Hydrogen Sulfide Epigenetically Attenuates Homocysteine‐Induced Mitochondrial Toxicity Mediated Through NMDA Receptor in Mouse Brain Endothelial (bEnd3) Cells

Abstract

Previously we have showed that homocysteine (Hcy) caused oxidative stress and altered mitochondrial function. Hydrogen sulphide (H2S) has potent anti-inflammatory, anti-oxidative and anti-apoptotic effects. Therefore, in the present study we examined whether H2S ameliorates Hcy-induced mitochondrial toxicity which led to endothelial dysfunction in part, by epigenetic alterations in mouse brain endothelial cells (bEnd3). The bEnd3 cells were exposed to 100μM Hcy treatment in the presence or absence of 30μM NaHS (donor of H2S) for 24hrs. Hcy-activate NMDA receptor and induced mitochondrial toxicity by increased levels of Ca2+, NADPH-oxidase-4 (NOX-4) expression, mitochondrial dehydrogenase activity and decreased the level of nitrate, superoxide dismutase (SOD-2) expression, mitochondria membrane potentials, ATP production. To confirm the role of epigenetic, 5′-azacitidine (an epigenetic modulator) treatment was given to the cells. Pretreatment with NaHS (30μM) attenuated the Hcy-induced increased expression of DNMT1, DNMT3a, Ca2+ and decreased expression of DNMT3b in bEND3 cells. Furthermore, NaHS treatment also enhanced mitochondrial oxidative stress (NOX4, ROS, and NO) and restored ATP that indicates its protective effects against mitochondrial toxicity. Additional, NaHS significantly alleviated Hcy-induced LC3-I/II, CSE, Atg3/7 and low p62 expression which confirm its effect on mitophagy. Likewise, NaHS also restored level of eNOS, CD31, VE-Cadherin and ET-1 and maintains endothelial function in Hcy treated cells. Molecular inhibition of NMDA receptor by using small interfering RNA showed protective effect whereas inhibition of H2S production by propargylglycine (PG) (inhibitor of enzyme CSE) showed mitotoxic effect. Taken together, results demonstrate that, administration of H2S protected the cells from HHcy-induced mitochondrial toxicity and endothelial dysfunction.

Hydrogen Sulfide in Renal Physiology and Disease

“…In the brain, HHCy induces the disruption of the bloodbrain barrier (39), a reduction of the cerebral blood flow (40), an increase in oxidative and nitrosative stress (39), and an increase in cerebral inflammation (39,40). The fact that all the consequences of HHCy on the vasculature, the myocardium, and the brain are counteracted by H2S donors (12,39,40) suggests that H2S deficiency is the major mechanism leading to tissue injury in HHCy. This is reinforced by the study showing that a triple gene therapy (CBS-CSE-3-MST) blocks the effects of HHCy on vasorelaxation in an ex vivo renal artery culture; this approach also restores the levels of vascular endothelial growth factor (VEGF), CD31 and reduces elevated endostatin levels (79).…”

“…H2S ameliorates oxidative stress by inhibiting mitochondrial ROS generation (88), increasing GSH production (43), and promoting the transcription of antioxidant genes via the activation of Nrf2 transcription factor (10,23,27). H2S has also been reported to inhibit HCy-induced NOX4 expression in the brain endothelial cells (40). Whether H2S regulation of NOX4 involves NO is not known.…”

A potential role of hydrogen sulfide (H2S) in the regulation of the Ras-ERK signaling-dependent transcription of DNA methyltransferases

“…The authors proved that H 2 S donors could regulate NADP+/NADPH balance and induce SOD2 expression, after which DNMTs expression is down-regulated [19].…”

“…Indeed, there are a lot of studies on the Ras-ERK signaling and DNMTs transcription regulation by H 2 S upon the oxidative stress conditions [17][18][19]. We also pointed out to the proteine sulfhydration and nitrosylation as well as lipid metabolism as new potential regulation targets of H 2 S important for the Ras-ERK dependent DNMTs transcription.…”

Controlled release hydrogen sulfide delivery system based on mesoporous silica nanoparticles protects graft endothelium from ischemia–reperfusion injury

“…15 Furthermore, H 2 S pretreatment of murine microvascular ECs reduced mitochondrial DNA damage that resulted from oxidative stress. Endothelial dysfunction, such as the detachment and apoptosis of ECs, is widely regarded as a robust independent predictor of CAV.…”