Screening for genes involved in apoptosis of hepatic stellate cells : a role of caspase-7

Abstract

Objective : Hepatic stellate cells (HSCs) play an important role in liver fibrogenesis. Therefore, induction of apoptosis in activated HSCs should lead to an effective modality to diminish and/or prevent liver fibrosis. Gliotoxin has been shown to induce apoptosis in the activated HSCs, although the molecular mechanisms remain obscure. To explore the molecular mechanisms involved in gliotoxin-induced HSC apoptosis, we used a randomized ribozyme library and screened genes that are associated with gliotoxin-induced HSC apoptosis. Materials & Methods : A stellate cell line was transiently transfected with a randomized ribozyme library. After 48 hours, cells were treated with gliotoxin (1.5μM) for another 24 hours, and then Rz-expressing plasmids from surviving cells were isolated. After the third round of selection with gliotoxin, the ribozymes were isolated and their sequences were determined. The target genes were analyzed on the BLAST database. Results : We identified caspase-7 as one of the participants in gliotoxin-induced apoptosis. A plasmid harboring the identified sequence was transiently transfected into HSC-T6 cells. The transfected cells were resistant to apoptosis due to gliotoxin. Conclusion : It is suggested that caspase-7 is implicated in the mechanism of gliotoxin-induced apoptosis.