Targeting transforming growth factor βRII expression inhibits the activation of hepatic stellate cells and reduces collagen synthesis

Abnormal production of extracellular matrix (ECM) components significantly contributes to the development of liver fibrosis. This study aimed at examining the effects of short-hairpin RNA (shRNA)-mediated transient knockdown of transforming growth factor beta RII (TGF beta RII) expression on the proliferation and activation of hepatic stellate cells (HSCs) and synthesis of fibrogenic ECM components in HSC cells. Three different shRNA-expressing plasmids were constructed for the expression of shRNA-(a, b, c) targeting to the rat TGF beta RII mRNA beginning at nucleotide position 339, 444 and 528 and they were transfected into a rat stellate cell line, HSC-T6 cells, respectively. The levels of TGF beta RII, alpha-smooth muscle actin (alpha-SMA), and type I and III collagen expressions were characterized by reverse transcription polymerase chain reaction and Western blot assays. The concentrations of hyaluronic acid (HA) and type IV collagen in the supernatants of cultured cells were measured by enzyme-linked immunosorbent assay. Transfection with the TGF beta RII-specific shRNAs resulted in varying levels of inhibition in the expression of TGF beta RII in HSC-T6 cells, and transfection with the potent shRNA-c inhibited the expression of TGF beta RII in a dose-dependent manner. Knockdown of TGF beta RII expression significantly reduced the levels of alpha-SMA, type I, III and IV collagen, and HA expression in HSC-T6 cells (P < 0.01). In conclusion, our data indicated that knockdown of TGF beta RII expression inhibited the activation of HSCs and the production of fibrogenic ECM components in HSC-T6 cells. Therefore, our findings support the notion that TGF beta RII is an important factor of the pathogenic process of liver fibrosis.