Endothelin-1 contributes to increased NFATc3 activation by chronic hypoxia in pulmonary arteries

Abstract

Chronic hypoxia (CH) activates the Ca(2+)-dependent transcription factor nuclear factor of activated T cells isoform c3 (NFATc3) in mouse pulmonary arteries. However, the mechanism of this response has not been explored. Since we have demonstrated that NFATc3 is required for CH-induced pulmonary arterial remodeling, establishing how CH activates NFATc3 is physiologically significant. The goal of this study was to test the hypothesis that endothelin-1 (ET-1) contributes to CH-induced NFATc3 activation. We propose that this mechanism requires increased pulmonary arterial smooth muscle cell (PASMC) intracellular Ca(2+) concentration ([Ca(2+)](i)) and stimulation of RhoA/Rho kinase (ROK), leading to calcineurin activation and actin cytoskeleton polymerization, respectively. We found that: 1) CH increases pulmonary arterial pre-pro-ET-1 mRNA expression and lung RhoA activity; 2) inhibition of ET receptors, calcineurin, L-type Ca(2+) channels, and ROK blunts CH-induced NFATc3 activation in isolated intrapulmonary arteries from NFAT-luciferase reporter mice; and 3) both ET-1-induced NFATc3 activation in isolated mouse pulmonary arteries ex vivo and ET-1-induced NFATc3-green fluorescence protein nuclear import in human PASMC depend on ROK and actin polymerization. This study suggests that CH increases ET-1 expression, thereby elevating PASMC [Ca(2+)](i) and RhoA/ROK activity. As previously demonstrated, elevated [Ca(2+)](i) is required to activate calcineurin, which dephosphorylates NFATc3, allowing its nuclear import. Here, we demonstrate that ROK increases actin polymerization, thus providing structural support for NFATc3 nuclear transport.

Endothelin‐1 induces hypoxia inducible factor 1α expression in pulmonary artery smooth muscle cells

“…2A, ET-1 dose-dependently increased calciuneurin activity, 100 nM ET-1 caused a 3-fold increase in calcineurin activity compared with control (P < 0.01), indicating that calcineurin is effectively activated in PASMCs by ET-1. This is consistent with the finding by de Frutos et al [24], who has reported that ET-1 activates calcineruin/NFAT signaling pathway in pulmonary arteries.…”

The role of nuclear factor of activated T cells in pulmonary arterial hypertension

“…ROK activiity is responsible for actin polymerization which supports nucleus translocation of NFATc3. 35 Constitutively activated NFATc3 promotes soluble guonylyl cyclase-a1 and upregulation of the SM hypertrophic marker SM-a-actin in PASMC. 36,37 By contrast, Kang et al reported that lentiviral overexpression NFATc3 alone in human PASMC decreased SM -a-actin expression.…”

Mechanisms of NFATc3 activation by increased superoxide and reduced hydrogen peroxide in pulmonary arterial smooth muscle

“…We previously demonstrated that NFATc3 is required for chronic hypoxia (CH)-induced pulmonary arterial remodeling and pulmonary hypertension in mice (10, 25). Pulmonary hypertension is associated with polycythemia, arterial remodeling, increased vascular contractility, augmented concentrations of circulating endothelin-1 (ET-1), and elevated reactive oxygen species (ROS) (1,9,19,24,28,32,36,55 (2): SOD1 and extracellular SOD3 (Cu,Zn-SOD) and mitochondrial SOD2 (Mn-SOD); SOD1, the predominant cytosolic isoform (4), is also present in the mitochondrial intermembrane space (42). We recently showed that SOD1 knockout (KO) mice develop NFAT-dependent spontaneous pulmonary hypertension (62).…”

“…We previously demonstrated that ET-1 contributes to CH-induced NFATc3 activation in PASMC (24). NFATc3 activation by ET-1 involves ET type A receptor (ET A R)-mediated elevation of PASMC intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) and stimulation of RhoA/Rho kinase (ROCK) activity (24).…”