NFAT regulation of cystathionine γ-lyase expression in endothelial cells is impaired in rats exposed to intermittent hypoxia

Abstract

Sleep apnea is a risk factor for cardiovascular disease, and intermittent hypoxia (IH, 20 episodes/h of 5% O-5% CO for 7 h/day) to mimic sleep apnea increases blood pressure and impairs hydrogen sulfide (HS)-induced vasodilation in rats. The enzyme that produces HS, cystathionine γ-lyase (CSE), is decreased in rat mesenteric artery endothelial cells (EC) following in vivo IH exposure. In silico analysis identified putative nuclear factor of activated T cell (NFAT) binding sites in the CSE promoter. Therefore, we hypothesized that IH exposure reduces Ca concentration ([Ca]) activation of calcineurin/NFAT to lower CSE expression and impair vasodilation. In cultured rat aortic EC, inhibiting calcineurin with cyclosporine A reduced CSE mRNA, CSE protein, and luciferase activity driven by a full-length but not a truncated CSE promoter. In male rats exposed to sham or IH conditions for 2 wk, [Ca] in EC in small mesenteric arteries from IH rats was lower than in EC from sham rat arteries (Δfura 2 ratio of fluorescence at 340 to 380 nm from Ca free: IH = 0.05 ± 0.02, sham = 0.17 ± 0.03, < 0.05), and fewer EC were NFATc3 nuclear positive in IH rat arteries than in sham rat arteries (IH = 13 ± 3, sham = 59 ± 11%, < 0.05). HS production was also lower in mesenteric tissue from IH rats vs. sham rats. Endothelium-dependent vasodilation to acetylcholine (ACh) was lower in mesenteric arteries from IH rats than in arteries from sham rats, and inhibiting CSE with β-cyanoalanine diminished ACh-induced vasodilation in arteries from sham but not IH rats but did not affect dilation to the HS donor NaHS. Thus, IH lowers EC [Ca], NFAT activity, CSE expression and activity, and HS production while inhibiting NFAT activation lowers CSE expression. The observations that IH exposure decreases NFATc3 activation and CSE-dependent vasodilation support a role for NFAT in regulating endothelial HS production. This study identifies the calcium-regulated transcription factor nuclear factor of activated T cells as a novel regulator of cystathionine γ-lyase (CSE). This pathway is basally active in mesenteric artery endothelial cells, but, after exposure to intermittent hypoxia to mimic sleep apnea, nuclear factor of activated T cells c3 nuclear translocation and CSE expression are decreased, concomitant with decreased CSE-dependent vasodilation.

Models of intermittent hypoxia and obstructive sleep apnea: molecular pathways and their contribution to cancer

“…Hypertension could be prevented by pharmacological inhibition or knockout of NFATc3. In contrast, NFAT activity decreases in rat endothelium following intermittent hypoxia (54).…”

Shear stress regulates cystathionine γ lyase expression to preserve endothelial redox balance and reduce membrane lipid peroxidation

“…To-date endothelial cell CSE has been reported to be regulated by redox-i.e., Nox4- [35], nutrient i.e. ATF4- [36,37], and NFAT/Ca 2+ - [38] dependent mechanisms. To assess the mechanism responsible for the regulation of CSE by shear stress, we focused initially on KLF2 which regulates the expression of eNOS [8,39].…”

The expression of cystathionine gamma-lyase is regulated by estrogen receptor alpha in human osteoblasts

“…This hypothesis linked to the wide modulation of the H 2 S signaling comes from a series of observations that demonstrate how many factors have been discovered to regulate CSE expression and activity at multiple levels, including transcriptional, post-transcriptional and post-translational levels. It is worth noting that up to now a small number of transcription factors, including Sp1, Nrf2, ATF4, Elk1 and NFAT, has been demonstrated to regulate CSE transcription through direct or indirect binding with CSE promoter [ 8 , 32 , 10 , 33 , 34 ]. miR-21 and miR-22 are reported to suppress but PI3K and TNF-α stimulate CSE transcription by targeting Sp1 gene [ 35 – 37 ].…”