UP-REGULATION OF TYPE-I PROCOLLAGEN C-PROTEINASE ENHANCER PROTEIN MESSENGER-RNA IN RATS WITH CCL4-INDUCED LIVER FIBROSIS

Using a polyclonal antibody raised against a liver stellate cell (LSC) line derived from a rat CCl4-cirrhotic liver, we isolated 14 clones f rom a complementary DNA library prepared with total RNA extracted from the same cell line, with nucleotide sequences homologous to that of t he type I procollagen C-proteinase enhancer protein (PCPE) gene. The l ongest PCPE insert of 1,530 base pairs contained an open reading frame coding for 468 amino acids, PCPE cDNA recognized by Northern blot a 1 .7-kilobase messenger RNA (mRNA) in total RNA extracted from freshly i solated and early passaged LSC, LSC lines derived from normal (NFSC) a nd cirrhotic (CFSC) rat livers, and various LSC clones derived from CF SC. The expression of PCPE mRNA was increased threefold in CFSC compar ed with NFSC. PCPE mRNA was not detected in total rat liver, freshly i solated hepatocytes, or endothelial or Kupffer cells. However, the exp ression of PCPE mRNA was induced in fibrotic livers of rats treated wi th CCl4. PCPE mRNA expression in LSC was up-regulated by transforming growth factor beta 1 (TGF-beta 1) and down-regulated by tumor necrosis factor alpha (TNF-alpha), similar to the changes in alpha 1 (I) proco llagen mRNA induced by these cytokines. PCPE was not detectable in liv er biomatrix proteins obtained from normal liver. However, PCPE was in creased in liver biomatrix proteins from cirrhotic livers and was prop ortional to the amount of collagen. These data suggest that PCPE may p lay an important role in the processing of type I collagen during live r fibrogenesis, and that TGF-beta 1 and TNF-alpha regulate its express ion.