The Protective Effect of 1,25(OH)2D3 on Myocardial Function is Mediated via Sirtuin 3-Regulated Fatty Acid Metabolism

Vitamin D Activates Nrf2 to Prevent Nerve Injury and Reduce Brain Damage in Acute Cerebral Infarction

OBJECTIVE

This study aimed to investigate the neuroprotective effects of cholecalciferol cholesterol emulsion (CCE), a vitamin D (VD) precursor, in a murine model of acute cerebral infarction (ACI) and to elucidate the role of the Nrf2 signaling pathway in mediating these effects.

METHODS

Forty C57BL/6J mice (male and female) were divided into five groups (n = 10 per group): control, control + CCE, ACI, ACI + CCE, and ACI + CCE + ML385 (an Nrf2 inhibitor). ACI was induced by middle cerebral artery occlusion (MCAO). CCE was administered for three weeks prior to ACI induction, and ML385 was administered intravenously to inhibit Nrf2. Neurological function, brain edema, and infarct size, as well as inflammatory and apoptotic marker levels, were assessed post-ACI. Statistical analyses were conducted via one-way ANOVA and Student's t test, with P < 0.05 considered significant.

RESULTS

Compared to ACI group, CCE significantly reduced neurological deficits, brain edema, and infarct size (P < 0.01). The ACI + CCE group presented improved short-term memory retention, as evidenced by shorter avoidance latency in shuttle avoidance tests (P < 0.01). CCE administration attenuated the expression of inflammatory markers (IL-6, MIF, Lp-PLA2) while increasing IL-10 levels (P < 0.001). Furthermore, CCE increased Nrf2 and HO-1 expression and reduced apoptosis by decreasing the Bax/Bcl-2 ratio in brain tissue (P < 0.001). ML385 abolished these neuroprotective effects, confirming the role of the Nrf2 pathway in mediating the benefits of VD.

CONCLUSION

VD, via VD receptor-mediated activation of the Nrf2/HO-1 pathway, reduces inflammation, apoptosis, and neurological damage following ACI. These findings support the therapeutic potential of VD in the treatment of ischemic stroke and highlight the importance of Nrf2 in mediating these effects.

Sirtuin 1 mediates the pro-survival effects of vitamin D in angiotensin II-induced hypertrophy of H9c2 cardiomyoblasts

BACKGROUND

The role of 1,25-dihydroxyvitamin-D3 (VitD) and sirtuin-1 (SIRT1) in mitigating pathological cardiac remodeling is well recognized. However, the potential for SIRT1 to mediate the inhibitory effects of VitD on angiotensin II (Ang II) -induced hypertrophy in H9c2 cardiomyoblasts remains unclear.

METHODS

H9c2 cardiomyoblasts were exposed to Ang II or a combination of VitD and Ang II, both in the absence and presence of SIRT1-specific siRNA. In each cell group, cell viability, hypertrophy, and redox state were evaluated using relevant techniques.

RESULTS

In H9c2 cells transfected with SIRT1 siRNA, VitD failed to significantly counteract the Ang II-induced perturbations, which included a reduction in cell viability, decreased CAT and SOD activity/mRNA levels, diminished MnSOD mRNA levels, and increased MDA content. Conversely, VitD significantly inhibited Ang II-induced hypertrophy in H9c2 cells by reducing cell size and lowering ANP and BNP mRNA levels, regardless of SIRT1 status. Notably, neither Ang II nor VitD altered the expression of SIRT1 mRNA or protein in H9c2 cells.

CONCLUSION

SIRT1 serves as an important regulator of pro-survival, but not anti-hypertrophic functions of VitD in hypertrophied cardiomyoblasts. Indeed, the absence of SIRT1 jeopardizes the capabilities of VitD to confer its pro-survival activity in H9c2 cells. Therefore, SIRT1-centered activating compounds may augment the protective effects of VitD, providing a promising therapeutic strategy to reduce the risk of cardiac hypertrophy and heart failure.

Resveratrol mediates mitochondrial function through the sirtuin 3 pathway to improve abnormal metabolic remodeling in atrial fibrillation

This study investigated the impact of resveratrol on abnormal metabolic remodeling in atrial fibrillation (AF) and explored potential molecular mechanisms. An AF cell model was established by high-frequency electrical stimulation of HL-1 atrial muscle cells. Resveratrol concentrations were optimized using CCK-8 and flow cytometry. AF-induced increases in ROS and mitochondrial calcium, along with decreased adenosine triphosphate (ATP) and mitochondrial membrane potential, were observed. Resveratrol mitigated these changes and maintained normal mitochondrial morphology. Moreover, resveratrol acted through the SIRT3-dependent pathway, as evidenced by its ability to suppress AF-induced acetylation of key metabolic enzymes. SIRT3 overexpression controls acetylation modifications, suggesting its regulatory role. In conclusion, resveratrol's SIRT3-dependent pathway intervenes in AF-induced mitochondrial dysfunction, presenting a potential therapeutic avenue for AF-related metabolic disorders. This study sheds light on the role of resveratrol in mitigating AF-induced mitochondrial remodeling and highlights its potential as a novel treatment for AF.

Vitamin D3 Exerts Beneficial Effects on C2C12 Myotubes through Activation of the Vitamin D Receptor (VDR)/Sirtuins (SIRT)1/3 Axis

The onset of sarcopenia is associated with a decline in vitamin D receptor (VDR) expression, wherein reduced VDR levels contribute to muscle atrophy, while heightened expression promotes muscle hypertrophy. Like VDR, the age-related decline in protein deacetylase sirtuin (SIRT) expression is linked to the development of sarcopenia and age-related muscle dysfunction. This study aimed to investigate whether the VDR agonist 1,25-dihydroxyvitamin D3 (1,25VD3) exerts beneficial effects on muscles through interactions with sirtuins and, if so, the underlying molecular mechanisms. Treatment of 1,25VD3 in differentiating C2C12 myotubes substantially elevated VDR, SIRT1, and SIRT3 expression, enhancing their differentiation. Furthermore, 1,25VD3 significantly enhanced the expression of key myogenic markers, including myosin heavy chain (MyHC) proteins, MyoD, and MyoG, and increased the phosphorylation of AMPK and AKT. Conversely, VDR knockdown resulted in myotube atrophy and reduced SIRT1 and SIRT3 levels. In a muscle-wasting model triggered by IFN-γ/TNF-α in C2C12 myotubes, diminished VDR, SIRT1, and SIRT3 levels led to skeletal muscle atrophy and apoptosis. 1,25VD3 downregulated the increased expression of muscle atrophy-associated proteins, including FoxO3a, MAFbx, and MuRF1 in an IFN-γ/TNF-α induced atrophy model. Importantly, IFN-γ/TNF-α significantly reduced the mtDNA copy number in the C2C12 myotube, whereas the presence of 1,25VD3 effectively prevented this decrease. These results support that 1,25VD3 could serve as a potential preventive or therapeutic agent against age-related muscle atrophy by enhancing the VDR/SIRT1/SIRT3 axis.

Ginsenoside AD-2 Ameliorating Lipopolysaccharide-Induced Activation in HSC-T6 Cells and Carbon Tetrachloride-Induced Hepatic Fibrosis in Mice via Regulation of VD-VDR Axis

Ginsenoside 25-hydroxy protopanaxadiol (AD-2) isolated from ginseng was proved to have anti-hepatic fibrosis (HF) effect in our previous study. But the mechanism is unknown. The present study investigated the anti-HF effects and mechanisms of AD-2 on the lipopolysaccharide (LPS)-induced activation in HSC-T6 cells and carbon tetrachloride (CCl4)-induced hepatic fibrosis (HF) in mice. Results showed that AD-2 significantly inhibited the LPS-induced activated HSC-T6 cells in vitro and markedly reduced the serum transaminase and hydroxyproline levels, pathological changes, and hepatic body ratio in CCl4-induced HF mice, indicating AD-2 ameliorated liver injury and reversed HF notably. Moreover, AD-2 decreased the expression of TGF-β1, α-SMA, and MMP2, and maintained TIMP1/MMP9 in balance with the level of vitamin D (VD) and the expression of VD nuclear receptor (VDR) and Sirt3 increased. In conclusion, the anti-HF mechanism of AD-2 is related to the inhibition of HSC activation, promotion of collagen degradation, and regulation of the VD/VDR axis.

Emerging Roles of SIRT3 in Cardiac Metabolism

The heart is a highly metabolically active organ that predominantly utilizes fatty acids as an energy substrate. The heart also derives some part of its energy by oxidation of other substrates, including glucose, lactose, amino acids and ketones. The critical feature of cardiac pathology is metabolic remodeling and loss of metabolic flexibility. Sirtuin 3 (SIRT3) is one of the seven mammalian sirtuins (SIRT1 to SIRT7), with NAD⁺ dependent deacetylase activity. SIRT3 is expressed in high levels in healthy hearts but downregulated in the aged or diseased hearts. Experimental evidence shows that increasing SIRT3 levels or activity can ameliorate several cardiac pathologies. The primary deacetylation targets of SIRT3 are mitochondrial proteins, most of which are involved in energy metabolism. Thus, SIRT3 improves cardiac health by modulating cardiac energetics. In this review, we discuss the essential role of SIRT3 in regulating cardiac metabolism in the context of physiology and pathology. Specifically, we summarize the recent advancements that emphasize the critical role of SIRT3 as a master regulator of cardiac metabolism. We also present a comprehensive view of all known activators of SIRT3, and elaborate on their therapeutic potential to ameliorate energetic abnormalities in various cardiac pathologies.

The Role of Estrogens and Vitamin D in Cardiomyocyte Protection: A Female Perspective

Women experience a dramatical raise in cardiovascular events after menopause. The decline in estrogens is pointed to as the major responsible trigger for the increased risk of cardiovascular disease (CVD). Indeed, the menopausal transition associates with heart macro-remodeling, which results from a fine-tuned cell micro-remodeling. The remodeling of cardiomyocytes is a biomolecular response to several physiologic and pathologic stimuli, allowing healthy adaptation in normal conditions or maladaptation in an unfavorable environment, ending in organ architecture disarray. Estrogens largely impinge on cardiomyocyte remodeling, but they cannot fully explain the sex-dimorphism of CVD risk. Albeit cell remodeling and adaptation are under multifactorial regulation, vitamin D emerges to exert significant protective effects, controlling some intracellular paths, often shared with estrogen signaling. In post-menopause, the unfavorable association of hypoestrogenism-D hypovitaminosis may converge towards maladaptive remodeling and contribute to increased CVD risk. The aim of this review is to overview the role of estrogens and vitamin D in female cardiac health, speculating on their potential synergistic effect in cardiomyocyte remodeling, an issue that is not yet fully explored. Further learning the crosstalk between these two steroids in the biomolecular orchestration of cardiac cell fate during adaptation may help the translational approach to future cardioprotective strategies for women health.