NO alters cell shape and motility in aortic smooth muscle cells via protein tyrosine phosphatase 1B activation.

Cell motility is an important determinant of vascular disease. We examined mechanisms underlying the effect of nitric oxide (NO) on motility in cultured primary aortic smooth muscle cells from newborn rats. The NO donor S-nitroso-N-acetyl-penicillamine (SNAP) increased the activity of protein tyrosine phosphatase 1B (PTP-1B). This effect was mimicked by a cGMP analog and blocked by the guanyl cyclase antagonist 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, indicating the involvement of cGMP. Treatment of cells with antisense, but not control oligodeoxynucleotide (ODN), against PTP-1B attenuated the inhibitory effect of NO on cell motility. Cell shape and adhesion are important determinants of cell motility. We report that SNAP induced cell rounding and reduced adhesion and caused dissociation of actin stress fibers. Moreover, SNAP reduced phosphotyrosine levels in focal adhesion proteins, paxillin, and focal adhesion kinase. The PTP inhibitor phenylarsine oxide or decrease of PTP-1B protein levels via the use of antisense ODN prevented NO-induced cell-shape change, altered adhesion, and migration. These results indicate that NO regulates cell shape, adhesion, and migration by dephosphorylation of focal adhesion proteins via a mechanism that requires PTP-1B activity.