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Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus that eventually progresses to heart failure. The sarco(endo)plasmic reticulum calcium ATPase 2a (SERCA2a), an important calcium pump in cardiomyocytes, is closely related to myocardial systolic-diastolic function. In mammalian cells, hydrogen sulfide (H 2 S), as a second messenger, antioxidant, and sulfurizing agent, is involved in diverse biological processes. Despite the importance of H 2 S for protection against DCM, the mechanisms remain poorly understood. The aim of the present study was to determine whether H 2 S regulates intracellular calcium homeostasis by acting on SERCA2a to reduce cardiomyocyte apoptosis during DCM. Db/db mice were injected with NaHS for 18 weeks. Neonatal rat cardiomyocytes (NRCMs) were treated with high glucose, palmitate, oleate, and NaHS for 48 h. Compared to the NaHS-treated groups, in vivo and in vitro type 2 diabetic models both showed reduced intracellular H 2 S content, reduced cystathionine γ-lyase (CSE) expression, impaired cardiac function, decreased SERCA2a expression and decreased SERCA2a activity, reduced SUMOylation of SERCA2a, increased sentrin-specific protease 1 (SENP1) expression, and disruption of calcium homeostasis leading to activation of the mitochondrial apoptosis pathway. Compared to the NaHS-treated type 2 diabetes cellular model, overexpression of SENP1 C683A reduced the S-sulfhydration of SENP1, reduced the SUMOylation of SERCA2a, reduced the increased expression and activity of SERCA2a, and induced mitochondrial apoptosis in cardiomyocytes. These results suggested that exogenous H 2 S elevates SENP1 S-sulfhydration to increase SERCA2a SUMOylation, improve myocardial systolic-diastolic function, and decrease cardiomyocyte apoptosis in DCM., Competing Interests: Conflict of interest statement The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier Masson SAS.)

Hydrogen sulfide (H 2 S), as a gasotransmitter, is involved in various pathophysiological processes. Diabetic cardiomyopathy (DCM) is a major complication of diabetes mellitus (DM), which leads to structural and functional abnormalities of the myocardium and eventually causes heart failure (HF). Systolic and diastolic dysfunction are fundamental features of heart failure. SERCA2a, as a key enzyme for calcium transport in the endoplasmic reticulum (ER), affects the process of myocardial relaxation and contraction. H 2 S can protect the cardiac function against diabetic hearts, however, its mechanisms are unclear. This study found that exogenous H 2 S affects cellular calcium transport by regulating the H 2 S/MuRF1/SERCA2a/cardiac contractile pathway. Our results showed that, compared with the db/db mice, exogenous H 2 S restored the protein expression levels of CSE and SERCA2a, and the activity of SERCA2a, while reducing cytosolic calcium concentrations and MuRF1 expression. We demonstrated that MuRF1 could interact with SERCA2a via co-immunoprecipitation. Using LC-MS/MS protein ubiquitylation analysis, we identified 147 proteins with increased ubiquitination levels, including SERCA2a, in the cardiac tissues of the db/db mice compared with NaHS-treated db/db mice. Our studies further revealed that NaHS administration modified MuRF1 S-sulfhydration and enhanced the activity and expression of SERCA2a. Under hyperglycemia and hyperlipidemia, overexpression of the MuRF1-Cys44 mutant plasmid reduced the S-sulfhydration level of MuRF1 and decreased the ubiquitination level of SERCA2a and the intracellular Ca 2+ concentration. These findings suggested that H 2 S modulates SERCA2a ubiquitination through MuRF1 S-sulfhydration of Cys44 to prevent decreased myocardial contractility due to increased cytosolic calcium.

Accumulation of lipid droplets (LDs) induces cardiac dysfunctions in type 2 diabetes patients. Recent studies have shown that hydrogen sulphide (H 2 S) ameliorates cardiac functions in db/db mice, but its regulation on the formation of LDs in cardiac tissues is unclear. Db/db mice were injected with NaHS (40 μmol·kg -1 ) for twelve weeks. H9c2 cells were treated with high glucose (40 mmol/L), oleate (200 µmol/L), palmitate (200 µmol/L) and NaHS (100 µmol/L) for 48 hours. Plasmids for the overexpression of wild-type Hrd1 and Hrd1 mutated at Cys115 were constructed. The interaction between Hrd1 and DGAT1 and DGAT2, the ubiquitylation level of DGAT1 and 2, the S-sulfhydration of Hrd1 were measured. Exogenous H 2 S ameliorated the cardiac functions, decreased ER stress and reduced the number of LDs in db/db mice. Exogenous H 2 S could elevate the ubiquitination level of DGAT 1 and 2 and increased the expression of Hrd1 in cardiac tissues of db/db mice. The S-sulfhydration of Hrd1 by NaHS enhanced the interaction between Hrd1 and DGAT1 and 2 to inhibit the formation of LD. Our findings suggested that H 2 S modified Hrd1 S-sulfhydration at Cys115 to reduce the accumulation of LDs in cardiac tissues of db/db mice., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Muscle atrophy occurs in many pathological states, including cancer, diabetes and sepsis, whose results primarily from accelerated protein degradation and activation of the ubiquitin-proteasome pathway. Expression of Muscle RING finger 1 (MuRF1), an E3 ubiquitin ligase, was increased to induce the loss of muscle mass in diabetic condition. However, hydrogen sulphide (H 2 S) plays a crucial role in the variety of physiological functions, including antihypertension, antiproliferation and antioxidant. In this study, db/db mice and C2C12 myoblasts treated by high glucose and palmitate and oleate were chose as animal and cellular models. We explored how exogenous H 2 S attenuated the degradation of skeletal muscle via the modification of MuRF1 S-sulfhydration in db/db mice. Our results show cystathionine-r-lyase expression, and H 2 S level in skeletal muscle of db/db mice was reduced. Simultaneously, exogenous H 2 S could alleviate ROS production and reverse expression of ER stress protein markers. Exogenous H 2 S could decrease the ubiquitination level of MYOM1 and MYH4 in db/db mice. In addition, exogenous H 2 S reduced the interaction between MuRF1 with MYOM1 and MYH4 via MuRF1 S-sulfhydration. Based on these results, we establish that H 2 S prevented the degradation of skeletal muscle via MuRF1 S-sulfhydration at the site of Cys44 in db/db mice., (© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Background and Purpose: Hydrogen sulfide (H 2 S) plays important roles as a gasotransmitter in pathologies. Increased expression of the E3 ubiquitin ligase, muscle RING finger-1 (MuRF1), may be involved in diabetic cardiomyopathy. Here we have investigated whether and how exogenous H 2 S alleviates cardiac muscle degradation through modifications of MuRF1 S-sulfhydration in db/db mice., Experimental Approach: Neonatal rat cardiomyocytes were treated with high glucose (40 mM), oleate (100 μM), palmitate (400 μM), and NaHS (100 μM) for 72 hr. MuRF1 was silenced with siRNA technology and mutation at Cys 44 . Endoplasmic reticulum stress markers, MuRF1 expression, and ubiquitination level were measured. db/db mice were injected with NaHS (39 μmol·kg -1 ) for 20 weeks. Echocardiography, cardiac ultrastructure, cystathionine-γ-lyase, cardiac structure proteins expression, and S-sulfhydration production were measured., Key Results: H 2 S levels and cystathionine-γ-lyase protein expression in myocardium were decreased in db/db mice. Exogenous H 2 S reversed endoplasmic reticulum stress, including impairment of the function of cardiomyocytes and structural damage in db/db mice. Exogenous H 2 S could suppress the levels of myosin heavy chain 6 and myosin light chain 2 ubiquitination in cardiac tissues of db/db mice, and MuRF1 was modified by S-sulfhydration, following treatment with exogenous H 2 S, to reduce the interaction between MuRF1 and myosin heavy chain 6 and myosin light chain 2., Conclusions and Implications: Our findings suggest that H 2 S regulates MuRF1 S-sulfhydration at Cys 44 to prevent myocardial degradation in the cardiac tissues of db/db mice., Linked Articles: This article is part of a themed section on Hydrogen Sulfide in Biology & Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc., (© 2019 The British Pharmacological Society.)

Hydrogen sulfide (H 2 S), a gaseous molecule, is involved in modulating multiple physiological functions, such as antioxidant, antihypertension, and the production of polysulfide cysteine. H 2 S may inhibit reactive oxygen species generation and ATP production through modulating respiratory chain enzyme activities; however, the mechanism of this effect remains unclear. In this study, db/db mice, neonatal rat cardiomyocytes, and H9c2 cells treated with high glucose, oleate, and palmitate were used as animal and cellular models of type 2 diabetes. The mitochondrial respiratory rate, respiratory chain complex activities, and ATP production were decreased in db/db mice compared with those in db/db mice treated with exogenous H 2 S. Liquid chromatography with tandem mass spectrometry analysis showed that the acetylation level of proteins involved in the mitochondrial respiratory chain were increased in the db/db mice hearts compared with those with sodium hydrosulfide (NaHS) treatment. Exogenous H 2 S restored the ratio of NAD + /NADH, enhanced the expression and activity of sirtuin 3 (SIRT3) and decreased mitochondrial acetylation level in cardiomyocytes under hyperglycemia and hyperlipidemia. As a result of SIRT3 activation, acetylation of the respiratory complexe enzymes NADH dehydrogenase 1 (ND1), ubiquinol cytochrome c reductase core protein 1, and ATP synthase mitochondrial F1 complex assembly factor 1 was reduced, which enhanced the activities of the mitochondrial respiratory chain activity and ATP production. We conclude that exogenous H 2 S plays a critical role in improving cardiac mitochondrial function in diabetes by upregulating SIRT3.

Background and Purpose: Hydrogen sulfide (H2 S) plays important roles as a gasotransmitter in pathologies. Increased expression of the E3 ubiquitin ligase, muscle RING finger-1 (MuRF1), may be involved in diabetic cardiomyopathy. Here we have investigated whether and how exogenous H2 S alleviates cardiac muscle degradation through modifications of MuRF1 S-sulfhydration in db/db mice.Experimental Approach: Neonatal rat cardiomyocytes were treated with high glucose (40 mM), oleate (100 μM), palmitate (400 μM), and NaHS (100 μM) for 72 hr. MuRF1 was silenced with siRNA technology and mutation at Cys44 . Endoplasmic reticulum stress markers, MuRF1 expression, and ubiquitination level were measured. db/db mice were injected with NaHS (39 μmol·kg-1 ) for 20 weeks. Echocardiography, cardiac ultrastructure, cystathionine-γ-lyase, cardiac structure proteins expression, and S-sulfhydration production were measured.Key Results: H2 S levels and cystathionine-γ-lyase protein expression in myocardium were decreased in db/db mice. Exogenous H2 S reversed endoplasmic reticulum stress, including impairment of the function of cardiomyocytes and structural damage in db/db mice. Exogenous H2 S could suppress the levels of myosin heavy chain 6 and myosin light chain 2 ubiquitination in cardiac tissues of db/db mice, and MuRF1 was modified by S-sulfhydration, following treatment with exogenous H2 S, to reduce the interaction between MuRF1 and myosin heavy chain 6 and myosin light chain 2.Conclusions and Implications: Our findings suggest that H2 S regulates MuRF1 S-sulfhydration at Cys44 to prevent myocardial degradation in the cardiac tissues of db/db mice.Linked Articles: This article is part of a themed section on Hydrogen Sulfide in Biology & Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc. [ABSTRACT FROM AUTHOR]