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Virtual screening based on pharmacophoric features of known calpain inhibitors to identify potent inhibitors of calpain. Med Chem Res 2013. [DOI: 10.1007/s00044-013-0842-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ma H, Nakajima E, Shih M, Azuma M, Shearer TR. Expression of calpain small subunit 2 in mammalian tissues. Curr Eye Res 2009; 29:337-47. [PMID: 15590481 DOI: 10.1080/02713680490516242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE The purpose of the current experiments was to more closely define the distribution and the function of calpain small subunit 2 (css2). Css2 is a newly discovered regulatory protein for the calcium activated proteases, mu- and m-calpains. METHODS Tissues from rat, monkey, and man of various ages were used to determine expression patterns of css2 by relative quantitative RT-PCR using 18S rRNA as an endogenous standard. Recombinant css2 and the 80 kDa catalytic subunit of m-calpain (80 kDa/css2) were co-expressed in Escherichia coli. Casein zymography was used to measure the enzymatic activity of 80 kDa/css2 proteins. Lens alpha-crystallin and beta B1-crystallin were used as substrates to determine proteolysis by 80 kDa/css2. Computer-based homology modeling was used to predict interactions between the traditional small subunit (css1) or css2 with the 80 kDa catalytic subunit. RESULTS Css2 appears to be a functional equivalent of css1 in vitro in that the calcium-dependent proteolytic activity of 80 kDa/css2 was similar to recombinant m-calpain (80 kDa/css1). In rat and human lens, css2 transcripts increased with age, whereas css1 transcripts decreased with age. Human beta B1-crystallin and rat alpha A-crystallin were cleaved similarly by 80 kDa/css2 and 80 kDa/css1. Interestingly, alpha A-insert crystallin was not hydrolyzed when css2 was substituted for css1 in the calpain dimer, suggesting that css2 may perform different functions from css1 in terms of proteolysis of lens crystallins during maturational growth of the lens. Css2 may also assist in the proper folding of the 80 kDa subunit and regulate protease activity in the absence of calcium. CONCLUSIONS The wide distribution of css2 transcripts in rat and monkey suggested that css2 is a second, widely distributed (rather than tissue-specific) calpain small subunit, in addition to the long-recognized css1. Further studies at the protein level will indicate if css2 has unique functions apart from css1.
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Affiliation(s)
- H Ma
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon 97239, USA.
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Akiyama N, Umeda IO, Sogo S, Nishigori H, Tsujimoto M, Natori S. 5-S-GAD, a novel radical scavenging compound, prevents lens opacity development. Free Radic Biol Med 2009; 46:511-9. [PMID: 19084592 DOI: 10.1016/j.freeradbiomed.2008.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 11/11/2008] [Accepted: 11/12/2008] [Indexed: 11/22/2022]
Abstract
The ability of N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD)-a novel catechol derivative isolated from an insect as an antibacterial substance-to scavenge free radicals and prevent cataract progression was examined. 5-S-GAD scavenged 1,1-diphenylpicrylhydrazyl (DPPH) and superoxide anions (O(2)(*)(-)), and inhibited lipid peroxidation. It also significantly inhibited the onset of glucocorticoid-induced lens opacification in chick embryos. These effects of 5-S-GAD were stronger than those of N-acetylcarnosine and TEMPOL, which are reported to be effective radical scavengers in the prevention of cataract progression. 5-S-GAD clearly delayed the maturation of cataracts induced by diamide in cultured lenses of rats. Daily instillation of 5-S-GAD retarded the development of lens opacity in galactose-fed rats. Biochemical analysis of the lenses revealed that 20-kDa proteins, presumably consisting of alpha-crystallin, were the most susceptible to oxidative stress, which leads to the carbonylation of the side chains of these proteins. alpha-Crystallin carbonylation induced by diamide or galactose was notably inhibited by 5-S-GAD in a dose-dependent manner. Our results show that 5-S-GAD prevents acute lens opacification in these short-term experimental models, possibly in part by virtue of its antioxidative property, and 5-S-GAD is expected to have long-term pharmaceutical effects.
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Covington MD, Arrington DD, Schnellmann RG. Calpain 10 is required for cell viability and is decreased in the aging kidney. Am J Physiol Renal Physiol 2009; 296:F478-86. [PMID: 19144693 DOI: 10.1152/ajprenal.90477.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aging is associated with abnormalities in kidney function, but the exact mechanisms are unknown. We examined calpains 1, 2, and 10 protein levels in kidneys from rats, mice, and humans of various ages and determined whether calpain 10 is required for cell viability. Calpain 10 protein expression decreased in the kidney, but not in the liver, of aging Fischer 344 rats, and this decrease was attenuated with caloric restriction. There was no change in calpains 1 or 2 levels in the kidney or liver in control and caloric-restricted aging rats. Aging mice also exhibited decreased calpain 10 protein levels. Calpain 10 protein and mRNA levels decreased linearly in human kidney samples with age in the absence of changes in calpains 1 or 2. Our laboratory previously found calpain 10 to be expressed in both the cytosol and mitochondria of rabbit renal proximal tubular cells (RPTC). Adenoviral-delivered shRNA to rabbit RPTC decreased mitochondrial calpain 10 expression below detectable levels by 3 days while cytosolic calpain 10 levels remained unchanged at 3 days and decreased to approximately 20% of control by 5 days. Knockdown of mitochondrial calpain 10 resulted in nuclear condensation and cleaved procaspase 3, markers of apoptosis. In summary, mitochondrial calpain 10 is required for cell viability and calpain 10 levels specifically decrease in aging rat, mice, and human kidney tissues when renal function decreases, suggesting that calpain 10 is required for renal function and is a biomarker of the aging kidney.
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Affiliation(s)
- Marisa D Covington
- Department of Pharmaceutical and Biomedical Sciences, Center for Cell Death, Injury, and Regeneration, South Carolina College of Pharmacy, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Zhang X, Dudek EJ, Liu B, Ding L, Fernandes AF, Liang JJ, Horwitz J, Taylor A, Shang F. Degradation of C-terminal truncated alpha A-crystallins by the ubiquitin-proteasome pathway. Invest Ophthalmol Vis Sci 2007; 48:4200-8. [PMID: 17724207 PMCID: PMC2098745 DOI: 10.1167/iovs.07-0196] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Calpain-mediated C-terminal cleavage of alpha A-crystallins occurs during aging and cataractogenesis. The objective of the present study was to explore the role of the ubiquitin-proteasome pathway (UPP) in degrading C-terminal truncated alpha A-crystallins. METHODS Recombinant wild-type (wt) alpha A-crystallin and C-terminal truncated alpha A(1-168)-, alpha A(1-163)-, and alpha A(1-162)-crystallins were expressed in Escherichia coli and purified to homogeneity. The wt and truncated alpha A-crystallins were labeled with (125)I, and proteolytic degradation was determined using both lens fiber lysate and reticulocyte lysate as sources of ubiquitinating and proteolytic enzymes. Far UV circular dichroism, tryptophan fluorescence intensity, and binding to the hydrophobic fluorescence probe Bis-ANS were used to characterize the wt and truncated alpha A-crystallins. Oligomer sizes of these crystallins were determined by multiangle light-scattering. RESULTS Whereas wt alpha A-crystallin was degraded moderately in both lens fiber and reticulocyte lysates, alpha A(1-168)-crystallin was resistant to degradation. The susceptibility of alpha A(1-163)-crystallin to degradation was comparable to that of wt alpha A-crystallin. However, alpha A(1-162)-crystallin was much more susceptible than wt alpha A-crystallin to degradation in both lens fiber and reticulocyte lysates. The degradation of both wt and C-terminal truncated alpha A(1-162)-crystallins requires adenosine triphosphate (ATP) and was stimulated by addition of a ubiquitin-conjugating enzyme, Ubc4. The degradation was substantially inhibited by the proteasome inhibitor MG132 and a dominant negative mutant of ubiquitin, K6W-Ub, indicating that at least part of the proteolysis was mediated by the UPP. Spectroscopic analyses of wt and C-terminal truncated alpha A-crystallins revealed that C-terminal truncation of alpha A-crystallin resulted in only subtle changes in secondary structures. However, C-terminal truncations resulted in significant changes in surface hydrophobicity and thermal stability. Thus, these conformational changes may reveal or mask the signals for the ubiquitin-dependent degradation. CONCLUSIONS The present data demonstrate that C-terminal cleavage of alpha A-crystallin not only alters its conformation and thermal stability, but also its susceptibility to degradation by the UPP. The rapid degradation of alpha A(1-162) by the UPP may prevent its accumulation in the lens.
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Affiliation(s)
- Xinyu Zhang
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Edward J. Dudek
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Bingfen Liu
- Center for Ophthalmic Research, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Linlin Ding
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California
| | - Alexandre F. Fernandes
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Jack J. Liang
- Center for Ophthalmic Research, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Joseph Horwitz
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California
| | - Allen Taylor
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Fu Shang
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
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6
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Costelli P, Reffo P, Penna F, Autelli R, Bonelli G, Baccino FM. Ca(2+)-dependent proteolysis in muscle wasting. Int J Biochem Cell Biol 2005; 37:2134-46. [PMID: 15893952 DOI: 10.1016/j.biocel.2005.03.010] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 02/24/2005] [Accepted: 03/11/2005] [Indexed: 11/25/2022]
Abstract
Skeletal muscle wasting is a prominent feature of cachexia, a complex systemic syndrome that frequently complicates chronic diseases such as inflammatory and autoimmune disorders, cancer and AIDS. Muscle wasting may also develop as a manifestation of primary or neurogenic muscular disorders. It is now generally accepted that muscle depletion mainly arises from increased protein catabolism. The ubiquitin-proteasome system is believed to be the major proteolytic machinery in charge of such protein breakdown, yet there is evidence suggesting that Ca(2+)-dependent system, lysosomes and, in some conditions at least, even caspases are involved as well. The role of Ca(2+)-dependent proteolysis in skeletal muscle wasting is reviewed in the present paper. This system relies on the activity of calpains, a family of Ca(2+)-dependent cysteine proteases, whose regulation is complex and not completely elucidated. Modulations of Ca(2+)-dependent proteolysis have been associated with muscle protein depletion in various pathological contexts and particularly with muscle dystrophies. Calpains can only perform a limited proteolysis of their substrates, however they may play a critical role in initiating the breakdown of myofibrillar protein, by releasing molecules that become suitable for further degradation by proteasomes. Some evidence would also support a role for lysosomes and caspases in muscle wasting. Thus it cannot be excluded that different intracellular proteolytic systems may coordinately concur in shifting muscle protein turnover towards excess catabolism. Many different signals have been proposed as potentially involved in triggering the enhanced protein breakdown that underlies muscle wasting. How they are transduced to initiate the hypercatabolic response and to activate the proteolytic pathways remains largely unknown, however.
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Affiliation(s)
- Paola Costelli
- Dipartimento di Medicina e Oncologia Sperimentale, Università di Torino, Corso Raffaello 30, 10125 Torino, Italy.
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Abstract
Calpains are a family of calcium-dependent cysteine proteases under complex cellular regulation. By making selective limited proteolytic cleavages, they modulate the activity of enzymes, including key signaling molecules, and induce specific cytoskeletal rearrangements, accounting for their roles in cell motility, signal transduction, vesicular trafficking and structural stabilization. Calpain activation has been implicated in various aging phenomena and diseases of late life, including cataract formation, erythrocyte senescence, diabetes mellitus type 2, hypertension, arthritis, and neurodegenerative disorders. The early and pervasive involvement of calpains in Alzheimer's disease potentially influences the development of beta-amyloid and tau disturbances and their consequences for neurodegeneration and neuronal cell loss.
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Affiliation(s)
- Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA.
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Hosler MR, Wang-Su ST, Wagner BJ. Targeted disruption of specific steps of the ubiquitin-proteasome pathway by oxidation in lens epithelial cells. Int J Biochem Cell Biol 2003; 35:685-97. [PMID: 12672460 DOI: 10.1016/s1357-2725(02)00397-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several steps in the ubiquitin-proteasome pathway have been shown to be inhibited in models of oxidative stress and aging. We have designed similar models of aging and oxidation in the HLE B-3 human lens epithelial cell line. Following hydrogen peroxide (H2O2) treatment, B-3 cells exhibited an expected activation of c-fos. The effect of these same and similar treatments on the lens proteasome system was unexpected. The 2D gel pattern and the chymotrypsin-like activity of the 20S core were unaffected by this H2O2 treatment, contrary to previous experience in other culture systems. The critical role of proteolysis in the aging lens, and the strong tie between oxidation and proteasome changes, urged us to further model lens oxidation and investigate several steps of the ubiquitin-proteasome pathway with an alternative agent: the thiol-specific oxidant, diamide. The 20S core proteasome, de-ubiquitinating, and ATP-dependent 26S proteasome activities all showed decreases 10 min after diamide was applied, and recovered to near normal within 1h. The higher, 300 microM dose inhibited the 20S by 43%, the de-ubiquitinating activity by 17% and the 26S by 31%. The comparable susceptibility of the 20S activity and the 26S activity differs from several previously published models. Such differences may be the result of tissue or cell line-specific variants in either the components of the ubiquitin-proteasome pathway or in their modification by intracellular oxidants or reductants.
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Affiliation(s)
- Mathew R Hosler
- Department of Biochemistry and Molecular Biology, 185 South Orange Avenue, Newark, NJ 07101, USA
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Ueda Y, Fukiage C, Shih M, Shearer TR, David LL. Mass measurements of C-terminally truncated alpha-crystallins from two-dimensional gels identify Lp82 as a major endopeptidase in rat lens. Mol Cell Proteomics 2002; 1:357-65. [PMID: 12118077 DOI: 10.1074/mcp.m200007-mcp200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular chaperone activity of lens alpha-crystallins is reduced by loss of the C terminus. The purpose of this experiment was to 1) determine the cleavage sites produced in vitro by ubiquitous m-calpain and lens-specific Lp82 on alpha-crystallins, 2) identify alpha-crystallin cleavage sites produced in vivo during maturation and cataract formation in rat lens, and 3) estimate the relative activities of Lp82 and m-calpain by appearance of protease-specific cleavage products in vivo. Total soluble protein from young rat lens was incubated with recombinant m-calpain or Lp82 and 2 mM Ca2+. Resulting fragmented alpha-crystallins were separated by two-dimensional gel electrophoresis. Eluted alpha-crystallin spots were analyzed by mass spectrometry. Cleavage sites on insoluble alpha-crystallins were determined similarly in mature rat lens nucleus and in cataractous rat lens nucleus induced by selenite. In vitro proteolysis of alphaA-crystallin by Lp82 and m-calpain produced unique cleavage sites by removing 5 and 11 residues, respectively, from the C terminus. In vivo, the protease-specific truncations removing 5 and 11 residues from alphaA were both found in maturing lens, whereas only the truncation removing 5 residues was found in cataractous lens. Other truncation sites, common to both calpain isoforms, resulted from the removal of 8, 10, 16, 17, and 22 residues from the C terminus of alphaA. Using uniquely truncated alphaA-crystallins as in vivo markers, Lp82 and m-calpain were both found to be active during normal maturation of rat lens, whereas Lp82 seemed especially active during selenite cataract formation. These C-terminal truncations decrease chaperone activity of alpha-crystallins, possibly leading to the observed increases in insoluble proteins during aging and cataract. The methodology that allowed accurate mass measurements of proteins eluted from 2D gels should be useful to examine rapidly other post-translational modifications.
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Affiliation(s)
- Yoji Ueda
- Department of Oral Molecular Biology and Casey Eye Institute, Oregon Health and Science University, Portland, Oregon 97201, USA
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10
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Malina H, Richter C, Frueh B, Hess OM. Lens epithelial cell apoptosis and intracellular Ca2+ increase in the presence of xanthurenic acid. BMC Ophthalmol 2002; 2:1. [PMID: 11934353 PMCID: PMC103667 DOI: 10.1186/1471-2415-2-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2001] [Accepted: 04/05/2002] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Xanthurenic acid is an endogenous product of tryptophan degradation by indoleamine 2,3-dioxygenase (IDO). We have previously reported that IDO is present in mammalian lenses, and xanthurenic acid is accumulated in the lenses with aging. Here, we studied the involvement of xanthurenic acid in the human lens epithelial cell physiology. METHODS Human lens epithelial cells primary cultures were used. Control cells, and cells in the presence of xanthurenic acid grow in the dark. Western blot analysis and immunofluorescence studies were performed. RESULTS In the presence of xanthurenic acid human lens epithelial cells undergo apoptosis-like cell death. In the control cells gelsolin stained the perinuclear region, whereas in the presence of 10 microM xanthurenic acid gelsolin is translocated to the cytoskeleton, but does not lead to cytoskeleton breakdown. In the same condition caspase-3 activation, and DNA fragmentation was observed. At low (5 to 10 microM) of xanthurenic acid concentration, the elongation of the cytoskeleton was associated with migration of mitochondria and cytochrome c release. At higher concentrations xanthurenic acid (20 microM and 40 microM) damaged mitochondria were observed in the perinuclear region, and nuclear DNA cleavage was observed. We observed an induction of calpain Lp 82 and an increase of free Ca2+ in the cells in a xanthurenic acid concentration-dependent manner. CONCLUSIONS The results show that xanthurenic acid accumulation in human lens epithelial cells disturbs the normal cell physiology and leads to a cascade of pathological events. Xanthurenic acid induces calpain Lp82 and caspases in the cells growing in the dark and can be involved in senile cataract development.
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Affiliation(s)
- Halina Malina
- Swiss Cardiovascular Research Center, Inselspital, CH-3010 Bern, Switzerland
- Institute of Biochemistry, Swiss Federal Institute of Technology (ETH), Universitaetstrasse 16, CH-8092 Zuerich, Switzerland
| | - Christoph Richter
- Institute of Biochemistry, Swiss Federal Institute of Technology (ETH), Universitaetstrasse 16, CH-8092 Zuerich, Switzerland
| | - Beatrice Frueh
- Department of Ophthalmology, Inselspital, CH-3010 Bern, Switzerland
| | - Otto M Hess
- Swiss Cardiovascular Research Center, Inselspital, CH-3010 Bern, Switzerland
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Carragher NO, Westhoff MA, Riley D, Potter DA, Dutt P, Elce JS, Greer PA, Frame MC. v-Src-induced modulation of the calpain-calpastatin proteolytic system regulates transformation. Mol Cell Biol 2002; 22:257-69. [PMID: 11739739 PMCID: PMC134206 DOI: 10.1128/mcb.22.1.257-269.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
v-Src-induced oncogenic transformation is characterized by alterations in cell morphology, adhesion, motility, survival, and proliferation. To further elucidate some of the signaling pathways downstream of v-Src that are responsible for the transformed cell phenotype, we have investigated the role that the calpain-calpastatin proteolytic system plays during oncogenic transformation induced by v-Src. We recently reported that v-Src-induced transformation of chicken embryo fibroblasts is accompanied by calpain-mediated proteolytic cleavage of the focal adhesion kinase (FAK) and disassembly of the focal adhesion complex. In this study we have characterized a positive feedback loop whereby activation of v-Src increases protein synthesis of calpain II, resulting in degradation of its endogenous inhibitor calpastatin. Reconstitution of calpastatin levels by overexpression of exogenous calpastatin suppresses proteolytic cleavage of FAK, morphological transformation, and anchorage-independent growth. Furthermore, calpastatin overexpression represses progression of v-Src-transformed cells through the G(1) stage of the cell cycle, which correlates with decreased pRb phosphorylation and decreased levels of cyclins A and D and cyclin-dependent kinase 2. Calpain 4 knockout fibroblasts also exhibit impaired v-Src-induced morphological transformation and anchorage-independent growth. Thus, modulation of the calpain-calpastatin proteolytic system plays an important role in focal adhesion disassembly, morphological transformation, and cell cycle progression during v-Src-induced cell transformation.
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Affiliation(s)
- N O Carragher
- The Beatson Institute for Cancer Research, Cancer Research Campaign Beatson Laboratories, Glasgow, Scotland, United Kingdom.
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12
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Nakamura Y, Fukiage C, Azuma M, Shearer TR. Calpain-induced light scattering in young rat lenses is enhanced by UV-B. J Ocul Pharmacol Ther 2001; 17:47-58. [PMID: 11322637 DOI: 10.1089/108076801750125676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The purpose of this study is to determine if UV-B enhances light scattering after proteolysis of crystallins by calpains, and to determine if lens-specific calpain Lp82 is involved, along with m-calpain, in the mechanism of in vitro precipitation. Lens soluble proteins from young rats were hydrolyzed for 24 hr by endogenous lens calpains, and the proteins were further incubated for up to 7 days with periodic irradiation by UV-B. Light scattering was measured daily at 405 nm. SDS-PAGE and immunoblotting assessed proteolysis of crystallins, activation of calpains, and formation of high molecular weight aggregations. Appreciable light scattering occurred in lens soluble proteins after proteolysis of crystallins by m-calpain and Lp82. UV-B markedly enhanced this light scattering and the formation of higher molecular weight aggregates consisting of proteolyzed alpha- and beta- and intact gamma-crystallins. Calpain inhibitor E64 and antioxidants DTE or GSH prevented the light scattering. These results show that calpain-induced light scattering is enhanced by the natural oxidant UV-B. Activation of Lp82, along with m-calpain, contributed to the light scattering. The linkage between proteolysis and oxidation is important because both oxidation and truncation of crystallins are found in aged human lenses, which are constantly exposed to UV irradiation.
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Affiliation(s)
- Y Nakamura
- Research Laboratory, Senju Pharmaceutical Corp., Ltd., Kobe, Japan
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13
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Ito Y, Cai H, Terao M, Tomohiro M. Preventive effect of diethyldithiocarbamate on selenite-induced opacity in cultured rat lenses. Ophthalmic Res 2001; 33:52-9. [PMID: 11114606 DOI: 10.1159/000055642] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Increasing evidence suggests the involvement of reactive oxygen species in the development of cataracts. In this study, we investigated the preventive effect of diethyldithiocarbamate (DDC) on the selenite-induced opacification of cultured rat lenses. Lens opacity was produced by incubation with 0.2 mM selenite for 24 h, which resulted in an increase in selenium content in the cultured lenses. The increase in selenium content and the onset of opacification and lens membrane damage were inhibited by preincubation with DDC. It is reasonable to assume that DDC contributed to anticataract ability. In addition, selenite resulted in a significant decrease in glutathione and protein thiol content and an increase in lipid peroxidation levels in the lenses. These alterations were also depressed by DDC, suggesting a contribution of an antioxidative effect by DDC in the inhibition of lens opacification. At the same lens selenium content, DDC treatment inhibited opacification and lipid peroxide. In conclusion, we propose that the antioxidative properties of DDC play a major role in its contribution to the anticataract effect.
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Affiliation(s)
- Y Ito
- School of Pharmacy, Kinki University, Higashi-Osaka, Japan.
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14
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Andersson M, Sjöstrand J, Petersen A, Karlsson JO. Calcium-dependent proteolysis in rabbit lens epithelium after oxidative stress. Ophthalmic Res 2000; 30:157-67. [PMID: 9618719 DOI: 10.1159/000055469] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to examine changes in calcium-dependent proteolytic activity in the lens epithelium from whole rabbit lenses exposed to long-term oxidative stress at near physiological levels. Rabbit lenses, incubated in 50 microM H2O2 for 1 or 24 h, were checked for clarity and morphological changes in the epithelium. Proteolytic activity was measured in the epithelium using a fluorogenic synthetic substrate; N-succinyl-Leu-Tyr-7-amino-4-methylocoumarin, both in the presence and the absence of calcium (1 mM Ca2+ and 5 mM EDTA respectively). The effect on transparency and morphology of the epithelium following a 1-hour incubation in 100 microM H2O2 was also studied. Lenses incubated in 50 microM H2O2 were clear even after 24h. After a 1-hour incubation in 50 microM H2O2 the epithelium of the exposed lens appeared normal. However, after 24 h the epithelium cells appeared swollen and microscopical examination showed extensive intracellular and subepithelial vacuolization. Incubation in 100 microM H2O2 for 1 h caused loss of transparency; vacuole formation, globulization of the superficial lens fibers and death of the epithelial cells. There was a 55% increase in calcium-dependent proteolytic activity after 1 h in 50 microM H2O2, implying a role for the calcium-activated protease calpain in oxidatively induced cataract.
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Affiliation(s)
- M Andersson
- Department of Histology, University of Göteborg, Sweden.
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15
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Nakamura Y, Fukiage C, Azuma M, Shearer TR. Oxidation enhances calpain-induced turbidity in young rat lenses. Curr Eye Res 1999; 19:33-40. [PMID: 10415455 DOI: 10.1076/ceyr.19.1.33.5335] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE To determine if oxidation enhances turbidity after proteolysis of rat lens crystallins by the calcium-activated protease calpain (EC 3.4.22.17). METHODS Total soluble proteins from young rat lens were hydrolyzed for 24 hr by endogenous lens calpain, and the proteins were further incubated with the oxidant diamide for up to 7 days. Turbidity was measured daily at 405 nm. To measure proteolysis and turbidity in cultured lenses, rat lenses were cultured for 6 days in low calcium medium and diamide. The lenses were then photographed to assess transmission of light. SDS-PAGE and immunoblotting assessed proteolysis of crystallins, alpha-spectrin, and activation of calpain. RESULTS Appreciable in vitro turbidity occurred in soluble proteins from young rat lenses after proteolysis of crystallins by endogenous calpain. Calpain inhibitor E64, or anti-oxidants DTE and GSH, inhibited this turbidity. On the other hand, the oxidant diamide markedly enhanced calpain-induced turbidity. Cultured rat lenses showed elevated intralenticular calcium and proteolysis of crystallins by calpain, but no nuclear cataract. Addition of diamide to the culture medium caused development of nuclear cataract. CONCLUSIONS Diamide enhanced turbidity only when crystallins were proteolyzed. Oxidation may be one of the factors promoting light scatter and insolubilization after proteolysis. These data are consistent with the hypothesis that proteolysis of crystallins from young rat lens may expose cysteine residues, which are then oxidized, become insoluble and scatter light.
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Affiliation(s)
- Y Nakamura
- Research Laboratories, Senju Pharmaceutical Corporation Limited, Kobe, Japan
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Inomata M, Nomura K, Takehana M, Saido TC, Kawashima S, Shumiya S. Evidence for the involvement of calpain in cataractogenesis in Shumiya cataract rat (SCR). BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1362:11-23. [PMID: 9434095 DOI: 10.1016/s0925-4439(97)00050-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Shumiya cataract rat (SCR) is a hereditary cataract model in which lens opacity appears spontaneously in the nuclear and perinuclear portions at 11-12 weeks of age. It was found that the proteolysis of some crystallins and cytoskeletal proteins is significantly enhanced in cataractous SCR lenses. The calcium concentrations in cataractous lenses rise markedly with age as compared with control lenses and the autolytic product of calpain is also detected in cataractous lenses. In order to provide direct evidence for the involvement of calpain in the proteolytic modification of lens proteins, we developed antibodies exclusively specific to the proteolytic products of some lens proteins produced by the action of calpain and analyzed their degradation during cataractogenesis in SCR by Western blotting and immunohistochemical staining. The results demonstrate that calpain participates in the proteolytic modification of lens proteins, at least alpha-crystallin (A and B chain), betaB1-crystallin, and alpha-fodrin. The proteolytic products formed by the action of calpain on these proteins are detected in cataractous lenses of SCR as young as 8 weeks of age and accumulate with age. It was also found that betaB1-crystallin, originally a soluble protein, is converted to an insoluble form by limited calpain proteolysis. The chaperon-like activity of alpha-crystallin from control lens is markedly reduced by calpain proteolysis in vitro, and alpha-crystallin in opaque lens that has already undergone proteolysis by calpain shows significantly reduced chaperon-like activity. Immunohistochemical studies reveal that the area where the calpain-mediated alpha-crystallin proteolysis is in progress coincides well with the area developing and destined to develop the opacification. These results strongly suggest that calpain may contribute to lens opacification during cataract formation in SCR.
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Affiliation(s)
- M Inomata
- Department of Enzyme Biochemistry, Tokyo Metropolitan Institute of Gerontology, Japan.
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17
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Abstract
Calpains are a family of calcium-dependent thiol-proteases which are proposed to be involved in many physiological processes as well as pathological conditions. Calpains are likely to be involved in processing of numerous enzymes and cytoskeletal components, thereby linking their activity to a variety of intracellular events. Although widely studied, the precise mechanism(s) involved in calpain activation and activity in vivo remain poorly understood. Initial studies suggested that calpain exists primarily as an inactive proenzyme that required autolytic cleavage for activation. It was also hypothesized that calpain associated with membrane phospholipids, serving to increase calcium sensitivity, facilitating autolytic conversion and thus activating the enzyme. These hypotheses, however, have not been universally accepted and there is increasing evidence that intact, non-autolyzed calpain is the physiologically active calpain form.
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Affiliation(s)
- G V Johnson
- Department of Psychiatry, University of Alabama at Birmingham, USA.
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18
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Taylor A, Shang F, Obin M. Relationships between stress, protein damage, nutrition, and age-related eye diseases. Mol Aspects Med 1997; 18:305-414. [PMID: 9578986 DOI: 10.1016/s0098-2997(95)00049-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- A Taylor
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
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19
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Walsh Clang CM, Aleo MD. Mechanistic analysis of S-(1,2-dichlorovinyl)-L-cysteine-induced cataractogenesis in vitro. Toxicol Appl Pharmacol 1997; 146:144-55. [PMID: 9299606 DOI: 10.1006/taap.1997.8236] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chronic exposure to low concentrations of the nephrotoxic cysteine conjugate S-(1,2-dichlorovinyl)-l-cysteine (DCVC) causes cataracts in mice. This study explored mechanisms of DCVC-induced cataractogenesis using explanted lenses from male Sprague-Dawley rats. Lenses placed in organ culture were exposed to 2.5 microM-1 mM DCVC for 24 hr. DCVC caused concentration and time-dependent changes in biochemical markers of toxicity (lenticular adenosine 5'-triphosphate (ATP) content, mitochondrial reduction of the tetrazolium dye MTT, and glutathione (GSH) content) at concentrations >/=25 microM. Lens clarity was adversely affected at concentrations >/=50 microM. Within 24 hr, 1 mM DCVC altered lens ATP content (-77 +/- 2%), mitochondrial MTT reduction (-40 +/- 3%), and GSH content (-19 +/- 4%) (percent difference from controls, p < 0.05). ATP was the most sensitive index of DCVC exposure in this model, while lens weight was not altered. The role of lenticular DCVC metabolism was investigated using the beta-lyase inhibitor aminooxyacetic acid (AOA) and the flavin monooxygenase (FMO) inhibitor methimazole (MAZ). AOA (1 mM) provided nearly complete protection from changes in biochemical parameters and lens transparency caused by DCVC, while MAZ (1 mM) provided only partial protection. The mitochondrial Ca2+ uniport inhibitor ruthenium red (30 microM) and the poly(ADP ribosyl)transferase inhibitor 3-aminobenzamide (3 mM) were only partially protective, whereas adverse changes in lens transparency and biochemical markers were not prevented by an antioxidant (2 mM dithiothreitol) or nontoxic transport substrates (200 microM probenecid or 10 mm phenylalanine, S-benzyl-L-cysteine or para-aminohippuric acid). Calpain inhibitors E64d (100 microM) and calpain inhibitor II (1 mM) were ineffective in preventing opacity formation caused by DCVC. In a small separate study, DCVC toxicity to explanted lenses from cynomologus monkeys was also ameliorated by coincubation with AOA. These results indicate that opacity formation by DCVC in rodent and primate lenses in vitro is primarily mediated via lenticular beta-lyase metabolism of DCVC to a reactive metabolite. Metabolism of DCVC by FMO and perturbations in mitochondrial calcium (Ca2+) homeostasis and increased poly(ADP-ribosylation) of nuclear proteins may play a limited role in opacity formation in vitro. However, opacity formation does not appear to be the result of oxidative stress or calpain activation. DCVC toxicity to the lens was not blocked with competitive inhibitors of the amino acid and organic anion transporters of DCVC as is found in the kidney.
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Affiliation(s)
- C M Walsh Clang
- Pfizer Central Research, Drug Safety Evaluation, Groton, Connecticut 06340, USA
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20
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Wang LF, Dhir P, Bhatnagar A, Srivastava SK. Contribution of osmotic changes to disintegrative globulization of single cortical fibers isolated from rat lens. Exp Eye Res 1997; 65:267-75. [PMID: 9268595 DOI: 10.1006/exer.1997.0330] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this study the contribution of osmotic changes to disintegrative globulization of lens cortical fibers was examined. Single fiber cells were isolated by trypsinization of adult rat lens cortex, and morphological changes elicited by exposure to different external solutions were monitored optically. The survival of the fiber-shaped cells was analysed in accordance with the Weibull distribution. Changes in [Ca2+]i were measured using the fluorescent calcium-sensitive dye-Fluo-3. Exposure of isolated fiber cells to Ringer's solution (containing 2 mm Ca2+) led to an exponential increase in [Ca2+]i with a time constant of 10.2+/-0.8 min, and caused disintegrative globulization in 25+/-4 min (=Tg). The process of globulization as well as the rate of increase in [Ca2+]i was delayed by removing Cl- ions from the external media. Globulization was also delayed by adding 20% bovine serum albumin (Tg=107+/-3 min) or chloride channel inhibitors 5, nitro-2-(3-phenylpropylamino) benzoate (NPPB), dideoxyforskolin, niflumic acid, and tamoxifen. When the fiber cells were suspended in isotonic (280 mm sucrose) HEPES-sucrose (HS) or HEPES-EDTA-sucrose (HES) solution, no globulization was observed for an observation time of 120 min. However, exposure to hypotonic (180 mm) HES solution led to disintegration of fiber cells in 75+/-7 min. Disintegration of the fiber induced by hypotonic HES solution could be delayed by either 0. 05 mm leupeptin (Tg=97+/-6 min) or by pre-loading the fibers with BAPTA (Tg=100+/-4 min). Inhibition of membrane calcium transport by 0.5 mm La3+ had no effect on Tg in hypotonic HES. Addition of 2 mm Ca2+ to HES solution accelerated globulization, and Tg was 57+/-4, 69+/-5 and 102+/-6 min for hypo-, iso- and hyper- tonic solutions, respectively. Transient exposure to calcium also accelerated disintegrative globulization of fiber cells exposed subsequently to HES solution. These results suggest that in ionic media, part of the calcium influx in isolated fiber cells is mediated by the influx of chloride ions. In the absence of other ions, the fiber cells still accumulate calcium, although this calcium influx was independent of medium tonicity. Globulization-induced by hypotonic sucrose solution appears to be mediated by the activation of intracellular proteases and by cell swelling-induced release of calcium from internal stores. Such swelling-mediated disintegrative globulization of fiber cells may be of significance in understanding the cellular basis of diabetic cataracts.
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Affiliation(s)
- L F Wang
- Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, TX 77555-0647, USA
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21
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Babiychuk E, Kushnir S, Belles-Boix E, Van Montagu M, Inzé D. Arabidopsis thaliana NADPH oxidoreductase homologs confer tolerance of yeasts toward the thiol-oxidizing drug diamide. J Biol Chem 1995; 270:26224-31. [PMID: 7592828 DOI: 10.1074/jbc.270.44.26224] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
To isolate new plant genes involved in the defense against oxidative stress, an Arabidopsis cDNA library in a yeast expression vector was transformed into a yeast strain deficient in the YAP1 gene, which encodes a b-Zip transcription factor and regulates general stress response in yeasts. Cells from approximately 10(5) primary transformants were subjected to a tolerance screen toward the thiol-oxidizing drug diamide, which depletes the reduced glutathione in the cell. Four types of Arabidopsis cDNAs were isolated. Three of these cDNAs (P1, P2, and P4) belong to a plant zeta-crystallin family and P3 is an Arabidopsis homolog of isoflavonoid reductases. As such, all four isolated cDNAs are homologous to NADPH oxidoreductases. P1, P2, and P3 steady-state mRNAs accumulated rapidly in Arabidopsis plants under various oxidative stress conditions, such as treatment with paraquat, t-butylhydroperoxide, diamide, and menadione. The data suggested that proteins encoded by the isolated cDNAs play a distinct role in plant antioxidant defense and are possibly involved in NAD(P)/NAD(P)H homeostasis.
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MESH Headings
- Amino Acid Sequence
- Animals
- Arabidopsis/enzymology
- Base Sequence
- Cloning, Molecular
- Crystallins/chemistry
- DNA, Complementary
- DNA, Plant/chemistry
- DNA, Plant/metabolism
- DNA-Binding Proteins/genetics
- Diamide/pharmacology
- Escherichia coli
- Genes, Plant
- Guinea Pigs
- Leishmania
- Molecular Sequence Data
- NADH, NADPH Oxidoreductases/chemistry
- NADH, NADPH Oxidoreductases/genetics
- NADH, NADPH Oxidoreductases/metabolism
- NADPH Oxidases
- Open Reading Frames
- Oxidative Stress
- Rabbits
- Saccharomyces cerevisiae/drug effects
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins
- Sequence Homology, Amino Acid
- Transcription Factors/genetics
- Transformation, Genetic
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Affiliation(s)
- E Babiychuk
- Laboratorium voor Genetica, Universiteit Gent, Belgium
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22
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Abstract
Calpains are calcium-activated proteinases which have been implicated in tissue differentiation and degeneration. The aims of the present study were: (1) to determine the relationship between postnatal age and calpain activity in the rat retina; (2) to test if calpain activity was aberrant in the RCS retina at different postnatal ages. Calpain activity was measured by a standard in vitro assay in fractions of retinas of rats, ranging in postnatal age of 2 to 42 days. Most retinal calpain activity was in the cytosolic fraction. Specific calpain activity declined with age. In the Long Evans rat, it was 8-fold higher on postnatal day 2 than on postnatal day 42. Comparison between RCS rats and their congenic controls showed that calpain activity was lower in the retinas of neonatal RCS rats. Specific calpain activity in RCS rat retinas was 46% lower on postnatal day 2 and 22% lower on postnatal day 3. It is concluded that during postnatal development of the retina, marked changes occurred in calpain activity. In addition, calpain activity is abnormal in the retina of the neonatal RCS rat--well before the onset of any morphological deterioration and preceding any other previously detected abnormality. Aberrant calpain activity appears to be a manifestation of very early events in processes that lead to retinal degeneration in the RCS rat.
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Affiliation(s)
- S M Azarian
- Laboratory of Cell Biology, School of Optometry, Indiana University, Bloomington 47405, USA
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23
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Shearer TR, Shih M, Azuma M, David LL. Precipitation of crystallins from young rat lens by endogenous calpain. Exp Eye Res 1995; 61:141-50. [PMID: 7556477 DOI: 10.1016/s0014-4835(05)80033-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The purpose of these experiments was to study the mechanism for precipitation of lens crystallins in cataract. An in vitro model was developed to activate the endogenous protease calpain II in the soluble proteins from young rat lens by addition of calcium in the presence of 120 mM KCl. Light-scattering, insoluble proteins were produced approximately 4-6 days after calpain II activation. Results showed that proteolysis was caused by activation of lens calpain II, proteolysis preceded precipitation by several days, and alpha-crystallin acted as a molecular chaperone against precipitation of crystallins caused by proteolysis. These data supported our hypothesis that calpain-induced proteolysis of the N-terminal arms of beta-crystallin polypeptides leads to a loss of normal oligomerization of beta-crystallin polypeptides and formation of abnormal insoluble aggregates, possibly stabilized by hydrophobic interactions.
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Affiliation(s)
- T R Shearer
- Department of Oral Molecular Biology, Oregon Health Sciences University, Portland 97201, USA
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24
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Affiliation(s)
- N S Kosower
- Department of Human Genetics, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv, Israel
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25
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Azuma M, Inoue E, Oka T, Shearer TR. Proteolysis by calpain is an underlying mechanism for formation of sugar cataract in rat lens. Curr Eye Res 1995; 14:27-34. [PMID: 7720403 DOI: 10.3109/02713689508999911] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To confirm the effect of a new aldose reductase inhibitor (ARI), rat lenses were cultured with xylose. ARI prevented opacities and reduced lens hydration caused by xylose. Next, cataract was produced by feeding a diet containing 50% galactose. ARI was tested for amelioration of cataract. On day 19 after feeding of galactose, nuclear cataracts were visible in 75% of the animals receiving only galactose, while nuclear cataracts were not observed in animals treated with ARI. In galactose cataract, lens hydration and calcium were significantly increased. Calpain in soluble and insoluble fractions was decreased. Alpha- and beta-crystallins were proteolyzed. These changes were inhibited by administration of ARI. These results suggested that proteolysis by calpain is an underlying mechanism in formation of sugar cataract in rat lens.
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Affiliation(s)
- M Azuma
- Department of Oral Molecular Biology, Oregon Health Sciences University, Portland 97201, USA
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26
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Nixon RA, Saito KI, Grynspan F, Griffin WR, Katayama S, Honda T, Mohan PS, Shea TB, Beermann M. Calcium-activated neutral proteinase (calpain) system in aging and Alzheimer's disease. Ann N Y Acad Sci 1994; 747:77-91. [PMID: 7847693 DOI: 10.1111/j.1749-6632.1994.tb44402.x] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Calpains (CANPs) are a family of calcium-dependent cysteine proteases under complex cellular regulation. By making selective limited proteolytic cleavages, they activate or alter the regulation of certain enzymes, including key protein kinases and phosphatases, and induce specific cytoskeletal rearrangements, accounting for their suspected involvement in intracellular signaling, vesicular trafficking, and structural stabilization. Calpain activity has been implicated in various aging phenomena, including cataract formation and erythrocyte senescence. Abnormal activation of the large stores of latent calpain in neurons induces cell injury and is believed to underlie neurodegeneration in excitotoxicity, Wallerian degeneration, and certain other neuropathologic states involving abnormal calcium influx. In Alzheimer's disease, we found the ratio of activated calpain I to its latent precursor isoform in neocortex to be threefold higher than that in normal individuals and those with Huntington's or Parkinson's disease. Immunoreactivity toward calpastatin, the endogenous inhibitor of calpain, was also markedly reduced in layers II-V of the neocortex in Alzheimer's disease. The excessive calpain system activation suggested by these findings represents a potential molecular basis for synaptic loss and neuronal cell death in the brain in Alzheimer's disease given the known destructive actions of calpain I and its preferential neuronal and synaptic localization. In surviving cells, persistent calpain activation may also contribute to neurofibrillary pathology and abnormal amyloid precursor protein trafficking/processing through its known actions on protein kinases and the membrane skeleton. The degree of abnormal calpain activation in the brain in Alzheimer's disease strongly correlated with the extent of decline in levels of secreted amyloid precursor protein in brain. Cytoskeletal proteins that are normally good calpain substrates become relatively calpain resistant when they are hyperphosphorylated, which may contribute to their accumulation in neurofibrillary tangles. As a major effector of calcium signals, calpain activity may mirror disturbances in calcium homeostasis and mediate important pathologic consequences of such disturbances.
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Affiliation(s)
- R A Nixon
- Laboratories for Molecular Neuroscience, McLean Hospital, Belmont, Massachusetts 02178
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27
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Song DK, Malmstrom T, Kater SB, Mykles DL. Calpain inhibitors block Ca(2+)-induced suppression of neurite outgrowth in isolated hippocampal pyramidal neurons. J Neurosci Res 1994; 39:474-81. [PMID: 7884824 DOI: 10.1002/jnr.490390414] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ca2+ is an important regulator of neurite elongation and growth cone movements but the mechanism(s) mediating these Ca(2+)-dependent effects is unclear. Since cytoskeletal proteins are rapidly degraded by Ca(2+)-dependent proteinases (calpains) in vitro and in vivo, we investigated whether Ca(2+)-induced pruning or regression of neuronal processes is mediated by calpains. Isolated hippocampal pyramidal-like neurons were cultured and the ability of the membrane-permeable calpain inhibitors ethyl(+)-(2S,3S)-3-[(S)-methyl-1-(3-methylbutylcarbamoyl)-butyl carbamoyl]-2 - oxiranecarboxylate (EST) and carbobenzoxyl-valyl-phenylalanyl-H (MDL 28170) to block the Ca2+ ionophore A23187-induced suppression in neurite outgrowth was investigated. Addition of 100 nM A23187 to the culture medium resulted in a retraction of dendrites without altering axonal elongation. The addition of 300 nM A23187 to the culture medium resulted in a significant decrease in the rate of axonal elongation as well as a retraction of dendritic processes. Administration of EST (5 or 20 microM) to the culture medium completely blocked the pruning effect of 100 nM A23187 on dendrites and of 300 nM A23187 on axons, while EST alone did not significantly affect neurite outgrowth rate. MDL 28170 (20 microM) showed the same effect as EST in preventing ionophore-induced pruning of dendrites and axons at 100 and 300 nM concentrations, respectively, of A23187. EST (20 microM) did not block the A23187-induced rise of [Ca2+]i as measured with fura-2. These results suggest that calpains play a role in Ca(2+)-induced pruning of neurites in isolated hippocampal pyramidal neurons.
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Affiliation(s)
- D K Song
- Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523
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28
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Shi H, Zhang R, Chandrasekher G, Ma Y. Simultaneous detection and quantitation of sodium, potassium calcium and magnesium in ocular lenses by high- performance capillary electrophoresis with indirect photometric detection. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)85165-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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29
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Kelley M, David L, Iwasaki N, Wright J, Shearer T. alpha-Crystallin chaperone activity is reduced by calpain II in vitro and in selenite cataract. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(17)46704-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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David LL, Shearer TR. Beta-crystallins insolubilized by calpain II in vitro contain cleavage sites similar to beta-crystallins insolubilized during cataract. FEBS Lett 1993; 324:265-70. [PMID: 8405363 DOI: 10.1016/0014-5793(93)80131-d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Incubation of soluble proteins from rat lens with the protease calpain II caused the precipitation of beta-crystallin polypeptides. Two-dimensional electrophoresis and sequence analysis identified beta-crystallin polypeptides both before and after their precipitation by calpain II. beta-crystallin polypeptides precipitated by calpain were cleaved at their NH2-terminal extensions. These cleavage sites were similar to cleavage sites occurring in beta-crystallin polypeptides precipitated during formation of experimental cataract induced by an overdose of selenite. These data suggested that calpain II caused beta-crystallin insolubilization during cataract formation, and indicated that the process can be mimicked in vitro.
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Affiliation(s)
- L L David
- Department of Oral Molecular Biology, Oregon Health Sciences University, Portland 97201
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31
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Abstract
The purpose of these experiments was to examine the relationship between oxidation cataract and proteolysis in cultured rat lens. Hydrogen peroxide cataract showed insolubilization of protein, loss of 31 kDa beta B1-crystallin polypeptide, decreases in soluble calpain, and increases in insoluble calpain. This suggested that calpain may be activated in hydrogen peroxide treated lenses, since beta B1 is a known calpain substrate, and calpain undergoes autolysis and degradation when activated. Furthermore, the cysteine protease inhibitor E64 was partially effective in preventing development of H2O2-cataract. E64 also prevented the loss of the 31 kDa beta B1-crystallin polypeptide and decreased the loss of calpain in the lens. These results suggested that development of hydrogen peroxide induced cataract in rat lenses was associated with activation of calpain.
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Affiliation(s)
- K Kadoya
- Department of Biochemistry, School of Dentistry and Medicine, Oregon Health Sciences University, Portland 97201
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32
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Sequence analysis of lens beta-crystallins suggests involvement of calpain in cataract formation. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53944-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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