Dopamine 1 receptors inhibit apoptosis via activating CSE/H2 S pathway in high glucose-induced vascular endothelial cells

Exogenous H2S alleviates senescence of glomerular mesangial cells through up-regulating mitophagy by activation of AMPK-ULK1-PINK1-parkin pathway in mice

Hydrogen sulfide (H2S) is the third gas signaling molecule that has been shown to be involved in the regulating vital activities in the body, including inhibition of aging. However, it is unknown whether H2S alleviates aging in the kidney and glomerular mesangial cells (GMCs) by modulating their mitophagy. Here, results of experiments in vivo and in vitro showed that compared with control group, the renal function of mice and GMCs viability were decreased in D-gal (D-galactose) group, while the activity of SA-β-gal and p21 expression were increased, Cyclin D1 and Klotho expressions were decreased; H2S content and CSE expression were lower; ROS and MDA contents and mitochondrial permeability transition pore (mPTP) opening were risedose; ATP production and mitochondrial membrane potential (Δψm) were reduced; Apoptotic rate, the expression of Cleaved caspase-9 and -3, Cyt c, p62 and Drp1 were enhanced and the expression of Bcl-2, Mfn2, Beclin-1, LC3 II/I, PINK1 and parkin were decreased. In addition, phospho-AMPK/AMPK and phospho-ULK1/ULK1 were also decreased significantly. Compared with the D-gal group, the changes of above indexes were reversed in the D-gal + NaHS (Sodium hydrosulfide, an exogenous H2S donor) group. The reverse effects of NaHS were similar to that of AICAR (an AMPK agonist) and kinetin (a PINK1 agonist), respectively. Taken together, these results suggest that exogenous H2S increases mitophagy and inhibits apoptosis as well as oxidative stress through up-regulation of AMPK-ULK1-PINK1-parkin pathway, which delays kidney senescence in mice.

Dopamine D1 receptor activation ameliorates ox-LDL-induced endothelial cell senescence via CREB/Nrf2 pathway

Endothelial cell senescence is involved in endothelial dysfunction and aging-related vascular diseases. The D1-like dopamine receptor (DR1), a number of G-protein-coupled receptors, is currently under consideration as a potential therapeutic target for the prevention of atherosclerosis. However, the role of DR1 in regulating ox-LDL-stimulated endothelial cell senescence remains unknown. Here, we found that the elevated Prx hyperoxidation and reactive oxygen species (ROS) levels in ox-LDL-treated Human umbilical vein endothelial cells (HUVECs) were observed, suppressed by DR1 agonist SKF38393. Increased proportion of senescence-associated β-galactosidase (SA-β-gal) positive staining cells and activated p16/p21/p53 pathway in ox-LDL-treated HUVECs were significantly abolished by DR1 activation. In addition, SKF38393 increased the phosphorylation of cAMP response element-binding protein (CREB) at serine-133, nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and expression of HO-1 in HUVECs. In contrast, adding H-89, a PKA inhibitor, diminished the effects of DR1 activation. Further studies performed with DR1 siRNA confirmed that DR1 was involved in CREB/Nrf2 pathway. Taken together, DR1 activation reduces ROS production and cell senescence by upregulating CREB/Nrf2 antioxidant signaling in ox-LDL-induced endothelial cells. Thus, DR1 could be a potential molecular target to counteract oxidative stress-induced cellular senescence.

DR1-CSE/H2S pathway upregulates autophagy and inhibits H9C2 cells damage induced by high glucose

In the cardiovascular system, long-term high glucose (HG) can lead to cardiomyocyte damage. Hydrogen sulfide (H₂S) reduces cell autophagy in cardiomyocytes. Dopamine 1 receptors (DR1), a specific binding receptor for dopamine, which has a significant regulatory effect on cardiomyocytes. However, it is unclear whether DR1 inhibits HG-induced cardiomyocyte damage by regulating endogenous H₂S production and the level of cell autophagy. The present data indicated that the expression of DR1 and cystathionine-γ-lyase (CSE, a key enzyme for endogenous H₂S production) and H₂S content were significantly reduced in HG-induced cardiomyocytes, which was reversed by SKF38393 (an agonist of DR1). NaHS (an exogenous H₂S donor) only increased H₂S content and the expression of CSE with no effect on DR1 expression. HG reduced cell viability, the expression of Bcl-2 and Beclin1, the production of autophagosomes and LC3 II/I ratio and increased the cell apoptotic ratio, the expression of cleaved caspase-3, cleaved caspase-9, cytochrome c, P62, and p-mTOR/t-mTOR ratio. SKF38393 and NaHS reversed the effects of HG. PPG (an inhibitor of CSE) and 3MA (an inhibitor of autophagy) abolished the beneficial effect of SKF38393. In addition, AICAR (an agonist of AMPK) and Rapamycin (an inhibitor of mTOR) increased the production of autophagosomes but decreased the p-mTOR/t-mTOR ratio, which was similar to the effects of SKF38393 and 3MA. Our findings suggest that DR1 reduces the HG-induced cardiomyocyte damage via up-regulating the CSE/H₂S pathway, which increases cell autophagy by inhibiting the activation of mTOR.