PYK2 selectively mediates signals for growth versus differentiation in response to stretch of spontaneously active vascular smooth muscle.

Anirban Bhattachariya,Ina Nordström,Leonard Buckbinder,Karolina M Turczyńska,Per Hellstrand,Sebastian Albinsson,Mario Grossi

doi:10.14814/phy2.12080

Anirban Bhattachariya, Ina Nordström + Show 5 more

Open Access

https://doi.org/10.14814/phy2.12080

Copy DOI

Journal: Physiological reports	Publication Date: Jul 1, 2014
Citations: 17	License type: cc-by

Affiliation: Lund University, Pfizer (United States)

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.

Highlights

Vascular smooth muscle cells play dual roles in the vessel wall by, on one hand, regulating blood flow and, on the other, preserving the integrity of the vessel wall via proliferation, migration, and protein synthesis in response to environmental challenges such as mechanical stimuli, tissue injury, and inflammation
Using organ culture of rat and mouse portal vein, we have previously demonstrated that actin polymerization in vascular smooth muscle is stimulated by stretch of the vessel wall, which correlates with synthesis of serum response factor (SRF)-dependent smooth muscle marker proteins (Albinsson et al 2004)
Since bone remodeling is stimulated by mechanical load, and proline-rich tyrosine kinase 2 (PYK2) is regulated both by integrins and calcium, it may exert partly similar functions in bone and vascular tissue

Summary

Introduction

Vascular smooth muscle cells play dual roles in the vessel wall by, on one hand, regulating blood flow and, on the other, preserving the integrity of the vessel wall via proliferation, migration, and protein synthesis in response to environmental challenges such as mechanical stimuli, tissue injury, and inflammation. This dual role of smooth muscle is reflected in phenotypic plasticity enabling vascular smooth muscle to take on either a “contractile” or a “synthetic” phenotype appropriate for these different roles (Owens 1995).

Methods

Results

Conclusion