Steatohepatitis-inducing drugs trigger cytokeratin cross-links in hepatocytes. Possible contribution to Mallory-Denk body formation.
Mallory-Denk bodies (MDB) are hepatocyte inclusions containing cytokeratin 8 (CK8) which can develop, along with other steatohepatitis lesions, in patients treated with amiodarone, perhexiline maleate or 4,4'-diethylaminoethoxyhexestrol. These drugs accumulate lipids, whose subsequent peroxidation liberates reactive by-products, like malondialdehyde (MDA). The formation of MDB has been previously reproduced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine or griseofulvin administration which cross-link CK8 by tissue transglutaminase, thus forming an entangled network, from which MDB progressively arise. The present study depicts the mechanisms initiating MDB formation by steatohepatitis-inducing drugs. Short incubation of hepatocytes with amiodarone (50 microM), 4,4'-diethylaminoethoxyhexestrol (50 microM) or perhexiline maleate (25 microM) increased the pool of CK8 monomers and increased cell calcium to activate Ca(++)-dependent transglutaminases which cross-linked the CK8 monomers into CK8-containing oligomers. The present study also provides the first evidence that MDA might directly participate in MDB formation, as this reactive agent cross-linked purified CK8 or albumin in vitro, disrupted the cytokeratin network of isolated hepatocytes, and bridged CK8 molecules. In conclusion, steatohepatitis-inducing drugs increase cell calcium and activate tissue transglutaminase, which cross-links CK8 to form a molecular scaffold, from which MDB might secondarily arise. Malondialdehyde also cross-links CK8, albeit through a different mechanism, and might also contribute to MDB formation.
Robin
Marie-Anne
MA
INSERM U773, Centre de Recherche Bichat Beaujon CRB3, Université Paris 7 Denis Diderot, site Bichat, Paris, France. robin@bichat.inserm.fr
Descatoire
Véronique
V
Pessayre
Dominique
D
Berson
Alain
A
D000638:Amiodarone / Q000633:toxicity; D000818:Animals; D002118:Calcium / Q000378:metabolism; D005234:Fatty Liver / Q000139:chemically induced; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006589:Hexestrol / Q000031:analogs & derivatives / Q000633:toxicity; D002479:Inclusion Bodies / Q000187:drug effects* / Q000378:metabolism; D053533:Keratin-8 / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism*; D010480:Perhexiline / Q000031:analogs & derivatives / Q000633:toxicity; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011506:Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D011503:Transglutaminases / Q000187:drug effects / Q000378:metabolism
D053533:Keratin-8; C488921:Mallory body protein, rat; D011506:Proteins; D006589:Hexestrol; D008315:Malondialdehyde; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; C023470:perhexiline maleate; D010480:Perhexiline; D000638:Amiodarone; D002118:Calcium; C100116:hexestrol bis(diethylaminoethyl ether)