Increased type I collagen in liver fibrosis results primarily from increased production by activated hepatic stellate cells (HSCs). Transcription of the collagen alpha1(I) gene increases 3 fold in activated HSCs compared to quiescent HSCs while the stability of the mRNA increases approximately 20 fold, which results in the 60 fold increased steady-state mRNA level. Collagen alpha1(I) mRNA stability is regulated by its 3' UTR, which binds alpha-CP, and by its stem-loop in the 5' UTR, which interacts with RNA binding proteins in the nucleus and in the cytoplasm. These proteins may also be involved in coordinate translation of alpha1(I) and alpha2(I) mRNAs and stimulation of collagen production by TGF-beta. To understand the posttranscriptional regulation of collagen alpha1(I) gene expression in HSCs, this proposal will study four specific aims: (1). To investigate the mechanisms of translation and degradation of collagen alpha1(I) mRNA. (2). To design molecular decoys that inhibit collagen type I expression in cultured hscs. (3). To evaluate molecular decoys as antifibrotic therapy in an animal model of liver fibrosis (4). To clone and characterize protein factors which bind the 5' stem-loop of the collagen alpaha1(I) mRNA. One of the goals of therapy of liver fibrosis is to prevent excessive accumulation of collagen type I. Elucidation of the mechanisms that regulate expression of collagen type I in hscs at the molecular level is essential for rational drug design. The proposed experiments will provide information about the critical steps in this regulation and about the molecules involved. Cloning of the 5' stem-loop binding proteins will lead to their characterization as potential targets of drug therapy. Molecular decoys that will be developed may be useful for gene therapy of liver fibrosis. Overall, these studies will greatly enhance our knowledge about the biosynthesis of type I collagen.
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