SIRT1-driven mechanism: sevoflurane's interference with mESC neural differentiation via PRRX1/DRD2 cascade.

Investigating the sevoflurane-induced perturbation in the differentiation of mouse embryonic stem cells (mESCs) into neural stem cells (mNSCs), our study delineates a novel SIRT1/PRRX1/DRD2/PKM2/NRF2 axis as a key player in this intricate process. Sevoflurane treatment hindered mESC differentiation, evidenced by altered expression patterns of pluripotency and neural lineage markers. Mechanistically, sevoflurane downregulated Sirt1, setting in motion a signaling cascade. Sevoflurane may inhibit PKM2 dimerization and NRF2 signaling pathway activation by inhibiting the expression of SIRT1 and its downstream genes Prrx1 and DRD2, ultimately inhibiting mESCs differentiation into mNSCs. These findings contribute to our understanding of the molecular basis of sevoflurane-induced neural toxicity, presenting a potential avenue for therapeutic intervention in sevoflurane-induced perturbation in the differentiation of mESCs into mNSCs by modulating the SIRT1/PRRX1/DRD2/PKM2/NRF2 axis.

Causes and consequences of impaired methionine synthase activity in acquired and inherited disorders of vitamin B12 metabolism.

Methyl-Cobalamin (Cbl) derives from dietary vitamin B12 and acts as a cofactor of methionine synthase (MS) in mammals. MS encoded by MTR catalyzes the remethylation of homocysteine to generate methionine and tetrahydrofolate, which fuel methionine and cytoplasmic folate cycles, respectively. Methionine is the precursor of S-adenosyl methionine (SAM), the universal methyl donor of transmethylation reactions. Impaired MS activity results from inadequate dietary intake or malabsorption of B12 and inborn errors of Cbl metabolism (IECM). The mechanisms at the origin of the high variability of clinical presentation of impaired MS activity are classically considered as the consequence of the disruption of the folate cycle and related synthesis of purines and pyrimidines and the decreased synthesis of endogenous methionine and SAM. For one decade, data on cellular and animal models of B12 deficiency and IECM have highlighted other key pathomechanisms, including altered interactome of MS with methionine synthase reductase, MMACHC, and MMADHC, endoplasmic reticulum stress, altered cell signaling, and genomic/epigenomic dysregulations. Decreased MS activity increases catalytic protein phosphatase 2A (PP2A) and produces imbalanced phosphorylation/methylation of nucleocytoplasmic RNA binding proteins, including ELAVL1/HuR protein, with subsequent nuclear sequestration of mRNAs and dramatic alteration of gene expression, including SIRT1. Decreased SAM and SIRT1 activity induce ER stress through impaired SIRT1-deacetylation of HSF1 and hypomethylation/hyperacetylation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), which deactivate nuclear receptors and lead to impaired energy metabolism and neuroplasticity. The reversibility of these pathomechanisms by SIRT1 agonists opens promising perspectives in the treatment of IECM outcomes resistant to conventional supplementation therapies.

A role for sirtuin 1 in FGF23 activation following ß-glycerophosphate treatment.

Phosphate homeostasis is vital for many biological processes and disruptions in circulating levels can be detrimental. While the mechanisms behind FGF23 regulation have been regularly studied, the role of extracellular phosphate sensing and its impact on fibroblast growth factor 23 (FGF23) expression remains unclear. This study aimed to investigate the involvement of reactive oxygen species (ROS), silent information regulator 1 (SIRT1), and Hairy and Enhancer of Split-1 (HES1) in regulating FGF23 in FGF23 expressing MC3T3-E1 cells. MC3T3-E1 cells treated with ß-glycerophosphate (BGP) resulted in increased Fgf23 expression. Inhibition of ROS formation by inhibition of NADPH oxidase, which is essential for ROS production, did not affect this response to BGP, suggesting ROS is not involved in this process. Moreover, treatment with tert-butyl hydroperoxide (TBHP), a ROS-inducing agent, did not increase Fgf23 expression. This suggests that ROS machinery is not involved in FGF23 stimulation as previously suggested. Nonetheless, inhibition of SIRT1 using Ex527 eliminated the Fgf23 response to BGP, indicating its involvement in FGF23 regulation after BGP treatment. Indeed, activation of SIRT1 using SRT1720 increased Fgf23 expression. Moreover, transcription factor Hes1 was upregulated by BGP treatment, which was diminished when cells were treated with Ex527 implying it is also regulated through SIRT1. These findings suggest the existence of an upstream SIRT1-HES1 axis in the regulation of FGF23 by phosphate, though we were unable to find a role for ROS in this process. Further research should provide insights into phosphate homeostasis and potential therapeutic targets for phosphate-related disorders.

Excess glucose alone depress young mesenchymal stromal/stem cell osteogenesis and mitochondria activity within hours/days via NAD+/SIRT1 axis.

BACKGROUND: The impact of global overconsumption of simple sugars on bone health, which peaks in adolescence/early adulthood and correlates with osteoporosis (OP) and fracture risk decades, is unclear. Mesenchymal stromal/stem cells (MSCs) are the progenitors of osteoblasts/bone-forming cells, and known to decrease their osteogenic differentiation capacity with age. Alarmingly, while there is correlative evidence that adolescents consuming greatest amounts of simple sugars have the lowest bone mass, there is no mechanistic understanding on the causality of this correlation. METHODS: Bioinformatics analyses for energetics pathways involved during MSC differentiation using human cell information was performed. In vitro dissection of normal versus high glucose (HG) conditions on osteo-/adipo-lineage commitment and mitochondrial function was assessed using multi-sources of non-senescent human and murine MSCs; for in vivo validation, young mice was fed normal or HG-added water with subsequent analyses of bone marrow CD45- MSCs. RESULTS: Bioinformatics analyses revealed mitochondrial and glucose-related metabolic pathways as integral to MSC osteo-/adipo-lineage commitment. Functionally, in vitro HG alone without differentiation induction decreased both MSC mitochondrial activity and osteogenesis while enhancing adipogenesis by 8 h' time due to depletion of nicotinamide adenine dinucleotide (NAD+), a vital mitochondrial co-enzyme and co-factor to Sirtuin (SIRT) 1, a longevity gene also involved in osteogenesis. In vivo, HG intake in young mice depleted MSC NAD+, with oral NAD+ precursor supplementation rapidly reversing both mitochondrial decline and osteo-/adipo-commitment in a SIRT1-dependent fashion within 1 ~ 5 days. CONCLUSIONS: We found a surprisingly rapid impact of excessive glucose, a single dietary factor, on MSC SIRT1 function and osteogenesis in youthful settings, and the crucial role of NAD+-a single molecule-on both MSC mitochondrial function and lineage commitment. These findings have strong implications on future global OP and disability risks in light of current worldwide overconsumption of simple sugars.

Sirtuin 1 in osteoarthritis: Perspectives on regulating glucose metabolism.

Osteoarthritis (OA) is a degenerative disease characterised by articular cartilage destruction, and its complex aetiology contributes to suboptimal clinical treatment outcomes. A close association exists between glucose metabolism dysregulation and OA pathogenesis. Owing to the unique environment of low oxygen and glucose concentrations, chondrocytes rely heavily on their glycolytic capacity, exhibiting distinct spatiotemporal differences. However, under pathological stimulation, chondrocytes undergo excessive glycolytic activity while mitochondrial respiration and other branches of glucose metabolism are compromised. This metabolic change induces cartilage degeneration by reprogramming the inflammatory responses. Sirtuins, a highly conserved family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases, regulate glucose metabolism in response to energy fluctuations in different cellular compartments，alleviating metabolic stress. SIRT1, the most extensively studied sirtuin, participates in maintaining glucose homeostasis in almost all key metabolic tissues. While actively contributing to the OA progression and displaying diverse biological effects in cartilage protection, SIRT1's role in regulating glucose metabolism in chondrocytes has not received sufficient attention. This review focuses on discussing the beneficial role of SIRT1 in OA progression from a metabolic regulation perspective based on elucidating the primary characteristics of chondrocyte glucose metabolism. We also summarise the potential mechanisms and therapeutic strategies targeting SIRT1 in chondrocytes to guide clinical practice and explore novel therapeutic directions.

Cytoplasmic SIRT1 promotes paclitaxel resistance in ovarian carcinoma through increased formation and survival of polyploid giant cancer cells.

Therapeutic resistance is a notable cause of death in patients with ovarian carcinoma. Polyploid giant cancer cells (PGCCs), commonly arising in tumor tissues following chemotherapy, have recently been considered to contribute to drug resistance. As a type III deacetylase, Sirtuin1 (SIRT1) plays essential roles in the cell cycle, cellular senescence, and drug resistance. Accumulating evidence has suggested that alteration in its subcellular localization via nucleocytoplasmic shuttling is a critical process influencing the functions of SIRT1. However, the roles of SIRT1 subcellular localization in PGCC formation and subsequent senescence escape remain unclear. In this study, we compared the differences in the polyploid cell population and senescence state of PGCCs following paclitaxel treatment between tumor cells overexpressing wild-type SIRT1 (WT SIRT1) and those expressing nuclear localization sequence (NLS)-mutated SIRT1 (SIRT1NLSmt ). We investigated the involvement of cytoplasmic SIRT1 in biological processes and signaling pathways, including the cell cycle and cellular senescence, in ovarian carcinoma cells' response to paclitaxel treatment. We found that the SIRT1NLSmt tumor cell population contained more polyploid cells and fewer senescent PGCCs than the SIRT1-overexpressing tumor cell population. Comparative proteomic analyses using co-immunoprecipitation (Co-IP) combined with liquid chromatography-mass spectrometry (LC-MS)/MS showed the differences in the differentially expressed proteins related to PGCC formation, cell growth, and death, including CDK1 and CDK2, between SIRT1NLSmt and SIRT1 cells or PGCCs. Our results suggested that ovarian carcinoma cells utilize polyploidy formation as a survival mechanism during exposure to paclitaxel-based treatment via the effect of cytoplasmic SIRT1 on PGCC formation and survival, thereby boosting paclitaxel resistance. © 2023 The Pathological Society of Great Britain and Ireland.

Protective effect of melatonin against methamphetamine-induced attention deficits through miR-181/SIRT1 axis in the prefrontal cortex.

INTRODUCTION: Methamphetamine (METH) is an addictive psychostimulant with deleterious effects on the central nervous system. Chronic use of METH in high doses impairs cognition, attention and executive functions, but the underlying mechanisms are still unclear. Sirtuin 1 (SIRT1) is a post-translational regulator that is downregulated following METH neurotoxicity. Melatonin is a neuroprotective hormone that enhances mitochondrial metabolism. Here, we evaluated the effect of melatonin on METH-induced attention deficits disorder and the involvement of the miR-181/SIRT1 axis in melatonin neuroprotection. METHODS AND RESULTS: METH at a dose of 5 mg/kg was injected for 21 consecutive days. The animals were assigned to receive either melatonin or the vehicle after METH injections. Attention levels were evaluated with abject-based attention test. In the prefrontal cortex, the expression levels of miR-181a-5p, SIRT1, p53 and CCAR2, as well as the mtDNA copy numbers were evaluated using qRT-PCR and western blotting. The outcomes revealed that melatonin treatment following METH injections improved METH-induced attention deficits. METH toxicity can be associated with changes in the miR-181/SIRT1 axis, elevated levels of p53 and COXII, and decreased levels of mtDNA in the prefrontal cortex of adult rats. Interestingly, administration of melatonin can improve the expression of these molecules and reduces the toxic effects of METH. CONCLUSION: Melatonin ameliorated the neurotoxicity of METH in the prefrontal cortex and the miR-181/SIRT1 axis is involve in the protective effects of melatonin. However, melatonin can be potentially administrated to improve attention impairment in METH use disorders.

Sirt1 activation prevents high glucose-induced angiotensin converting enzyme 2 downregulation in renal tubular cells by regulating the TIMP3/ADAM17 pathway.

BACKGROUND: Angiotensin converting enzyme 2 (ACE2) exerts renoprotective effects in diabetic kidney disease (DKD) by converting angiotensin (Ang) II into Ang (1-7). Previous studies have demonstrated that ACE2 expression in renal tubules is downregulated in DKD, but the mechanism is not fully understood. Sirtuin-1 (Sirt1) is a protein deacetylase that may regulate the activity of the renin-angiotensin system. The present study investigated the effects of Sirt1 on ACE2 expression under high glucose (HG) conditions and the underlying signaling pathway. METHODS AND RESULTS: Rats with DKD and NRK-52E cells cultured with HG were employed in this study. Western blotting, immunohistochemistry detection and qRT-PCR were performed for protein and mRNA expression analyses. Rats subjected to DKD displayed downregulated expression of Sirt1 and ACE2 in kidneys. Resveratrol, an activator of Sirt1, restored ACE2 expression and ameliorated renal injuries. Similarly, pharmacological activation of Sirt1 with SRT1720 markedly upregulated ACE2 in NRK-52E cells cultured with HG, while Sirt1 small interfering RNA (siRNA) further suppressed ACE2 expression. In addition, A disintegrin and metalloproteinase (ADAM) 17 was observed to be upregulated, and its inhibitor, tissue inhibitor of metalloproteinase 3 (TIMP3), was downregulated in the kidneys of diabetic rats and NRK-52E cells incubated with HG. The TIMP3/ADAM17 pathway was involved in the regulation of ACE2 expression, as evidenced by decreased ACE2 expression levels after TIMP3-siRNA pretreatment. SRT1720 ameliorated the imbalance of TIMP3/ADAM17 induced by HG and consequently enhanced the expression of ACE2. Notably, the above effect of SRT1720 on ACE2 was interrupted by TIMP3-siRNA. CONCLUSIONS: Our findings suggest that Sirt1 activation may prevent HG-induced downregulation of renal tubular ACE2 by modulating the TIMP3/ADAM17 pathway. Sirt1 stimulation might be a potential strategy for the treatment of DKD.

ß-lapachone protects against doxorubicin-induced hepatotoxicity through modulation of NAD+ /SIRT-1/FXR/p-AMPK/NF-kB and Nrf2 signaling axis.

Doxorubicin (DOX) is a widely used antineoplastic drug, but its clinical use is limited by significant toxicities, such as hepatotoxicity. In this study, we evaluated the effects of ß-lapachone (ß-LAP), a natural quinone-containing compound, in a mouse model of DOX-induced hepatotoxicity. ß-LAP was orally administered at 1.25, 2.5, and 5 mg/kg for 4 days, and a single dose of DOX (20 mg/kg) was injected intraperitoneally on the second day. Histopathological changes, liver function markers, antioxidant and inflammatory markers were assessed. ß-LAP ameliorated liver injury and liver function markers evoked by DOX. ß-LAP also downregulated the mRNA expression of nuclear factor-kB-corresponding genes including interleukin-6, interleukin-1ß, and tumor necrosis factor-α. Moreover, ß-LAP increased the nuclear factor erythroid 2-related factor 2 target genes heme oxygenase-1 and NAD(P)H: quinone oxidoreductase 1, along with antioxidant enzymes including reduced glutathione, catalase, and superoxide dismutase with simultaneous reduction in the lipid peroxidation product malondialdehyde. Meanwhile, it recovered NAD+ /NADH ratios and subsequently elevated the protein levels of sirtuin-1 (SIRT-1), farnesoid X receptor (FXR), and phosphorylated AMP-activated protein kinase (p-AMPK). Collectively, these findings suggest a protective role of ß-LAP against DOX-induced hepatotoxicity by partly regulating the NAD+ /SIRT-1/FXR/p-AMPK axis.

Metformin Attenuates Manganese-Induced Oxidative Stress in N27-A Dopaminergic Neuronal Cells.

Metformin is an anti-diabetic drug that exerts protective effects against neurodegenerative diseases. In this study, we investigated the protective effects of metformin against manganese (Mn)-induced cytotoxicity associated with Parkinson's disease-like symptoms in N27-A dopaminergic (DA) cells. Metformin (0.1-1 mM) suppressed Mn (0.4 mM)-induced cell death in a concentration-dependent manner. Metformin pretreatment effectively suppressed the Mn-mediated increase in the levels of oxidative stress markers, such as reactive oxygen species (ROS) and thiobarbituric acid reactive substances. Moreover, metformin restored the levels of the antioxidants, superoxide dismutase, intracellular glutathione, and glutathione peroxidase, which were reduced by Mn. Metformin (0.5 mM) significantly attenuated the decrease in sirtuin-1 (SIRT1) and peroxisome proliferator activated receptor gamma coactivator-1 alpha levels, which were increased by Mn (0.4 mM). In addition, metformin inhibited the expression of microRNA-34a, which directly targeted SIRT1. Metformin also inhibited the loss of Mn-induced mitochondrial membrane potential (ΔΨm) and activation of the apoptosis marker, caspase-3. Furthermore, metformin-mediated inhibition of ROS generation and caspase-3 activation, recovery of ΔΨm, and restoration of cell viability were partially reversed by the SIRT1 inhibitor, Ex527. These results suggest that metformin may protects against Mn-induced DA neuronal cell death mediated by oxidative stress and mitochondrial dysfunction possibly via the regulation of SIRT1 pathway.

Ability of NAD and Sirt1 to epigenetically suppress albuminuria.

The time for diabetic nephropathy (DN) to progress from mild to severe is long. Thus, methods to continuously repress DN are required to exert long-lasting effects mediated through epigenetic regulation. In this study, we demonstrated the ability of nicotinamide adenine dinucleotide (NAD) and its metabolites to reduce albuminuria through Sirt1- or Nampt-dependent epigenetic regulation. We previously reported that proximal tubular Sirt1 was lowered before glomerular Sirt1. Repressed glomerular Sirt1 was found to epigenetically elevate Claudin-1. In addition, we reported that proximal tubular Nampt deficiency epigenetically augmented TIMP-1 levels in Sirt6-mediated pathways, leading to type-IV collagen deposition and diabetic fibrosis. Altogether, we propose that the Sirt1/Claudin-1 axis may be crucial in the onset of albuminuria at the early stages of DN and that the Nampt/Sirt6/TIMP-1 axis promotes diabetic fibrosis in the middle to late stages of DN. Finally, administration of NMN, an NAD precursor, epigenetically potentiates the regression of the onset of DN to maintain Sirt1 and repress Claudin-1 in podocytes, suggesting the potential use of NAD metabolites as epigenetic medications for DN.

Cardiometabolic Changes in Sirtuin1-Heterozygous Mice on High-Fat Diet and Melatonin Supplementation.

A hypercaloric fatty diet predisposes an individual to metabolic syndrome and cardiovascular complications. Sirtuin1 (SIRT1) belongs to the class III histone deacetylase family and sustains anabolism, mitochondrial biogenesis, and fat distribution. Epididymal white adipose tissue (eWAT) is involved in inflammation, whilst interscapular brown adipose tissue (iBAT) drives metabolism in obese rodents. Melatonin, a pineal indoleamine, acting as a SIRT1 modulator, may alleviate cardiometabolic damage. In the present study, we morphologically characterized the heart, eWAT, and iBAT in male heterozygous SIRT1+/- mice (HET mice) on a high-fat diet (60%E lard) versus a standard rodent diet (8.5% E fat) and drinking melatonin (10 mg/kg) for 16 weeks. Wild-type (WT) male C57Bl6/J mice were similarly fed for comparison. Cardiomyocyte fibrosis and endoplasmic reticulum (ER) stress response worsened in HET mice on a high-fat diet vs. other groups. Lipid peroxidation, ER, and mitochondrial stress were assessed by 4 hydroxy-2-nonenal (4HNE), glucose-regulated protein78 (GRP78), CCAA/enhancer-binding protein homologous protein (CHOP), heat shock protein 60 (HSP60), and mitofusin2 immunostainings. Ultrastructural analysis indicated the prevalence of atypical inter-myofibrillar mitochondria with short, misaligned cristae in HET mice on a lard diet despite melatonin supplementation. Abnormal eWAT adipocytes, crown-like inflammatory structures, tumor necrosis factor alpha (TNFα), and iBAT whitening characterized HET mice on a hypercaloric fatty diet and were maintained after melatonin supply. All these data suggest that melatonin's mechanism of action is strictly linked to full SIRT1 expression, which is required for the exhibition of effective antioxidant and anti-inflammatory properties.

Berberine Ameliorates Abnormal Lipid Metabolism via the Adenosine Monophosphate-Activated Protein Kinase/Sirtuin 1 Pathway in Alcohol-Related Liver Disease.

Alcoholic fatty liver disease (AFLD) is an early stage of alcohol-related liver disease characterized by abnormal lipid metabolism in hepatocytes. To date, to our knowledge, there have been no effective strategies for preventing or treating alcohol-related liver disease besides alcohol abstinence. Berberine (BBR) is the main bioactive ingredient extracted from traditional Chinese medicines, such as Coptis and Scutellaria, which protect liver function and relieve liver steatosis. However, the potential role of BBR in AFLD remains unclear. Therefore, this study investigated the protective effects of BBR against Gao-binge model-induced AFLD in 6- to 8-week-old C57BL/6J male mice in vivo and ethyl alcohol (EtOH)-induced alpha mouse liver 12 (AML-12) cells in vitro. The results showed that BBR (200 mg/kg) attenuated alcoholic liver injury and suppressed lipid accumulation and metabolism disorders in vivo. Consistently, BBR effectively inhibited the expression of sterol regulatory element-binding transcription factor 1C, sterol regulatory element-binding transcription factor 2, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoenzymeA reductase in EtOH-stimulated AML-12 cells in vitro and promoted the expression of sirtuin 1 (SIRT1) in EtOH-fed mice and EtOH-treated AML-12 cells. Furthermore, SIRT1 silencing attenuated the hepatic steatosis alleviation potential of BBR treatment. Mechanistically, molecular docking revealed the binding effect of BBR and adenosine monophosphate-activated protein kinase (AMPK). The results of further studies showed that a decrease in AMPK activity was accompanied by a significant inhibition of SIRT1 expression. SIRT1 silencing attenuated the protective effect of BBR, whereas the inhibition of its expression had no apparent effect on AMPK phosphorylation, suggesting that SIRT1 acts downstream of AMPK in AFLD. Collectively, BBR ameliorated abnormal lipid metabolism and alleviated EtOH-induced liver injury via the AMPK/SIRT1 pathway in AFLD mice.

Contribution of microRNA-30d to the prevention of the thyroid cancer occurrence and progression: mechanism and implications.

Thyroid cancer is a major endocrine tumor and represents an emerging health problem worldwide. MicroRNAs (miRNAs) have been addressed to participate in the pathogenesis and progression of thyroid cancer. However, it remains largely unknown what functions miR-30d may exert on thyroid cancer. This study, herein, aimed to identify the functional significance and machinery of miR-30d in the progression of thyroid cancer. MiR-30b presented aberrant low expression and ubiquitin-specific protease 22 (USP22) exhibited aberrant high expression in thyroid cancer tissues and cells. The current study proposed the possible machinery that miR-30d could target and negatively regulate USP22. Additionally, USP22 could enhance the stability of SIRT1 by inducing deubiquitination which consequently contributed to FOXO3a deacetylation-induced PUMA repression. Responding to the gain- or loss-of-function of miR-30d and/or USP22, behaviors of thyroid cancer cells were altered. Accordingly, miR-30d inhibited proliferation and promoted apoptosis of thyroid cancer cells by suppressing USP22 through SIRT1/FOXO3a/PUMA axis. The effects of miR-30d and USP22-mediated SIRT1/FOXO3a/PUMA axis on thyroid tumorigenesis were finally validated in murine models. We ultimately confirmed the anti-proliferative and pro-apoptotic effect of miR-30d via suppressing USP22 through in vivo findings. Conclusively, our findings highlight that the occurrence and progression of thyroid cancer can be suppressed by miR-30d-mediated inhibition of USP22 via the SIRT1/FOXO3a/PUMA axis, which provides a attractive therapeutic target for thyroid cancer treatment.

An Fgr kinase inhibitor attenuates sepsis-associated encephalopathy by ameliorating mitochondrial dysfunction, oxidative stress, and neuroinflammation via the SIRT1/PGC-1α signaling pathway.

BACKGROUND: Sepsis-associated encephalopathy (SAE) is characterized by diffuse brain dysfunction, long-term cognitive impairment, and increased morbidity and mortality. The current treatment for SAE is mainly symptomatic; the lack of specific treatment options and a poor understanding of the underlying mechanism of disease are responsible for poor patient outcomes. Fgr is a member of the Src family of tyrosine kinases and is involved in the innate immune response, hematologic cancer, diet-induced obesity, and hemorrhage-induced thalamic pain. This study investigated the protection provided by an Fgr kinase inhibitor in SAE and the underlying mechanism(s) of action. METHODS: A cecal ligation and puncture (CLP)-induced mouse sepsis model was established. Mice were treated with or without an Fgr inhibitor and a PGC-1α inhibitor/activator. An open field test, a novel object recognition test, and an elevated plus maze were used to assess neurobehavioral changes in the mice. Western blotting and immunofluorescence were used to measure protein expression, and mRNA levels were measured using quantitative PCR (qPCR). An enzyme-linked immunosorbent assay was performed to quantify inflammatory cytokines. Mitochondrial membrane potential and morphology were measured by JC-1, electron microscopy, and the MitoTracker Deep Red probe. Oxidative stress and mitochondrial dysfunction were analyzed. In addition, the regulatory effect of Fgr on sirtuin 1 (SIRT1) was assessed. RESULTS: CLP-induced sepsis increased the expression of Fgr in the hippocampal neurons. Pharmacological inhibition of Fgr attenuated CLP-induced neuroinflammation, the survival rate, cognitive and emotional dysfunction, oxidative stress, and mitochondrial dysfunction. Moreover, Fgr interacted with SIRT1 and reduced its activity and expression. In addition, activation of SIRT1/PGC-1α promoted the protective effects of the Fgr inhibitor on CLP-induced brain dysfunction, while inactivation of SIRT1/PGC-1α counteracted the benefits of the Fgr inhibitor. CONCLUSIONS: To our knowledge, this is the first report of Fgr kinase inhibition markedly ameliorating SAE through activation of the SIRT1/PGC-1α pathway, and this may be a promising therapeutic target for SAE.

Involvement of the SIRT1-NLRP3 pathway in the inflammatory response.

The silent information regulator 2 homolog 1-NACHT, LRR and PYD domains-containing protein 3 (SIRT1-NLRP3) pathway has a crucial role in regulation of the inflammatory response, and is closely related to the occurrence and development of several inflammation-related diseases. NLRP3 is activated to produce the NLRP3 inflammasome, which leads to activation of caspase-1 and cleavage of pro-interleukin (IL)-1ß and pro-IL-18 to their active forms: IL-1ß and IL-18, respectively. They are proinflammatory cytokines which then cause an inflammatory response.SIRT1 can inhibit this inflammatory response through nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B pathways. This review article focuses mainly on how the SIRT1-NLRP3 pathway influences the inflammatory response and its relationship with melatonin, traumatic brain injury, neuroinflammation, depression, atherosclerosis, and liver damage. Video Abstract.

The sirtuin 1 activator YK 3-237 stimulates capacitation-related events in human spermatozoa.

RESEARCH QUESTION: Does sirtuin-1 (SIRT1) have a role in the human spermatozoa capacitation process? DESIGN: Human spermatozoa were incubated for 6 h in a capacitating medium in presence or absence of the specific SIRT1 activator, YK 3-237. Several sperm parameters were determined by flow cytometry: viability, acrosome reaction and mitochondria membrane status. Sperm motility was determined objectively by computer-assisted semen analysis. Sperm capacitation status was evaluated by the extent of protein tyrosine phosphorylation and by the percentage of spermatozoa with the acrosome reacted by a calcium ionophore challenge. RESULTS: SIRT1 was detected in the connecting piece of human spermatozoa where a lysine acetylation pattern was mainly found along the sperm tail. SIRT1 activation accelerates the occurrence of a phenotype associated with human sperm capacitation, with no differences seen in the lysine acetylation pattern. After 1 h of co-incubation of YK 3-237 with human spermatozoa, tyrosine phosphorylation levels were comparable to control levels after 6 h of incubation in capacitating conditions. In addition, the activator improved sperm responsiveness to a Ca2+ ionophore (A23187) challenge determined by an increase in acrosome-reacted spermatozoa (P = 0.025). Importantly, sperm viability and mitochondrial activity-related parameters assessed by flow cytometry were not affected by YK 3-237. CONCLUSION: YK 3-237 induces capacitation-related events in human spermatozoa such an increase of tyrosine phosphorylation levels and acrosome-reacted spermatozoa after the ionophore challenge. Together, these results show that YK 3-237 affects human spermatozoa capacitation-related events by a mechanism independent of protein lysine acetylation but dependent on bicarbonate and calcium.

Evaluation of potential aging biomarkers in healthy individuals: telomerase, AGEs, GDF11/15, sirtuin 1, NAD+, NLRP3, DNA/RNA damage, and klotho.

Aging is a natural process of gradual decrease in physical and mental capacity. Biological age (accumulation of changes and damage) and chronological age (years lived) may differ. Biological age reflects the risk of various types of disease and death from any cause. We selected potential biomarkers of aging - telomerase, AGEs, GDF11 and 15 (growth differentiation factor 11/15), sirtuin 1, NAD+ (nicotinamide adenine dinucleotide), inflammasome NLRP3, DNA/RNA damage, and klotho to investigate changes in their levels depending on age and sex. We included 169 healthy volunteers and divided them into groups according to age (under 35; 35-50; over 50) and sex (male, female; male and female under 35; 35-50, over 50). Markers were analyzed using commercial ELISA kits. We found differences in values depending on age and gender. GDF15 increased with age (under 30 and 35-50 p < 0.002; 35-50 and over 50; p < 0.001; under 35 and over 50; p < 0.001) as well as GDF11 (35-50 and over 50; p < 0.03; under 35 and over 50; p < 0.02), AGEs (under 30 and 35-50; p < 0.005), NLRP3 (under 35 over 50; p < 0.03), sirtuin 1 (35-50 and over 50; p < 0.0001; under 35 and over 50; p < 0.004). AGEs and GDF11 differed between males and females. Correlations were identified between individual markers, markers and age, and markers and sex. Markers that reflect the progression of biological aging vary with age (GDF15, GDF11, AGEs, NLRP3, sirtuin) and sex (AGEs, GDF11). Their levels could be used in clinical practice, determining biological age, risk of age-related diseases and death of all-causes, and initiating or contraindicating a therapy in the elderly based on the patient's health status.

Matrine Attenuates Lung Injury by Modulating Macrophage Polarization and Suppressing Apoptosis.

INTRODUCTION: Persistent lung inflammation is a characteristic of sepsis-induced lung injury. Matrine, the active ingredient from Sophora flavescens, has exhibited anti-inflammatory activities. This study investigated the effects of prophylactic administration of matrine on macrophage polarization, apoptosis, and tissue injury in a cecal ligation and puncture (CLP)-induced murine lung injury model. METHODS: Mice were randomly allocated into four groups: Sham, CLP, Sham + Matrine, and CLP + Matrine. Lung tissues were collected at 24 h post-CLP. Histopathology and immunofluorescence analysis were performed to evaluate lung injury and macrophage infiltration in the lung, respectively. Caspase-3 activities, TUNEL staining, and anti-apoptotic proteins were examined to assess apoptosis. To determine the mechanism of action of matrine, protein levels of Sirtuin 1 (SIRT1), nuclear factor κB (NF-κB), p53 and the messenger RNA levels of p53-mediated proapoptotic genes were examined to elucidate the associated signaling pathways. RESULTS: Histopathological evaluation showed that matrine prophylaxis attenuated sepsis-induced lung injury. Matrine prophylaxis attenuated sepsis-induced infiltration of the total population of macrophages in the lung. Matrine inhibited M1 macrophage infiltration, but increased M2 macrophage infiltration, thus resulting in a decrease in the proportion of M1 to M2 macrophages in septic lung. Sepsis-induced lung injury was associated with apoptotic cell death as evidenced by increases in caspase-3 activity, TUNEL-positive cells, and decreases in antiapoptotic proteins, all of which were reversed by matrine prophylaxis. Matrine restored sepsis-induced downregulation of SIRT1 and deacetylation of NF-κB p65 subunit and p53, thus inactivating NF-κB pathway and suppressing p53-induced proapoptotic pathway in septic lung. CONCLUSIONS: In summary, this study demonstrated that matrine exhibited pro-M2 macrophage polarization and antiapoptotic effects in sepsis-induced lung injury, which might be, at least partly, due to the modulation of SIRT1/NF-κB and SIRT1/p53 pathways.

Sirt1 regulates microglial activation and inflammation following oxygen-glucose deprivation/reoxygenation injury by targeting the Shh/Gli-1 signaling pathway.

BACKGROUND: Cerebral ischemic injury leads to over-activation of microglia, which release pro-inflammatory factors that deteriorate neurological function during the acute phase of stroke. Thus, inhibiting microglial over-activation is crucial for reducing ischemic injury. Sirtuin 1 (Sirt1) has been shown to play a critical role in stroke, neurodegenerative diseases and aging. However, the effect of Sirt1 on the regulation of microglial activation following cerebral ischemic injury, as well as the underlying mechanism, remain unknown. Therefore, the purpose of the present study is to mainly investigate the effect of Sirt1 on oxygen-glucose deprivation/reoxygenation (OGD/R)-treated N9 microglia following treatment with the Sirt1 agonists resveratrol and SRT1720 and the Sirt1 antagonist sirtinol. METHODS: Cell viability, Apoptosis, activation and inflammatory responses of microglia, expressions and activity of Shh signaling pathway proteins were detected by Cell Counting Kit 8, Flow Cytometry, immunocytochemistry, ELISA, and Western blotting, respectively. RESULTS: The results demonstrated that treatment with resveratrol or SRT1720 could inhibit the activation of microglia and inflammation during OGD/R. Moreover, these treatments also led to the translocation of the GLI family zinc finger-1 (Gli-1) protein from the cytoplasm to the nucleus and upregulated the expression of Sonic hedgehog (Shh), Patched homolog-1 (Ptc-1), smoothened frizzled class receptor and Gli-1. By contrast, the inhibition of Sirt1 using sirtinol had the opposite effect. CONCLUSION: These findings suggested that Sirt1 may regulate microglial activation and inflammation by targeting the Shh/Gli-1 signaling pathway following OGD/R injury. Schematic representation of Sirt1 regulating the microglial activation and inflammation following oxygen-glucose deprivation/reoxygenation injury via mediation of Shh/Gli-1 signaling pathway.