Effects of G protein-coupled estrogen receptor on hydrogen sulfide production and cystathionine γ-lyase expression in human endothelial cells

Hydrogen sulfide (H₂S) is an important regulator of cardiovascular homeostasis, along with nitric oxide (NO). In endothelial cells, H₂S is primarily synthesized by cystathionine γ-lyase (CSE) using L-cysteine and homocysteine as substrates. However, it has not been elucidated how G protein-coupled estrogen receptor 1 (GPER) affects H₂S production in endothelial cells. In this study, we investigated whether GPER activation enhances H₂S production by upregulating CSE expression in endothelial cells, and identified the underlying molecular mechanism. G-1 increased the phosphorylation of cAMP response element binding (CREB), protein kinase B (Akt), extracellular signal-regulated kinase 1/2 (ERK1/2), AMP-activated protein kinase (AMPK), Ca²⁺/calmodulin protein kinase kinase β (CaMKKβ), and Ca²⁺/calmodulin-dependent protein kinase II α (CaMKIIα). Blockade of Akt, ERK1/2, AMPK, CaMKKβ, and CaMKIIα signaling pathways suppressed G-1-induced CSE expression by inhibiting CREB transcriptional activity. In addition, CSE expression was suppressed by inhibiting G protein alpha q subunit (Gαq) and G protein beta gamma subunit complex (Gβγ), which are subunits of GPER. In particular, G-1 induced CSE expression and increased H₂S production in human endothelial EA.hy926 cells, inhibited tumor necrosis factor-alpha (TNF-α)-induced expression of nuclear factor kappa B (NF-kB), and decreased the expression of intracellular adhesion molecules. These findings confirm that GPER affects H₂S production by regulating CSE expression through novel signaling mechanisms, which could be utilized as a potential therapeutic target to prevent endothelial dysfunction in cardiovascular disease.