Studies on the expression and regulation of transcription factors in hepatic stellate cells

A key event in the pathogenesis of liver fibrosis is the activation of hepatic stellate cells (HSCs). Three major transcription factors (MyoD, Sp1 and AP-1) that may be important regulators of HSC activation have been analysed.

Both in vitro and in vivo models of HSC activation were associated with changes in E-box DNA binding activities. Freshly isolated HSCs from untreated rats expressed a high mobility complex (C) that was replaced upon activation with two low mobility complexes (A and B). The assembly of complexes A and B was inhibited with an antibody against MyoD. Further studies demonstrated that HSCs did express the transcription factor, MyoD, and its expression may be controlled by a post-transcription mechanism.

Both in vitro and in vivo models of HSC activation revealed induction of a low mobility GC-box (LMGC) binding complex and was subsequently identified as Sp1.

Culture activation of rat HSCs (in vitro) indicated transient expression of low mobility AP-1 (LMAP-1) complexes that were maximally induced at 24 hours of culture and then fell to undetectable levels with further culture. Supershift Electromobility Shift Assay (EMSA) identified its components as c-Jun, JunD, c-Fos and FosB. Further culture of HSCs led to the detection of sustained high mobility AP-1 (HMAP-1) complexes. Supershift EMSA described these proteins as JunD, Fra2 and FosB. Finally, in vivo studies revealed a slightly different AP-1 profile where the complexes consisted of JunB, JunD, Fra1 and Fra2.

Further experiments are now required to elucidate the functions of these transcription factors in the HSC. Greater understanding of the molecular events that underlie liver fibrosis may lead to the development of new therapeutic strategies in the future.

University of Southampton

Vincent, Karen Jane

0a7c5857-18ea-4e41-a5ba-441b80859bef

2000

Vincent, Karen Jane

0a7c5857-18ea-4e41-a5ba-441b80859bef

Vincent, Karen Jane (2000) Studies on the expression and regulation of transcription factors in hepatic stellate cells. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Both in vitro and in vivo models of HSC activation revealed induction of a low mobility GC-box (LMGC) binding complex and was subsequently identified as Sp1.