The Mechanism Research On The Regulation Of Vascular Endothelial Growth Factor

Topic I:FHL1and Smad4synergistically inhibit vascular endothelial growth factor expressionVascular endothelial growth factor (VEGF) plays an important role in many disease states, including ischemia, chronic and acute inflammation, and pathologies associated with angiogenesis such as tumors and wounds. A number of factors regulate VEGF promoter activity and VEGF expression such as four and a half LIM domains1(FHL1) and Smad4. FHL1belongs to a family of LIM-only proteins that regulate gene transcription, cell proliferation, differentiation and apoptosis. Smad4is a tumor suppressor gene, initially identified as deleted in pancreatic carcinoma locus4(DPC4). The aim of this study was to determine whether FHL1and Smad4inhib-ited VEGF signaling. HepG2cells were transfected with the VEGF-Luc reporter, Smad4and FHL1or Smad4and FHL1siRNA. Results showed that the overexpression of FHL1and Smad4synergistically inhibited the promoter activity, mRNA expression and secretion of VEGF, whereas knockdown of endogenous Smad4and FHL1had opposite effects. Moreover, the reduction of endogenous Smad4eliminated FHL1-mediated inhibition of the VEGF promoter activity. In conclusion, a cooperative regulation of VEGF signaling by FHL1and Smad4was evidenced, which may provide a novel regulation mechanism underlying cancer development and progression.Topic Ⅱ:Mark1inhibit vascular endothelial growth factor expressionMark1(microtubule affinity-regulating kinasel),which can inhibit the promoter activity,was found by analysis for luciferase activity from704transcription factors in this research.MARK was originally purified from the rat brain and characterized as a protein-serine kinase.MARK proteins are homologous to the KIN1/PAR-1/Snfl kinase family of CaMK II and are subdivided into five domains:(i) N-terminal header,(ii)catalytic domain,(iii)common docking domain(CD),(iv)ubiquitin-associated (UBA) domain,(v)spacer region, and (vi) C-terminal tail. The effect of Markl inhibiting the VEGF promoter activity is dose-dependent.The deletion mutants of VEGF promoter were designed by200bp. The domain of Markl inhibits VEGF promoter activity was within fragment-800/-600of the human VEGF promoter.103-311amino acid of Markl plays an important role in the effect of Markl inhibiting the VEGF promoter activity.The expression of Markl in breast cancer tissue is lower than that in normal tissue.It suggests the effect of Markl inhibits VEGF promoter activity was impaired in breast cancer tissue which may enhance the growth of breast cancer tissue.