title: PYK2 selectively mediates signals for growth versus differentiation in response to stretch of spontaneously active vascular smooth muscle.
abstract: Stretch of vascular smooth muscle stimulates growth and proliferation as well as contraction and expression of contractile/cytoskeletal proteins, all of which are also regulated by calcium-dependent signals. We studied the role of the calcium- and integrin-activated proline-rich tyrosine kinase 2 (PYK2) in stretch-induced responses of the rat portal vein loaded by a hanging weight ex vivo. PYK2 phosphorylation at Tyr-402 was increased both by a 10-min stretch and by organ culture with load over several days. Protein and DNA synthesis were reduced by the novel PYK2 inhibitor PF-4594755 (0.5-1 μmol/L), while still sensitive to stretch. In 3-day organ culture, PF-4594755 caused maintained myogenic spontaneous activity but did not affect contraction in response to high-K(+) (60 mmol/L) or to α1-adrenergic stimulation by cirazoline. Basal and stretch-induced PYK2 phosphorylation in culture were inhibited by PF-4594755, closely mimicking inhibition of non-voltage-dependent calcium influx by 2-APB (30 μmol/L). In contrast, the L-type calcium channel blocker, nifedipine (1 μmol/L) eliminated stretch-induced but not basal PYK2 phosphorylation. Stretch-induced Akt and ERK1/2 phosphorylation was eliminated by PF-4594755. PYK2 inhibition had no effect on mRNA expression of several smooth muscle markers, and stretch-sensitive SM22α synthesis was preserved. Culture of portal vein with the Ang II inhibitor losartan (1 μmol/L) eliminated stretch sensitivity of PYK2 and Akt phosphorylation, but did not affect mRNA expression of smooth muscle markers. The results suggest that PYK2 signaling functionally distinguishes effects of voltage- and non-voltage-dependent calcium influx. A small-molecule inhibitor of PYK2 reduces growth and DNA synthesis but does not affect contractile differentiation of vascular smooth muscle.
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Anirban
authors.initials: A
authors.lastname: Bhattachariya
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Karolina M
authors.initials: KM
authors.lastname: Turczyńska
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Mario
authors.initials: M
authors.lastname: Grossi
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Ina
authors.initials: I
authors.lastname: Nordström
authors.affiliation: Pfizer Global Research and Development, Cambridge, 02139, Massachusetts.
authors.forename: Leonard
authors.initials: L
authors.lastname: Buckbinder
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Albinsson
authors.affiliation: Department of Experimental Medical Science, Lund University, Lund, SE-22184, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Hellstrand
keywords: Calcium; PF‐4594755; contraction; ion channel; stretch