Increased Sirtuin 1 Expression Research Articles

MiR-155 induces sepsis-associated damage to the intestinal mucosal barrier via sirtuin 1/nuclear factor-κB-mediated intestinal pyroptosis.

Sepsis is a life-threatening state of organ dysfunction caused by systemic inflammation and a dysfunctional response to host infections that can induce severe intestinal mucosal damage. Pyroptosis is mediated by the activated NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome after stimulation by various inflammatory factors during sepsis. The inflammatory response is a major driver of intestinal damage during sepsis. Intestinal mucosal barrier dysfunction in sepsis is associated with pyroptosis, a type of programmed inflammatory cell death. Several studies have confirmed the role of miR-155 in sepsis and other diseases. However, the effect of miR-155 on intestinal pyroptosis in the context of intestinal mucosal barrier dysfunction during sepsis remains unclear. Thus, a model of sepsis in Sprague-Dawley rats is established using cecal ligation and puncture (CLP), and a series of molecular biological methods are used in this study. The results show that the expression of miR-155 is increased and that of sirtuin 1 (SIRT1) is decreased in the intestinal tissues of patients with sepsis. miR-155 expression is negatively correlated with SIRT1 expression. Increased miR-155 expression significantly inhibits SIRT1 activity and upregulates the expressions of NOD-like receptor family pyrin domain-containing 3 (NLRP3), caspase-1, apoptosis-associated speck-like protein containing a CARD (ASC), interleukin-1β (IL-1β) and interleukin-18 (IL-18) to promote pyroptosis. The inhibition of miR-155 expression is associated with increased SIRT1 expression, promotes the deacetylation of p65, and significantly downregulates p65 acetylation. Herein, we propose that miR-155 induces pyroptosis in the intestine partly by regulating SIRT1, thereby reducing the deacetylation of the nuclear factor (NF)-κB subunit p65 and increasing NF-κB signaling activity in sepsis, leading to intestinal barrier damage.

Relationship between COVID-19 and orofacial clefts.

MicroRNAs (miRNAs) are essential modulators of gene expression and are associated with various pathological processes, including spinal cord injury (SCI). This investigation aimed to elucidate miR-10a activity in SCI and its potential interaction with sirtuin 1 (SIRT1). The SCI rat model was established to assess hind limb movement, measure levels of miR-10a, SIRT1, neuronal survival, and inflammatory factors. An in-vitro SCI cell model was also developed to evaluate cell viability and inflammatory factor levels. The interaction between miR10a and SIRT1 was verified. Upregulated miR-10a and downregulated SIRT1 expression were found in the tissues of SCI rats. miR-10a knockdown in SCI rats enhanced the recovery of motor function, increased neuronal survival, and reduced the levels of inflammatory cytokines. Luciferase reporter assays confirmed that miR-10a targeted SIRT1 directly. In PC12 cells, downregulation of miR-10a increased SIRT1 expression, enhanced cell viability, and reduced inflammatory factor levels after LPS stimulation. Conversely, SIRT1 knockdown inhibited the protective effects of downregulated miR-10a on cell viability and inflammatory responses. The results suggest that miR-10a downregulation protects against SCI by upregulating SIRT1 expression, improving functional recovery, and reducing inflammation. Targeting the miR-10a/SIRT1 axis is a promising strategy for SCI treatment.

Mitochondrial antioxidant elamipretide improves learning and memory impairment induced by chronic sleep deprivation in mice.

The inflammation and synaptic dysfunction induced by mitochondrial dysfunction play essential roles in the learning and memory impairment associated with sleep dysfunction. Elamipretide (SS-31), a novel mitochondrion-targeted antioxidant, was proven to improve mitochondrial dysfunction, the inflammatory response, synaptic dysfunction, and cognitive impairment in models of cerebral ischemia, sepsis, and type 2 diabetes. However, the potential for SS-31 to improve the cognitive impairment induced by chronic sleep deprivation (CSD) and its underlying mechanisms is unknown. Adult c57BL/6J mice were subjected to CSD for 21 days using an activity wheel accompanied by daily intraperitoneal injection of SS-31 (5mg/kg). The novel object recognition and Morris water maze test were used to evaluate hippocampus-dependent cognitive function. Western blotting and reverse transcription-quantitative polymerase chain reaction assays were used to determine the effects of CSD and SS-31 on markers of mitochondria, inflammation response, and synaptic function. Enzyme-linked immunosorbent assays were used to examine the levels of proinflammatory cytokines. SS-31 could improve the cognitive impairment induced by CSD. In particular, SS-31 treatment restored the CSD-induced decrease in sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator alpha levels and the increase in levels nuclear factor kappa-B and inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha. Furthermore, SS-31 significantly increased the levels of brain-derived neurotrophic factor, postsynaptic density protein-95, and synaptophysin in CSD mice. Taken together, these results suggest that SS-31 could improve CSD-induced mitochondrial biogenesis dysfunction, inflammatory response, synaptic dysfunction, and cognitive impairment by increasing SIRT1 expression levels.

SIRT1 downregulation in pneumonia is associated with an immature neutrophil response and increased disease severity.

Pneumonia remains a common complication in trauma patients. Sirtuin 1 (SIRT1) is an anti-inflammatory NAD + -dependent deacetylase that has been shown to reduce the severity of ARDS in polymicrobial sepsis. The impact of SIRT1 in acute pneumonia, however, remains unknown. We hypothesized that SIRT1 deletion in pneumonia would worsen the inflammatory response and clinical severity, and that increased SIRT1 expression would be protective. Ten- to 14-week-old male and female SIRT1 knockout (S1KO) mice, SIRT1 overexpressor (S1OE) mice, and their wildtype (WT) littermates underwent intra-tracheal inoculation with Pseudomonas aeruginosa . Rectal temperature was recorded, SIRT1 lung protein was quantified by western blotting, Sirt1 mRNA was measured by qPCR, and lung leukocyte subpopulations were analyzed by flow cytometry. Data were analyzed by one-way ANOVA using Prism software. Pneumonia created a functional SIRT1 knockdown in the lungs of WT mice by 4 hours, resulting in comparable SIRT1 levels and temperatures to the S1KO mice by 12 hours. Pneumonia also partially reduced SIRT1expression in S1OE mice, but S1OE mice still had improved thermoregulation 12 hours after pneumonia. In all groups, Sirt1 mRNA expression was not affected by infection. Sirtuin 1 deletion was associated with decreased neutrophil infiltration in the lung, as well as a shift toward a more immature neutrophil phenotype. SIRT1 deletion was also associated with decreased myeloperoxidase-positive neutrophils in the lungs following pneumonia, indicating decreased neutrophil activity. S1OE mice had no change in lung leukocyte subpopulations when compared to WT. Pneumonia creates a functional SIRT1 knockdown in mice. SIRT1 deletion altered the early inflammatory cell response to pneumonia, resulting in a neutrophil response that would be less favorable for bacterial clearance. Despite overexpression of SIRT1, S1OE mice also developed low SIRT1 levels and exhibited only minimal improvement. This suggests increasing SIRT1 transcription is not sufficient to overcome pneumonia-induced downregulation and has implications for future treatment options. Targeting SIRT1 through increasing protein stability may promote a more efficient inflammatory cell response to pneumonia, thereby preventing subsequent lung injury.

Resveratrol Nanoparticles Inhibit Endothelial Dysfunction in Abdominal Aortic Aneurysm by Preventing eNOS Uncoupling Through Sirtuin 1 Pathway

Abdominal aortic aneurysm (AAA) is a pathological condition of chronic dilation of the aorta. This study investigated the mechanism underlying the inhibitory effect of resveratrol nanoparticles on AAA endothelial dysfunction. Mice in the control group received normal saline (n = 18) while those in the model group (n = 18) were implanted with Alzet micropumps to induce AAA. After modeling, the endothelial cells of abdominal aortic tissue were collected and treated with resveratrol nanoparticles and resveratrol nanoparticles plus sirtuin 1 (SIRT1) (resveratrol nanoparticles+SIRT1 group). CCK-8 method detected proliferation ability of abdominal aortic endothelial cells, flow cytometry assessed cell apoptosis, and transwell method measured the migration ability along with analysis of SIRT1 level, eNOS and NO content. The proliferation ability of endothelial cells was significantly decreased in resveratrol nanoparticles group (0.41±0.04, 0.60±0.05, 0.69±0.04) and resveratrol+SIRT1 group (0.37±0.05, 0.49±0.04, 0.57±0.04), with lower proliferation in resveratrol+SIRT1 group (P <0.05). Treatment resulted in enhancement of endothelial cell apoptosis and decreased migration ability (P <0.05), as the effect of combined treatment was more significant. Moreover, resveratrol nanoparticles (0.44±0.02, 0.34±0.05) or resveratrol nanoparticles plus SIRT1 (0.50±0.01, 0.44±0.03) increased SIRT1 level (P <0.05), eNOS activity and NO secretion (P <0.05) in the resveratrol+SIRT1 group. Resveratrol nanoparticles can reduce endothelial cell proliferation and migration and induce apoptosis when increasing SIRT1 expression.

Pterostilbene ameliorates type-2 diabetes mellitus – Induced depressive-like behavior by mitigating insulin resistance, inflammation and ameliorating HPA axis dysfunction in rat brain

One of the most serious mental health comorbidities associated with diabetes mellitus is depression. The occurrence is almost double in type 2 diabetes mellitus (T2DM) compared with the general population. Pterostilbene (PTE), a dimethylated analog of resveratrol, has been reported for significant neuroprotective, anti-inflammatory, hypolipidemic, hypoglycaemic and antioxidant effects. However, its effect on diabetes-induced depression-like behavior (DID) has not been studied.The current study aimed at studying the effects of PTE on depressive-like behavior in male Wistar rats with T2DM. It was induced by single dose administration of nicotinamide (NA) and streptozotocin (STZ). On day 21, forced swim test (FST) was conducted for the confirmation of DID. Rats demonstrating depressive-like behavior were treated with PTE (10, 20 and 40 mg/kg), metformin (MET; 500 mg/kg) and fluoxetine (FLX; 10 mg/kg) for 28 days, orally. At the end of the treatment, behavioral assessment for depression, blood glucose (BG) and lipid profile, oxidative stress markers, gene expression of Sirtuin 1 (SIRT1) and histopathological parameters were investigated. PTE significantly reduced weight loss and mitigated depressive-like behavior paradigms such as sucrose preference test (SPT), resident intruder test (RIT) and open field test (OFT). It significantly restored BG, lipid and liver profile, creatinine and antioxidant level. It Improved glucose tolerance, insulin resistance (IR) and reduced cortisol level as well as inflammatory markers. It showed improved morphology of the pancreas, brain, liver and kidney. Gene expression studies revealed that, PTE significantly increased SIRT1 expression. PTE by its virtue to maintain BG, reduced IR, amelioration of the HPA axis, anti-inflammatory, antioxidant activity and improvement of SIRT1 gene expression proved to be effective in the treatment of DID-like behavior in rats.

A new treatment approach: Melatonin and ascorbic acid synergy shields against sepsis-induced heart and kidney damage in male rats

AimTo investigate the combined therapeutic potential of melatonin and ascorbic acid in mitigating sepsis-induced heart and kidney injury in male rats and assess the combination therapy's effects on inflammation, cellular damage, oxidative stress, and vascular function-related markers. Materials and methodsCecal ligation and puncture (CLP) induced sepsis in male rats, which were divided into five groups: Sham, CLP, MEL (melatonin), ASA (ascorbic acid), and MEL+ASA (melatonin and ascorbic acid). Rats were treated, and heart and kidney tissues were collected for biochemical and histopathological analyses. Inflammatory markers (presepsin, procalcitonin, NF-κB, IL-1β, IL-6, TNF-α), cellular damage marker (8-OHDG), oxidative status, nitric oxide (NO), vascular endothelial growth factor (VEGF), and sirtuin 1 (SIRT1) levels were assessed. Key findingsMelatonin and ascorbic acid treatment reduced inflammatory and cellular damage markers compared to the CLP group. Combined treatment improved NO, VEGF levels, and increased SIRT1 expression, suggesting a synergistic effect in mitigating sepsis-induced inflammation, cellular damage, and oxidative stress. Histopathological analyses supported these findings, revealing reduced heart and kidney injury in the MEL+ASA group. SignificanceOur study highlights potential benefits of combining melatonin and ascorbic acid as a therapeutic strategy for alleviating sepsis-induced heart and kidney injury. The synergistic effects of these agents may provide stronger protection against inflammation, oxidative stress, and tissue damage, opening new avenues for future research and clinical applications in sepsis management.

Hydrogen sulfide attenuates TMAO‑induced macrophage inflammation through increased SIRT1 sulfhydration.

Chronic inflammation is a key factor that accelerates the progression of inflammatory vascular disease. Hydrogen sulfide (H2S) has potent anti‑inflammatory effects; however, its underlying mechanism of action has not been fully elucidated. The present study aimed to investigate the potential effect of H2S on sirtuin 1 (SIRT1) sulfhydration in trimethylamine N‑oxide (TMAO)‑induced macrophage inflammation, and its underlying mechanism. Pro‑inflammatory M1 cytokines (MCP‑1, IL‑1β, and IL‑6) and anti‑inflammatory M2 cytokines (IL‑4 and IL‑10) were detected by RT‑qPCR. CSE, p65 NF‑κB, p‑p65 NF‑κB, IL‑1β, IL‑6 and TNF‑α levels were measured by Western blot. The results revealed that cystathionine γ‑lyase protein expression was negatively associated with TMAO‑induced inflammation. Sodium hydrosulfide (a donor of H2S) increased SIRT1 expression and inhibited the expression of inflammatory cytokines in TMAO‑stimulated macrophages. Furthermore, nicotinamide, a SIRT1 inhibitor, antagonized the protective effect of H2S, which contributed to P65 NF‑κB phosphorylation and upregulated the expression of inflammatory factors in macrophages. H2S ameliorated TMAO‑induced activation of the NF‑κB signaling pathway via SIRT1 sulfhydration. Moreover, the antagonistic effect of H2S on inflammatory activation was largely eliminated by the desulfhydration reagent dithiothreitol. These results indicated that H2S may prevent TMAO‑induced macrophage inflammation by reducing P65 NF‑κB phosphorylation via the upregulation and sulfhydration of SIRT1, suggesting that H2S may be used to treat inflammatory vascular diseases.

Tanshinone IIA ameliorates Aβ transendothelial transportation through SIRT1-mediated endoplasmic reticulum stress

BackgroundThe disruption of blood-brain barrier (BBB), predominantly made up by brain microvascular endothelial cells (BMECs), is one of the characteristics of Alzheimer’s disease (AD). Thus, improving BMEC function may be beneficial for AD treatment. Tanshinone IIA (Tan IIA) has been proved to ameliorate the cognitive dysfunction of AD. Herein, we explored how Tan IIA affected the function of BMECs in AD.MethodsAβ1–42-treated brain-derived endothelium cells.3 (bEnd.3 cells) was employed for in vitro experiments. And we performed molecular docking and qPCR to determine the targeting molecule of Tan IIA on Sirtuins family. The APPswe/PSdE9 (APP/PS1) mice were applied to perform the in vivo experiments. Following the behavioral tests, protein expression was determined through western blot and immunofluorescence. The activities of oxidative stress-related enzymes were analyzed by biochemically kits. Nissl staining and thioflavin T staining were conducted to reflect the neurodegeneration and Aβ deposition respectively.ResultsMolecular docking and qPCR results showed that Tan IIA mainly acted on Sirtuin1 (SIRT1) in Sirtuins family. The inhibitor of SIRT1 (EX527) was employed to further substantiate that Tan IIA could attenuate SIRT1-mediated endoplasmic reticulum stress (ER stress) in BMECs. Behavioral tests suggested that Tan IIA could improve the cognitive deficits in APP/PS1 mice. Tan IIA administration increased SIRT1 expression and alleviated ER stress in APP/PS1 mice. In addition, LRP1 expression was increased and RAGE expression was decreased after Tan IIA administration in both animals and cells.ConclusionTan IIA could promote Aβ transportation by alleviating SIRT1-mediated ER stress in BMECs, which ameliorated cognitive deficits in APP/PS1 mice.

PGC-1α/NRF1-dependent cardiac mitochondrial biogenesis: A druggable pathway of calycosin against triptolide cardiotoxicity.

Mitochondrion-related cardiotoxicity due to cardiotoxin stimuli is closely linked to abnormal activities of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), followed by co-inactivation of nuclear respiratory factor-1(NRF1). Pharmacological interventions targeting mitochondria may be effective for developing agents against cardiotoxicity. Herein, in triptolide-treated H9C2 cardiomyocytes, we observed defective mitochondrial biogenesis and respiration, characterized by depletion of mitochondrial mass and mitochondrial DNA copy number, downregulation of mitochondrial respiratory chain complexes subunits, and disorders of mitochondrial membrane potential and mitochondrial oxidative phosphorylation. Dysregulation of mitochondria led to cardiac pathological features, such as myocardial fiber fracture, intercellular space enlargement, and elevation of serum aspartate aminotransferase, creatine kinase isoenzyme, lactate dehydrogenase, and cardiac troponin I. However, following calycosin treatment, an active compound from Astragali Radix, the mitochondrion-related disorders at both cell and tissue levels were significantly ameliorated, which was facilitated by the activation of PGC-1α via deacetylation, followed by NRF1 co-activation. Calycosin-enhanced PGC-1α deacetylation is impelled by increasing sirtuin-1 expression and NAD+/NADH ratio. PGC-1α/NRF1 signaling in calycosin-mediated mitochondrial biogenesis protection was further confirmed by NRF1 knockdown and PGC-1α inhibition with SR18292. We conclude that calycosin ameliorated triptolide-induced cardiotoxicity by protecting PGC-1α/NRF1-dependent cardiac mitochondrial biogenesis and respiration, which is the druggable pathway for cardiotoxicity mitigation.

Protective roles of apremilast via Sirtuin 1 in atherosclerosis

ABSTRACT Atherosclerosis is an inflammatory disease with a high level of cholesterol in the blood. Apremilast is a new anti-inflammatory drug that possesses a potential anti-atherosclerosis effect. RT-qPCR and western blot were undertaken to assay the levels of Sirtuin 1 (SIRT1), oxidized low density lipoprotein receptor 1 (LOX-1), and CD36 molecule (CD36). Reactive oxygen species (ROS) levels were evaluated by 2’, 7’-dichlorodihydrofluorescein diacetate (DCFH-DA) staining, and Oil Red O staining was performed to show lipid accumulation. The result showed that apremilast treatment reduced the expression levels of pro-inflammatory factors and p-p65, as well as lipid accumulation. Meanwhile, triglyceride (TG), total cholesterol (TC) and free cholesterol (FC) levels declined in oxidized low density lipoprotein (ox-LDL)-treated macrophages. Mechanistically, apremilast targets SIRT1 and increases SIRT1 expression. The efficacy of apremilast on inflammatory response and lipid formation required the involvement of SIRT1. Additionally, apremilast treatment reduced scavenger receptors, LOX-1, and CD36 levels. These findings suggest the protective effects of apremilast via SIRT1 in atherogenesis and highlight the need for translational research from bench to bedside.

Protective effect of liquiritin on coronary heart disease through regulating the proliferation of human vascular smooth muscle cells via upregulation of sirtuin1

ABSTRACT This study aimed to explore whether liquiritin affects the development of coronary heart disease by regulating the proliferation and migration of human vascular smooth muscle cells (hVSMCs). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release detection were performed to measure the toxic effects of liquiritin on hVSMCs. An in vitro atherosclerosis model in hVSMCs was established using oxidized low-density lipoprotein (ox-LDL), and cell proliferation and apoptosis were detected using an MTT assay and flow cytometry analysis. Western blotting and reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) were used to detect protein and mRNA expressions, respectively. Caspase3 activity and cell migration were measured using an activity detection kit and Transwell assay, respectively. The results indicated that liquiritin at doses <160 μM had no significant effect on cell viability and LDH release in hVSMCs. Ox-LDL significantly induced cell proliferation and migration, and inhibited hVSMCs apoptosis. Liquiritin significantly inhibited cell proliferation and migration, and enhanced cell apoptosis in ox-LDL induced hVSMCs. Sirtuin1 (SIRT1) was lowly expressed in atherosclerotic plaque tissues in coronary heart disease patients and in ox-LDL-induced hVSMCs. Liquiritin improved SIRT1 expression in ox-LDL-induced hVSMCs, whereas the improvement was inhibited by Selisistat (EX 527, an effective SIRT1 inhibitor) treatment. EX 527 reversed the effects of liquiritin on cell proliferation, migration, and apoptosis in ox-LDL-induced hVSMCs In conclusion, liquiritin plays a protective role in coronary heart disease by regulating the proliferation and migration of hVSMCs by increasing SIRT1 expression.

Capsaicin inhibits cell proliferation by enhancing oxidative stress and apoptosis through SIRT1/NOX4 signaling pathways in HepG2 and HL-7702 cells.

Capsaicin could suppress the proliferation of cancer cells and inhibit many biochemical pathways associated with tumorigenesis and metastasis. This study investigates the effects of capsaicin in both hepatocellular carcinoma (HepG2) and normal hepatocytes (HL-7702) via the SIRT1/NOX4 signaling pathway. After determination of cytotoxic concentrations of capsaicin on HL-7702 and HepG2 cells, we measured total oxidant status (TOS), reduced glutathione (GSH), 8-hydroxydeoxyguanosine (8-OHdG), cytochrome c (CYC), caspase3 (CASP3), Bcl-2, Bax, sirtuin1 (SIRT1), and NADPH oxidases4 (NOX4) levels. Besides this, we analyzed the messenger RNA and protein levels of SIRT1 and NOX4. We found that capsaicin increased TOS, 8-OHdG, CASP3, CYC, Bax, and NOX4 levels, and decreased Bcl-2, GSH, and SIRT1 in a concentration-dependent manner in HepG2 cells. However, especially low capsaicin concentration (128.75 µM) enhanced GSH and SIRT levels and reduced TOS, CASP3, CYC, 8-OHdG, and NOX4 levels in HL-7702 cells (p < 0.05). Interestingly, 128.75 and 172.8 µM capsaicin treatment increased SIRT1 expression levels in HL-7702 cells, resulting in an increase in GSH levels and a decrease in TOS, CYC, CAPS3, and 8-OHdG levels through NOX4 inhibition. Furthermore, we demonstrated a significant decrease in SIRT1 protein levels and an increase in NOX4 protein levels and caspase-3/-7 activities in both HL-7702 and HepG2 cells treated with 261.5 µM capsaicin. Additionally, morphological changes in HL-7702 and HepG2 cells treated with capsaicin correlated with the enhancement in oxidative burden, DNA damage, and apoptosis. Our results show that capsaicin effectively might cause higher oxidative, apoptotic, and DNA damage in HepG2 cells than in HL-7702 cells through the SIRT1/NOX4 signaling pathway.

Cerebroprotection by dioscin after experimental subarachnoid haemorrhage via inhibiting NLRP3 inflammasome through SIRT1-dependent pathway.

Dioscin has multiple biological activities and is beneficial for cardiovascular and cerebral vascular diseases. Here, we investigated the protective effects of dioscin against subarachnoid haemorrhage and the molecular mechanisms involved. Dioscin was administered after subarachnoid haemorrhage induced in rats. MCC950, a potent selective nod-like receptor pyrin domain-containing 3 (NLRP3) inhibitor, was used to suppress NLRP3 and EX527 (selisistat) was used to inhibit sirtuin 1 (SIRT1). In vivo, dioscin inhibited acute inflammatory response, oxidative damage, neurological impairment and neural cell degeneration after subarachnoid haemorrhage along with dramatically suppressing NLRP3 inflammasome activation. While pretreatment with MCC950 reduced the inflammatory response and improved neurological outcomes it did not lessen ROS production. However, giving dioscin after MCC950 reduced acute brain damage and ROS production. Dioscin increased SIRT1 expression after subarachnoid haemorrhage, whereas EX527 abolished the up-regulation of SIRT1 induced by dioscin and offset the inhibitory effects of dioscin on NLRP3 inflammasome activation. EX527 pretreatment also reversed the neuroprotective effects of dioscin against subarachnoid haemorrhage. Similarly, in vitro, dioscin dose-dependently suppressed inflammatory response, oxidative damage and neuronal degeneration and improved cell viability in neurons and microglia co-culture system. These effects were associated with inhibition of the NLRP3 inflammasome and stimulation of SIRT1 signalling, which could be inhibited by EX527 pretreatment. Dioscin provides protection against subarachnoid haemorrhage via the suppression of NLRP3 inflammasome activation through SIRT1-dependent pathway. Dioscin may be a new candidate to ameliorate early brain injury after subarachnoid haemorrhage.

Resveratrol protects intestinal epithelial cells against radiation-induced damage by promoting autophagy and inhibiting apoptosis through SIRT1 activation.

Intrinsic autophagy is important for the maintenance of intestinal homeostasis and intestinal regeneration. Ionizing radiation suppresses intrinsic autophagy and reduces damage-induced regeneration in the intestine, resulting in intestinal injury. Resveratrol, a sirtuin 1 (SIRT1) agonist, promotes autophagy and exerts radioprotective effect. In this study, the protective effect of resveratrol against radiation-induced intestinal injury and its potential mechanism were investigated. Intestinal epithelial cells (IEC-6) were exposed to 10 Gy ionizing radiation and resveratrol (0.1–40.0 μM). Cell viability was investigated using Cell Counting Kit 8 (CCK8), apoptosis was observed by Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining and flow cytometry, and the expression of apoptotic and autophagic proteins was determined by western blotting. Resveratrol exerted a high toxicity against IEC-6 cells, but at low concentrations, it inhibited ionizing radiation-induced apoptosis. Resveratrol increased SIRT1 expression after irradiation and inhibited ionizing radiation-induced p53 acetylation and pro-apoptotic protein, Bax, expression. Furthermore, resveratrol promoted autophagy via the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, thereby protecting IEC-6 cells against radiation-induced damage. These results suggest that resveratrol reduces radiation-induced IEC-6 cell damage by inhibiting apoptosis and promoting autophagy via the activation of SIRT1, and that the PI3K/AKT/mTOR signaling pathway is involved in the induction of autophagy.

Sirtuin 1 promotes autophagy and proliferation of endometrial cancer cells by reducing acetylation level of LC3.

Endometrial cancer (EC) constitutes a common female genital tract tumor with a rising incidence rate. Sirtuin 1 (SIRT1) is a member of histone deacetylase, which extensively participates in the progression of aging, cell death, and tumorigenesis. This study explored the effect of SIRT1-mediated LC3 acetylation on autophagy and proliferation of EC cells. SIRT1 expression in EC tissues and adjacent tissues, EC cell lines and normal human epithelial cells was detected. SIRT1 expression was elevated in EC cell lines and tissues. Knockdown of SIRT1 inhibited proliferation, migration, and invasion of EC cells. Then, EC cells were starved in serum-free medium, and levels of autophagy-related proteins were detected. Starvation induced autophagy of EC cells. The starvation-treated EC cells showed an increased SIRT1 expression, a decreased LC3 acetylation level and an increased autophagy level. The proliferation and autophagy of EC cells under different treatments were evaluated. In EC cells transfected with overexpressing SIRT1, LC3 acetylation was inhibited and cell proliferation was promoted. Moreover, overexpressing SIRT1 facilitated growth and autophagy of transplanted tumors in nude mice. In conclusion, SIRT1 promoted autophagy and proliferation of EC cells by reducing acetylation level of LC3.

MiR-34a regulates lipid metabolism by targeting SIRT1 in non-alcoholic fatty liver disease with iron overload

BackgroundMicro-ribonucleic acids (miRNAs) have been implicated in the regulation of non-alcoholic fatty liver disease (NAFLD), a leading cause of chronic liver disease worldwide. The mechanisms by which miR-34a influences NAFLD through the Sirtuin 1 (SIRT1)-related pathway were investigated herein. MethodsMale C57BL/6 mice were injected with a miR-34a lentivirus vector inhibitor or control. HepG2 cells were transfected with a miR-34a mimic, inhibitor, SIRT1 small interfering RNA (siRNA), SIRT1 plasmid, and a negative oligonucleotide control to evaluate their role in oleic acid (OA) and excess iron-induced NAFLD. The accumulation of lipids in the mice liver and HepG2 cells was analyzed by triglyceride (TG) detection and hematoxylin and eosin (HE) staining. Additionally, the indexes of oxidative stress related to lipid metabolism were evaluated by western blotting and real-time PCR (qRT-PCR). The levels of intracellular reactive oxygen species (ROS) and mitochondrial membrane potentials were measured by flow cytometry and laser confocal microscopy, respectively. Finally, the dual luciferase reporter assay was conducted to further confirm whether SIRT1 was a direct target of miR-34a. ResultsOverexpression of miR-34a resulted in increased triglyceride accumulation as well as in decreased mitochondrial membrane potential and SIRT1 levels. Silencing of miR-34a increased SIRT1 expression and alleviated triglyceride accumulation in the presence of OA and iron. Additionally, miR-34a directly inhibited SIRT1 by binding to the 3′-untranslated region, as determined via the luciferase reporter assay. ConclusionsOur results support the existence of a link between the liver cell mitochondria and miR-34a/SIRT1 signaling. Potential endogenous modulators of NAFLD pathogenesis may ultimately provide new tools for therapeutic intervention.

3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced Inflammatory Response by Increasing SIRT1 Expression in Human Umbilical Vein Endothelial Cells

3,4,5-Trihydroxycinnamic acid (THC) has been demonstrated to exert anti-inflammatory activities in LPS-induced RAW264.7 murine macrophage cells and in LPS-induced septic mice. However, the effect of THC on the inflammatory response in vascular endothelial cells has not been clearly examined. The goal of the present study was to elucidate the anti-inflammatory properties of THC and its underlying mechanism in LPS-challenged human umbilical vein endothelial cells (HUVECs). THC significantly suppressed LPS-induced interleukin-1β production and intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression and significantly decreased LPS-induced nuclear factor-κB activation by attenuating p65 phosphorylation and inhibitor of kappa B degradation. To understand the underlying mechanism of the anti-inflammatory effect of THC, the involvement of the sirtuin 1 (SIRT1) signaling pathway was examined. THC resulted in increased expression of SIRT1 in LPS-challenged HUVECs. Among the downstream molecular targets of SIRT1, the level of LPS-induced acetylated p53 was significantly decreased by THC treatment, whereas no noticeable change was observed in the levels of forkhead box O3 and peroxisome proliferator activated receptor gamma coactivator 1 alpha. In conclusion, the results clearly demonstrate that THC possesses anti-inflammatory properties by increasing SIRT1 expression and subsequent suppression of p53 activation in LPS-challenged HUVECs.

Astaxanthin Inhibits Alcohol-Induced Inflammation and Oxidative Stress by Mediating the Sirtuin 1 and Histone Deacetylase 4 Axis in Macrophages

Abstract Objectives We previously demonstrated that astaxanthin (ASTX), a xanthophyll carotenoid, exerts anti-inflammatory and antioxidant properties in macrophages exposed to ethanol. In this study, to gain mechanistic insight, we explored the role of sirtuin 1 (SIRT1) and histone deacetylase 4 (HDAC4) in the prevention of ethanol-induced inflammation and oxidative stress by ASTX in macrophages. Methods RAW 264.7 macrophages and bone marrow-derived macrophages (BMDMs) isolated from wild-type (WT) and mice with macrophage specific-deletion of HDAC4 (Hdac4MKO) were used. Cells were stimulated with 80 mM ethanol in the absence or presence of 25 mM of ASTX for 72 h. The expression of genes associated with inflammation, SIRT1 and HDAC4 was measured. RAW 264.7 macrophages were treated with sirtinol or resveratrol, which are known inhibitor or activator of SIRT1 activity, respectively, to determine the effect of SIRT1 activity on HDAC4 expression. Parameters related to mitochondrial respiration were determined using a Seahorse XFe24 Extracellular Flux analyzer in both macrophage cell types. Results Ethanol decreased mRNA and protein levels of SIRT1 but increased those of HDAC4, which was attenuated by ASTX in RAW 264.7 macrophages. ASTX abolished an increase in acetylated histone H3 by ethanol in RAW 264.7 macrophages. Knockdown of HDAC4 increased SIRT1 expression, concomitantly decreasing ethanol-induced inflammatory gene expression. Furthermore, BMDMs from Hdac4MKO mice showed significant decreases in ethanol-induced inflammatory genes but an increase in SIRT1 expression compared with WT BMDMs. Ethanol increased mitochondrial respiration, ATP production, and proton leak, but decreased maximal respiration and spare respiratory capacity. The changes by ethanol were abolished by ASTX in RAW 264.7 macrophages. Compared with WT BMDMs, the ethanol-induced alterations in mitochondrial respiration were abrogated in Hdac4MKO BMDMs. Conclusions The anti-inflammatory and antioxidant properties of ASTX in ethanol-treated macrophages may be mediated, at least in part, by the crosstalk between SIRT1 and/HDAC4. This study, therefore, provides new mechanisms in preventing the alcohol-induced inflammation and oxidative stress through the crosstalk between SIRT1 and HDAC4. Funding Sources This study was supported by NIH 1R01DK108254–01.

SIRT1 enhances hepatitis virus B transcription independent of hepatic autophagy

Autophagy is an intracellular process that can lead to the degradation of malfunctioned proteins and damaged organelles to maintain homeostasis during cellular stress. Here, we evaluated the change in hepatitis B virus (HBV) production by regulating hepatic autophagy in HBV-producing cells. We examined focusing on a relation with a positive autophagy regulator, sirtuin1 (SIRT1).Starvation and rapamycin treatment induced autophagy with increasing SIRT1 protein, HBc protein and pregenomic RNA (pgRNA) levels in HBV- producing cells. Knockdown of Atg7 or Atg13 suppressed hepatic autophagy, and it did not change SIRT1 protein, HBc protein or pgRNA levels in HBV- producing cells. Resveratrol, which increases SIRT1 expression and activity, promoted autophagy and increased HBc protein and pgRNA levels. siRNA-mediated knockdown of SIRT1 inhibited autophagy and decreased HBc protein and pgRNA levels. In SIRT1-knockdown cells, starvation promoted autophagy but did not increase HBc protein and pgRNA levels.In conclusion, HBc protein and pgRNA levels are upregulated not by the autophagic process itself but by the SIRT1 expression level.