Effects of p-CREB-1 on Transforming Growth Factor-β3 Auto-Regulation in Hepatic Stellate Cells

Previous studies have demonstrated that transforming growth factor-beta 3 (TGF-beta 3) protected liver against fibrosis in vivo and vitro, but its regulation is poorly understood. In addition, the cAMP-responsive element (CRE) in TGF-beta 3 promoter is recognized as an important regulatory site for TGF-beta 3 auto-regulation. Thus, we hypothesize that transcription factor CRE-binding protein-1 (CREB-1) regulates the auto-induction of TGF-beta 3 in hepatic stellate cells (HSCs). We used exogenous TGF-beta 3 to activate the signal pathway of TGF-beta 3 autoregulation in HSCs, results indicated that exogenous TGF-beta 3 could up-regulate the protein and mRNA expressions of TGF-beta 3, and provoke the phosphorylation of CREB-1 on Ser-133, besides, it could induce the DNA binding activity of p-CREB-1 and activate TGF-beta 3 promoter as well. Additionally, we used pGenesil-1.1-shRNA-CREB-1 and pRSV-CREB-1 expression vector to silence and up-regulate CREB-1 gene expression respectively, and the results indicated that inhibition of CREB-1 suppressed exogenous TGF-beta 3 stimulation of TGF-beta 3 mRNA and protein expressions in HSCs, whereas up-regulation of CREB-1 induced this stimulation. Our results indicate that exogenous TGF-beta 3 up-regulates the activity of TGF-beta 3 promoter by activating CREB-1, then induces the mRNA and protein expressions of TGF-beta 3. Especially, p-CREB-1 is a critical transcription factor in mediating TGF-beta 3 auto-induction. J. Cell. Biochem. 112: 1046-1054, 2011. (C) 2011 Wiley-Liss, Inc.