17β-estradiol inhibits H2O2-induced senescence in HUVEC cells through upregulating SIRT3 expression and promoting autophagy

Sex-specific mechanisms in vascular aging: exploring cellular and molecular pathways in the pathogenesis of age-related cardiovascular and cerebrovascular diseases

Aging remains the foremost risk factor for cardiovascular and cerebrovascular diseases, surpassing traditional factors in epidemiological significance. This review elucidates the cellular and molecular mechanisms underlying vascular aging, with an emphasis on sex differences that influence disease progression and clinical outcomes in older adults. We discuss the convergence of aging processes at the macro- and microvascular levels and their contributions to the pathogenesis of vascular diseases. Critical analysis of both preclinical and clinical studies reveals significant sex-specific variations in these mechanisms, which could be pivotal in understanding the disparity in disease morbidity and mortality between sexes. The review highlights key molecular pathways, including oxidative stress, inflammation, and autophagy, and their differential roles in the vascular aging of males and females. We argue that recognizing these sex-specific differences is crucial for developing targeted therapeutic strategies aimed at preventing and managing age-related vascular pathologies. The implications for personalized medicine and potential areas for future research are also explored, emphasizing the need for a nuanced approach to the study and treatment of vascular aging.

The Estrogen-Autophagy Axis: Insights into Cytoprotection and Therapeutic Potential in Cancer and Infection

Macroautophagy, commonly referred to as autophagy, is an essential cytoprotective mechanism that plays a significant role in cellular homeostasis. It has emerged as a promising target for drug development aimed at treating various cancers and infectious diseases. However, the scientific community has yet to reach a consensus on the most effective approach to manipulating autophagy, with ongoing debates about whether its inhibition or stimulation is preferable for managing these complex conditions. One critical factor contributing to the variability in treatment responses for both cancers and infectious diseases is estrogen, a hormone known for its diverse biological effects. Given the strong correlations observed between estrogen signaling and autophagy, this review seeks to summarize the intricate molecular mechanisms that underlie the dual cytoprotective effects of estrogen signaling in conjunction with autophagy. We highlight recent findings from studies that involve various ligands, disease contexts, and cell types, including immune cells. Furthermore, we discuss several factors that regulate autophagy in the context of estrogen's influence. Ultimately, we propose a hypothetical model to elucidate the regulatory effects of the estrogen-autophagy axis on cell fate. Understanding these interactions is crucial for advancing our knowledge of related diseases and facilitating the development of innovative treatment strategies.

Upregulation of Mitochondrial Sirt3 and Alleviation of the Inflammatory Phenotype in Macrophages by Estrogen

BACKGROUND

Aging and comorbidities like type 2 diabetes and obesity contribute to the development of chronic systemic inflammation, which impacts the development of heart failure and vascular disease. Increasing evidence suggests a role of pro-inflammatory M1 macrophages in chronic inflammation. A shift of metabolism from mitochondrial oxidation to glycolysis is essential for the activation of the pro-inflammatory M1 phenotype. Thus, reprogramming the macrophage metabolism may alleviate the pro-inflammatory phenotype and protect against cardiovascular diseases. In the present study, we hypothesized that the activation of estrogen receptors leads to the elevation of the mitochondrial deacetylase Sirt3, which supports mitochondrial function and mitigates the pro-inflammatory phenotype in macrophages.

MATERIALS AND METHODS

Experiments were performed using the mouse macrophage cell line RAW264.7, as well as primary male or female murine bone marrow macrophages (BMMs). Macrophages were treated for 24 h with estradiol (E2) or vehicle (dextrin). The effect of E2 on Sirt3 expression was investigated in pro-inflammatory M1, anti-inflammatory/immunoregulatory M2, and naïve M0 macrophages. Mitochondrial respiration was measured by Seahorse assay, and protein expression and acetylation were determined by western blotting.

RESULTS

E2 treatment upregulated mitochondrial Sirt3, reduced mitochondrial protein acetylation, and increased basal mitochondrial respiration in naïve RAW264.7 macrophages. Similar effects on Sirt3 expression and mitochondrial protein acetylation were observed in primary female but not in male murine BMMs. Although E2 upregulated Sirt3 in naïve M0, pro-inflammatory M1, and anti-inflammatory/immunoregulatory M2 macrophages, it reduced superoxide dismutase 2 acetylation and suppressed mitochondrial reactive oxygen species formation only in pro-inflammatory M1 macrophages. E2 alleviated the pro-inflammatory phenotype in M1 RAW264.7 cells.

CONCLUSIONS

The study suggests that E2 treatment upregulates Sirt3 expression in macrophages. In primary BMMs, female-specific Sirt3 upregulation was observed. The Sirt3 upregulation was accompanied by mitochondrial protein deacetylation and the alleviation of the oxidative and pro-inflammatory phenotype in M1 macrophages. Thus, the E2-Sirt3 axis might be used in a therapeutic strategy to fight chronic systemic inflammation and prevent the development of inflammation-linked diseases.

SIRT-associated attenuation of cellular senescence in vascular wall

This review focuses on the vital function that SIRT1 and other sirtuins play in promoting cellular senescence in vascular smooth muscle cells, which is a key element in the pathogenesis of vascular aging and associated cardiovascular diseases. Vascular aging is a gradual process caused by the accumulation of senescent cells, which results in increased vascular remodeling, stiffness, and diminished angiogenic ability. Such physiological alterations are characterized by a complex interplay of environmental and genetic variables, including oxidative stress and telomere attrition, which affect gene expression patterns and trigger cell growth arrest. SIRT1 has been highlighted for its potential to reduce cellular senescence through modulation of multiple signaling cascades, particularly the endothelial nitric oxide (eNOS)/NO signaling pathway. It also modulates cell cycle through p53 inactivation and suppresses NF-κB mediated expression of adhesive molecules at the vascular level. The study also examines the therapeutic potential of sirtuin modulation in vascular health, identifying SIRT1 and its sirtuin counterparts as potential targets for reducing vascular aging. This study sheds light on the molecular basis of vascular aging and the beneficial effects of sirtuins, paving the way for the development of tailored therapies aimed at enhancing vascular health and prolonging life.

GPER activation attenuates cardiac dysfunction by upregulating the SIRT1/3-AMPK-UCP2 pathway in postmenopausal diabetic rats

Postmenopausal diabetic women are at higher risk to develop cardiovascular diseases (CVD) compared with nondiabetic women. Alterations in cardiac cellular metabolism caused by changes in sirtuins are one of the main causes of CVD in postmenopausal diabetic women. Several studies have demonstrated the beneficial actions of the G protein-coupled estrogen receptor (GPER) in postmenopausal diabetic CVD. However, the molecular mechanisms by which GPER has a cardioprotective effect are still not well understood. In this study, we used an ovariectomized (OVX) type-two diabetic (T2D) rat model induced by high-fat diet/streptozotocin to investigate the effect of G-1 (GPER-agonist) on sirtuins, and their downstream pathways involved in regulation of cardiac metabolism and function. Animals were divided into five groups: Sham-Control, T2D, OVX+T2D, OVX+T2D+Vehicle, and OVX+T2D+G-1. G-1 was administrated for six weeks. At the end, hemodynamic factors were measured, and protein levels of sirtuins, AMP-activated protein kinase (AMPK), and uncoupling protein 2 (UCP2) were determined by Western blot analysis. In addition, cardiac levels of oxidative stress biomarkers were measured. The findings showed that T2D led to left ventricular dysfunction and signs of oxidative stress in the myocardium, which were accompanied by decreased protein levels of Sirt1/2/3/6, p-AMPK, and UCP2 in the heart. Moreover, the induction of the menopausal state exacerbated these changes. In contrast, treatment with G-1 ameliorated the hemodynamic changes associated with ovariectomy by increasing Sirt1/3, p-AMPK, UCP2, and improving oxidative status. The results provide evidence of the cardioprotective effects of GPER operating through Sirt1/3, p-AMPK, and UCP2, thereby improving cardiac function. Our results suggest that increasing Sirt1/3 levels may offer new therapeutic approaches for postmenopausal diabetic CVD.

Estrogen receptor alpha mediates 17β-estradiol, up-regulates autophagy and alleviates hydrogen peroxide-induced vascular senescence

Atherosclerosis threatens human health by developing cardiovascular diseases, the deadliest disease world widely. The major mechanism contributing to the formation of atherosclerosis is mainly due to vascular endothelial cell (VECs) senescence. We have shown that 17β-estradiol (17β-E2) may protect VECs from senescence by upregulating autophagy. However, little is known about how 17β-E2 activates the autophagy pathway to alleviate cellular senescence. Therefore, the aim of this study is to determine the role of estrogen receptor (ER) α and β in the effects of 17β-E2 on vascular autophagy and aging through in vitro and in vivo models. Hydrogen peroxide (H2O2) was used to establish Human Umbilical Vein Endothelial Cells (HUVECs) senescence. Autophagy activity was measured through immunofluorescence and immunohistochemistry staining of light chain 3 (LC3) expression. Inhibition of ER activity was established using shRNA gene silencing and ER antagonist. Compared with ER-β knockdown, we found that knockdown of ER-α resulted in a significant increase in the extent of HUVEC senescence and senescence-associated secretory phenotype (SASP) secretion. ER-α-specific shRNA was found to reduce 17β-E2-induced autophagy, promote HUVEC senescence, disrupt the morphology of HUVECs, and increase the expression of Rb dephosphorylation and SASP. These in vitro findings were found consistent with the in vivo results. In conclusion, our data suggest that 17β-E2 activates the activity of ER-α and then increases the formation of autophagosomes (LC3 high expression) and decreases the fusion of lysosomes with autophagic vesicles (P62 low expression), which in turn serves to decrease the secretion of SASP caused by H2O2 and consequently inhibit H2O2-induced senescence in HUVEC cells.

The Current State of Research on Sirtuin-Mediated Autophagy in Cardiovascular Diseases

Sirtuins belong to the class III histone deacetylases and possess nicotinamide adenine dinucleotide-dependent deacetylase activity. They are involved in the regulation of multiple signaling pathways implicated in cardiovascular diseases. Autophagy is a crucial adaptive cellular response to stress stimuli. Mounting evidence suggests a strong correlation between Sirtuins and autophagy, potentially involving cross-regulation and crosstalk. Sirtuin-mediated autophagy plays a crucial regulatory role in some cardiovascular diseases, including atherosclerosis, ischemia/reperfusion injury, hypertension, heart failure, diabetic cardiomyopathy, and drug-induced myocardial damage. In this context, we summarize the research advancements pertaining to various Sirtuins involved in autophagy and the molecular mechanisms regulating autophagy. We also elucidate the biological function of Sirtuins across diverse cardiovascular diseases and further discuss the development of novel drugs that regulate Sirtuin-mediated autophagy.

17β-estradiol suppresses H2O2-induced senescence in human umbilical vein endothelial cells by inducing autophagy through the PVT1/miR-31/SIRT3 axis

OBJECTIVE

17β-estradiol (17β-E₂) has been implicated in activating autophagy by upregulating SIRT3 (Sirtuin 3) expression, thereby inhibiting the senescence of vascular endothelial cells. Herein, we further examined the molecular mechanisms that regulate SIRT3 expression in 17β-E₂-induced autophagy.

METHODS

Reverse-transcription-polymerase chain reaction was employed to measure the expression of plasmacytoma variant translocation 1 (PVT1), microRNAs (miRNAs), and SIRT3, and the dual-luciferase assay was used to determine their interaction. Electron microscopy observes autophagosomes, green fluorescent protein-microtubule-associated protein 1 light chain 3 (GFP-LC3) staining, and immunoblot analysis with antibodies against LC3，beclin-1, and P62 were conducted to measure autophagy. Cellular senescence was determined using immunoblot analysis with anti-phosphorylated retinoblastoma and senescence-associated β-galactosidase staining.

RESULTS

Women with higher estrogen levels (during the 10-13th day of the menstrual cycle or premenopausal) exhibit markedly higher serum levels of PVT1 than women with lower estrogen levels (during the menstrual period or postmenopausal). The dual-luciferase assay showed that PVT1 acts as a sponge for miR-31, and miR-31 binds to its target gene, SIRT3. The 17β-E₂ treatment increased the expression of PVT1 and SIRT3 and downregulated miR-31 expression in human umbilical vein endothelial cells (HUVECs). Consistently, PVT1 overexpression suppresses miR-31 expression, promotes 17β-E2-induced autophagy, and inhibits H₂O₂-induced senescence. miR-31 inhibitor increases SIRT3 expression and leads to activation of 17β-E₂-induced autophagy and suppression of H₂O₂-induced senescence.

CONCLUSION

Our findings demonstrated that 17β-E₂ upregulates PVT1 gene expression and PVT1 functions as a sponge to inhibit miR-31, resulting in the upregulation of SIRT3 expression and activation of autophagy and subsequent inhibition of H₂O₂-induced senescence in HUVECs.

Sirt3 activates autophagy to prevent DOX-induced senescence by inactivating PI3K/AKT/mTOR pathway in A549 cells

Sirtuin 3 (Sirt3), a mitochondrial deacetylase, regulates mitochondrial redox homeostasis and autophagy and is involved in physiological and pathological processes such as aging, cellular metabolism, and tumorigenesis. We here investigate how Sirt3 regulates doxorubicin (DOX)-induced senescence in lung cancer A549 cells. Sirt3 greatly reduced DOX-induced upregulation of senescence marker proteins p53, p16, p21 and SA-β-Gal activity as well as ROS levels. Notably, Sirt3 reversed DOX-induced autophagic flux blockage, as shown by increased p62 degradation and LC3II/LC3I ratio. Importantly, the autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) partially abolished the antioxidant stress and antiaging effects of Sirt3, while the autophagy activator rapamycin (Rap) potentiated these effects of Sirt3, demonstrating that autophagy mediates the anti-aging effects of Sirt3. Additionally, Sirt3 inhibited the DOX-induced activation of the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway, which in turn activated autophagy. The PI3K inhibitor LY294002 promoted the antioxidant stress and antiaging effects of Sirt3, while the AKT activator SC-79 reversed these effects of Sirt3. Taken together, Sirt3 counteracts DOX-induced senescence by improving autophagic flux.

Research progress on the mechanism of aging of vascular endothelial cells and the intervention of traditional Chinese medicine: A review

Vascular senescence is the basic factor of many cardiovascular diseases. Vascular endothelium, as a protective barrier between blood and vascular wall, plays an important role in maintaining the integrity and homeostasis of vascular system. Endothelial cell senescence is an important pathological change of vascular senescence. In recent years, more and more studies have been conducted on vascular endothelial cell senescence, especially on its mechanism. Many research results showed that the mechanism is various, but the systematic elucidation still lacks. Western medicine has little choice in the prevention and treatment of endothelial cell senescence, and the control effect is also limited, while Chinese medicine makes up for the deficiency in this regard. The main mechanisms of vascular endothelial cell aging and the related research progress of traditional Chinese medicine in the prevention and treatment of vascular endothelial aging in recent years were summarized in this paper to provide reference for the research of traditional Chinese medicine in anti-vascular aging and the prevention and treatment of cardiovascular disease.

Mammalian Sirtuins and Their Relevance in Vascular Calcification

Cardiovascular diseases are a group of diseases with high morbidity and mortality that affect millions of people each year. Vascular calcification (VC) is an active process that involves the mineral deposition of calcium-phosphate complexes. VC is closely related to cardiovascular diseases, such as hypertension, heart failure, and calcific aortic stenosis, and is a type of ectopic calcification that occurs in the vessel walls. The sirtuins (silent mating-type information regulation 2; SIRTs), are a family of histone deacetylases whose function relies on nicotinamide adenine dinucleotide (NAD+). They have non-negligible functions in the regulation of energy metabolism, senescence, apoptosis, and other biological processes. Sirtuins have important effects on bone homeostasis and VC processes that share many similarities with bone formation. Sirtuins have been confirmed to deacetylate a variety of target proteins related to the occurrence and development of VC, thereby affecting the process of VC and providing new possibilities for the prevention and treatment of cardiovascular diseases. To facilitate the understanding of vascular calcification and accelerate the development of cardiovascular drugs, we reviewed and summarized recent research progress on the relationship between different types of sirtuins and VC.

p53 SUMOylation Mediates AOPP-Induced Endothelial Senescence and Apoptosis Evasion

The aging of endothelial cells plays a critical role in the development of age-related vascular disease. We established a model of endothelial premature senescence by application of Advanced oxidation protein products (AOPPs) modified bovine serum albumin (AOPP-BSA) in human umbilical vein endothelial cells (HUVECs). This cellular senescence was accompanied with endothelial barrier dysfunction and angiogenesis impairment. It was further revealed that these senescent HUVECs underwent apoptosis evasion and the receptor for advanced glycation endproducts (RAGE) played a role in these processes. The AOPP-induced senescence was regulated by the state of autophagy in HUVECs. We further proved that AOPP-BSA attenuated the autophagy of HUVECs, led to p53 SUMOylation at K386, resulting in endothelial senescence. We also established the animal model of vascular senescence by using ApoE^−/− mice fed with high-fat diet plus daily injection of AOPP-BSA to verify the role of p53 SUMOylation in vascular senescence. Combined with intraperitoneal injection of rapamycin, the effect of autophagy on AOPP-induced p53 SUMOylation was also confirmed in vivo. Our data indicates that p53 SUMOylation at K386 plays an important role in AOPP-induced endothelial senescence and apoptosis evasion, suggesting that p53 K386 SUMOylation may serve as a potential therapeutic target in protecting against vascular senescence.

Melatonin alleviates hydrogen peroxide induced oxidative damage in MC3T3-E1 cells and promotes osteogenesis by activating SIRT1

Oxidative stress is an important contributor to the development of osteoporosis. Melatonin, an indoleamine secreted by the pineal gland, has antioxidant properties. This study aims to explore whether melatonin can promote bone formation and elucidate the mechanisms underlying this process. In this study, we used an in vitro hydrogen peroxide (H₂O₂)-induced oxidative stress model in MC3T3-E1 cells and an in vivo ovariectomized osteoporotic bone defect model in rats to explore the protective effects of melatonin against osteoporotic bone defects along with the mechanism underlying these effects. We found that melatonin significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of BMP2, RUNX2, and OPN in MC3T3-E1 cells treated with H₂O₂. Furthermore, melatonin was found to activate SIRT1, SIRT3 and inhibit p66Shc, reduce the intracellular reactive oxygen species levels, stabilize mitochondria, reduce malondialdehyde levels, increase superoxide dismutase activity, and reduce apoptosis in MC3T3-E1 cells treated with H₂O₂. Intriguingly, these effects could be reversed by the SIRT1 inhibitor EX527. In vivo experiments confirmed that melatonin improves the microstructure and bone mineral density of the distal femoral bone trabecula and promotes bone formation. Meanwhile, melatonin activated SIRT1, inhibited p66Shc and increased SIRT3 expression. Taken together, our findings showed that melatonin can restrain oxidative damage in MC3T3-E1 cells and promote osteogenesis by activating SIRT1 which regulate the activity of SIRT3 and inhibit the expression of p66Shc, suggesting that melatonin could be a potential therapeutic agent for osteoporosis-related bone metabolic diseases.

17β-Estradiol alleviates cardiac aging induced by d-galactose by downregulating the methylation of autophagy-related genes

Intrinsic cardiac aging increases cardiovascular mortality and morbidity in the elderly. Estrogen helps reduce the risk of cardiovascular disease in women, with 17β-estradiol (17β-E2) activating the autophagy pathway and inhibiting vascular aging, mainly through estrogen receptor alpha (ER α) to prevent atherosclerosis. Abnormal methylation of autophagy-related genes can impact autophagic regulation. We hypothesized that 17β-E2, specifically 17β-E2 α, downregulates the methylation of autophagy factors and delays cardiac aging. Here, we used d-galactose, 17β-E2, and ER α receptor antagonist methyl-piperidino-pyrazole (MPP) to establish different aging models in mice divided into four groups, namely negative control, D.gal, D.gal + 17β-E2, and D.gal + 17β-E2 + MPP groups. Echocardiography showed that compared with the D.gal group group, the D.gal + 17β-E2 showed substantially increased cardiac function. The level of cardiac aging markers in mice in the D.gal + 17β-E2 group was lower than that in mice in the D.gal group. Beclin1, LC3, and Atg5 mRNA and protein expression levels in mice in the D.gal + 17β-E2 group were significantly increased compared with those in the D.gal group. Additionally, Beclin1, LC3, and Atg5 methylation levels were significantly decreased in the D.gal + 17β-E2 group. All the above values of the D.gal + 17β-E2 + MPP group were between those of the D.gal and D.gal + 17β-E2 groups. The expression of Dnmt1, Dnmt2, and Dnmt3A genes was the highest in the D.gal group. In summary, our results suggest that 17β-E2, specifically 17β-E2 α, promotes autophagy by downregulating the methylation of autophagy factors, thereby inhibiting galactose-induced cardiac aging in mice. 17β-E2 may be a potential therapeutic target to mitigate the effects of cardiac aging.

Protective effect of hydrogen sulfide on endothelial cells through Sirt1-FoxO1-mediated autophagy

Background

As a new member of the vasculoprotective gasotransmitter family, hydrogen sulfide (H₂S) functions similar to nitric oxide (NO) and carbon monoxide (CO). Endothelial cell (EC) death and autophagy enable cells to cope with the progression of cardiovascular diseases. However, the impacts and underlying mechanisms of H₂S in the autophagic process in ECs are not completely understood. Here, we investigated the effects of H₂S on autophagy in human vascular ECs.

Methods

Human umbilical vein endothelial cells (HUVECs) were exposed to different concentrations (0, 50, 100, 200, 500 and 1,000 µmol/L) GYY4137 (H₂S donor) for indicated times (0, 0.5, 1, 2, 4 and 8 h), with or without pre-treatment with the autophagy inhibitor 3-methyladenine (3-MA) or bafilomycin A1. HUVECs were transfected with sirtuin 1 (Sirt1) overexpression plasmids (PIRES-Sirt1), Sirt1-siRNAs or forkhead box O1 (FoxO1)-siRNA using Lipofectamine 2000. Cell autophagy was evaluated via Western blotting and fluorescence microscopy. Co-immunoprecipitation assay was used to measure acetylation level of FoxO1. The distribution of FoxO1 in the cytoplasm and nucleus was observed using Western blotting and immunofluorescence. Western blotting, flow cytometric analysis, and cell count kit-8 assay were conducted to evaluate the effect of H₂S on the oxidized low-density lipoprotein (Ox-LDL) induced apoptosis of HUVECs.

Results

Using both gain- and loss-of-function experiments, we showed that Sirt1-dependent activation of FoxO1, including its nuclear translocation and deacetylation, was critical for mediating H₂S-induced autophagy in ECs. Furthermore, H₂S-induced autophagy protected ECs from Ox-LDL-induced apoptosis by activating Sirt1.

Conclusions

These results suggest that Sirt1-mediated autophagy in ECs is a novel mechanism by which H₂S exerts vascular-protective actions.

miR-138-5p suppresses glioblastoma cell viability and leads to cell cycle arrest by targeting cyclin D3

Although malignant glioblastoma (GBM) treatment has significantly improved in the past few decades, the prognosis of GBM remains unsatisfactory. MicroRNA (miR)-138-5p has been reported as a tumor suppressor in several types of human cancer; however, little is known about the function of miR-138-5p in GBM. The present study aimed to investigate the role of miR-138-5p in GBM as well as the underlying molecular mechanisms. The present study performed bioinformatics analysis, reverse transcription-quantitative (RT-q)PCR, western blotting, cell viability assays, colony formation assays, invasion assays and cell cycle analysis to investigate the biological function of miR-138-5p in both patient tissues and cell lines. In addition, miR-138-5p targets in GBM were predicted using Gene Expression Omnibus website and further validated by a dual luciferase reporter gene assay. The results revealed that miR-138-5p expression levels in patients with GBM from a Gene Expression Omnibus dataset were significantly downregulated. RT-qPCR analysis of miR-138-5p expression levels also revealed similar results in GBM tissues and cell lines. The upregulation of miR-138-5p expression levels using a mimic significantly inhibited the cell viability, colony formation and the G₀/G₁ to S progression in GBM cell lines, suggesting that miR-138-5p may be a tumor suppressor. Moreover, miR-138-5p was discovered to directly target cyclin D3 (CCND3), a protein that serves an important role in the cell cycle, and inhibited its expression. Finally, silencing CCND3 using small interfering RNA suppressed the viability of GBM cells. In conclusion, the results of the present study suggested that miR-138-5p may function as a tumor suppressor in GBM by targeting CCND3, indicating that miR-138-5p may be a novel therapeutic target for patients with GBM.

Potential relationship between Sirt3 and autophagy in ovarian cancer

Sirtuin 3 (Sirt3) is an important member of the sirtuin protein family. It is a deacetylase that was previously reported to modulate the level of reactive oxygen species (ROS) production and limit the extent of oxidative damage in cellular components. As an important member of the class III type of histone deacetylases, Sirt3 has also been documented to mediate nuclear gene expression, metabolic control, neuroprotection, cell cycle and proliferation. In ovarian cancer (OC), Sirt3 has been reported to regulate cellular metabolism, apoptosis and autophagy. Sirt3 can regulate autophagy through a variety of different molecular signaling pathways, including the p62, 5'AMP-activated protein kinase and mitochondrial ROS-superoxide dismutase pathways. However, autophagy downstream of Sirt3 and its association with OC remains poorly understood. In the present review, the known characteristics of Sirt3 and autophagy were outlined, and their potential functional roles were discussed. Following a comprehensive analysis of the current literature, Sirt3 and autophagy may either serve positive or negative roles in the regulation of OC. Therefore, it is important to identify the appropriate expression level of Sirt3 to control the activation of autophagy in OC cells. This strategy may prove to be a novel therapeutic method to reduce the mortality of patients with OC. Finally, potential research directions into the association between Sirt3 and other signaling pathways were provided.

SirT3 activates AMPK-related mitochondrial biogenesis and ameliorates sepsis-induced myocardial injury

Sirtuin-3 (SirT3) and AMPK stimulate mitochondrial biogenesis, which increases mitochondrial turnover and cardiomyocyte regeneration. We studied the effects of SirT3, AMPK, and mitochondrial biogenesis on sepsis-induced myocardial injury. Our data showed that after treating cardiomyocytes with lipopolysaccharide, SirT3 and AMPK levels decreased, and this was followed by mitochondrial dysfunction and cardiomyocyte death. Overexpression of SirT3 activated the AMPK pathway and improved mitochondrial biogenesis, which is required to sustain mitochondrial redox balance, maintain mitochondrial respiration, and suppress mitochondrial apoptosis. Inhibition of mitochondrial biogenesis abolished SirT3/AMPK-induced cardioprotection by causing mitochondrial damage. These findings indicate that SirT3 reduces sepsis-induced myocardial injury by activating AMPK-related mitochondrial biogenesis.