Involvement of 90-kuD ribosomal S6 kinase in collagen type I expression in rat hepatic fibrosis.

Abstract

AIM:

To investigate the relationship between 90-kuD ribosomal S6 kinase (p90RSK) and collagen type I expression during the development of hepatic fibrosis in vivo and in vitro.

METHODS:

Rat hepatic fibrosis was induced by intraperitoneal injection of dimethylnitrosamine. The protein expression and cell location of p90RSK and their relationship with collagen type I were determined by co-immunofluoresence and confocal microscopy. Subsequently, RNAi strategy was employed to silence p90RSK mRNA expression in HSC-T6, an activated hepatic stellate cell (HSC) line. The expression of collagen type I in HSC-T6 cells was assessed by Western blotting and real-time polymerase chain reaction. Furthermore, HSCs were transfected with expression vectors or RNAi constructs of p90RSK to increase or decrease the p90RSK expression, then collagen type I promoter activity in the transfected HSCs was examined by reporter assay. Lastly HSC-T6 cells transfected with p90RSK siRNA was treated with or without platelet-derived growth factor (PDGF)-BB at a final concentration of 20 microg/L and the cell growth was determined by MTS conversion.

RESULTS:

In fibrotic liver tissues, p90RSK was over-expressed in activated HSCs and had a significant positive correlation with collagen type I levels. In HSC-T6 cells transfected with RNAi targeted to p90RSK, the expression of collagen type I was down-regulated (61.8% in mRNA, P < 0.01, 89.1% in protein, P < 0.01). However, collagen type I promoter activity was not increased with over-expression of p90RSK and not decreased with low expression either, compared with controls in the same cell line (P = 0.076). Furthermore, p90RSK siRNA exerted the inhibition of HSC proliferation, and also abolished the effect of PDGF on the HSC proliferation.

CONCLUSION:

p90RSK is over-expressed in activated HSCs and involved in regulating the abnormal expression of collagen type I through initiating the proliferation of HSCs.

• Authors: Miao-Fang Yang, Jun Xie, Xiao-Yi Gu, Xiao-Hua Zhang, Andrew-K Davey, Shuang-Jie Zhang, Ji-Ping Wang, Ren-Min Zhu
• Journal: World journal of gastroenterology (World J Gastroenterol) Vol. 15 Issue 17 Pg. 2109-15 (May 07 2009) ISSN: 2219-2840 [Electronic] United States
• PMID: 19418583 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Collagen Type I
• RNA, Small Interfering
• Ribosomal Protein S6 Kinases, 90-kDa
• Dimethylnitrosamine

Topics

• Animals
• Cell Proliferation
• Collagen Type I (genetics, metabolism)
• Dimethylnitrosamine (administration & dosage, toxicity)
• Hepatic Stellate Cells (cytology, physiology)
• Liver Cirrhosis (metabolism)
• Male
• Promoter Regions, Genetic
• RNA, Small Interfering (genetics, metabolism)
• Rats
• Rats, Sprague-Dawley
• Ribosomal Protein S6 Kinases, 90-kDa (genetics, metabolism)