: Aberrant vascular smooth muscle cell (VSMC) growth has been implicated in atherosclerosis, hypertension and restenosis. The long-term goal of this proposal is to characterize the coordinated regulation of signal transduction cascades that mediate VSMC growth and to determine differential regulation of these cascades by growth factors and hypertrophic agonists. VSMC are capable of hypertrophic and proliferative growth. Although a myriad of signaling pathways are activated by both G-protein coupled receptors and receptor tyrosine kinases, little is known about how these signals are integrated and whether common receptor-proximal signaling control points synchronize growth and migration. The nonreceptor, tyrosine kinase PYK2 links G-protein- and growth factor receptors to downstream signaling cascades. New preliminary data indicate that PYK2 downregulation by antisense oligonucleotides blocks Angiotensin II- (Ang II) and platelet derived growth factor (PDGF)-induced protein and DNA synthesis that was associated with inhibition of focal adhesion kinase (FAK), the p38 and ERK1/2 MAP kinases, as well the phosphatidylinositol 3-kinase/Akt/p70S6 kinase pathway. The hypothesis of the current proposal is that PYK2 represents a proximal signaling event that integrates (links) signals from both Gq-coupled receptors and receptor tyrosine kinases to control downstream signaling cascades involved in VSMC growth and migration.
Three specific aims will test this hypothesis:
In Aim 1, studies with antisense oligonucleotides and adenoviral constructs will be used to determine whether PYK2 is required for protein translation initiation, cell cycle progression and VSMC migration.
In Aim 2, experiments with PYK2 antisense and pharmacological inhibitors of ERK1/2, p38 and PI3K pathways will determine which cellular signaling cascades are downstream of PYK2 activation in response to Ang II and PDGF.
In Aim 3, dominant negative PYK2 adenoviral constructs or PYK2 antisense will be used to block VSMC hypertrophy and proliferation in vivo using a mouse carotid artery injury model. The results may provide new insight coordinated VSMC growth regulation and may determine the feasibility of targeting the proximal signaling intermediates as potential therapeutic strategies for vascular disease.
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