S1P₂ receptor-dependent Rho-kinase activation mediates vasoconstriction in the murine pulmonary circulation induced by sphingosine 1-phosphate

Abstract

Vasoactive properties of sphingosine 1-phosphate (S1P) have been demonstrated by many investigators to vary in systemic vascular beds. These variations appear to reflect differential S1P receptor expression in the vasculature of these tissues. Although S1P has been demonstrated to enhance endothelial barrier function, induce airway hyperresponsiveness, and modulate immune responses in the lung, the pulmonary vasomotor effects of S1P remain poorly defined. In the present study, we sought to define the vasoregulatory effects of S1P in the pulmonary vasculature and to elucidate the underlying mechanisms operative in effecting the response in the intact lung. S1P (10 microM) increased pulmonary vascular resistance (PVR) by 36% in the isolated perfused mouse lung. S1P-induced vasoconstriction was reduced by 64% by concomitant administration of the Rho-kinase inhibitor Y27632 (10 microM). Similarly, the S1P response was attenuated by >50% after S1P(2) receptor antagonism (JTE-013; 10 microM) and in S1P(2) receptor null mice. In contrast, S1P(3) receptor antagonism (VPC23019; 10 microM) had no effect on the contractile response to S1P. Furthermore, we confirmed the role of Rho-kinase as an important regulator of basal vasomotor tone in the isolated perfused mouse lung. These results suggest that S1P is capable of altering pulmonary vascular tone in vivo and may play an important role in the modulation of pulmonary vascular tone both in the normal lung and under pathological conditions.

CFTR and sphingolipids mediate hypoxic pulmonary vasoconstriction

“…Albeit S1P was not required for TRPC6 recruitment to caveolae, SphK inhibition or SphK1 deficiency markedly inhibited HPV, demonstrating that TRPC6 translocation alone is not sufficient to elicit a full HPV response, which instead requires additional S1P signaling. In line with previous data demonstrating that S1P can trigger pulmonary vasoconstriction by acting through either S1P 2 (29) or S1P 4 (30), we found HPV similarly inhibited by the dual S1P 2/4 inhibitor JTE-013. Intriguingly, while S1P increased [Ca 2+ ] i in smooth muscle cells of both the pulmonary and the systemic circulation, CFTR inhibition attenuated S1P-induced Ca 2+ mobilization in PASMCs, but amplified the response in CASMCs.…”

“…6A). This notion was confirmed by experiments demonstrating that JTE-013, which blocks S1P receptors 2 and 4, both of which have been shown to promote pulmonary vasoconstriction (29,30), similarly inhibited HPV (Fig. 6A).…”

“…In the lung, SphK1 is the predominant SphK isoform (27) and has been shown to modulate pulmonary vascular responsiveness and remodeling (28). S1P acts intracellularly as a second messenger or extracellularly via activation of five G protein-coupled receptors (GPCRs) termed S1P [1][2][3][4][5] (25), of which S1P 2 (29) and S1P 4 (30) mediate pulmonary vasoconstriction. Because S1P 2 (29,31) and S1P 4 (32) receptor engagement activates PLC and RhoK, and S1P is a known activator of TRPC5 (33), we hypothesized that S1P may trigger both central pathways of HPV, DAG formation and consecutive TRPC6-induced Ca 2+ mobilization, as well as RhoK-mediated Ca 2+ sensitization (1).…”

“…S1P acts intracellularly as a second messenger or extracellularly via activation of five G protein-coupled receptors (GPCRs) termed S1P [1][2][3][4][5] (25), of which S1P 2 (29) and S1P 4 (30) mediate pulmonary vasoconstriction. Because S1P 2 (29,31) and S1P 4 (32) receptor engagement activates PLC and RhoK, and S1P is a known activator of TRPC5 (33), we hypothesized that S1P may trigger both central pathways of HPV, DAG formation and consecutive TRPC6-induced Ca 2+ mobilization, as well as RhoK-mediated Ca 2+ sensitization (1). A potential role of S1P in HPV is particularly intriguing in consideration of its potential tie to CFTR, in that CFTR is one of only two transporters shown to translocate S1P across biological membranes (17).…”

Les récepteurs de la sphingosine 1-phosphate

“…Les récepteurs de S1P concourent aussi à la régulation du tonus vasculaire, régulant à la fois la contraction et la relaxation des cellules musculaires lisses. Le S1P 3 [12] et le S1P 2 [13] seraient responsables de l'effet vasoconstricteur de la S1P. Le S1P 3 induit la relaxation des cellules musculaires lisses via la production de NO à partir de l'endothélium [14].…”