Cooperativity Between FGF1/Jagged Signaling--Angiogenesi

Maine Medical Center, Portland ME

Investigators

Linked publications & trials

Abstract

This laboratory isolated the human Jagged(J)-1 gene by a differential display of human endothelial cells (EC) exposed in vitro to the angiogenic factors, VEGF and FGF, on fibrin clots and demonstrated that anti-sense J-1 treated EC augment FGF but not VEGF responses. Since (1) J-1 is a transmembrane protein which serves as a ligand for the cell fate determinant transmembrane receptor, Notch, (2) the oncogene, int-3, encodes the intracellular domain of the Nothc-4 protooncogene and (3) J- 1 null mice exhibit an embryonic lethal phenotype with complete vasculogenesis (VEGF-dependent) but no angiogenesis (putative FGF- dependent), we constructed a soluble(s) and non-transmembrane form of J-1 and demonstrated that stable sJ-1 NIH 3T3 transfectants are capable of generating an angiogenic response in nude mice and in the chlorioallantoic membrane assay. Serial Analysis of Gene Expression followed by immunoblot analysis revealed a dramatic repression in type 1 collagen synthesis, and as a result, the sJ transfectants were exposed to type I collagen and they rapidly exhibited the formation of three dimensional chord-like structures similar to that similar to that normally observed with EC in vitro. As a result of studies designed to assess the ability of FGF to modify this chord-like phenotype, we noted that the sJ-1 transfectants assume the phenotype characteristics of a transformed NIH 3T3 cell in the presence of FGF, suggesting that FGF- and J-mediated signaling events may cooperate to yield a transformed phenotype in vitro. Since FGF-dependent signaling is mediated by the tyrosine kinase of a Src-like kinase and the F-actin binding protein, cortactin, the major substrate for Src in these cells. Indeed, co-transfection of the sJ-1 transfectant with a dominant-negative (dn) form of Src completely reverted the ability of type I collagen to induce the appearance of a chord- like phenotype and studies are in progress to assess the ability of dnSrc to modify the ability of erogenous FGF to modify sJ-1 transformation. Because FGF and J-1 are angiogenic factors in vivo, tissue fibrosis is a major cause of organ dysfunction and sJ-1. Because FGF and J-1 are angiogenic factors in vivo, tissue fibrosis is a major cause of organ dysfunction and sJ-1 completely represses type I collagen expression in vitro, sJ-1 enables NIH 3T3 fibroblasts to assume an EC-like chord phenotype involving Src/cortactin phosphorylation and exogenous FGF and endogenous J-1 receptor-mediated signaling pathways are involved in mediating NIH 3T3 cell transformation, we quest support to extend these studies and propose (1) to define the Notch receptor responsible for the sJ-1 signaling pathway and identify the minimal sJ-1 structural domain responsible for chord formation and FGF-dependent cell transformation in vitro and (2) to assess the value of cooperative sJ-1/FGF signaling in vivo to form stable collateral blood vessels on the surfaces of ischemic myocardium using murine transgenic methods in vivo.