Sirtuin 1 Activity Research Articles

Injection of Collagen Binding Domain-Brain Derived Neurotrophic Factor Promotes SIRT1 Expression: Improving Neuroinflammation in Experimental Subarachnoid Hemorrhage.

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease, often leading to neuroinflammation and neuronal damage. Activation of the Nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is closely associated with post-SAH neuroinflammation, while activation of Nicotinamide Adenine Dinucleotide (NAD)-dependent deacetylase sirtuin-1 (SIRT1) has neuroprotective effects. This study aimed to investigate the impact of injectable Collagen Binding Domain-Brain Derived Neurotrophic Factor (CBD-BDNF) on neuroinflammation and neuronal damage following SAH. After establishing the SAH model, experimental animals were divided into three groups: sham surgery group (Sham), SAH group, and SAH+neuroregenerative scaffold (CBD-BDNF treatment) group. Behavioral performance was evaluated using neurofunctional deficit, beam balance, and Y-maze tests. Expression of inflammatory factors and essential proteins was quantitatively analyzed using Enzyme-Linked Immunosorbent Assay (ELISA) kits and immunoblotting. Terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) staining was used to assess cell apoptosis. To further investigate the mechanism of action of CBD-BDNF on SIRT1, the model animals were treated with EX527 (SIRT1 inhibitor) for comparative studies. Neurological deficit tests, CBD-BDNF improves functional outcomes after SAH. Compared to the SAH group, the SAH+neuroregenerative scaffold group showed significantly increased expression of SIRT1 protein and significantly decreased expression of NLRP3, Apoptosis-associated speck-like protein containing a CARD (ASC), and c-caspase-1. The inflammatory cytokines Interleukin-1 beta (IL-1β), IL-6, and IL-18 levels also significantly decreased in the SAH+neuroregenerative scaffold group. Additionally, animals in the SAH+neuroregenerative scaffold group showed better neurofunctional recovery in neurofunctional deficit and beam balance tests. The number of apoptotic cells significantly decreased in the SAH+neuroregenerative scaffold group compared to the SAH group. However, when SIRT1 was inhibited with EX527, the aforementioned neuroprotective effects were reversed, indicating the involvement of CBD-BDNF through SIRT1 activation. This study demonstrates that injectable CBD-BDNF can significantly alleviate neuroinflammation and neuronal damage resulting from SAH by blocking NLRP3 inflammasome activation and promoting SIRT1 expression. These findings provide a new therapeutic strategy for neuroprotection after SAH and reveal the mechanism of action of CBD-BDNF as a potential therapeutic agent. Future research will further explore the long-term efficacy and safety of CBD-BDNF.

Dietary Tomato Powder Feeding Attenuated Non-Alcoholic Fatty Liver Disease Independent of Sirtuin1 Activity in Mice

Dietary Tomato Powder Feeding Attenuated Non-Alcoholic Fatty Liver Disease Independent of Sirtuin1 Activity in Mice

Formulation and Characterization of Nanoparticle-Protein Sirtuin 1 (NPS1) by Nanoprecipitation Technique

Atherosclerosis is a cardiovascular disease caused by endothelial dysfunction. This situation will trigger the bone marrow to immediately replace it with new endothelial progenitor cells (EPC) cells. However, some studies suggest that EPC can experience premature senescence. Sirtuin-1 (SIRT1) is a cellular post-translational protein that has the task of repairing dysfunctional EPC cells. Studies have tried to develop SIRT1 activation, but currently, there are no studies that have attempted to increase SIRT1 levels in cells. Nanoparticles (NPS) are one of the methods in nanomedicine, which has the advantage of being a drug carrier. So, further research is needed on adding exogenous SIRT1 levels, NPS, which can improve the quality of EPC cells and prevent premature senescence. This study aims to report the formulation and characterization stages of nanoparticles carrying SIRT1 (NPS1) with different solvents, such as ethanol and aquadest. The method used in this formulation uses nanoprecipitation. The characterization of nanoparticles at this stage included organoleptic tests, pH tests, and quantifying using Nanodrops in determining the presence of adsorbed proteins. The pH and organoleptic test showed that the NPS1 formulation was acidic (K1 = 5.412 ± 0.73; K2 = 3.624 ± 0.45; F1 = 5.418 ± 0.55; F2 = 4.182 ± 0.07), yellow in color, and had a characteristic odor. Thus, the formulation and characteristics of NPS1 can be used as a method in drug development for anti-senescence therapy in EPC cells in further research, both in vitro, in vivo, and evaluation of preparations that are still very possible to be developed.

Effect of Combined Exercises on Glucose Homeostasis and Plasma Levels of Sirtuin 1 and FOXO1 in Obese Elderly Men

Introduction: Aging and obesity have common symptoms, including glucose and lipid metabolism changes. Activation of sirtuin 1 and FOXO1 (Forkhead Box Protein O1) can positively affect metabolic disorders associated with aging and obesity. This research aimed to investigate 16 weeks of combined exercise on the plasma levels of sirtuin 1, FOXO1, and glucose homeostasis in obese elderly. Methods: 40 obese elderly men with an average age of 61.90 ± 2.84 were selected and randomly divided into two experimental and control groups. The participants trained three days a week (each session 90 minutes) for 16 weeks. 48 hours before and after exercise, anthropometric characteristics and plasma values of sirtuin 1, FOXO1, fasting blood sugar, insulin, HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), and HOMA-B (Homeostasis Model Assessment of β-Cell) were taken from the samples and measured by ELISA method. Data analysis was done using SPSS 16 software, independent and dependent t-tests at a significance level of P˂ 0.05. Results: Levels of fasting blood sugar (P=0.04), and insulin (P=0.008) in the experimental group decreased significantly compared to the control group, while the serum levels of sirtuin1 (P=0.0001) and FOXO1 (P=0.0001) had a significant increase. Correlated t results in the experimental group showed a significant decrease in insulin, HOMA-IR, and HOMA-B (P = 0.001) and a significant increase in the serum levels of sirtuin1 (P = 0.0001) and FOXO1 (P = 0.0001) (P ˂ 0.05). Conclusion: Based on the results of this study, it seems that 16 weeks of combined training has a favorable effect on improving glucose homeostasis, increasing sirtuin 1 and FOXO1 levels in elderly obese men.

The Citrus flavanone naringenin prolongs the lifespan in C. elegans and slows signs of brain aging in mice

Aging is one of the main risk factors for neurodegenerative disorders, which represent a global burden on healthcare systems. Therefore, identifying new strategies to slow the progression of brain aging is a compelling challenge. In this article, we first assessed the potential anti-aging effects of the Citrus flavanone naringenin (NAR), an activator of the enzyme sirtuin-1 (SIRT1), in a 3R-compliant and short-lived aging model (i.e., the nematode C. elegans). Then, we investigated the preventive effects of a 6-month treatment with NAR (100 mg/kg, orally) against brain aging and studied its mechanism of action in middle-aged mice. We demonstrated that NAR (100 μM) extends lifespan and improves healthspan in C. elegans. In the brain of middle-aged mice, NAR promotes the activity of metabolic enzymes (citrate synthase, cytochrome C oxidase) and increases the expression of the SIRT1 enzyme. Consistently, NAR up-regulates the expression of downstream antioxidant (Foxo3, Nrf2, Ho-1), anti-senescence (p16), and anti-inflammatory (Il-6, Il-18) markers. Our findings support NAR supplementation to slow the signs of brain aging.

Cardiotoxicity Induced by Intratracheal Instillation of Diesel Exhaust Particles in Mice, and the Protective Effects of Carnosol: Suppression of Inflammation and Oxidative and Nitrosative Stress via Modulation of NF-κb/MAPKs Signaling Pathways.

Inhaled particulate air pollution is associated with cardiotoxicity with underlying mechanisms including oxidative stress and inflammation. Carnosol, commonly found in rosemary and sage, is known to possess a broad range of therapeutic properties such as antioxidant, anti-inflammatory and antiapoptotic. However, its cardioprotective effects on diesel exhaust particles (DEPs)-induced toxicity have not been studied yet. Hence, we evaluated the potential ameliorative effects of carnosol on DEPs-induced heart toxicity in mice, and the underlying mechanisms involved. Mice were intratracheally instilled with DEPs (1 mg/kg) or saline, and 1 hour prior to instillation they were given intraperitoneally either carnosol (20 mg/kg) or saline. Twenty-four hours after the DEPs instillation, multiple parameters were evaluated in the heart by enzyme-linked immunosorbent assay, colorimetric assay, Comet assay and Western blot technique. Carnosol has significantly reduced the elevation in the plasma levels of lactate hydrogenase and brain natriuretic peptide induced by DEPs. Likewise, the augmented cardiac levels of proinflammatory cytokines, lipid peroxidation, and total nitric oxide in DEPs-treated groups were significantly normalized with the treatment of carnosol. Moreover, carnosol has markedly reduced the heart mitochondrial dysfunction, as well as DNA damage and apoptosis of mice treated with DEPs. Similarly, carnosol significantly reduced the elevated expressions of phosphorylated nuclear factor-кB (NF-кB) and mitogen-activated protein kinases (MAPKs) in the hearts. Furthermore, the treatment with carnosol has restored the decrease in the expression of sirtuin-1 in the hearts of mice exposed to DEPs. Carnosol significantly attenuated DEP-induced cardiotoxicity in mice by suppressing inflammation, oxidative stress, DNA damage, and apoptosis, at least partly via mechanisms involving sirtuin-1 activation and the inhibition of NF-кB and MAPKs activation.

Regulation of TSC2 lysosome translocation and mitochondrial turnover by TSC2 acetylation status

Sirtuin1 (SIRT1) activity decreases the tuberous sclerosis complex 2 (TSC2) lysine acetylation status, inhibiting the mechanistic target of rapamycin complex 1 (mTORC1) signalling and concomitantly, activating autophagy. This study analyzes the role of TSC2 acetylation levels in its translocation to the lysosome and the mitochondrial turnover in both mouse embryonic fibroblast (MEF) and in mouse insulinoma cells (MIN6) as a model of pancreatic β cells. Resveratrol (RESV), an activator of SIRT1 activity, promotes TSC2 deacetylation and its translocation to the lysosome, inhibiting mTORC1 activity. An improvement in mitochondrial turnover was also observed in cells treated with RESV, associated with an increase in the fissioned mitochondria, positive autophagic and mitophagic fluxes and an enhancement of mitochondrial biogenesis. This study proves that TSC2 in its deacetylated form is essential for regulating mTORC1 signalling and the maintenance of the mitochondrial quality control, which is involved in the homeostasis of pancreatic beta cells and prevents from several metabolic disorders such as Type 2 Diabetes Mellitus.

SIRT1 regulates hepatic vldlr levels

BackgroundEndoplasmic reticulum (ER) stress-mediated increases in the hepatic levels of the very low-density lipoprotein (VLDL) receptor (VLDLR) promote hepatic steatosis by increasing the delivery of triglyceride-rich lipoproteins to the liver. Here, we examined whether the NAD(+)-dependent deacetylase sirtuin 1 (SIRT1) regulates hepatic lipid accumulation by modulating VLDLR levels and the subsequent uptake of triglyceride-rich lipoproteins.MethodsRats fed with fructose in drinking water, Sirt1−/− mice, mice treated with the ER stressor tunicamycin with or without a SIRT1 activator, and human Huh-7 hepatoma cells transfected with siRNA or exposed to tunicamycin or different inhibitors were used.ResultsHepatic SIRT1 protein levels were reduced, while those of VLDLR were upregulated in the rat model of metabolic dysfunction-associated steatotic liver disease (MASLD) induced by fructose-drinking water. Moreover, Sirt1−/− mice displayed increased hepatic VLDLR levels that were not associated with ER stress, but were accompanied by an increased expression of hypoxia-inducible factor 1α (HIF-1α)-target genes. The pharmacological inhibition or gene knockdown of SIRT1 upregulated VLDLR protein levels in the human Huh-7 hepatoma cell line, with this increase abolished by the pharmacological inhibition of HIF-1α. Finally, SIRT1 activation prevented the increase in hepatic VLDLR protein levels in mice treated with the ER stressor tunicamycin.ConclusionsOverall, these findings suggest that SIRT1 attenuates fatty liver development by modulating hepatic VLDLR levels.

FNDC5 prevents oxidative stress and neuronal apoptosis after traumatic brain injury through SIRT3-dependent regulation of mitochondrial quality control

Mitochondrial dysfunction and oxidative stress are important mechanisms for secondary injury after traumatic brain injury (TBI), which result in progressive pathophysiological exacerbation. Although the Fibronectin type III domain-containing 5 (FNDC5) was reported to repress oxidative stress by retaining mitochondrial biogenesis and dynamics, its possible role in the secondary injury after TBI remain obscure. In present study, we observed that the level of serum irisin (the cleavage product of FNDC5) significantly correlated with the neurological outcomes of TBI patients. Knockout of FNDC5 increased the lesion volume and exacerbated apoptosis and neurological deficits after TBI in mice, while FNDC5 overexpression yielded a neuroprotective effect. Moreover, FNDC5 deficiency disrupted mitochondrial dynamics and function. Activation of Sirtuin 3 (SIRT3) alleviated FNDC5 deficiency-induced disruption of mitochondrial dynamics and bioenergetics. In neuron-specific SIRT3 knockout mice, FNDC5 failed to attenuate TBI-induced mitochondrial damage and brain injuries. Mechanically, FNDC5 deficiency led to reduced SIRT3 expression via enhanced ubiquitin degradation of transcription factor Nuclear factor erythroid 2-related factor 2 (NRF2), which contributed to the hyperacetylation and inactivation of key regulatory proteins of mitochondrial dynamics and function, including OPA1 and SOD2. Finally, engineered RVG29-conjugated nanoparticles were generated to selectively and efficiently deliver irisin to the brain of mice, which yielded a satisfactory curative effect against TBI. In conclusion, FNDC5/irisin exerts a protective role against acute brain injury by promoting SIRT3-dependent mitochondrial quality control and thus represents a potential target for neuroprotection after TBI.

Cellular senescence as a key factor in osteoporosis: the role of SIRT1

Osteoporosis, a prevalent age-related condition, is characterized by decreased in bone mass and bone quality. Among the pathogenetic mechanisms, cellular senescence has been suggested to induce inflammation and affect bone cell function, contributing to bone fragility. In this context, sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, emerges as a central regulator of musculoskeletal health, influencing osteoblastic differentiation, suppressing osteoclastic activity and maintaining bone mass by the deacetylation of critical targets. Interestingly, a close association was found between an elevated senescence-associated secretory phenotype and aged bone cells, confirming a role for senescence in bone aging. The aim of our minireview is to highlight cellular senescence as a key factor in osteoporosis, focusing on the central role of SIRT1 and exploring potential strategies to modulate its activity, including diet, exercise and pharmacological interventions. In conclusion, enhancing SIRT1 activity represents a potential therapeutic approach for age-related bone disorders, offering interesting perspectives for future research and therapeutic development. KEY WORDS: SIRT1, osteoporosis aging senescence bone cells, diet, exercise, pharmacological interventions.

Anti-inflammatory effects of ginsenoside compound K in ethanol-stimulated macrophages by modulating sirtuin 1

Inflammatory responses by macrophages have been pivotal in the pathogenesis of various diseases. We previously demonstrated the anti-inflammatory effects of ginsenoside compound K (GCK) through sirtuin 1 (SIRT1) activation in lipopolysaccharide-treated macrophages. This study extended the efficacy of GCK in mitigating ethanol-induced inflammation in macrophages through the interplay between SIRT1 and estrogen receptor α (ERα). Ethanol elevated inflammatory and oxidative stress genes with reduced SIRT1 expression. GCK reversed these effects, concomitantly inhibiting M1 polarization in macrophages. The efficacy of GCK in modulating ethanol-altered glycolysis and NAD+ salvage pathway was demonstrated through its interaction with SIRT1 and ERα. Activation of SIRT1 by GCK leads to the activation of ERα, and vice versa, suggesting a synergistic relationship between SIRT1 and ERα mediated by GCK. In conclusion, GCK exhibited anti-inflammatory and antioxidant properties, which may counteract energy metabolism disruptions in ethanol-stimulated macrophages, through the interplay between SIRT1 and ERα.

Targeting the SIRT1 pathway to modulate inflammation in a murine model of Kawasaki Disease vasculitis

Abstract Kawasaki Disease (KD) is an acute febrile systemic vasculitis and the leading cause of acquired heart disease among children. Overactivation of the NLRP3 inflammasome and IL-1b production are critical for the development of cardiovascular lesions during KD. Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase, is crucial for responding to cellular stress, and regulates NLRP3 activation as well as clearance of damaged mitochondria in cardiovascular diseases. However, its role in KD pathophysiology remains unknown. Here, we used the Lactobacillus casei cell wall extract (LCWE) murine model of KD to determine the role of SIRT1 on the development of cardiovascular lesions. We show that Sirt1 expression is downregulated in LCWE-injected mice with a significant reduction of nicotinamide, a product resulting from NAD+ degradation by SIRT1. In addition, supplementation of mice with NAD+ precursors significantly reduced the development of LCWE-induced cardiovascular lesions. Furthermore, KD development was less severe in SIRT1 overexpressing mice but was exacerbated with the specific deletion of Sirt1 in vascular smooth muscle cells. Treatment of LCWE-stimulated coronary smooth muscle cells with a SIRT1 activator favored mitophagy by inhibiting ribosomal S6 phosphorylation. These results indicate an impaired NAD+/SIRT1 axis during LCWE-induced KD vasculitis, which could potentially be targeted to reduce cardiovascular lesions in KD.

Effect of intermittent fasting on fasting blood glucose, sirtuin 1, and total antioxidant capacity in rat models of diabetes mellitus

Background: Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycaemia. DM therapy is mainly purposed to control blood glucose levels by adjusting diet and reducing body fat, which can be implemented with calorie restriction (CR) by intermittent fasting (IF), a diet that alternates periods between eating and fasting. Sirtuins, proteins activated by CR, can regulate glucose metabolism, regulate insulin secretion, and protect cells from oxidative stress, so IF is considered to be an opportunity for DM management.Objective: This study is to determine effects of IF on Fasting Blood Glucose (FBG) levels, sirtuin 1 (SIRT1) activity, and total antioxidants (TAOC) in rat models of Wistar with DM.Methods: This experimental study applied a post-test control group design involving 24 Wistar rats which were divided into 4 groups: K1 (rats with DM without IF), K2 (rats with DM treated with metformin 45 mg/kg BW, K3 (rats with DM treated with IF), and K4 (normal rats treated with IF). The diabetes condition were induced with intraperitoneal injection of streptozotocin (STZ). The rats received IF treatment, fasted for 16 hours and ate window open for 8 hours. This treatment was conducted for 14 days. The FBG levels were measured by using a glucometer, while SIRT1 activity and TAOC were measured by using the ELISA method.Results: The statistical analysis using the Kruskal Wallis test for the FBG levels indicated that there was a significant difference among the four groups (p = 0.000). The ANOVA test for SIRT1 activity revealed that there was a significant difference among the four groups (p = 0.001). The Kruskal Wallis test for TAOC pointed out that there was no significant difference among the four groups (p = 0.529).Conclusion: The IF method using a 16:8 regimen reduced the FBG levels and increased the sirtuin 1 activity, but it was not proven to increase the TAOC in the rat models of Wistar with DM.

Nephroprotective effect of Ginsenoside Rg1 in lipopolysaccharide-induced sepsis in mice through the SIRT1/NF-κB signaling.

During sepsis, the kidney is one of the most vulnerable organs. Sepsis-associated acute kidney injury (S-AKI) is hallmarked by renal inflammation, apoptosis, and oxidative injury. Ginsenoside Rg1 (Rg1) is a natural product that possesses abundant pharmacological actions and protects against many sepsis-related diseases. Nevertheless, its role and related mechanism in S-AKI remain to be determined. S-AKI was induced using lipopolysaccharide (LPS, 10 mg/kg) via a single intraperitoneal injection. Rg1 (200 mg/kg) was intraperitoneally administered for 3 consecutive days before LPS treatment. For histopathological examination, murine kidney tissues were stained with hematoxylin and eosin. Tubular injury score was calculated to evaluate kidney injury. Serum creatinine and BUN levels were measured for assessing renal dysfunction. The levels and activities of oxidative stress markers (MDA, 4-HNE, PC, GSH, SOD, and CAT) in renal tissue were measured by corresponding kits. Renal cell apoptosis was detected by TUNEL staining. The protein levels of apoptosis-related markers (Bcl-2, Bax, and Cleaved caspase-3), proinflammatory factors, SIRT1, IκBα, p-NF-κB p65, and NF-κB p65 in kidneys were determined using western blotting. Immunofluorescence staining was employed to assess p-NF-κB p65 expression in renal tissues. LPS-induced injury of kidneys and renal dysfunction in mice were ameliorated by Rg1. Rg1 also impeded LPS-evoked renal cell apoptosis in kidneys. Moreover, Rg1 attenuated LPS-triggered inflammation and oxidative stress in kidneys by inhibiting proinflammatory cytokine release, enhancing antioxidant levels and activities, and reducing lipid peroxidation. However, all these protective effects of Rg1 in LPS-induced AKI mice were reversed by EX527, an inhibitor of sirtuin 1 (SIRT1). Mechanistically, Rg1 upregulated SIRT1 protein expression, increased SIRT1 activity, and inactivated NF-κB signaling in the kidney of LPS-induced AKI mice, which was also reversed by EX527. Rg1 ameliorates LPS-induced kidney injury and suppresses renal inflammation, apoptosis, and oxidative stress in mice via regulating the SIRT1/NF-κB signaling.

Clinical studies with drugs and biologics aimed at slowing or reversing normal aging processes—emerging results and future perspectives

Five families of investigational products are in clinical investigation to slow or reverse normal aging processes [longevity candidates, mesenchymal stem cells, senolytics drugs, sirtuin activators, and nicotinamide adenine dinucleotide (NAD)+ precursors]. The longevity candidates, vitamin D and metformin, appear to significantly reduce all-cause mortality and prolong life expectancy. This should be confirmed by interventional studies. The mesenchymal stem cell family is the most advanced in clinical trial development [phase 2b randomized controlled trial (RCT)]. An allogeneic bone marrow stem cell preparation (Lomecel-B) reduced locomotor frailty in older people. The improvement in locomotion was modest. In the future, attempts could be made to improve potency through a precondition or genetic modification of naive bone marrow stem cells. Autologous adipose stem cell-assisted fat grafting increased graft survival, facial volume, and skin quality. The association of the senolytic drugs dasatinib and quercetin was well tolerated, with low brain penetration of dasatinib and undetectable levels of quercetin. The sirtuin-1 activator resveratrol (combined with physical exercise) improved physical function in older adults with physical limitations. The NAD+ precursor nicotinamide riboside improved physical exercise performance. In conclusion, Lomecel-B is the most advanced agent in clinical trial development for normal aging processes (phase 2b for locomotion frailty), followed by resveratrol and nicotinamide riboside.

Gracilaria chorda attenuates obesity-related muscle wasting through activation of SIRT1/PGC1α in skeletal muscle of mice.

Gracilaria chorda (GC) is a red algal species that is primarily consumed in Asia. Here, we investigated the effect of GC on obesity-related skeletal muscle wasting. Furthermore, elucidating its impact on the activation of sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α) constituted a critical aspect in understanding the underlying mechanism of action. In this study, 6-week-old male C57BL/6 mice were fed a high-fat diet (HFD) for 8 weeks to induce obesity, then continued on the HFD for another 8 weeks while orally administered GC. GC decreased ectopic fat accumulation in skeletal muscle and increased muscle weight, size, and function in obese mice. Furthermore, GC reduced skeletal muscle atrophy and increased hypertrophy in mice. We hypothesized that the activation of SIRT1/PGC1α by GC regulates skeletal muscle atrophy and hypertrophy. We observed that GC increased the expression of SIRT1 and PGC1α in skeletal muscle of mice and in C2C12 cells, which increased mitochondrial function and biogenesis. In addition, when C2C12 cells were treated with the SIRT1-specific inhibitor EX-527, no changes were observed in the protein levels of SIRT1 and PGC1α in the GC-treated C2C12 cells. Therefore, GC attenuated obesity-related muscle wasting by improving mitochondrial function and biogenesis through the activation of SIRT1/PGC1α in the skeletal muscle of mice.

Myricanol attenuates sepsis-induced inflammatory responses by nuclear factor erythroid 2-related factor 2 signaling and nuclear factor kappa B/mitogen-activated protein kinase pathway via upregulating Sirtuin 1.

Sepsis, a life-threatening condition characterized by dysregulated immune responses, remains a significant clinical challenge. Myricanol, a natural compound, plays a variety of roles in regulating lipid metabolism, anti-cancer, anti-neurodegeneration, and it could act as an Sirtuin 1 (SIRT1) activator. This study aimed to explore the therapeutic potential and underlying mechanism of myricanol in the lipopolysaccharide (LPS)-induced sepsis model. In vivo studies revealed that myricanol administration significantly improved the survival rate of LPS-treated mice, effectively mitigating LPS-induced inflammatory responses in lung tissue. Furthermore, in vitro studies demonstrated that myricanol treatment inhibited the expression of pro-inflammatory cytokines, attenuated signal pathway activation, and reduced oxidative stress in macrophages. In addition, we demonstrated that myricanol selectively enhances SIRT1 activation in LPS-stimulated macrophages, and all of the protective effect of myricanol were reversed through SIRT1 silencing. Remarkably, the beneficial effects of myricanol against LPS-induced sepsis were abolished in SIRT1 myeloid-specific knockout mice, underpinning the critical role of SIRT1 in mediating myricanol's therapeutic efficacy. In summary, this study provides significant evidence that myricanol acts as a potent SIRT1 activator, targeting inflammatory signal pathways and oxidative stress to suppress excessive inflammatory responses. Our findings highlight the potential of myricanol as a novel therapeutic agent for the treatment of LPS-induced sepsis.

Silent information regulator sirtuin 1 ameliorates acute liver failure via the p53/glutathione peroxidase 4/gasdermin D axis.

Acute liver failure (ALF) has a high mortality with widespread hepatocyte death involving ferroptosis and pyroptosis. The silent information regulator sirtuin 1 (SIRT1)-mediated deacetylation affects multiple biological processes, including cellular senescence, apoptosis, sugar and lipid metabolism, oxidative stress, and inflammation. To investigate the association between ferroptosis and pyroptosis and the upstream regulatory mechanisms. This study included 30 patients with ALF and 30 healthy individuals who underwent serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) testing. C57BL/6 mice were also intraperitoneally pretreated with SIRT1, p53, or glutathione peroxidase 4 (GPX4) inducers and inhibitors and injected with lipopolysaccharide (LPS)/D-galactosamine (D-GalN) to induce ALF. Gasdermin D (GSDMD)-/- mice were used as an experimental group. Histological changes in liver tissue were monitored by hematoxylin and eosin staining. ALT, AST, glutathione, reactive oxygen species, and iron levels were measured using commercial kits. Ferroptosis- and pyroptosis-related protein and mRNA expression was detected by western blot and quantitative real-time polymerase chain reaction. SIRT1, p53, and GSDMD were assessed by immunofluorescence analysis. Serum AST and ALT levels were elevated in patients with ALF. SIRT1, solute carrier family 7a member 11 (SLC7A11), and GPX4 protein expression was decreased and acetylated p5, p53, GSDMD, and acyl-CoA synthetase long-chain family member 4 (ACSL4) protein levels were elevated in human ALF liver tissue. In the p53 and ferroptosis inhibitor-treated and GSDMD-/- groups, serum interleukin (IL)-1β, tumour necrosis factor alpha, IL-6, IL-2 and C-C motif ligand 2 levels were decreased and hepatic impairment was mitigated. In mice with GSDMD knockout, p53 was reduced, GPX4 was increased, and ferroptotic events (depletion of SLC7A11, elevation of ACSL4, and iron accumulation) were detected. In vitro, knockdown of p53 and overexpression of GPX4 reduced AST and ALT levels, the cytostatic rate, and GSDMD expression, restoring SLC7A11 depletion. Moreover, SIRT1 agonist and overexpression of SIRT1 alleviated acute liver injury and decreased iron deposition compared with results in the model group, accompanied by reduced p53, GSDMD, and ACSL4, and increased SLC7A11 and GPX4. Inactivation of SIRT1 exacerbated ferroptotic and pyroptotic cell death and aggravated liver injury in LPS/D-GalN-induced in vitro and in vivo models. SIRT1 activation attenuates LPS/D-GalN-induced ferroptosis and pyroptosis by inhibiting the p53/GPX4/GSDMD signaling pathway in ALF.

Dihydroquercetin improves experimental acute liver failure by targeting ferroptosis and mitochondria-mediated apoptosis through the SIRT1/p53 axis

BackgroundFerroptosis and mitochondria-mediated apoptosis are both involved in the pathogenesis of acute liver failure (ALF). Ferroptosis-produced reactive oxygen species (ROS) trigger the chain oxidation of polyunsaturated phospholipids and promote mitochondrial apoptosis. Dihydroquercetin (DHQ) also plays an important protective role against liver injury. PurposeHere, we aimed to investigate the protective effects of DHQ on ALF. We also explored the underlying mechanism. MethodsWe established a Lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced ALF mouse model and tumor necrosis factor-α (TNF-α)/D-Gal-induced ALF LO2 cell model. 2′,7′-Dichlorofluorescein diacetate (DCFH-DA) and Dihydroethidium (DHE) were used to detect total ROS levels. Lipid ROS was assessed using C11-BODIPY flow cytometry. Lipid peroxidative products levels were detected using MDA ELISA assay and 4-hydroxynonenal (4-HNE) immunohistochemistry. QRT-PCR and western blots were used to test mRNA and protein expression levels, respectively. Cell viability was evaluated with CCK8 assay, and apoptosis was analyzed using flow cytometry. ResultsDHQ treatment improved LPS/D-Gal-induced ALF, as well as TNF-α/D-Gal-induced reductions in LO2 viability and increased sirtuin 1 (SIRT1) expression. DHQ pretreatment also reduced the accumulation of ROS, reduced lipid peroxidation, elevated mitochondrial membrane potentials (ΔΨm), and decreased liver cell apoptosis both in vivo and in vitro. Additionally, the knockdown of SIRT1 and p53 activator (Tenovin-6) treatment reversed DHQ's inhibitory effects on ferroptosis and mitochondria-mediated apoptosis in vitro. DHQ enhanced p53 deacetylation by both up-regulating SIRT1 expression and directly bonding to SIRT1. We also found that Tenovin-6′s stimulatory effects on ferroptosis and mitochondria-mediated apoptosis in the DHQ-treated LO2 ALF cell model were partially attenuated by overexpression of solute carrier family 7member 11 (SLC7A11), as well as by apoptotic protease activating factor 1 (Apaf-1) knockdown. ConclusionOur results suggest that DHQ alleviated ALF by inhibiting both ferroptosis and mitochondria-mediated apoptosis by regulating the SIRT1/p53 axis. Thus, DHQ may serve as a novel therapy for ALF.

Current Trends in Sirtuin Activator and Inhibitor Development.

Sirtuins are NAD+-dependent protein deacylases and key metabolic regulators, coupling the cellular energy state with selective lysine deacylation to regulate many downstream cellular processes. Humans encode seven sirtuin isoforms (Sirt1-7) with diverse subcellular localization and deacylase targets. Sirtuins are considered protective anti-aging proteins since increased sirtuin activity is canonically associated with lifespan extension and decreased activity with developing aging-related diseases. However, sirtuins can also assume detrimental cellular roles where increased activity contributes to pathophysiology. Modulation of sirtuin activity by activators and inhibitors thus holds substantial potential for defining the cellular roles of sirtuins in health and disease and developing therapeutics. Instead of being comprehensive, this review discusses the well-characterized sirtuin activators and inhibitors available to date, particularly those with demonstrated selectivity, potency, and cellular activity. This review also provides recommendations regarding the best-in-class sirtuin activators and inhibitors for practical research as sirtuin modulator discovery and refinement evolve.