiles of the empty and loaded PLDs, the thickness and density of the PEG layers, and the structure of the drug inside the liposomes. Conclusions The liposomal membranes had the same structure for both ammonium salts. We found that the drug formed crystals inside PLDs loaded by ammonium sulfate, whereas it had an amorphous morphology in the PLD loaded by ammonium methanesulfonate. The variations of the drug's structural parameters between the generics of Doxil® are similar to the variations between batches of the same product, suggesting that all these products were structurally similar. General significance This paper demonstrates that solution X-ray scattering, when combined with our powerful analysis tools, can determine the high-resolution structure of complex non-crystallized nanoparticle dispersions used in nanomedicine, thereby providing useful physical insights into their functions.
Graphical abstract
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Y. Schilt, T. Berman, X. Wei, Y. Barenholz, U. Raviv
Background Among nanodrugs, PEGylated nanoliposomes loaded with an active agent are of major importance. In this paper we studied the structures and morphology of PEGylated nanoliposomes before and after remote loading with doxorubicin. Methods High-resolution structures were obtained by solution X-ray scattering combined with our advanced analysis tools. We studied the PEGylated liposomal doxorubicin (PLD) product Doxil®, and its generics, where remote doxorubicin loading is performed by a gradient of ammonium sulfate, and LC100, a novel PLD under development, where remote loading was done by a gradient of ammonium methanesulfonate. The PLD structures were compared with drug-free nanoliposomes having identical composition. Results We determined the membrane electron density profiles of the empty and loaded PLDs, the thickness and density of the PEG layers, and the structure of the drug inside the liposomes. Conclusions The liposomal membranes had the same structure for both ammonium salts. We found that the drug formed crystals inside PLDs loaded by ammonium sulfate, whereas it had an amorphous morphology in the PLD loaded by ammonium methanesulfonate. The variations of the drug's structural parameters between the generics of Doxil® are similar to the variations between batches of the same product, suggesting that all these products were structurally similar. General significance This paper demonstrates that solution X-ray scattering, when combined with our powerful analysis tools, can determine the high-resolution structure of complex non-crystallized nanoparticle dispersions used in nanomedicine, thereby providing useful physical insights into their functions.
Graphical abstract
Therapeutic potential of α-crystallin
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Ram H. Nagaraj, Rooban B. Nahomi, Niklaus H. Mueller, Cibin T. Raghavan, David A. Ammar, J. Mark Petrash
Background The findings that α-crystallins are multi-functional proteins with diverse biological functions have generated considerable interest in understanding their role in health and disease. Recent studies have shown that chaperone peptides of α-crystallin could be delivered into cultured cells and in experimental animals with beneficial effects against protein aggregation, oxidation, inflammation and apoptosis. Scope of review In this review, we will summarize the latest developments on the therapeutic potential of α-crystallins and their functional peptides. Major conclusions α-Crystallins and their functional peptides have shown significant favorable effects against several diseases. Their targeted delivery to tissues would be of great therapeutic benefit. However, α-crystallins can also function as disease-causing proteins. These seemingly contradictory functions must be carefully considered prior to their therapeutic use. General significance αA and αB-Crystallin are members of the small heat shock protein family. These proteins exhibit molecular chaperone and anti-apoptotic activities. The core crystallin domain within these proteins is largely responsible for these prosperities. Recent studies have identified peptides within the crystallin domain of both α- and αB-crystallins with remarkable chaperone and anti-apoptotic activities. Administration of α-crystallin or their functional peptides has shown substantial inhibition of pathologies in several diseases. However, α-crystallins have been shown to promote disease-causing pathways. These two sides of the proteins are discussed in this review. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Ram H. Nagaraj, Rooban B. Nahomi, Niklaus H. Mueller, Cibin T. Raghavan, David A. Ammar, J. Mark Petrash
Background The findings that α-crystallins are multi-functional proteins with diverse biological functions have generated considerable interest in understanding their role in health and disease. Recent studies have shown that chaperone peptides of α-crystallin could be delivered into cultured cells and in experimental animals with beneficial effects against protein aggregation, oxidation, inflammation and apoptosis. Scope of review In this review, we will summarize the latest developments on the therapeutic potential of α-crystallins and their functional peptides. Major conclusions α-Crystallins and their functional peptides have shown significant favorable effects against several diseases. Their targeted delivery to tissues would be of great therapeutic benefit. However, α-crystallins can also function as disease-causing proteins. These seemingly contradictory functions must be carefully considered prior to their therapeutic use. General significance αA and αB-Crystallin are members of the small heat shock protein family. These proteins exhibit molecular chaperone and anti-apoptotic activities. The core crystallin domain within these proteins is largely responsible for these prosperities. Recent studies have identified peptides within the crystallin domain of both α- and αB-crystallins with remarkable chaperone and anti-apoptotic activities. Administration of α-crystallin or their functional peptides has shown substantial inhibition of pathologies in several diseases. However, α-crystallins have been shown to promote disease-causing pathways. These two sides of the proteins are discussed in this review. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Ankyrin exposure induced by activated protein kinase C plays a potential role in erythrophagocytosis
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Fuzhou Tang, Yang Ren, Ruofeng Wang, Xiaofeng Lei, Xueru Deng, Yajin Zhao, Dong Chen, Xiang Wang
Background In physiological and pathological conditions activated protein kinace C (PKC) has been observed in the erythrocytes. Externalization of ankyrin followed by Arg–Gly–Asp (RGD)/integrin recognition also triggers erythrophagocytosis. In the present study, to test whether activated PKC is associated with ankyrin exposure in erythrophagocytosis. Methods Phorbol 12-myristate-13-acetate (PMA)-induced PKC activation and ankyrin phosphorylation were tested, and under different treatment conditions the subpopulation of erythrocytes with ankyrin exposure and the levels of intracellular calcium were analyzed by flow cytometry. Results Results showed that treatment of erythrocytes with PMA in a calcium-containing buffer led to ankyrin exposure. In the absence of extracellular calcium, no ankyrin exposure was observed. PKC inhibition with calphostin C, a blocker of the PMA binding site, completely prevented the calcium entry, protein phosphorylation and ankyrin exposure. PKC inhibition with chelerythrine chloride, an inhibitor of the active site, diminished the level of ankyrin-exposing cells and ankyrin phosphorylation; however it even led to a higher percentage of cells with increased levels of calcium than with PMA treatment alone. Although PKC was activated and ankyrin phosphorylation occurred, no ankyrin exposure was observed in the absence of extracellular calcium. Conclusion Analyses of results suggested that PMA induces calcium influx into the erythrocytes, leading to the activation of calcium-dependent enzymes and the phosphorylation of membrane proteins, ultimately inducing ankyrin exposure and erythrophagocytosis. This study may provide insights into the molecular mechanisms of removing aged or diseased erythrocytes.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Fuzhou Tang, Yang Ren, Ruofeng Wang, Xiaofeng Lei, Xueru Deng, Yajin Zhao, Dong Chen, Xiang Wang
Background In physiological and pathological conditions activated protein kinace C (PKC) has been observed in the erythrocytes. Externalization of ankyrin followed by Arg–Gly–Asp (RGD)/integrin recognition also triggers erythrophagocytosis. In the present study, to test whether activated PKC is associated with ankyrin exposure in erythrophagocytosis. Methods Phorbol 12-myristate-13-acetate (PMA)-induced PKC activation and ankyrin phosphorylation were tested, and under different treatment conditions the subpopulation of erythrocytes with ankyrin exposure and the levels of intracellular calcium were analyzed by flow cytometry. Results Results showed that treatment of erythrocytes with PMA in a calcium-containing buffer led to ankyrin exposure. In the absence of extracellular calcium, no ankyrin exposure was observed. PKC inhibition with calphostin C, a blocker of the PMA binding site, completely prevented the calcium entry, protein phosphorylation and ankyrin exposure. PKC inhibition with chelerythrine chloride, an inhibitor of the active site, diminished the level of ankyrin-exposing cells and ankyrin phosphorylation; however it even led to a higher percentage of cells with increased levels of calcium than with PMA treatment alone. Although PKC was activated and ankyrin phosphorylation occurred, no ankyrin exposure was observed in the absence of extracellular calcium. Conclusion Analyses of results suggested that PMA induces calcium influx into the erythrocytes, leading to the activation of calcium-dependent enzymes and the phosphorylation of membrane proteins, ultimately inducing ankyrin exposure and erythrophagocytosis. This study may provide insights into the molecular mechanisms of removing aged or diseased erythrocytes.
Alpha crystallins in the retinal pigment epithelium and implications for the pathogenesis and treatment of age-related macular degeneration
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Ram Kannan, Parameswaran G. Sreekumar, David R. Hinton
Background αA- and αB crystallins are principal members of the small heat shock protein family and elicit both a cell protective function and a chaperone function. α-Crystallins have been found to be prominent proteins in normal and pathological retina emphasizing the importance for in-depth understanding of their function and significance. Scope of review Retinal pigment epithelial cells (RPE) play a vital role in the pathogenesis of age-related macular degeneration (AMD). This review addresses a number of cellular functions mediated by α-crystallins in the retina. Prominent expression of αB crystallin in mitochondria may serve to protect cells from oxidative injury. αB crystallin as secretory protein via exosomes can offer neuroprotection to adjacent RPE cells and photoreceptors. The availability of chaperone-containing minipeptides of αB crystallin could prove to be a valuable new tool for therapeutic treatment of retinal disorders. Major conclusions α-Crystallins are expressed in cytosol and mitochondria of RPE cells and are regulated during oxygen-induced retinopathy and during development. α-Crystallins protect RPE from oxidative-and ER stress-induced injury and autophagy. αB-Crystallin is a modulator of angiogenesis and vascular endothelial growth factor. αB Crystallin is secreted via exosomal pathway. Minichaperone peptides derived from αB Crystallin prevent oxidant induced cell death and have therapeutic potential. General significance Overall, this review summarizes several novel properties of α-crystallins and their relevance to maintaining normal retinal function. In particular, the use of α-crystallin derived peptides is a promising therapeutic strategy to combat retinal diseases such as AMD. This article is part of a Special Issue entitled Crystallin biochemistry in health and disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Ram Kannan, Parameswaran G. Sreekumar, David R. Hinton
Background αA- and αB crystallins are principal members of the small heat shock protein family and elicit both a cell protective function and a chaperone function. α-Crystallins have been found to be prominent proteins in normal and pathological retina emphasizing the importance for in-depth understanding of their function and significance. Scope of review Retinal pigment epithelial cells (RPE) play a vital role in the pathogenesis of age-related macular degeneration (AMD). This review addresses a number of cellular functions mediated by α-crystallins in the retina. Prominent expression of αB crystallin in mitochondria may serve to protect cells from oxidative injury. αB crystallin as secretory protein via exosomes can offer neuroprotection to adjacent RPE cells and photoreceptors. The availability of chaperone-containing minipeptides of αB crystallin could prove to be a valuable new tool for therapeutic treatment of retinal disorders. Major conclusions α-Crystallins are expressed in cytosol and mitochondria of RPE cells and are regulated during oxygen-induced retinopathy and during development. α-Crystallins protect RPE from oxidative-and ER stress-induced injury and autophagy. αB-Crystallin is a modulator of angiogenesis and vascular endothelial growth factor. αB Crystallin is secreted via exosomal pathway. Minichaperone peptides derived from αB Crystallin prevent oxidant induced cell death and have therapeutic potential. General significance Overall, this review summarizes several novel properties of α-crystallins and their relevance to maintaining normal retinal function. In particular, the use of α-crystallin derived peptides is a promising therapeutic strategy to combat retinal diseases such as AMD. This article is part of a Special Issue entitled Crystallin biochemistry in health and disease.
Synthetic stigmastanes with dual antiherpetic and immunomodulating activities inhibit ERK and Akt signaling pathways without binding to glucocorticoid receptors
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Flavia M. Michelini, Carlos A. Bueno, Alejandro M. Molinari, Mario D. Galigniana, Lydia R. Galagovsky, Laura E. Alché, Javier A. Ramírez
Background We have previously shown that some synthetic hydroxylated stigmastanes derived from plant sterols inhibit in vitro HSV-1 replication in ocular cell lines and decrease cytokine production in stimulated macrophages, suggesting that these steroids might combine antiviral and immunomodulating properties. In this paper we report the synthesis of some analogs fluorinated at C-6 in order to study the effect of this modification on bioactivity. Methods The following methods were used: organic synthesis of fluorinated analogs, cytotoxicity determination with MTT assays, cytokine production quantification with ELISAs, glucocorticoid activity determination by displacement assays, immunofluorescence and transcriptional activity assays, studies of the activation of signaling pathways by Western blot, antiviral activity evaluation through virus yield reduction assays. Results We report the chemical synthesis of new fluorinated stigmastanes and show that this family of steroidal compounds exerts its immunomodulating activity by inhibiting ERK and Akt signaling pathways, but do not act as glucocorticoids. We also demonstrate that fluorination enhances the antiviral activity. Conclusions Fluorination on C-6 did not enhance the anti-inflammatory effect, however, an increase in the in vitro antiviral activity was observed. Thus, our results suggest that it is possible to introduce chemical modifications on the parent steroids in order to selectively modulate one of the effects. General significance This family of steroids could allow the development of an alternative treatment for ocular immunopathologies triggered by HSV-1, without the undesirable side effects of the currently used drugs.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Flavia M. Michelini, Carlos A. Bueno, Alejandro M. Molinari, Mario D. Galigniana, Lydia R. Galagovsky, Laura E. Alché, Javier A. Ramírez
Background We have previously shown that some synthetic hydroxylated stigmastanes derived from plant sterols inhibit in vitro HSV-1 replication in ocular cell lines and decrease cytokine production in stimulated macrophages, suggesting that these steroids might combine antiviral and immunomodulating properties. In this paper we report the synthesis of some analogs fluorinated at C-6 in order to study the effect of this modification on bioactivity. Methods The following methods were used: organic synthesis of fluorinated analogs, cytotoxicity determination with MTT assays, cytokine production quantification with ELISAs, glucocorticoid activity determination by displacement assays, immunofluorescence and transcriptional activity assays, studies of the activation of signaling pathways by Western blot, antiviral activity evaluation through virus yield reduction assays. Results We report the chemical synthesis of new fluorinated stigmastanes and show that this family of steroidal compounds exerts its immunomodulating activity by inhibiting ERK and Akt signaling pathways, but do not act as glucocorticoids. We also demonstrate that fluorination enhances the antiviral activity. Conclusions Fluorination on C-6 did not enhance the anti-inflammatory effect, however, an increase in the in vitro antiviral activity was observed. Thus, our results suggest that it is possible to introduce chemical modifications on the parent steroids in order to selectively modulate one of the effects. General significance This family of steroids could allow the development of an alternative treatment for ocular immunopathologies triggered by HSV-1, without the undesirable side effects of the currently used drugs.
Role of crystallins in diabetic complications
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Vadde Sudhakar Reddy, G. Bhanuprakash Reddy
Background Crystallins are the major structural proteins of vertebrate eye lens responsible for maintaining the refractive index of the lens. However, recent studies suggest that they also have a functional significance in non-lenticular tissues. Prolonged uncontrolled diabetes results in the development of macro and microvascular complications that are the leading causes of morbidity and mortality in diabetic patients all over the world. Scope of review Recent studies have shown that crystallins play an instrumental role in diabetes and its complications. Therefore, this review highlights the current data on the impact of chronic hyperglycemia on expression, distribution, glycation, phosphorylation, chaperone-like function and, anti-apoptotic activity of crystallins. Furthermore, we discussed the insights for developing therapeutic strategies for diabetic complications including natural agents, peptides, and pharmacological chaperones that modulate or mimic chaperone activity of α-crystallins. Major conclusions Upregulation of crystallins appears to be a common feature of chronic diabetes. Further, chronic hyperglycemia induces the glycation and phosphorylation of crystallins, mainly α-crystallins and thereby alters their properties. The disturbed interaction of αB-crystallin with various apoptotic mediators including Bax and caspases is also an important factor for increased cell death in diabetes. Numerous dietary agents, peptides, and chemical chaperones prevent apoptosis and the loss of chaperone activity in diabetes. General significance Understanding the role of crystallins will aid in developing therapeutic strategies for alleviating pathophysiological conditions such as protein aggregation, inflammation, oxidative stress and apoptosis associated with chronic complications of diabetes including cataract, retinopathy, and cardiomyopathy. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Vadde Sudhakar Reddy, G. Bhanuprakash Reddy
Background Crystallins are the major structural proteins of vertebrate eye lens responsible for maintaining the refractive index of the lens. However, recent studies suggest that they also have a functional significance in non-lenticular tissues. Prolonged uncontrolled diabetes results in the development of macro and microvascular complications that are the leading causes of morbidity and mortality in diabetic patients all over the world. Scope of review Recent studies have shown that crystallins play an instrumental role in diabetes and its complications. Therefore, this review highlights the current data on the impact of chronic hyperglycemia on expression, distribution, glycation, phosphorylation, chaperone-like function and, anti-apoptotic activity of crystallins. Furthermore, we discussed the insights for developing therapeutic strategies for diabetic complications including natural agents, peptides, and pharmacological chaperones that modulate or mimic chaperone activity of α-crystallins. Major conclusions Upregulation of crystallins appears to be a common feature of chronic diabetes. Further, chronic hyperglycemia induces the glycation and phosphorylation of crystallins, mainly α-crystallins and thereby alters their properties. The disturbed interaction of αB-crystallin with various apoptotic mediators including Bax and caspases is also an important factor for increased cell death in diabetes. Numerous dietary agents, peptides, and chemical chaperones prevent apoptosis and the loss of chaperone activity in diabetes. General significance Understanding the role of crystallins will aid in developing therapeutic strategies for alleviating pathophysiological conditions such as protein aggregation, inflammation, oxidative stress and apoptosis associated with chronic complications of diabetes including cataract, retinopathy, and cardiomyopathy. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Ab initio electron propagator calculations of transverse conduction through DNA nucleotide bases in 1-nm nanopore corroborate third generation sequencing
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Aleksey A. Kletsov, Evgeny G. Glukhovskoy, Aleksey S. Chumakov, Joseph V. Ortiz
Background The conduction properties of DNA molecule, particularly its transverse conductance (electron transfer through nucleotide bridges), represent a point of interest for DNA chemistry community, especially for DNA sequencing. However, there is no fully developed first-principles theory for molecular conductance and current that allows one to analyze the transverse flow of electrical charge through a nucleotide base. Methods We theoretically investigate the transverse electron transport through all four DNA nucleotide bases by implementing an unbiased ab initio theoretical approach, namely, the electron propagator theory. Results The electrical conductance and current through DNA nucleobases (guanine [G], cytosine [C], adenine [A] and thymine [T]) inserted into a model 1-nm Ag–Ag nanogap are calculated. The magnitudes of the calculated conductance and current are ordered in the following hierarchies: g A > g G > g C > g T and I G > I A > I T > I C correspondingly. The new distinguishing parameter for the nucleobase identification is proposed, namely, the onset bias magnitude. Nucleobases exhibit the following hierarchy with respect to this parameter: V onset (A)< V onset (T)< V onset (G)< V onset (C). Conclusions The difference in current magnitudes and onset voltages implies the possibility of nucleobases electrical identification by virtue of DNA translocation through an electrode-equipped nanopore. General significance The results represent interest for the theorists and practitioners in the field of third generation sequencing techniques as well as in the field of DNA chemistry.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part A
Author(s): Aleksey A. Kletsov, Evgeny G. Glukhovskoy, Aleksey S. Chumakov, Joseph V. Ortiz
Background The conduction properties of DNA molecule, particularly its transverse conductance (electron transfer through nucleotide bridges), represent a point of interest for DNA chemistry community, especially for DNA sequencing. However, there is no fully developed first-principles theory for molecular conductance and current that allows one to analyze the transverse flow of electrical charge through a nucleotide base. Methods We theoretically investigate the transverse electron transport through all four DNA nucleotide bases by implementing an unbiased ab initio theoretical approach, namely, the electron propagator theory. Results The electrical conductance and current through DNA nucleobases (guanine [G], cytosine [C], adenine [A] and thymine [T]) inserted into a model 1-nm Ag–Ag nanogap are calculated. The magnitudes of the calculated conductance and current are ordered in the following hierarchies: g A > g G > g C > g T and I G > I A > I T > I C correspondingly. The new distinguishing parameter for the nucleobase identification is proposed, namely, the onset bias magnitude. Nucleobases exhibit the following hierarchy with respect to this parameter: V onset (A)< V onset (T)< V onset (G)< V onset (C). Conclusions The difference in current magnitudes and onset voltages implies the possibility of nucleobases electrical identification by virtue of DNA translocation through an electrode-equipped nanopore. General significance The results represent interest for the theorists and practitioners in the field of third generation sequencing techniques as well as in the field of DNA chemistry.
Crystallins and neuroinflammation: The glial side of the story
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Jennifer E. Dulle, Patrice E. Fort
Background There is an abundance of evidence to support the association of damaging neuroinflammation and neurodegeneration across a multitude of diseases. One of the links between these pathological phenomena is the role of chaperone proteins as both neuroprotective and immune-regulatory agents. Scope of review Chaperone proteins are highly expressed at sites of neuroinflammation both in glial cells and in the injured neurons that initiate the immune response. For this reason, the use of chaperones as treatment for various diseases associated with neuroinflammation is a highly active area of investigation. This review explores the various ways that the small heat shock protein chaperones, α-crystallins, can affect glial cell function with a specific focus on their implication in the inflammatory response associated with neurodegenerative disorders, and their potential as therapeutic treatment. Major conclusions Although the mechanisms are still under investigation, a clear link has now been established between alpha-crystallins and neuroinflammation, especially through their roles in microglial and macroglial cells. Interestingly, similar to inflammation in itself, crystallins can have a beneficial or detrimental impact on the CNS based on the context and duration of the condition. General significance Overall this review points out the novel roles that chaperones such as alpha-crystallins can play outside of the classical protein folding pathways, and their potential in the development of new therapies for the treatment of neuroinflammatory/neurodegenerative diseases. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Jennifer E. Dulle, Patrice E. Fort
Background There is an abundance of evidence to support the association of damaging neuroinflammation and neurodegeneration across a multitude of diseases. One of the links between these pathological phenomena is the role of chaperone proteins as both neuroprotective and immune-regulatory agents. Scope of review Chaperone proteins are highly expressed at sites of neuroinflammation both in glial cells and in the injured neurons that initiate the immune response. For this reason, the use of chaperones as treatment for various diseases associated with neuroinflammation is a highly active area of investigation. This review explores the various ways that the small heat shock protein chaperones, α-crystallins, can affect glial cell function with a specific focus on their implication in the inflammatory response associated with neurodegenerative disorders, and their potential as therapeutic treatment. Major conclusions Although the mechanisms are still under investigation, a clear link has now been established between alpha-crystallins and neuroinflammation, especially through their roles in microglial and macroglial cells. Interestingly, similar to inflammation in itself, crystallins can have a beneficial or detrimental impact on the CNS based on the context and duration of the condition. General significance Overall this review points out the novel roles that chaperones such as alpha-crystallins can play outside of the classical protein folding pathways, and their potential in the development of new therapies for the treatment of neuroinflammatory/neurodegenerative diseases. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
βA3/A1-crystallin and persistent fetal vasculature (PFV) disease of the eye
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): J. Samuel Zigler, Mallika Valapala, Peng Shang, Stacey Hose, Morton F. Goldberg, Debasish Sinha
Background Persistent fetal vasculature (PFV) is a human disease in which the fetal vasculature of the eye fails to regress normally. The fetal, or hyaloid, vasculature nourishes the lens and retina during ocular development, subsequently regressing after formation of the retinal vessels. PFV causes serious congenital pathologies and is responsible for as much as 5% of blindness in the United States. Scope of review The causes of PFV are poorly understood, however there are a number of animal models in which aspects of the disease are present. One such model results from mutation or elimination of the gene (Cryba1) encoding βA3/A1-crystallin. In this review we focus on the possible mechanisms whereby loss of functional βA3/A1-crystallin might lead to PFV. Major conclusions Cryba1 is abundantly expressed in the lens, but is also expressed in certain other ocular cells, including astrocytes. In animal models lacking βA3/A1-crystallin, astrocyte numbers are increased and they migrate abnormally from the retina to ensheath the persistent hyaloid artery. Evidence is presented that the absence of functional βA3/A1-crystallin causes failure of the normal acidification of endolysosomal compartments in the astrocytes, leading to impairment of certain critical signaling pathways, including mTOR and Notch/STAT3. General significance The findings suggest that impaired endolysosomal signaling in ocular astrocytes can cause PFV disease, by adversely affecting the vascular remodeling processes essential to ocular development, including regression of the fetal vasculature. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): J. Samuel Zigler, Mallika Valapala, Peng Shang, Stacey Hose, Morton F. Goldberg, Debasish Sinha
Background Persistent fetal vasculature (PFV) is a human disease in which the fetal vasculature of the eye fails to regress normally. The fetal, or hyaloid, vasculature nourishes the lens and retina during ocular development, subsequently regressing after formation of the retinal vessels. PFV causes serious congenital pathologies and is responsible for as much as 5% of blindness in the United States. Scope of review The causes of PFV are poorly understood, however there are a number of animal models in which aspects of the disease are present. One such model results from mutation or elimination of the gene (Cryba1) encoding βA3/A1-crystallin. In this review we focus on the possible mechanisms whereby loss of functional βA3/A1-crystallin might lead to PFV. Major conclusions Cryba1 is abundantly expressed in the lens, but is also expressed in certain other ocular cells, including astrocytes. In animal models lacking βA3/A1-crystallin, astrocyte numbers are increased and they migrate abnormally from the retina to ensheath the persistent hyaloid artery. Evidence is presented that the absence of functional βA3/A1-crystallin causes failure of the normal acidification of endolysosomal compartments in the astrocytes, leading to impairment of certain critical signaling pathways, including mTOR and Notch/STAT3. General significance The findings suggest that impaired endolysosomal signaling in ocular astrocytes can cause PFV disease, by adversely affecting the vascular remodeling processes essential to ocular development, including regression of the fetal vasculature. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Ca2+ and βγ-crystallins: An affair that did not last?
Publication date: January 2016
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Amita Mishra, Bal Krishnan, Rajeev Raman, Yogendra Sharma
Background During the last three decades, lens β- and γ-crystallins have found a huge number of kin from numerous taxonomical sources. Most of these proteins from invertebrates and microbes have been demonstrated or predicted to bind Ca2+ involving a distinct double-clamp motif, which is largely degenerated in lens homologues. Scope of review The various aspects of transformation of βγ-crystallins from a quintessential Ca2+-binding protein into a primarily structural molecule have been reviewed. Major conclusions In lens members of βγ-crystallins, the residues involved in Ca2+ binding have diverged considerably from the classical consensus with consequent reduction in their Ca2+-binding properties. This evolutionary change is congenial to their new role as robust constituents of lens. The exact functions of the residual affinity for Ca2+ are yet to be established. General significance This review highlights the significance of reduction in Ca2+-binding ability of the βγ-crystallins for lens physiology and why this residual affinity may be functionally important. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Source:Biochimica et Biophysica Acta (BBA) - General Subjects, Volume 1860, Issue 1, Part B
Author(s): Amita Mishra, Bal Krishnan, Rajeev Raman, Yogendra Sharma
Background During the last three decades, lens β- and γ-crystallins have found a huge number of kin from numerous taxonomical sources. Most of these proteins from invertebrates and microbes have been demonstrated or predicted to bind Ca2+ involving a distinct double-clamp motif, which is largely degenerated in lens homologues. Scope of review The various aspects of transformation of βγ-crystallins from a quintessential Ca2+-binding protein into a primarily structural molecule have been reviewed. Major conclusions In lens members of βγ-crystallins, the residues involved in Ca2+ binding have diverged considerably from the classical consensus with consequent reduction in their Ca2+-binding properties. This evolutionary change is congenial to their new role as robust constituents of lens. The exact functions of the residual affinity for Ca2+ are yet to be established. General significance This review highlights the significance of reduction in Ca2+-binding ability of the βγ-crystallins for lens physiology and why this residual affinity may be functionally important. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.