(883.5) Protease-Activated Receptor-2 Differentially Regulates Vascular Smooth Muscle Cell Proliferation in Cyclic AMP-Dependent Protein Kinase/Phosphoinositide 3-Kinase-Dependent Manner

Poster Board Number: E296

Madison Williams (Department of Physiology, Brody School of Medicine, East Carolina University), Michael Bullock (Department of Physiology, Brody School of Medicine, East Carolina University), Nathan Holland (Department of Physiology, Brody School of Medicine, East Carolina University), Sean Johnson (Department of Internal Medicine/Pediatrics, Indiana University School of Medicine), Danielle Vuncannon (Department of Gynecology and Obstetrics, Emory University School of Medicine), Joani Oswald (Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University), Shaquria Adderley (Basic Science Department, Touro University), David Tulis (Department of Physiology, Brody School of Medicine, East Carolina University)

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, despite decades of extensive research. One key facet in CVD pathogenesis is the phenotypic transition of affected vascular smooth muscle (VSM) from a quiescent, contractile state to a synthetic, proliferative state. Protease-activated receptors (PARs) are of emerging interest in CVD; however, their potential impact on VSM phenotypic switching inherent in CVD is unclear. The overall objective of the current study was to determine the role of PAR2 and PAR4 in phenotypic switching and VSM growth. We hypothesized that PAR2 and PAR4 increase following arterial injury in vivo and after growth stimulation in vitro, that they serve to protect against VSM cell growth, and that they signal primarily through specific protein kinases in phenotype-specific fashion. In rat carotid arteries, PAR2 expression and activity increased following mechanical distension injury compared to uninjured controls. In rat primary VSM cells, PAR2 expression also increased in response to growth stimulation. Differential expression of cyclic GMP-dependent protein kinase PKG-1 and the PKG target VASP distinguished low passage (P3-P6) from high P (P10-P15) VSM cells, with low P cells showing elevated PKG-1, phosphorylated (Ser239) VASP and total VASP compared to high P cells. Pharmacologic PAR2 agonism promoted DNA synthesis and proliferation in low P cells but decreased DNA synthesis and proliferation in high P cells. Western blotting analyses showed increased expression of MEK1/2 MAPK, PKA, and PI3K in low P cells versus high P cells. Specific protein kinase blockade revealed that PAR2 differentially controls proliferation of phenotypically distinct low versus high P VSM cells predominantly through PKA and PI3K. Our findings highlight potential (patho)physiological relevance of PAR2 and PAR2-driven PKA/PI3K in the control of VSM cell growth and provide evidence for continued study of VSM PAR2 in CVD.

Support or Funding Information

This work was supported in part by NIH grants R01HL81720 (D.A.T.), R01HL81720-05S1 (D.A.T.), and R15HL135699 (D.A.T.), an ECU Brody School of Medicine Seed/Bridge Grant (D.A.T.), and a Brody Brothers Endowment Fund Award (D.A.T.). This content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, ECU, or the Brody Brothers Endowment Fund.

lt;pgt;This work was supported in part by NIH grants R01HL81720 (D.A.T.), R01HL81720-05S1 (D.A.T.), and R15HL135699 (D.A.T.), an ECU Brody School of Medicine Seed/Bridge Grant (D.A.T.), and a Brody Brothers Endowment Fund Award (D.A.T.). This content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, ECU, or the Brody Brothers Endowment Fund.lt;/pgt;