calpain and Liver-Diseases

Ischemia/reperfusion (I/R) injury unavoidably occurs during hepatic resection and transplantation. Aged livers poorly tolerate I/R during surgical treatment. Although livers have a powerful endogenous inhibitor of calpains, calpastatin (CAST), I/R activates calpains, leading to impaired autophagy, mitochondrial dysfunction, and hepatocyte death. It is unknown how I/R in aged livers affects CAST. Human and mouse liver biopsies at different ages were collected during in vivo I/R. Hepatocytes were isolated from 3-month- (young) and 26-month-old (aged) mice, and challenged with short in vitro simulated I/R. Cell death, protein expression, autophagy, and mitochondrial permeability transition (MPT) between the two age groups were compared. Adenoviral vector was used to overexpress CAST. Significant cell death was observed only in reperfused aged hepatocytes. Before the commencement of ischemia, CAST expression in aged human and mouse livers and mouse hepatocytes was markedly greater than that in young counterparts. However, reperfusion substantially decreased CAST in aged human and mouse livers. In hepatocytes, reperfusion rapidly depleted aged cells of CAST, cleaved autophagy-related protein 5 (ATG5), and induced defective autophagy and MPT onset, all of which were blocked by CAST overexpression. Furthermore, mitochondrial morphology was shifted toward an elongated shape with CAST overexpression. In conclusion, CAST in aged livers is intrinsically short-lived and lost after short I/R. CAST depletion contributes to age-dependent liver injury after I/R.

Topics: Age Factors; Animals; Autophagy; Autophagy-Related Protein 5; Calcium-Binding Proteins; Calpain; Cell Death; Cells, Cultured; Disease Models, Animal; Gene Expression Regulation; Hepatocytes; Humans; Liver; Liver Diseases; Male; Mice, Inbred C57BL; Mitochondria, Liver; Reperfusion Injury; Signal Transduction; Time Factors

Recently, synthesis and secretion of connective tissue growth factor (CTGF)/CYR61/CTGF/NOV-family member 2 (CCN2) in cultures of hepatocytes were shown, which are sensitively up-regulated by exogenous TGF-beta. In this study TGF-beta-dependent CTGF/CCN2 expression in hepatocytes cultured under completely TGF-beta-free conditions was analysed by Western-blots, metabolic labelling, and CTGF-reporter gene assays. In alkaline phosphatase monoclonal anti-alkaline phosphatase complex (APAAP)-staining of cultured hepatocytes it was demonstrated that latent TGF-beta within the hepatocytes becomes rapidly detectable during culture indicating an intracellular demasking of the mature TGF-beta antigen. Subsequent signaling to theCTGF/CCN2 promoter occurs via p-Smad2, whereas p-Smad3 does not seem to be involved. Cycloheximide did not abolish the rapid immunocytochemical appearance of mature TGF-beta, but calpain inhibitors partially suppressed intracellular TGF-beta activation and subsequently CTGF up-regulation. Calpain treatment had the reverse effect. None of the inhibitors of extracellular TGF-beta signalling was effective in the reduction of spontaneous CTGF synthesis, but intracellularly acting Alk 4-/Alk 5-specific inhibitor SB-431542 was able to diminish CTGF expression. The assumption that latent intracellular TGF-beta is activated by calpains during culture-induced stress or injurious conditions in the liver in vivo was further validated by a direct effect of calpains on the activation of recombinant latent TGF-beta. In conclusion, these data are the first to suggest the possibility of intracrine TGF-beta signalling due to calpain-dependent intracellular proteolytic activation leading to transcriptional activation of CTGF/CCN2 as a TGF-beta-sensitive reporter gene. This mechanism might be deleterious for keeping long-term hepatocyte cultures due to TGF-beta-induced apoptosis and, further, might be of relevance for induction of apoptosis or epithelial-mesenchymal transition of hepatocytes in injured liver.

Topics: Alkaline Phosphatase; Animals; Calpain; Cells, Cultured; Connective Tissue Growth Factor; Enzyme Inhibitors; Hepatocytes; Humans; Intracellular Space; Liver Diseases; Male; Models, Biological; Phosphorylation; Rats; Rats, Sprague-Dawley; Signal Transduction; Smad Proteins; Time Factors; Transcriptional Activation; Transforming Growth Factor beta

We present a girl with dermatomyositis, liver cysts and choroid plexus papilloma who was treated and followed for 7 years. Muscle histology revealed an inflammatory muscle disease and similar changes were detected in a brain tumor that was surgically removed at onset. Western blot analysis of the muscle revealed severely reduced calpain-3 protein. She was treated with pulse methylprednisolone treatment (800 mg i.v. for 4 days) followed by oral prednisone treatment (16 mg on alternate day) for 14 months, which improved muscle strength. Moreover, the cystic liver formations disappeared during steroid treatment. This is an unusual association of muscular disorder, steroid-responsive liver cysts, intracranial tumor and secondary calpain-3 deficiency. We speculate that this association is not coincidental, but mediated by an autoimmune attack against an antigen that is shared among the target tissues.

Topics: Antigens, CD; Calpain; Cerebral Ventricle Neoplasms; Child; Cysts; Dermatomyositis; Female; Humans; Liver Diseases; Magnetic Resonance Imaging; Muscle Proteins; Muscle, Skeletal; Paraneoplastic Syndromes; Ultrasonography

Liver injury is known to progress even after the hepatotoxicant is long gone and the mechanisms of progressive injury are not understood. We tested the hypothesis that hydrolytic enzymes such as calpain, released from dying hepatocytes, destroy the surrounding cells causing progression of injury. Calpain inhibitor, N-CBZ-VAL-PHE-methyl ester (CBZ), administered 1 h after a toxic but nonlethal dose of CCl(4) (2 ml/kg, ip) to male Sprague Dawley rats substantially mitigated the progression of liver injury (6 to 48 h) and also led to 75% protection against CCl(4)-induced lethality following a lethal dose (LD75) of CCl(4) (3 ml/kg). Calpain leakage in plasma and in the perinecrotic areas increased until 48 h and decreased from 72 h onward paralleling progression and regression of liver injury, respectively, after CCl(4) treatment. Mitigation of progressive injury was accompanied by substantially low calpain in perinecrotic areas and in plasma after CBZ treatment. Normal hepatocytes incubated with the plasma collected from CCl(4)-treated rats (collected at 12 h when most of the CCl(4) is eliminated) resulted in extensive cell death prevented by CBZ. Cell-impermeable calpain inhibitor E64 also protected against progression of CCl(4)-induced liver injury, thereby confirming the role of released calpain in progression of liver injury. Following CCl(4) treatment, calpain-specific breakdown of alpha-fodrin increased, while it was negligible in rats receiving CBZ after CCl(4). Hepatocyte cell death in incubations containing calpain was completely prevented by CBZ. Eighty percent of Swiss Webster mice receiving a lethal dose (LD80) of acetaminophen (600 mg/kg, ip) survived if CBZ was administered 1 h after acetaminophen, suggesting that calpain-mediated progression of liver injury is neither species nor chemical specific. These findings suggest the role of calpain in progression of liver injury.

Topics: Acetaminophen; Animals; Blotting, Western; Calpain; Carbon Tetrachloride; Carrier Proteins; Chemical and Drug Induced Liver Injury; Cysteine Proteinase Inhibitors; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Dipeptides; Disease Progression; Hepatocytes; Immunohistochemistry; Liver Diseases; Male; Mice; Microfilament Proteins; Necrosis; Random Allocation; Rats; Rats, Sprague-Dawley

Calpain proteases have been implicated in cell death by necrosis and more recently by apoptosis. Experiments were designed to determine the role of calpain proteases in ischemic rat liver injury by measurement of cytosolic calpain activity after different periods of ischemia-reperfusion and by evaluation of the effects of calpain inhibition on tissue injury and animal survival.. Calpain activity was measured in the cytosol using Suc-Leu-Leu-Val-Try-7 amino-4 methyl coumarin, a specific fluorogenic substrate, and Cbz-Leu-Leu-Tyr-CHN2, a specific inhibitor.. Calpain activity increased significantly with the duration of ischemia-reperfusion and was inhibited more than 80% by the inhibitor. Calpain inhibition resulted in a significant decrease in transaminase release and tissue necrosis and converted nonsurvival ischemic conditions to survival conditions. When the in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling assay for apoptosis was used, 35% +/- 6% of nonparenchymal cells and 16% +/- 3% of hepatocytes stained positively after 60 minutes of ischemia and 6 hours of reperfusion. In contrast, animals pretreated with the calpain inhibitor showed minimal evidence of apoptosis. This was further substantiated by gel electrophoresis assay for DNA fragmentation and by electron-microscopic evaluation.. These data suggest that calpain proteases play a pivotal role in warm ischemia-reperfusion injury of the rat liver through modulation of apoptosis and necrosis.

Topics: Alanine Transaminase; Animals; Apoptosis; Aspartate Aminotransferases; Calpain; Caspase Inhibitors; Cysteine Proteinase Inhibitors; Cytosol; Diazomethane; Dipeptides; DNA Fragmentation; Electrophoresis, Agar Gel; In Situ Nick-End Labeling; Ischemia; Liver; Liver Diseases; Necrosis; Oligopeptides; Rats; Rats, Wistar; Reperfusion Injury