Neurokinin B (NK-B) is a member of tachykinin family of peptides. Classically, NK-B expression and function was studied in the context of the nervous system. However overexpression of NK-B has been implicated in the pregnancy-associated disorder preeclampsia, which is characterized by defective remodeling of the placental vasculature and systemic vascular deregulation. We demonstrated that NK-B reversibly inhibits endothelial cell vascular network assembly in vitro on Matrigel and opposes angiogenesis in vivo. Mechanistic analyses revealed that NK-B signaling inhibited angiogenic signal-induced expression of vascular endothelial growth factor receptor1 (VEGFR1) and VEGFR2, and reduced endothelial cell migration. The objective of this proposal is to determine the regulatory mechanisms, by which NK-B inhibits angiogenic signal-induced VEGFR1 and VEGFR2 induction, and endothelial cell migration. We will institute two specific aims to address this. In the first Specific Aim we will determine how neurokinin B represses angiogenic signal-dependent VEGFR induction. Transcription factors Ets1 and HIF-2alpha have been implicated in the transcriptional regulation of VEGFR1 and VEGFR2. We will test whether Ets1 and HIF-2alpha directly activate transcription of VEGFR1 and VEGFR2 in response to angiogenic signals in vitro and in vivo, and whether NK-B signaling represses transcription by blocking Ets1/HIF-2alpha chromatin occupancy or a critical function post-occupancy. In the second Specific Aim we will determine the mechanism of NK-B-mediated inhibition of endothelial cell migration. We hypothesize that, in endothelial cells, NK-B signaling modulates critical signaling pathways that mediate directed cell migration. To test this hypothesis we will document signal transduction events in endothelial cells stimulated to undergo migration and the effect of NK-B on those events, including phosphorylation of focal adhesion kinase, paxillin, p130Cas, spatial and temporal association of these molecules to form focal adhesions, and activation of Rho family of GTPases Rac1 and CDC42.
Angiogenesis, the development of new blood vessels from existing vasculature, is a key event in many physiological processes, like organ growth and development, wound healing, and reproduction. Angiogenesis is also critical for certain pathological disorders including tumor growth/metastasis. Information gleaned from these studies will contribute to our understanding of the molecular mechanisms of angiogenesis and hopefully will lead to novel therapeutic modalities.
