Hypoxia increases AP-1 binding activity by enhancing capacitative Ca²⁺entry in human pulmonary artery endothelial cells

Abstract

[Ca 2ϩ ]cyt in pulmonary artery endothelial cells (PAEC). Using combined molecular biological, fluorescence microscopy, and biophysical approaches, we examined the effect of chronic hypoxia (3% O 2, 72 h) on AP-1 DNA binding activity, CCE, and transient receptor potential (TRP) gene expression in human (h) PAEC. EMSA showed that AP-1 binding to hPAEC nuclear protein extracts was significantly enhanced by hypoxia, the increase being dependent on storeoperated Ca 2ϩ influx and sensitive to La 3ϩ , an SOC inhibitor. Hypoxia also increased basal [Ca 2ϩ ]cyt, the amount of CCE produced by store depletion with cyclopiazonic acid, and the amplitude of SOC-mediated currents (I SOC). The increases of CCE amplitude and I SOC current density by hypoxia were paralleled by enhanced TRPC4 mRNA and protein expression. Hypoxia-enhanced CCE and TRPC4 expression were also attenuated by La 3ϩ . These data suggest that hypoxia increases AP-1 binding activity by enhancing Ca 2ϩ influx via La 3ϩ -sensitive TRP-encoded SOC channels in hPAEC. The Ca 2ϩ -mediated increase in AP-1 binding may play an important role in upregulating AP-1-responsive gene expression, in stimulating pulmonary vascular cell proliferation and, ultimately, in pulmonary vascular remodeling in patients with hypoxia-mediated pulmonary hypertension. activating protein-1; store-operated channels; transient receptor potential genes PULMONARY VASCULAR REMODELING in patients and animals with hypoxia-mediated pulmonary hypertension is characterized by pulmonary arterial medial hyper-

Identification of functional voltage-gated Na+ channels in cultured human pulmonary artery smooth muscle cells

“…Ion channels, which can both control and be controlled by E m , therefore are important mediators of the pulmonary vascular response. Indeed, dysfunctional K + channels and upregulated transient receptor potential (TRP) channels have been implicated in the development of idiopathic pulmonary arterial hypertension [9,32,35,36]. Although there is no direct evidence to suggest alterations of Na + channel function in sustained pulmonary vasoconstriction and excessive pulmonary vascular medial hypertrophy in patients with pulmonary arterial hypertension, a recent cDNA microarray study showed that the mRNA expression of the voltage-gated Na + channel β 1 (SCN1B) subunit was increased in lungs tissues from patients with idiopathic and familial pulmonary arterial hypertension [14].…”

Imbalance and dysfunction of transient receptor potential channels contribute to the pathogenesis of hypertension

“…Based on their amino acid sequence homology, mammalian TRP channels can be divided into six subfamilies, including TRP canonical (TRPC; TRPC1-7), TRP vanilloid (TRPV; TRPV1-6), TRP melastatin (TRPM; TRPM1-8), TRP mucolipin (TRPML; TRPML1-3), TRP ankyrin (TRPA; TRPA1) and TRP polycystin (TRPP; TRPP2, TRPP3, TRPP5) [20]. In general, all seven members of TRPC [2125]; TRPV1, -2, -4 [2628]; all TRPM, except TRPM5 [27] and TRPP1 and -2 [29,30], have been reported to expressed in vascular endothelial cells (ECs) from various sources. TRP channels other than TRPV5, TRPV6, and TRPM1 are found in arterial smooth muscle from different segments of the vasculature [31].…”

Pulmonary Hypertension Is a Probable NO/ONOO−Cycle Disease: A Review

“…PAH is thought to be triggered, in this condition, by hypoxia. Although animals are susceptible to high altitude PAH [100,101], most animal model studies of this condition have studied animal responses to hypoxia [102][103][104][105][106][107][108].…”

“…Fantozzi et al [103] showed that hypoxia increased calcium in�ux into human arterial endothelial cells and Remillard and Yuan [99] also implicated increased calcium in�ux. From these and other studies, Fantozzi et al [103] conclude that such calcium in�ux plays a role in "stimulating pulmonary vascular cell proliferation and ultimately, in pulmonary vascular cell remodeling in patients with hypoxia-mediated pulmonary hypertension. "…”

“…Fantozzi et al [103] showed that hypoxia increased calcium in�ux into human arterial endothelial cells and Remillard and Yuan [99] also implicated increased calcium in�ux. From these and other studies, Fantozzi et al [103] conclude that such calcium in�ux plays a role in "stimulating pulmonary vascular cell proliferation and ultimately, in pulmonary vascular cell remodeling in patients with hypoxia-mediated pulmonary hypertension. " Bartsch et al [104] showed that the calcium channel blocker nifedipine lowered high-altitude edema associated with high-altitude hypertension, suggesting an important role for elevated intracellular calcium in high-altitude PAH.…”