Sirtuin Research Articles

Mitochondrial protein deacetylation by SIRT3 in osteoclasts promotes bone resorption with aging in female mice

ObjectivesThe mitochondrial deacetylase sirtuin-3 (SIRT3) is necessary for the increased bone resorption and enhanced function of mitochondria in osteoclasts that occur with advancing age; how SIRT3 drives bone resorption remains elusive. MethodsTo determine the role of SIRT3 in osteoclast mitochondria, we used mice with conditional loss of Sirt3 in osteoclast lineage and mice with germline deletion of either Sirt3 or its known target Pink1. ResultsSIRT3 stimulates mitochondrial quality in osteoclasts in a PINK1-independent manner, promoting mitochondrial activity and osteoclast maturation and function, thereby contributing to bone loss in female but not male mice. Quantitative analyses of global proteomes and acetylomes revealed that deletion of Sirt3 dramatically increased acetylation of osteoclast mitochondrial proteins, particularly ATPase inhibitory factor 1 (ATPIF1), an essential protein for mitophagy. Inhibition of mitophagy via mdivi-1 recapitulated the effect of deletion of Sirt3 or Atpif1 in osteoclast formation and mitochondrial function. ConclusionsDecreasing mitophagic flux in osteoclasts may be a promising pharmacotherapeutic approach to treat osteoporosis in older adults.

Sirt1 m6A modification-evoked Leydig cell senescence promotes Cd-induced testosterone decline

Diminished testosterone levels have been documented as a key factor in numerous male health disorders. Both human and animal studies have consistently demonstrated that cadmium (Cd), a pervasive environmental heavy metal, results in decreased testosterone levels. However, the exact mechanism through which Cd interferes with testosterone synthesis remains incompletely elucidated. This research sought to examine the impact of cellular senescence on Cd-suppressed testosterone synthesis. We also investigated the related m6A modification mechanism. The results demonstrated that Cd (100 mg/L) led to a decrease in testosterone levels, along with downregulated expression of testosterone synthase in C57BL/6 N male mice. Furthermore, Cd significantly increased β-galactosidase staining intensity, senescence-related proteins, and senescence-related secretory phenotypes in mouse testicular Leydig cells. Subsequent investigations revealed that Cd decreased the mRNA and protein levels of NAD-dependent deacetylase Sirtuin-1 (SIRT1) in Leydig cells. Mechanistically, mice treated with resveratrol (50 mg/kg), a specific SIRT1 activator, mitigated Leydig cell senescence and reversed Cd-reduced testosterone levels in mouse testes. These effects were also restored by SIRT1 overexpression in Leydig cells. Additionally, we found that Cd increased the level of methyltransferase enzyme METTL3 and Sirt1 m6A modification in Leydig cells. Mettl3 siRNA effectively restored Cd-enhanced Sirt1 m6A level and reversed Cd-downregulated Sirt1 mRNA expression in Leydig cells. Overall, our findings suggest that Cd exposure inhibits testosterone synthesis via Sirt1 m6A modification-mediated senescence in mouse testes. These results offer an experimental basis for investigating the causes and potential treatments of hypotestosteronemia induced by environmental factors.

Activation of SIRT3 by Tanshinone IIA ameliorates renal fibrosis by suppressing the TGF-β/TSP-1 pathway and attenuating oxidative stress

Although doxorubicin (DOX) is a common chemotherapeutic drug, the serious nephrotoxicity caused by DOX-induced renal fibrosis remains a considerable clinical problem. Tanshinone IIA (Tan IIA), a compound extracted from Salvia miltiorrhiza, has been reported to have an anti-fibrotic effect. Therefore, this study investigated the molecular pathway whereby Tan IIA protects the kidneys from DOX administration. DOX (3 mg/kg body weight) was intraperitoneally administered every 3 d for a total of 7 injections (cumulative dose of 21 mg/kg) to induce nephrotoxicity. Then, Tan IIA (5 or 10 mg/kg/d) was administered by intraperitoneal injection for 28 d. In an in vitro study, 293 T cells were cultured and treated with DOX and Tan IIA for 24 h. Tan IIA reduced the blood urea nitrogen levels elevated by DOX while increasing superoxide dismutase activity, down-regulating reactive oxygen species, ameliorating renal-tubule thickening, and rescuing mitochondrial morphology. Additionally, Tan IIA reduced the renal collagen deposition, increased ATP production and complex-I activity, down-regulated transforming growth factor-β1 (TGF-β1) and thrombospondin-1 (TSP-1), and up-regulated sirtuin 3 (SIRT3). Tan IIA significantly increased cell viability. Additionally, RNA interference was employed to silence the expression of SIRT3, which eliminated the effect of Tan IIA in suppressing the expression of TGF-β1 and TSP-1. In conclusion, Tan IIA ameliorated DOX-induced nephrotoxicity by attenuating oxidative injury and fibrosis. The Tan IIA-induced rescue of mitochondrial morphology and function while alleviating renal fibrosis may be associated with the activation of SIRT3 to suppress the TGF-β/TSP-1 pathway.

SIRT5 suppresses the trophoblast cell proliferation, invasion, and migration to promote preeclampsia via desuccinylating HOXB3.

Preeclampsia (PE) is a pregnancy-specific syndrome with increasing maternal and perinatal morbidity and mortality. Succinylation, a post-translational modification event, has been found in various diseases. However, the role of succinylation in PE has not been explored. This study aimed to investigate the effect of succinylation on PE and the underlying mechanisms. Thirty-two PE patients and 32 normal pregnancy volunteers were recruited. Human extravasated trophoblast cells (HTR-8/SVneo) were used in in vitro study. RT-qPCR was performed to detect the expression of succinylation-related mRNAs. The cell proliferation, invasion, and migration were assessed using cell counting kit-8, ethynyldeoxyuridine, transwell, and wound healing assays. Co-immunoprecipitation and dual-luciferase reporter assays were performed to analyze the interaction between sirtuin (SIRT)5 and homeobox box 3 (HOXB3). SIRT5 was increased in the placental tissues of PE patients. SIRT5 inhibition increased cell proliferation, invasion, and migration in HTR-8/SVneo cells. Mechanistic investigations indicated that HOXB3 was a downstream regulatory target of SIRT5-mediated desuccinylation. Rescue experiments further verified that silencing of HOXB3 inhibited cell proliferation, invasion, and migration. Additionally, HOXB3 deficiency reversed the activation of the Notch and β-catenin signaling pathway induced by SIRT5 inhibition. SIRT5 inhibited the trophoblast cell proliferation, invasion, and migration to promote PE through suppressing Notch and β-catenin signaling pathway activation via desuccinylating HOXB3.

Lamin A/C deficiency-mediated ROS elevation contributes to pathogenic phenotypes of dilated cardiomyopathy in iPSC model

Mutations in the nuclear envelope (NE) protein lamin A/C (encoded by LMNA), cause a severe form of dilated cardiomyopathy (DCM) with early-onset life-threatening arrhythmias. However, molecular mechanisms underlying increased arrhythmogenesis in LMNA-related DCM (LMNA-DCM) remain largely unknown. Here we show that a frameshift mutation in LMNA causes abnormal Ca2+ handling, arrhythmias and disformed NE in LMNA-DCM patient-specific iPSC-derived cardiomyocytes (iPSC-CMs). Mechanistically, lamin A interacts with sirtuin 1 (SIRT1) where mutant lamin A/C accelerates degradation of SIRT1, leading to mitochondrial dysfunction and oxidative stress. Elevated reactive oxygen species (ROS) then activates the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-ryanodine receptor 2 (RYR2) pathway and aggravates the accumulation of SUN1 in mutant iPSC-CMs, contributing to arrhythmias and NE deformation, respectively. Taken together, the lamin A/C deficiency-mediated ROS disorder is revealed as central to LMNA-DCM development. Manipulation of impaired SIRT1 activity and excessive oxidative stress is a potential future therapeutic strategy for LMNA-DCM.

Osteoarthritis rat serum-derived extracellular vesicles aggravate osteoarthritis development by inducing NLRP3-mediated pyroptotic cell death and cellular inflammation.

Osteoarthritis (OA), degenerative joint disease, is the most prevalent form of arthritis worldwide. Besides its substantial burden on society, the high OA morbidity greatly diminishes patients' quality of life. According to recent research, patients-derived serum extracellular vesicles (EVs) are critically involved in sustaining the corresponding disease progression. However, limited research has fully explored the specific functions and molecular mechanisms of OA serum-derived EVs in disease progression. Consequently, we aimed to investigate the underlying mechanism of OA rats-derived serum EVs in regulating OA progression. Before constructing the exosome-cell co-culture system, EVs were extracted from OA and control rat serum and co-cultured with bone marrow mesenchymal stem cells (BM-MSCs). Western blotting (WB), RT-qPCR, and enzyme-linked immunosorbent assay (ELISA) results revealed that OA rat serum-derived EVs upregulated cell pyroptosis-related markers, including nod-Like receptor protein-3 (NLRP3), apoptosis-associated speck-like protein (ASC), gasdermin D (GSDMD), and cleaved caspase-1. The OA rat-EVs also induced the release of LDH and inflammatory cytokines, including interleukin (IL)-1β, IL-18, IL-6, and TNF-α. Additional experiments revealed that OA rat-EVs delivered miR-133a-3p to BM-MSCs and upregulated miR-133a-3p to degrade sirtuin 1 (SIRT1), and activating the downstream NF-κB signaling pathway. Furthermore, the rescuing experiments confirmed that silencing SIRT1 abrogated the miR-133a-3p-induced protective effects in OA-EVs-treated BM-MSCs. In conclusion, OA rats-derived miR-133a-3p-containing EVs modulated the downstream SIRT1/NF-κB pathway-mediated pyroptotic cell death and inflammation in OA. In other words, this study confirmed the role and underlying mechanisms by which OA-associated serum EVs regulate pyroptosis and inflammation response in OA development.

The Role of Sirtuin-1 Isoforms in Regulating Mitochondrial Function.

The sirtuin-1 (SIRT1) gene contains multiple exons that usually undergo alternative splicing. The exclusion of one or more exons causes domain loss in the alternatively spliced isoforms and may change their functions. However, it is not completely established to what extent the loss of a non-catalytic domain could affect its regulatory function. Using muscle cells and SIRT1-knockout cells, we examined the function of the constitutively spliced isoform (SIRT1-v1) versus the alternatively spliced isoforms SIRT1-v2 and SIRT1-v3 that had lost part of the N-terminal region. Our data indicate that partial loss of the N-terminal domains in SIRT1-v2 and SIRT1-v3 attenuated their function. The full-length SIRT1-v1 significantly increased the oxidative phosphorylation and ATP production rate. Furthermore, SIRT1-v1 specifically upregulated the mitochondrial respiratory complex I without affecting the activity of complexes II, III, and IV. Additionally, domain loss affected the regulation of site-specific lysine acetylation in the histone H4 protein, the gene expression of respiratory complex I subunits, and the metabolic balance of oxidative phosphorylation versus glycolysis. Since alternatively spliced isoforms tend to increase with advancing age, the impact of SIRT1 isoforms on mitochondrial respiratory complexes warrants further investigation.

Resveratrol by elevating the SIRT1 BDNF, GDNF and PSD95 levels reduce heroin addiction related behaviors

ObjectiveTo study the effects of resveratrol on heroin addiction-related behaviors and to preliminarily explore the possible intervention mechanism of resveratrol in heroin dependence. MethodsThe effects of resveratrol on heroin withdrawal symptoms were observed by naloxone; The effect of resveratrol on heroin reward memory acquisition was detected by CPP paradigm; The effect of resveratrol on the mental excitability of heroin was tested by open field experiment; The effect of resveratrol on heroin spatial learning and memory was tested by water maze test. Western blot was used to detect Sirtuin 1 (SIRT1) Expression of brain-derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF), and postsynaptic density protein (PSD95). ResultsThe behavioral results showed that the withdrawal behavior of the resveratrol intervention group was reduced compared with the heroin chronic dependence group (P<0.05), and the shift score of the conditioned place preference test of the resveratrol intervention group was reduced compared with the heroin chronic dependence group (P<0.05) The spatial learning and memory ability of the water maze in the resveratrol intervention group was improved compared with the heroin chronic dependence group (P<0.05), and the mental excitability of the resveratrol intervention group was lower than that of the heroin chronic dependence group (P<0.05), but higher than that of the saline group (P<0.05); SIRT1 The expression levels of BDNF, GDNF and PSD95 protein were significantly increased (P<0.05). ConclusionThe behavioral results of this study suggest that resveratrol can be used as a potential drug to treat heroin dependence. At the same time, SIRT1 The expression of BDNF, GDNF, and PSD95 increased; SIRT1, BDNF, GDNF, and PSD95 play an essential role in heroin addiction.

SIRT1 promotes doxorubicin-induced breast cancer drug resistance and tumor angiogenesis via regulating GSH-mediated redox homeostasis.

Sirtuin 1 (SIRT1), a member of histone deacetylase III family, plays a pivotal role in mediating chemoresistance in several cancers, including breast cancer. However, the molecular mechanism by which the deregulated SIRT1 promotes doxorubicin (Dox) resistance is still elusive. Here, we showed that the cell proliferation rates and invasive properties of MDA-MB-231 breast cancer cells were increased from low- to high-Dox-resistant cells. In agreement, severe combined immunodeficiency disease (SCID) mice bearing labeled MDA-MB-231high Dox-Res cells showed significantly higher tumor growth, angiogenesis, and metastatic ability than parental MDA-MB-231 cells. Interestingly, the levels of SIRT1 and glutathione (GSH) were positively correlated with the degree of Dox-resistance. Dox-induced SIRT1 promoted NRF2 nuclear translocation with an accompanying increase in the antioxidant response element promotor activity and GSH levels. In contrast, inhibition of SIRT1 by EX527 greatly reversed these events. More so, Dox-resistance-induced pro-proliferative, proangiogenic, and invasive effects were obviated with depletion of either SIRT1 or GSH. Together, Dox-induced SIRT1 promotes dysregulation of redox homeostasis leading to breast cancer chemoresistance, tumor aggressiveness, angiogenesis, and metastasis.

The effect of weight loss therapies on sirtuin 1 regulation: a systematic review and meta-analysis of randomized controlled trials

BackgroundRecent evidence shows the role of sirtuin 1(SIRT1), a family of evolutionarily conserved proteins, as a potential therapeutic target in the prevention and treatment of obesity and metabolic diseases. Some evidence shows the moderating effects of weight loss interventions on this factor. However, the findings are contradictory. In order to obtain a better viewpoint from them, this study aimed to comprehensively investigate the effects of weight loss interventions on SIRT 1 modulation.MethodsFor this study, we searched four electronic databases using predefined keywords from inception until March 2024. We includedrandomized controlled trials that evaluated the effect of weight reduction strategies on SIRT1 levels. The random-effects model analysis was used to obtain the pooled weighted mean difference (WMD) and 95% confidence intervals (95% CI). The meta-analysis was conducted using RevMan version 5.3 software and Stata version 12.0.ResultsTwelve studies with 627 volunteers were included. The pooled findings showed that weight loss interventions have no significant effect on the modulation of SIRT1 compared to the control group (pooled WMD of 0.58 ng/mL; 95% confidence interval [CI] -0.17 to 1.33; p = 0.130). However, subgroup analysis showed that weight loss interventions significantly modulate SIRT1 at metabolic disease (WMD: 1.2 ng/mL, 95% CI: 0.11 to 2.62, I2 = 82.9%). In addition, subgroup findings indicated health status and body mass index (BMI) as sources of high and potential heterogeneity.ConclusionsBased on the findings, weight loss therapies in individuals having a metabolic disorder appear to generate a considerable increase in SIRT1 levels.

Nanoparticle-activated SIRT3/SOD2 axis involves amelioration of chondrocyte senescence to delay osteoarthritis progression

Osteoarthritis (OA) manifests as a joint condition marked by the gradual deterioration of articular cartilage and the neighboring subchondral bone. Treatment avenues focusing on the regulation of autophagy and targeting senescence pathways are gaining considerable attention as promising therapeutic approaches. The clinical application of intra-articular agents for knee OA treatment is common. However, their effectiveness is insufficient owing to the rapid clearance of the agents. To address this challenge, nanoparticles present a promising solution as delivery systems, offering significant potential for regulating the local pharmacokinetics of therapeutic agents. Herein, we have developed chitosan-based nanoparticles for the sustained delivery of berberine chloride (BBR). These BBR-encapsulated chitosan nanoparticles (BBR-CNPs) demonstrated potent efficacy, safety, and prolonged retention time (up to 20 days) within rat joints. When administered as a therapeutic regimen, intra-articular injection of BBR-CNPs effectively alleviated age-related cartilage tissue degradation in surgically induced OA, whereas CNPs and pure BBR exhibited very limited effects on cartilage aging resistance function. BBR-CNPs penetrated the cartilage matrix, induced autophagy, and prevented senescence in interleukin-1 beta-induced rat chondrocytes. Additionally, BBR-CNPs resisted rat chondrocyte senescence and regulated mitochondrial function by activating the sirtuin 3 (SIRT3)/superoxide dismutase 2 (SOD2) signaling pathway. Collectively, these findings demonstrate the feasibility of employing BBR-CNPs as a potentially translatable clinical therapy with anti-aging properties, which are capable of impeding the advancement of OA. These particulate systems show promise as a viable option for sustained intra-articular delivery in OA treatment.

Based on SIRT1/NF-κB/NLRP3 Signal Pathway to Explore the Effect of Yiqi Huatan Huoxue Recipe on Inflammatory Injury in AIT Mice by Pyroptosis.

Autoimmune thyroiditis (AIT) is the most common autoimmune thyroid disease. In recent decades, its incidence and prevalence have sharply increased. Yiqi Huatan Huoxue recipe is a traditional Chinese medicine formula we use to treat AIT. Its clinical efficacy is clear, but the specific mechanism remains unclear. This study aims to explore whether pyroptosis mediated by the SIRT1/NF-κB/NLRP3 signaling pathway is one of the therapeutic mechanisms of Yiqi Huatan Huoxue recipe. Forty 8-week-old female NOD.H-2h4 mice were randomly divided into four groups: the normal group (NG), model group (MG), Yiqi Huatan Huoxue recipe group (YG), and western medicine group (selenium yeast tablet, SeG). The normal group was gavaged with distilled water, while the remaining groups were gavaged with 0.05% sodium iodide (NaI) solution for 8 weeks. After the AIT animal model formed naturally, the mice were euthanized by gavage after 8 weeks. Hematoxylin-eosin staining was used to observe thyroid tissue changes, and enzymelinked immunosorbent assay (ELISA) was used to detect serum anti-thyroglobulin antibodies (TGAb) and mouse anti-thyroid peroxidase antibodies (TPOAb). Real-time quantitative PCR (qRT-PCR), Western blot, and immunohistochemistry were used to detect the expression of sirtuin 1 (SIRT1), nuclear factor κB p65 (NF-κB p65), nod-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase- 1, gasdermin D (GSDMD), and interleukin (IL)-1β in thyroid tissue. Compared with the NG group, the thyroid structure of rats in the MG group was severely damaged, with significant lymphocyte infiltration, significantly increased serum TGAb and TPOAb levels, and significantly increased expression levels of SRIT1, NF-κB p65, NLRP3, ASC, Caspase-1, GSDMD, IL-1β mRNA, and protein. Compared with the MG group, the thyroid structure damage and lymphocyte infiltration in rats of each treatment group were improved, and the serum TGAb, TPOAb, SRIT1, NF-κB p65, NLRP3, ASC, Caspase-1, GSDMD, IL-1β mRNA, and protein expression levels were significantly reduced. Yiqi Huatan Huoxue recipe can alleviate thyroid structural damage in AIT mice, and its mechanism may be related to the upregulation of SIRT1, NF-κB deacetylation, and inhibition of NLRP3-mediated pyroptosis.

SIRT2 regulates high mobility group protein B1 nucleoplasmic shuttle and degradation via deacetylation in microglia.

High mobility group protein B1 (HMGB1) acts as a pathogenic inflammatory response to mediate ranges of conditions such as epilepsy, septic shock, ischemia, traumatic brain injury, Parkinson's disease, Alzheimer's disease and mass spectrometry. HMGB1 promotes inflammation during sterile and infectious damage and plays a crucial role in disease development. Mobilization from the nucleus to the cytoplasm is the first important step in the release of HMGB1 from activated immune cells. Here, we demonstrated that Sirtuin 2 (SIRT2) physically interacts with and deacetylates HMGB1 at 43 lysine residue at nuclear localization signal locations, strengthening its interaction with HMGB1 and causing HMGB1 to be localized in the cytoplasm. These discoveries are the first to shed light on the SIRT2 nucleoplasmic shuttle, which influences HMGB1 and its degradation, hence revealing novel therapeutic targets and avenues for neuroinflammation treatment.

Decreased sirtuin 4 levels promote cellular proliferation and invasion in papillary thyroid carcinoma.

This study examined the effect of sirtuin 4 (SIRT4), a NAD+-dependent deacetylase, on the proliferation and progression of papillary thyroid carcinoma (PTC). Data from The Cancer Genome Atlas (TCGA) were analyzed to identify SIRT4 expression in thyroid cancer. Subsequently, the correlation between SIRT4 expression and clinical characteristics was examined in 205 PTC tissue samples. In vitro assays using three human thyroid cancer cell lines (B-CPAP, TPC-1, and SNU-790) were conducted to assess the effects of regulated SIRT4 expression on cell growth, apoptosis, invasion, and migration. Furthermore, in vivo experiments were performed in a xenograft mouse model. Gene Expression Omnibus (GEO) and TCGA data indicated that SIRT4 expression is lower in thyroid cancer and SIRT4 downregulation is associated with poor overall survival. In PTC tissues, positive SIRT4 expression was associated with decreased extracapsular extension. In in vitro experiments using three human thyroid cancer cell lines, overexpression of SIRT4 decreased cell survival, clonogenic potential, and invasion and migratory capabilities, as well as inducing apoptosis and increasing reactive oxygen species levels. SIRT4 overexpression upregulated E-cadherin and downregulated N-cadherin, suggesting its potential involvement in the regulation of epithelial-mesenchymal transition. These findings were confirmed in vivo using a xenograft mouse model. This study provides novel insight into the potential contribution of SIRT4 to the regulation of the pathological progression of PTC. The data suggest that SIRT4 plays a tumor-suppressive role in PTC by inhibiting growth, survival, and invasive potential. Future research should investigate the molecular mechanisms underlying these effects of SIRT4.

Exploring the Role of Bergamot Polyphenols in Alleviating Morphine-Induced Hyperalgesia and Tolerance through Modulation of Mitochondrial SIRT3.

Morphine is an important pain reliever employed in pain management, its extended utilize is hindered by the onset of analgesic tolerance and oxidative stress. Long-term morphine administration causes elevated production of reactive oxygen species (ROS), disrupting mitochondrial function and inducing oxidation. Sirtuin 3 (SIRT3), a mitochondrial protein, is essential in modulating ROS levels by regulating mitochondrial antioxidant enzymes as manganese superoxide dismutase (MnSOD). Our investigation focused on the impact of SIRT3 on hyperalgesia and morphine tolerance in mice, as evaluating the antioxidant effect of the polyphenolic fraction of bergamot (BPF). Mice were administered morphine twice daily for four consecutive days (20 mg/kg). On the fifth day, mice received an acute dose of morphine (3 mg/kg), either alone or in conjunction with BPF or Mn (III)tetrakis (4-benzoic acid) porphyrin (MnTBAP). We evaluated levels of malondialdehyde (MDA), nitration, and the activity of SIRT3, MnSOD, glutamine synthetase (GS), and glutamate 1 transporter (GLT1) in the spinal cord. Our findings demonstrate that administering repeated doses of morphine led to the development of antinociceptive tolerance in mice, accompanied by increased superoxide production, nitration, and inactivation of mitochondrial SIRT3, MnSOD, GS, and GLT1. The combined administration of morphine with either BPF or MnTBAP prevented these effects.

Sirt1: An Increasingly Interesting Molecule with a Potential Role in Bone Metabolism and Osteoporosis.

Osteoporosis (OP) is a common metabolic bone disease characterized by low bone mass, decreased bone mineral density, and degradation of bone tissue microarchitecture. However, our understanding of the mechanisms of bone remodeling and factors affecting bone mass remains incomplete. Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase that regulates a variety of cellular metabolisms, including inflammation, tumorigenesis, and bone metabolism. Recent studies have emphasized the important role of SIRT1 in bone homeostasis. This article reviews the role of SIRT1 in bone metabolism and OP and also discusses therapeutic strategies and future research directions for targeting SIRT1.

Baicalin Attenuates Diabetic Cardiomyopathy In Vivo and In Vitro by Inhibiting Autophagy and Cell Death Through SENP1/SIRT3 Signaling Pathway Activation.

Aims: Diabetic heart damage can lead to cardiomyocyte death, which endangers human health. Baicalin (BAI) is a bioactive compound that plays an important role in cardiovascular diseases. Sentrin/SUMO-specific protease 1 (SENP1) regulates the de-small ubiquitin-like modifier (deSUMOylation) process of Sirtuin 3 (SIRT3) and plays a crucial role in regulating mitochondrial mass and preventing cell injury. Our hypothesis is that BAI regulates the deSUMOylation level of SIRT3 through SENP1 to enhance mitochondrial quality control and prevent cell death, ultimately improving diabetic cardiomyopathy (DCM). Results: The protein expression of SENP1 decreased in cardiomyocytes induced by high glucose and in db/db mice. The cardioprotective effects of BAI were eliminated by silencing endogenous SENP1, whereas overexpression of SENP1 showed similar cardioprotective effects to those of BAI. Furthermore, co-immunoprecipitation experiments showed that BAI's cardioprotective effect was due to the inhibition of the SUMOylation modification level of SIRT3 by SENP1. Inhibition of SENP1 expression resulted in an increase in SUMOylation of SIRT3. This led to increased acetylation of mitochondrial protein, accumulation of reactive oxygen species, impaired autophagy, impaired mitochondrial oxidative phosphorylation, and increased cell death. None of these changes could be reversed by BAI. Conclusion: BAI improves DCM by promoting SIRT3 deSUMOylation through SENP1, restoring mitochondrial stability, and preventing the cell death of cardiomyocytes. Innovation: This study proposes for the first time that SIRT3 SUMOylation modification is involved in the development of DCM and provides invivo and in vitro data support that BAI inhibits cardiomyocyte ferroptosis and apoptosis in DCM through SENP1. [Figure: see text].

Combination antiretroviral therapy prevents SIV- induced aging in the hippocampus and neurodegeneration throughout the brain.

Virus-induced accelerated aging has been proposed as a potential mechanism underlying the persistence of HIV-associated neurocognitive disorders (HAND) despite advances in access and adherence to combination antiretroviral therapies (cART). While some studies have demonstrated evidence of accelerated aging in PLWH, studies examining acute infection, and cART intervention are limited, with most studies being in vitro or utilizing small animal models. Here, we utilized FFPE tissues from Simian immunodeficiency virus (SIV) infected rhesus macaques to assess the levels of two proteins commonly associated with aging - the cellular senescence marker p16INK4a (p16) and the NAD-dependent deacetylase sirtuin 1 (SIRT1). Our central hypothesis was that SIV infection induces accelerated aging phenotypes in the brain characterized by increased expression of p16 and altered expression of SIRT1 that correlate with increased neurodegeneration, and that cART inhibits this process. We found that SIV infection induced increased GFAP, p16, SIRT1, and neurodegeneration in multiple brain regions, and treatment with cART reduced GFAP expression in SIV-infected animals and thus likely decreases inflammation in the brain. Importantly, cART reversed SIV-induced accelerated aging (p16 and SIRT1) and neurodegeneration in the frontal lobe and hippocampus. Combined, these data suggest that cART is both safe and effective in reducing neuroinflammation and age-associated alterations in astrocytes that contribute to neurodegeneration, providing possible therapeutic targets in the treatment of HAND.

Deacetylase SIRT2 Inhibition Promotes Microglial M2 Polarization Through Axl/PI3K/AKT to Alleviate White Matter Injury After Subarachnoid Hemorrhage.

White matter injury (WMI) subsequent to subarachnoid hemorrhage (SAH) frequently leads to an unfavorable patient prognosis. Previous studies have indicated that microglial M1 polarization following SAH results in the accumulation of amyloid precursor protein (APP) and degradation of myelin basic protein (MBP), thereby catalyzing the exacerbation of WMI. Consequently, transitioning microglial polarization towards the M2 phenotype (neuroprotective state) represents a potential therapeutic approach for reversing WMI. The SIRT2 gene is pivotal in neurological disorders such as neurodegeneration and ischemic stroke. However, its function and underlying mechanisms in SAH, particularly how it influences microglial function to ameliorate WMI, remain unclear. Our investigations revealed that in post-SAH, there was a temporal increase in SIRT2 expression, predominantly in the cerebral corpus callosum area, with notable colocalization with microglia. However, following the administration of the SIRT2 inhibitor AK-7, a shift in microglial polarization towards the M2 phenotype and an improvement in both short-term and long-term neuronal functions in rats were observed. Mechanistically, CO-IP experiments confirmed that SIRT2 can interact with the receptor tyrosine kinase Axl within the TAM receptor family and act as a deacetylase to regulate the deacetylation of Axl. Concurrently, the inhibition of SIRT2 by AK-7 can lead to increased expression of Axl and activation of the anti-inflammatory pathway PI3K/Akt signaling pathway, which regulates microglial M2 polarization and consequently reduces WMI. However, when Axl expression was inhibited by the injection of the shAxl virus into the lateral ventricles, the downstream signaling pathways were significantly suppressed. Rescue experiments also confirmed that the neuroprotective effects of AK-7 can be reversed by PI3K inhibitors. These data suggest that SIRT2 influences WMI by affecting microglial polarization through the Axl/PI3K/AKT pathway, and that AK-7 could serve as an effective therapeutic drug for improving neurological functions in SAH patients.

The Beneficial Effect of the SGLT2 Inhibitor Dapagliflozin in Alleviating Acute Myocardial Infarction-Induced Cardiomyocyte Injury by Increasing the Sirtuin Family SIRT1/SIRT3 and Cascade Signaling.

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have a variety of cardiovascular and renoprotective effects and have been developed as novel agents for the treatment of heart failure. However, the beneficial mechanisms of SGLT2i on cardiac tissue need to be investigated further. In this study, we established a mouse model of acute myocardial infarction (AMI) using coronary artery constriction surgery and investigated the role of dapagliflozin (DAPA) in protecting cardiomyocytes from hypoxic injury induced by AMI. In vitro experiments were done using hypoxic cultured H9c2 ventricular cells to verify this potential mechanism. Expression of the SIRT family and related genes and proteins was verified by qPCR, Western blotting and immunofluorescence staining, and the intrinsic potential mechanism of cardiomyocyte death due to AMI and hypoxia was comprehensively investigated by RNA sequencing. The RNA sequencing results of cardiomyocytes from AMI mice showed that the SIRT family may be mainly involved in the mechanisms of hypoxia-induced cardiomyocyte death. In vitro hypoxia-induced ventricular cells showed the role of dapagliflozin in conferring resistance to hypoxic injury in cardiomyocytes. It showed that SIRT1/3/6 were downregulated in H9c2 cells in a hypoxic environment, and the addition of dapagliflozin significantly increased the gene and protein expression of SIRT1, 3 and 6. We then verified the underlying mechanisms induced by dapagliflozin in hypoxic cardiomyocytes using RNA-seq, and found that dapagliflozin upregulated the hypoxia-induced gene downregulation, which includes ESRRA, EPAS1, AGTRAP, etc., that associated with SIRTs-related and apoptosis-related signaling to prevent H9c2 cell death. This study provides laboratory data for SGLT2i dapagliflozin treatment of AMI and confirms that dapagliflozin can be used to treat hypoxia-induced cellular necrosis in cardiomyocytes, in which SIRT1 and SIRT3 may play an important role. This opens up further opportunities for SGLT2i in the treatment of heart disease.