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ACETALDEHYDE INDUCES C-FOS AND C-JUN PROTO-ONCOGENES IN FAT-STORING CELL CULTURES THROUGH PROTEIN KINASE C ACTIVATION

ALESSANDRO CASIN, GIANNA GALLI, RENATA SAIZANO, ELISABETTA CENI, FRANCESCO FRANCESCHELLI, CARLO MARIA ROTELLA, CALOGERO SURRENTI
DOI: http://dx.doi.org/ 303-314 First published online: 1 May 1994

Abstract

Hepatic fibrosis is an important morphological feature of alcohol-induced liver injury. We previously reported that acetaldehyde stimulates collagen I and fibronectin gene transcription in rat fatstoring cell (FSC) culture. We here evaluated whether acetaldehyde increases Col I and FN gene transcription through the induction of c-fos and c-jun proto-oncogenes and studied the possible role played by protein kinase C (PKC) and c-AMP. FSCs, isolated from rat liver on a Nycodenz density gradient, were exposed to acetaldehyde for 1/2, 1, 3, 6, 12, 24 hr and for 10, 20,30,45,60,90 min in the experiments for jun and fos expression, respectively. Acetaldehyde produced a rapid and transient induction of fos mRNA (undetectable at t=0, peak at t=45 and still evident at t=90). Jun mRNA was weakly expressed in unstimulated FSCs; acetaldehyde induced a prolonged activation of jun expression up to 24 hr with a peak at 3 hr. To study the role of PKC we repeated the experiments in the presence of Staurosporine and H-7. These inhibitors of PKC activity blocked the stimulatory effect of acetaldehyde on fos and jun mRNA expression. Furthermore, they abolished the stimulatory effect of acetaldehyde on collagen I and fibronectin gene expression by FSCs. Acetaldehyde increased the cell membrane PKC activity in FSC cultures in a dose-dependent way. Intracellular cAMP levels were not significantly modified by acetaldehyde in the first 30 min of incubation. We conclude that acetaldehyde increases procollagen I and fibronectin gene transcription in FSCs, possibly through c-fos and c-jun expression, and that PKC may play a regulatory role in this chain of events.