Deletion of SIRT6 in vascular smooth muscle cells facilitates vascular calcification via suppression of DNA damage repair

Elabela alleviates cuproptosis and vascular calcification in vitaminD3- overloaded mice via regulation of the PPAR-γ /FDX1 signaling

BACKGROUND

Vascular calcification is a crucial pathophysiological process associated with age-related cardiovascular diseases. Elabela, a recently identified peptide, has emerged as a significant player in the regulation of cardiovascular function and homeostasis. However, the effects and underlying mechanisms of Elabela on age-related vascular calcification remain largely unexplored.

METHODS

In-vivo vascular calcifications of C57BL/6J mice (8-week-old) and young (8-week-old) or aged (72-week-old) SD rats were injected with vitamin D3 (VitD3) or saline, respectively. Furthermore, the VitD3-overloaded mice received Elabela (1 mg/kg/d), peroxisome proliferators-activated receptor-γ (PPAR-γ) activator Rosiglitazone (5 mg/kg/d) or copper-ionophore Elesclomol (20 mg/kg/d), respectively. As for in-vitro studies, primary rat vascular smooth muscle cells (VSMCs) were isolated from aortas and cultured for explore the role and underlying mechanism of Elabela in vascular calcification.

RESULTS

There were marked increases in FDX1 and Slc31a1 levels in both aortas and VSMCs during vascular calcification, coinciding with a rise in copper levels and a decrease in Elabela levels. Alizarin red and von-Kossa staining indicated that the administration of Elabela effectively hindered the progression of vascular cuproptosis and arterial calcification in VitD3-overloaded mice and rat arterial rings models. Moreover, Elabela significantly suppressed osteogenic differentiation and calcium deposition in VSMCs and strikingly reversed high phosphate-induced augmentation of FDX1 expression, DLAT aggregation as well as intracellular copper ion levels. More importantly, Elabela exhibited remarkable abilities to prevent mitochondrial dysfunctions in primary rat VSMCs by maintaining mitochondrial membrane potential, inhibiting mitochondrial division, reducing mitochondrial ROS production and increasing ATP levels. Interestingly, Elabela mitigated cellular senescence and production of pro-inflammatory cytokines including IL-1α, IL-1β, IL-6, IL-18 and TNF-α, respectively. Furthermore, Elabela upregulated the protein levels of PPAR-γ in VitD3-overloaded mice. Administrating PPAR-γ inhibitor GW9662 or blocking the efflux of intracellular copper abolished the protective effect of Elabela on vascular calcification by enhancing levels of FDX1, Slc31a1, Runx2, and BMP2.

CONCLUSION

Elabela plays a crucial role in protecting against vascular cuproptosis and arterial calcification by activating the PPAR-γ /FDX1 signaling. Elabela supplementation and cuproptosis suppression serve as effective therapeutic approaches for managing vascular calcification and related cardiovascular disorders.

Sirt7 protects against vascular calcification via modulation of reactive oxygen species and senescence of vascular smooth muscle cells

Vascular calcification is frequently seen in patients with chronic kidney disease (CKD), and significantly increases cardiovascular mortality and morbidity. Sirt7, a NAD+-dependent histone deacetylases, plays a crucial role in cardiovascular disease. However, the role of Sirt7 in vascular calcification remains largely unknown. Using in vitro and in vivo models of vascular calcification, this study showed that Sirt7 expression was significantly reduced in calcified arteries from mice administered with high dose of vitamin D3 (vD3). We found that knockdown or inhibition of Sirt7 promoted vascular smooth muscle cell (VSMC), aortic ring and vascular calcification in mice, whereas overexpression of Sirt7 had opposite effects. Intriguingly, this protective effect of Sirt7 on vascular calcification is dependent on its deacetylase activity. Unexpectedly, Sirt7 did not alter the osteogenic transition of VSMCs. However, our RNA-seq and subsequent studies demonstrated that knockdown of Sirt7 in VSMCs resulted in increased intracellular reactive oxygen species (ROS) accumulation, and induced an Nrf-2 mediated oxidative stress response. Treatment with the ROS inhibitor N-acetylcysteine (NAC) significantly attenuated the inhibitory effect of Sirt7 on VSMC calcification. Furthermore, we found that knockdown of Sirt7 delayed cell cycle progression and accelerated cellular senescence of VSMCs. Taken together, our results indicate that Sirt7 regulates vascular calcification at least in part through modulation of ROS and cellular senescence of VSMCs. Sirt7 may be a potential therapeutic target for vascular calcification.

Role of transcriptional cofactors in cardiovascular diseases

Cardiovascular disease is a main cause of mortality in the world and the highest incidence of all diseases. However, the mechanism of the pathogenesis of cardiovascular disease is still unclear, and we need to continue to explore its mechanism of action. The occurrence and development of cardiovascular disease is significantly associated with genetic abnormalities, and gene expression is affected by transcriptional regulation. In this complex process, the protein-protein interaction promotes the RNA polymerase II to the initiation site. And in this process of transcriptional regulation, transcriptional cofactors are responsible for passing cues from enhancers to promoters and promoting the binding of RNA polymerases to promoters, so transcription cofactors playing a key role in gene expression regulation. There is growing evidence that transcriptional cofactors play a critical role in cardiovascular disease. Transcriptional cofactors can promote or inhibit transcription by affecting the function of transcription factors. It can affect the initiation and elongation process of transcription by forming complexes with transcription factors, which are important for the stabilization of DNA rings. It can also act as a protein that interacts with other proteins to affect the expression of other genes. Therefore, the aim of this overview is to summarize the effect of some transcriptional cofactors such as BRD4, EP300, MED1, EZH2, YAP, SIRT6 in cardiovascular disease and to provide a promising therapeutic strategy for the treatment of cardiovascular disease.

The transcription factor GATA6 accelerates vascular smooth muscle cell senescence-related arterial calcification by counteracting the role of anti-aging factor SIRT6 and impeding DNA damage repair

Arterial calcification is a hallmark of vascular pathology in the elderly and in individuals with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs), after attaining a senescent phenotype, are implicated in the calcifying process. However, the underlying mechanism remains to be elucidated. Here, we reveal an aberrant upregulation of transcriptional factor GATA6 in the calcified aortas of humans, mice with CKD and mice subjected to vitamin D3 injection. Knockdown of GATA6, via recombinant adeno-associated virus carrying GATA6 shRNA, inhibited the development of arterial calcification in mice with CKD. Further gain- and loss-of function experiments in vitro verified the contribution of GATA6 in osteogenic differentiation of VSMCs. Samples of human aorta exhibited a positive relationship between age and GATA6 expression and GATA6 was also elevated in the aortas of old as compared to young mice. Calcified aortas displayed senescent features with VSMCs undergoing premature senescence, blunted by GATA6 downregulation. Notably, abnormal induction of GATA6 in senescent and calcified aortas was rescued in Sirtuin 6 (SIRT6)-transgenic mice, a well-established longevity mouse model. Suppression of GATA6 accounted for the favorable effect of SIRT6 on VSMCs senescence prevention. Mechanistically, SIRT6 inhibited the transcription of GATA6 by deacetylation and increased degradation of transcription factor Nkx2.5. Moreover, GATA6 was induced by DNA damage stress during arterial calcification and subsequently impeded the Ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair process, leading to accelerated VSMCs senescence and osteogenic differentiation. Thus, GATA6 is a novel regulator in VSMCs senescence. Our findings provide novel insight in arterial calcification and a potential new target for intervention.

The role of mammalian Sirtuin 6 in cardiovascular diseases and diabetes mellitus

Cardiovascular diseases are severe diseases posing threat to human health because of their high morbidity and mortality worldwide. The incidence of diabetes mellitus is also increasing rapidly. Various signaling molecules are involved in the pathogenesis of cardiovascular diseases and diabetes. Sirtuin 6 (Sirt6), which is a class III histone deacetylase, has attracted numerous attentions since its discovery. Sirt6 enjoys a unique structure, important biological functions, and is involved in multiple cellular processes such as stress response, mitochondrial biogenesis, transcription, insulin resistance, inflammatory response, chromatin silencing, and apoptosis. Sirt6 also plays significant roles in regulating several cardiovascular diseases including atherosclerosis, coronary heart disease, as well as cardiac remodeling, bringing Sirt6 into the focus of clinical interests. In this review, we examine the recent advances in understanding the mechanistic working through which Sirt6 alters the course of lethal cardiovascular diseases and diabetes mellitus.