Hypoxia is well recognized as an important stimulus during the wound healing process. Recent studies have defined a hypoxia-sensitive pathway involving the induction of hypoxia-inducible factor-1 (HIF- 1), a vascular endothelial growth factor (VEGF), a key angiogenic protein which plays a critical role in tissue repair. Hypoxia stimulated signaling during hepatic fibrogenesis is poorly understood and the mechanisms have not been explored. Preliminary results indicate that the hepatic stellate cell (HSC) (also called Ito cell, lipocyte or perisinusoidal cell), the principal matrix producing cells during hepatic wound healing, is an oxygen sensing cell. The immediate goal of this project is to test the working hypothesis, that hepatic stellate cells respond to hypoxia through increased expression of HIF-1, which then drives an angiogenic response mediated by VEGF and its receptors.
The specific aims of this proposal are to: 1) Examine the mRNA and protein expression of HIF-1 in primary cultures of HSCs and sinusoidal endothelial cells under hypoxic and normoxic conditions. 2) Characterize the pattern of VEGF expression and its receptor modulation during HSC activation in response to hypoxia in stellate cells and endothelial cells. 3) Determine a transcriptional regulatory role of HIF-1 in the transcriptional activation of VEGF during hypoxic liver injury in vitro. A targeted approach will be employed to achieve these specific aims, taking advantage of experimental methods acquired during the candidate's training (molecular biology techniques), and new skills that will be learned as part of this structured career development plan (e.g. transient expression assay transcriptional regulation methods). These studies will improve our understanding of the mechanisms underlying oxidative stress during wound healing in the liver and facilitate the development of novel agents for the treatment of cirrhosis. These studies, performed in an outstanding research environment as par of a structured career development program, will provide the technical research skills and critical conceptualizations that will facilitate the candidate's long term career goal of being an independent, productive biomedical scientist investigating hypoxia stimulated signaling during liver injury and repair.
|Ankoma-Sey, V; Wang, Y; Dai, Z (2000) Hypoxic stimulation of vascular endothelial growth factor expression in activated rat hepatic stellate cells. Hepatology 31:141-8|