Down-regulation by Antisense Oligonucleotides Establishes a Role for the Proline-rich Tyrosine Kinase PYK2 in Angiotensin II-induced Signaling in Vascular Smooth Muscle

Abstract

Abnormal vascular smooth muscle cell (VSMC) growth plays a key role in the pathogenesis of hypertension and atherosclerosis. Angiotensin II (Ang II) elicits a hypertrophic growth response characterized by an increase in protein synthesis in the absence of DNA synthesis and cell proliferation. Intracellular signaling mechanisms linking angiotensin type I receptor activation to protein synthesis in VSMC have not been fully characterized. The present study investigates the role of the nonreceptor proline-rich tyrosine kinase 2 (PYK2) in Ang II-induced VSMC protein synthesis and in the regulation of two signaling pathways that have been implicated in the control of protein synthesis, the extracellular signal-regulated kinase (ERK1/2) and the phosphatidylinositol 3-kinase/Akt pathways. PYK2 antisense oligonucleotides were used to down-regulate PYK2 expression in cultured VSMC. An 80% down-regulation in PYK2 expression resulted in an ∼80% inhibition of ERK1/2 (3.8 ± 1.3 versus 16.6 ± 1.8), p70S6 kinase (1.03 ± 0.03 versus 3.8 ± 0.5), and Akt activation (3.0 ± 0.8 versus 16.0 ± 1.0) by Ang II. Furthermore, PYK2 down-regulation resulted in a complete inhibition of Ang II-induced VSMC protein synthesis. These data conclusively identify PYK2 as an upstream regulator of both the ERK1/2 and the phosphatidylinositol 3-kinase/Akt pathways that are involved in Ang II-induced VSMC protein synthesis.