Water-soluble 4-(dimethylaminomethyl)heliomycin exerts greater antitumor effects than parental heliomycin by targeting the tNOX-SIRT1 axis and apoptosis in oral cancer cells

The antibiotic heliomycin (resistomycin), which is generated from Streptomyces resistomycificus, has multiple activities, including anticancer effects. Heliomycin was first described in the 1960s, but its clinical applications have been hindered by extremely low solubility. A series of 4-aminomethyl derivatives of heliomycin were synthesized to increase water solubility; studies showed that they had anti-proliferative effects, but the drug targets remained unknown. In this study, we conducted cellular thermal shift assays (CETSA) and molecular docking simulations to identify and validate that heliomycin and its water-soluble derivative, 4-(dimethylaminomethyl)heliomycin (designated compound 4-dmH) engaged and targeted with sirtuin-1 (SIRT1) in p53-functional SAS and p53-mutated HSC-3 oral cancer cells. We further addressed the cellular outcome of SIRT1 inhibition by these compounds and found that, in addition to SIRT1, the water-soluble 4-dmH preferentially targeted a tumor-associated NADH oxidase (tNOX, ENOX2). The direct binding of 4-dmH to tNOX decreased the oxidation of NADH to NAD+ which diminished NAD+-dependent SIRT1 deacetylase activity, ultimately inducing apoptosis and significant cytotoxicity in both cell types, as opposed to the parental heliomycin-induced autophagy. We also observed that tNOX and SIRT1 were both upregulated in tumor tissues of oral cancer patients compared to adjacent normal tissues, suggesting their clinical relevance. Finally, the better therapeutic efficacy of 4-dmH was confirmed in tumor-bearing mice, which showed greater tNOX and SIRT1 downregulation and tumor volume reduction when treated with 4-dmH compared to heliomycin. Taken together, our in vitro and in vivo findings suggest that the multifaceted properties of water-soluble 4-dmH enable it to offer superior antitumor value compared to parental heliomycin, and indicated that it functions through targeting the tNOX-NAD+-SIRT1 axis to induce apoptosis in oral cancer cells.

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

INTRODUCTION

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

Rg1 ameliorates LPS-induced kidney injury and suppresses renal inflammation, apoptosis, and oxidative stress in mice via regulating the SIRT1/NF-κB signaling.

Development and Characterization of a Novel Carbon-11 Labeled Positron Emission Tomography Radiotracer for Neuroimaging of Sirtuin 1 with Benzoxazine-Based Compounds

Introduction

Sirtuins (SIRTs) comprise a group of histone deacetylase enzymes crucial for regulating metabolic pathways and contributing significantly to various disease mechanisms. Sirtuin 1 (SIRT1), among the seven known mammalian homologs, is extensively investigated and understood, playing a key role in neurodegenerative disorders and cancer. This study focuses on potential as a therapeutic target for conditions such as Parkinson's disease (PD), Huntington's disease (HD), and Alzheimer's disease (AD).

Methods

Utilizing positron emission tomography (PET) as a noninvasive molecular imaging modality, we aimed to expedite the validation of a promising sirtuin 1 inhibitor for clinical trials. However, the absence of a validated sirtuin 1 PET radiotracer impedes clinical translation. We present the development of [11C]1, and 11C-labeled benzoxazine-based derivative, as a lead imaging probe. The radiosynthesis of [11C]1 resulted in a radiochemical yield of 31 ± 4%.

Results

Baseline studies demonstrated that [11C]1 exhibited excellent blood-brain barrier (BBB) penetration capability, with uniform accumulation throughout various brain regions. Self-blocking studies revealed that introducing an unlabeled compound 1, effectively blocking sirtuin 1, led to a substantial reduction in whole-brain uptake, emphasizing the in vivo specificity of [11C]1 for sirtuin 1.

Discussion

The development of [11C]1 provides a valuable tool for noninvasive imaging investigations in rodent models with aberrant sirtuin 1 expression. This novel radiotracer holds promise for advancing our understanding of sirtuin 1's role in disease mechanisms and may facilitate the validation of sirtuin 1 inhibitors in clinical trials.

Sirtuin 1 serum concentration in healthy children - dependence on sex, age, stage of puberty, body weight and diet

Introduction

Sirtuin 1 (SIRT1) is known to be involved in sensing cellular energy levels and regulating energy metabolism. This study aimed to evaluate fasting serum SIRT1 levels in healthy children, and to analyse the influence of age, sex, puberty, body weight, height, and diet on its concentration.

Methods

47 healthy children aged 4-14 with weight and height within normal range and no chronic disease were included into the study. Fasting serum SIRT1 concentrations were estimated by Enzyme Linked Immunosorbent Assay (ELISA).

Results

Results showed that serum SIRT1 concentrations in healthy children did not differ with respect to sex, age, height, weight and puberty. Whereas, it appeared that a higher frequency of fruits, vegetables and dairy products consumption was associated with an increase in serum SIRT1 levels.

Discussion

Studying SIRT1 in the context of children's health may have implications for a broader understanding of growth processes, pubertal development, metabolic disorders and nutrition.

Exercise alleviates renal interstitial fibrosis by ameliorating the Sirt1-mediated TGF-β1/Smad3 pathway in T2DM mice

Background

Renal interstitial fibrosis is the pathophysiological basis of type 2 diabetes mellitus (T2DM). Exercise appears to improve kidney interstitial fibrosis in T2DM, in which silent information regulator factor 2-related enzyme 1 (Sirt1) is a critical regulator. However, the role of Sirt1 in mediating exercise on renal tissue as well as its mechanism remains unknown.

Methods

T2DM mouse models were created using a high-fat diet mixed with streptozotocin, followed by 8 weeks of treadmill exercise and niacinamide (Sirt1 inhibitor) intervention. Kits for detecting biochemical indices of renal function were used. The pathological appearance and severity of renal tissue were examined using hematoxylin and eosin, Masson and immunohistochemical staining. The mRNA and protein expression of relevant signaling pathway factors were determined to use real-time reverse transcriptase-polymerase chain reaction and western blotting.

Results

T2DM can promote renal interstitial fibrosis, increase kidney index, serum creatinine, blood urea nitrogen and 24 h urinary total protein and cause pathological changes in renal tissue and affect renal function. After 8 weeks of exercise intervention, the biochemical indicators in the kidney of T2DM mice were decreased, Sirt1 expression was increased, the expression of TGF-β1, Smad3, collagen type I (COL1) and collagen type III (COL3) were decreased, and the renal interstitial fibrosis, renal tissue structural lesions and renal function were improved. However, after the nicotinamide intervention, renal interstitial fibrosis of T2DM mice was aggravated, and the improvement effect of exercise on renal interstitial fibrosis of T2DM mice was abolished.

Conclusion

The upregulation of Sirt1 expression by exercise can inhibit the transforming growth factor β1/Smad3 pathway, thereby inhibiting the expression and deposition of COL1 and COL3 in renal interstitium, thereby improving renal interstitial fibrosis in T2DM.

CM1, a Chrysin Derivative, Protects from Endotoxin-Induced Lethal Shock by Regulating the Excessive Activation of Inflammatory Responses

Sepsis, a leading cause of death worldwide, is a harmful inflammatory condition that is primarily caused by an endotoxin released by Gram-negative bacteria. Effective targeted therapeutic strategies for sepsis are lacking. In this study, using an in vitro and in vivo mouse model, we demonstrated that CM1, a derivative of the natural polyphenol chrysin, exerts an anti-inflammatory effect by inducing the expression of the ubiquitin-editing protein TNFAIP3 and the NAD-dependent deacetylase sirtuin 1 (SIRT1). Interestingly, CM1 attenuated the Toll-like receptor 4 (TLR4)-induced production of inflammatory cytokines by inhibiting the extracellular-signal-regulated kinase (ERK)/MAPK and nuclear factor kappa B (NF-κB) signalling pathways. In addition, CM1 induced the expression of TNFAIP3 and SIRT1 on TLR4-stimulated primary macrophages; however, the anti-inflammatory effect of CM1 was abolished by the siRNA-mediated silencing of TNFAPI3 or by the genetic or pharmacologic inhibition of SIRT1. Importantly, intravenous administration of CM1 resulted in decreased susceptibility to endotoxin-induced sepsis, thereby attenuating the production of pro-inflammatory cytokines and neutrophil infiltration into the lung compared to control mice. Collectively, these findings demonstrate that CM1 has therapeutic potential for diverse inflammatory diseases, including sepsis.

Quercetin Prevents HSpertension in Dahl Salt-sensitive Rats Fed a High-salt Diet Through Balancing Endothelial Nitric Oxide Synthase and Sirtuin 1

BACKGROUND

A high-salt diet is a leading dietary risk factor for elevated blood pressure and cardiovascular disease. Quercetin reportedly exhibits cardioprotective and antihypertensive therapeutic effects.

OBJECTIVES

The objective of this study is to examine the effect of quercetin on high-salt dietinduced elevated blood pressure in Dahl salt-sensitive (SS) rats and determine the underlying molecular mechanism.

MATERIALS AND METHODS

Rats of the Dahl SS and control SS-13 BN strains were separated into five groups, SS-13 BN rats fed a low-salt diet (BL group), SS-13 BN rats fed a high-salt diet (BH group), Dahl SS rats fed a low-salt diet (SL group), Dahl SS rats fed a high-salt diet (SH group), and SH rats treated with quercetin (SHQ group). Blood pressure was checked three weeks into the course of treatment, and biochemical markers in the urine and serum were examined. Additionally, western blot was done to evaluate the sirtuin 1 (SIRT1) and endothelial nitric oxide synthase (eNOS) expression levels. Immunohistochemical analysis was performed to verify SIRT1 levels.

RESULTS

We demonstrated that a high-salt diet elevated blood pressure in both SS-13 BN and Dahl SS rats, and quercetin supplementation alleviated the altered blood pressure. Compared with the SH group, quercetin significantly elevated the protein expression of SIRT1 and eNOS. Immunohistochemistry results further confirmed that quercetin could improve the protein expression of SIRT1.

CONCLUSION

Quercetin reduced blood pressure by enhancing the expression of SIRT1 and eNOS in Dahl SS rats fed a high-salt diet.

Effects of Schumann resonance on the proliferation and migration of normal human epidermal keratinocytes and the expression of DEFB1 and SIRT1

BACKGROUND

When the skin is damaged and its barrier function is disrupted, the proliferation and migration of epidermal keratinocytes are vital for repairing the damaged area. The Schumann resonance at 7.8 Hz has been reported to protect rat cardiomyocytes against oxidative stress and inhibit the proliferation of B16 mouse melanoma cells. However, its effect on the skin is unknown.

AIMS

In this study, we applied 7.8-Hz electromagnetic waves to normal human epidermal keratinocytes (NHEKs) and investigated its effects on cell proliferation and migration, β-defensin (DEFB1) and sirtuin 1 (SIRT1) expression.

METHODS

We performed cell proliferation assay, cell migrationassay and gene expression analysis of DEFB1 and SIRT1.

RESULTS

We found that the application of 7.8-Hz electromagnetic waves caused a 2.8-fold increase in NHEK proliferation, enhanced cell migration, and increased the expression of DEFB1 and SIRT1 by 2.4-fold and 4.9-fold, respectively.

CONCLUSIONS

These results suggest that the application of 7.8-Hz electromagnetic waves may contribute to improving the skin barrier function and skin ulcer.

The Influence of Metabolic Syndrome on Potential Aging Biomarkers in Participants with Metabolic Syndrome Compared to Healthy Controls

BACKGROUND

Biological aging is a physiological process that can be altered by various factors. The presence of a chronic metabolic disease can accelerate aging and increase the risk of further chronic diseases. The aim of the study was to determine whether the presence of metabolic syndrome (MetS) affects levels of markers that are associated with, among other things, aging.

MATERIAL AND METHODS

A total of 169 subjects (58 with MetS, and 111 without metabolic syndrome, i.e., non-MetS) participated in the study. Levels of telomerase, GDF11/15, sirtuin 1, follistatin, NLRP3, AGEs, klotho, DNA/RNA damage, NAD+, vitamin D, and blood lipids were assessed from blood samples using specific enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Telomerase (p < 0.01), DNA/RNA damage (p < 0.006) and GDF15 (p < 0.02) were higher in MetS group compared to non-MetS group. Only vitamin D levels were higher in the non-MetS group (p < 0.0002). Differences between MetS and non-MetS persons were also detected in groups divided according to age: in under 35-year-olds and those aged 35-50 years.

CONCLUSIONS

Our results show that people with MetS compared to those without MetS have higher levels of some of the measured markers of biological aging. Thus, the presence of MetS may accelerate biological aging, which may be associated with an increased risk of chronic comorbidities that accompany MetS (cardiovascular, inflammatory, autoimmune, neurodegenerative, metabolic, or cancer diseases) and risk of premature death from all causes.

β-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 β-lapachone (β-LAP), a natural quinone-containing compound, in a mouse model of DOX-induced hepatotoxicity. β-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. β-LAP ameliorated liver injury and liver function markers evoked by DOX. β-LAP also downregulated the mRNA expression of nuclear factor-kB-corresponding genes including interleukin-6, interleukin-1β, and tumor necrosis factor-α. Moreover, β-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 β-LAP against DOX-induced hepatotoxicity by partly regulating the NAD+ /SIRT-1/FXR/p-AMPK axis.

Fucoxanthin Abrogates Ionizing Radiation-Induced Inflammatory Responses by Modulating Sirtuin 1 in Macrophages

Ionizing radiation (IR) triggers an overproduction of reactive oxygen species (ROS), disrupting the normal function of both immune and metabolic systems, leading to inflammation and metabolic disturbances. To address the pressing requirement for protection against IR, fucoxanthin (FX), a naturally occurring compound extracted from algae, was utilized as an efficient radioprotective agent in macrophages. In this study, we cultured murine RAW 264.7 macrophages and treated them with FX, along with agents influencing the activity of sirtuin 1 (SIRT1) and estrogen receptor α (ERα), to investigate their impact on IR-induced cellular responses. FX significantly attenuated IR-induced upregulation of pro-inflammatory genes (Il1b, Tnf, and Ccl2) and inhibited macrophage polarization toward the pro-inflammatory M1 phenotype. Additionally, FX regulated IR-induced metabolic genes mediating glycolysis and mitochondrial biogenesis. The ability of FX to mitigate IR-induced inflammation and glycolysis was ascribed to the expression and activity of SIRT1 and ERα in macrophages. This study not only uncovers the underlying mechanisms of FX's radioprotective properties but also highlights its potential as a protective agent against the detrimental effects of IR, thus offering new opportunities for enhancing radiation protection in the future.

Knockdown of lncRNA MALAT1 induces pyroptosis by regulating the miR‑124/SIRT1 axis in cervical cancer cells

The aim of the present study was to elucidate the role and downstream mechanism of long non‑coding RNA (lncRNA) metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1) in the process of cervical cancer cell pyroptosis. The effect of inhibiting lncRNA MALAT1 on cervical cancer cells was determined using primary cells isolated from patients and U14 cervical tumor‑bearing nude mice. The level of lncRNA MALAT1 expression and cell viability were determined for relationship analysis. Pyroptosis was then investigated in HeLa cells with lncRNA MALAT1 knockdown or overexpression with or without lipopolysaccharide (LPS) treatment. Bioinformatics tools were used to identify downstream factors of lncRNA MALAT1, which were subsequently verified by gain‑ or loss‑of‑function analyses in the process of cervical cancer cell pyroptosis. It was observed that the level of lncRNA MALAT1 was markedly higher in cervical carcinoma cells compared with expression in paracarcinoma cells, and knockdown of lncRNA MALAT1 induced cervical cancer cell death through pyroptosis. By contrast, overexpression of lncRNA MALAT1 blocked LPS‑induced pyroptosis. These results, combined with bioinformatics statistical tools, demonstrated that the microRNA (miR)‑124/sirtuin 1 (SIRT1) axis may affect the progression of cervical cancer at least partly by mediating the effect of lncRNA MALAT1 on the pyroptosis of cervical cancer cells. In conclusion, the lncRNA MALAT1/miR‑124/SIRT1 regulatory axis in cervical cancer cells may mediate pyroptosis and may provide potential targets against the progression of cervical cancer.

Sirtuin 1 is a potential therapeutic candidate gene for fetal growth restriction via insulin-like 4

OBJECTIVE

Insufficient placental development causes various obstetric complications, including fetal growth restriction (FGR). The Sirtuin 1 (SIRT1) and insulin-like 4 (INSL4) protein-coding genes have been demonstrated to play an important role in placental development. However, no treatment for FGR is available due to placental dysfunction. Therefore, this study aimed to examine the potential of the SIRT1-INSL4 axis as a treatment candidate for FGR caused by insufficient placental development.

METHODS

Twenty patients were enrolled, including 10 with FGR and 10 full-term controls. FGR and control placental samples were collected. Quantitative real-time polymerase chain reaction, immunohistochemical analysis, and western blotting were used to analyze INSL4 and SIRT1 expression. An in-vitro loss-of-function approach with the human choriocarcinoma cell line BeWo was applied for functional analyses of SIRT1 in placental development. BeWo cells were differentiated into syncytiotrophoblasts by silencing SIRT1 using small interfering RNA. SIRT1 activator was added during differentiation of SIRT1-knockdown BeWo cells into syncytiotrophoblasts.

RESULTS

The FGR samples had lower INSL4 and SIRT1 mRNA and protein expression levels than the control samples. Immunohistochemistry showed that both SIRT1 and INSL4 were expressed mainly in syncytiotrophoblasts. In-vitro analyses showed that SIRT1 knockdown decreased INSL4 expression; however, SIRT1 activator restored SIRT1 expression in SIRT1-silenced BeWo cells.

CONCLUSIONS

SIRT1 and INSL4 are downregulated in the placenta of FGR, and INSL4 is regulated by SIRT1. These findings indicate that the SIRT1-INSL4 axis may be a potential therapeutic target for FGR.

MicroRNA-599-Regulated Susceptibility to Acute Kidney Injury in Patients with Cirrhosis is Mediated by the Sirtuin 1 (SIRT1) rs4746720 Single Nucleotide Polymorphism

OBJECTIVE

The aim of this case-control study was to analyze the association between sirtuin 1 (SIRT1) single nucleotide polymorphism (SNP) and the risk of acute kidney injury (AKI) in Han Chinese patients with cirrhosis and to explore its potential mechanism.

METHODS

Twenty-nine AKI patients with cirrhosis (AKI group) and 87 non-AKI patients with cirrhosis (control group) were recruited from a Han Chinese population. SNaPshot sequencing technology was used for the detection of SNPs. Dual luciferase reporter vectors were constructed and co-transfected into HK-2 human proximal tubular epithelial cells. SIRT1-overexpressing recombinant plasmids were constructed and co-transfected into HK-2 cells. The expression of microRNA-599 (miR-599) and SIRT1/peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α)/nuclear respiratory factor 1 (NRF1)/mitochondrial transcription factor A (TFAM) was detected by the quantitative polymerase chain reaction, and the expression of the corresponding proteins was detected by Western blotting.

RESULTS

There were no statistically significant between-group differences in the genotype and allele frequencies of SIRT1 rs4746720. In the subgroup of patients with hepatic encephalopathy, the SIRT1 rs4746720 SNP was significantly associated with the development of AKI, and the risk of AKI in patients with the T allele was six times higher than in those with the C allele. The results of the in vitro experiments demonstrated that the T allele of SIRT1 rs4746720 increased the binding of miR-599 to the rs4746720 locus within the 3'-UTR of SIRT1 (p < 0.001). The results of the SIRT1-overexpressing recombinant plasmid experiments confirmed that the T allele of SIRT1 rs4746720 mediated the binding of miR-599, leading to decreased SIRT1 and PGC-1α, NRF1, and TFAM (p < 0.05).

CONCLUSIONS

The SIRT1 rs4746720 SNP might be linked with AKI in cirrhotic patients, and the T allele increased the risk of AKI in those with hepatic encephalopathy. The rs4746720 SNP in the SIRT1 3'-UTR is linked to the development of AKI in cirrhotic patients with hepatic encephalopathy, potentially by mediating the binding of miR-599.

Resveratrol inhibits basic fibroblast growth factor-induced macrophage colony-stimulating factor synthesis via the PI3-kinase/Akt pathway in osteoblasts

Resveratrol is a natural polyphenol found in grapes and beneficial for human health. Resveratrol regulates basic fibroblast growth factor (bFGF)-induced osteoprotegerin synthesis through Akt pathway in osteoblast-like MC3T3-E1 cells. In this study, we investigated resveratrol effects on bFGF-induced macrophage colony-stimulating factor (M-CSF) synthesis in MC3T3-E1 cells. bFGF significantly stimulated release and mRNA expression of M-CSF, which was reduced by resveratrol and SRT1720, sirtuin 1 (SIRT1) activator. Inauhzin, SIRT1 inhibitor, reversed inhibitory effects of resveratrol on bFGF-induced mRNA expression of M-CSF. Deguelin, Akt inhibitor, and LY294002, phosphatidylinositol 3-kinase (PI3-kinase) inhibitor, reduced bFGF-induced M-CSF synthesis. Inauhzin reversed inhibitory effects of resveratrol on bFGF-induced Akt phosphorylation. Suppressive effect of resveratrol on bFGF-induced osteoprotegerin mRNA expression was confirmed in the identical samples using in experiment of M-CSF mRNA expression. Therefore, resveratrol reduces bFGF-induced M-CSF synthesis in addition to osteoprotegerin synthesis by inhibiting PI3-kinase/Akt pathway and suppressive effects are mediated through SIRT1 activation in osteoblasts.

Involvement of Sirtuin 1 in the Growth Hormone/Insulin-like Growth Factor 1 Signal Transduction and Its Impact on Growth Processes in Children

The regulation of growth processes in children depends on the synthesis of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Insulin-like growth factor 1, which is mainly secreted in the liver in response to GH, is the main peripheral mediator of GH action. Newly discovered factors regulating GH secretion and its effects are being studied recently. One of them is sirtuin 1 (SIRT1). This NAD+-dependent deacetylase, by modulating the JAK2/STAT pathway, is involved in the transduction of the GH signal in hepatocytes, leading to the synthesis of IGF-1. In addition, it participates in the regulation of the synthesis of GHRH in the hypothalamus and GH in the somatotropic cells. SIRT1 is suggested to be involved in growth plate chondrogenesis and longitudinal bone growth as it has a positive effect on the epiphyseal growth plate. SIRT1 is also implicated in various cellular processes, including metabolism, cell cycle regulation, apoptosis, oxidative stress response, and DNA repair. Thus, its expression varies depending on the different metabolic states. During malnutrition, SIRT1 blocks GH signal transduction in hepatocytes to reduce the IGF-1 secretion and prevent hypoglycemia (i.e., it causes transient GH resistance). In this review, we focused on the influence of SIRT1 on GH signal transduction and the implications that may arise for growth processes in children.

Estradiol as the Trigger of Sirtuin-1-Dependent Cell Signaling with a Potential Utility in Anti-Aging Therapies

Aging entails the inevitable loss of the structural and functional integrity of cells and tissues during the lifetime. It is a highly hormone-dependent process; although, the exact mechanism of hormone involvement, including sex hormones, is unclear. The marked suppression of estradiol synthesis during menopause suggests that the hormone may be crucial in maintaining cell lifespan and viability in women. Recent studies also indicate that the same may be true for men. Similar anti-aging features are attributed to sirtuin 1 (SIRT1), which may possibly be linked at the molecular level with estradiol. This finding may be valuable for understanding the aging process, its regulation, and possible prevention against unhealthy aging. The following article summarizes the initial studies published in this field with a focus on age-associated diseases, like cancer, cardiovascular disease and atherogenic metabolic shift, osteoarthritis, osteoporosis, and muscle damage, as well as neurodegenerative and neuropsychiatric diseases.

Resveratrol‑mediated activation of SIRT1 inhibits the PERK‑eIF2α‑ATF4 pathway and mitigates bupivacaine‑induced neurotoxicity in PC12 cells

Endoplasmic reticulum (ER) stress and apoptosis play significant roles in the development of neurotoxicity caused by bupivacaine (BUP). By activating sirtuin 1 (SIRT1), resveratrol (RSV) can regulate various cellular processes associated with anti-oxidative stress, anti-apoptosis and anti-inflammatory responses, thereby exerting neuroprotective effects. However, it remains unknown whether the activation of SIRT1 by RSV is able to attenuate BUP-induced ER stress and apoptosis. Therefore, the present study aimed to explore the effect of RSV on BUP-induced cytotoxicity in PC12 cells and the underlying mechanism. Cell Counting Kit-8 assays, flow cytometry and inverted phase-contrast microscopy were used to assess the viability, apoptosis rate and morphological changes of the cells, respectively. Western blotting and immunofluorescence staining were used to analyze the levels of SIRT1, the apoptosis-related proteins Bax, Bcl-2 and cleaved caspase-3, the ER stress-related proteins glucose-regulated protein 78, caspase-12 and CHOP, and the protein kinase RNA-like ER kinase (PERK)-eukaryotic translation initiation factor 2 α (eIF2α)-activating transcription factor 4 (ATF4) pathway-associated proteins phosphorylated (p)-PERK, PERK, p-eIF2α, eIF2α and ATF4. The results revealed that BUP induced cell apoptosis and decreased cell viability, accompanied by the downregulation of SIRT1. However, RSV restored SIRT1 protein expression, downregulated the expression of the pro-apoptotic protein Bax, upregulated the expression of the anti-apoptotic protein Bcl-2, decreased the apoptosis rate of the cells and increased cell viability. Furthermore, the anti-apoptotic effects exhibited by RSV were associated with inhibition of the PERK-eIF2α-ATF4 pathway of ER stress. However, the protective effect of RSV was significantly mitigated by the SIRT1 inhibitor EX527. These results indicate that the activation of SIRT1 by RSV alleviates BUP-induced PC12 cell ER stress and apoptosis via regulation of the PERK-eIF2α-ATF4 pathway. These findings offer insights into the molecular mechanism underlying BUP-induced apoptosis and suggest the potential of RSV as a therapeutic agent against the neurotoxicity caused by BUP.

Salvianolic acid B ameliorates neuroinflammation and neuronal injury via blocking NLRP3 inflammasome and promoting SIRT1 in experimental subarachnoid hemorrhage

The nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated immuno-inflammatory response plays a critical role in exacerbating early brain injury (EBI) after subarachnoid hemorrhage (SAH). Salvianolic acid B (SalB) has previously been shown to suppress neuroinflammatory responses in many disorders. Meanwhile, a previous study has demonstrated that SalB mitigated oxidative damage and neuronal degeneration in a prechiasmatic injection model of SAH. However, the therapeutic potential of SalB on immuno-inflammatory responses after SAH remains unclear. In the present study, we explored the therapeutic effects of SalB on neuroinflammatory responses in an endovascular perforation SAH model. We observed that SalB ameliorated SAH-induced functional deficits. Additionally, SalB significantly mitigated microglial activation, pro-inflammatory cytokines release, and neuronal injury. Mechanistically, SalB inhibited NLRP3 inflammasome activation and increased sirtuin 1 (SIRT1) expression after SAH. Administration of EX527, an inhibitor of SIRT1, abrogated the anti-inflammatory effects of SalB against SAH and further induced NLRP3 inflammasome activation. In contrast, MCC950, a potent and selective NLRP3 inflammasome inhibitor, reversed the detrimental effects of SIRT1 inhibition by EX527 on EBI. These results indicated that SalB effectively repressed neuroinflammatory responses and neuronal damage after SAH. The action of SalB appeared to be mediated by blocking NLRP3 inflammasome and promoting SIRT1 signaling.

Interplay between Systemic Glycemia and Neuroprotective Activity of Resveratrol in Modulating Astrocyte SIRT1 Response to Neuroinflammation

The flow of substances between the blood and the central nervous system is precisely regulated by the blood-brain barrier (BBB). Its disruption due to unbalanced blood glucose levels (hyper- and hypoglycemia) occurring in metabolic disorders, such as type 2 diabetes, can lead to neuroinflammation, and increase the risk of developing neurodegenerative diseases. One of the most studied natural anti-diabetic, anti-inflammatory, and neuroprotective compounds is resveratrol (RSV). It activates sirtuin 1 (SIRT1), a key metabolism regulator dependent on cell energy status. The aim of this study was to assess the astrocyte SIRT1 response to neuroinflammation and subsequent RSV treatment, depending on systemic glycemia. For this purpose, we used an optimized in vitro model of the BBB consisting of endothelial cells and astrocytes, representing microvascular and brain compartments (MC and BC), in different glycemic backgrounds. Astrocyte-secreted SIRT1 reached the highest concentration in hypo-, the lowest in normo-, and the lowest in hyperglycemic backgrounds. Lipopolysaccharide (LPS)-induced neuroinflammation caused a substantial decrease in SIRT1 in all glycemic backgrounds, as observed earliest in hyperglycemia. RSV partially counterbalanced the effect of LPS on SIRT1 secretion, most remarkably in normoglycemia. Our results suggest that abnormal glycemic states have a worse prognosis for RSV-therapy effectiveness compared to normoglycemia.

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.

Combination of Panax ginseng and Diospyros kaki Leaf Inhibits White Adipocyte Differentiation and Browning Process through AMP-Activated Protein Kinase (AMPK) Activation In Vitro and In Vivo

Activating brown adipose tissue (BAT) and stimulating white adipose tissue (WAT) browning is a prospective obesity treatment method. Dietary components derived from plants are the most effective approach to activate BAT and promote WAT browning in rodents. This study investigated the synergistic effects of Panax ginseng (PG) and Diospyros kaki leaf (DKL) extract on adipocyte differentiation and browning, as well as the molecular mechanism underlying their beneficial effects. The administration of PG and DKL to HFD-induced obese mice significantly decreased body weight and epididymal and abdominal adipose tissue mass. In in vitro, PG inhibited the adipogenesis of 3T3-L1 adipocytes by regulating the expression of key adipogenic regulators, such as peroxisome proliferator-activated receptor (PPAR)γ and CCAAT/enhancer-binding protein (C/EBP)-α. In contrast, DKL negligibly influenced the adipogenesis of 3T3-L1 adipocytes but greatly increased the protein expression of UCP-1, PGC-1α, and PPARα in BAT and/or WAT. Moreover, PG and DKL inhibited adipogenesis synergistically and activated white adipocyte browning via AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1) pathways. These results suggest that a combination of PG and DKL regulates adipogenesis in white adipocytes and browning in brown adipocytes by activating AMPK/SIRT1 axis. The potential use of PG and DKL may represent an important strategy in obesity management that will be safer and more effective.

The Role of Sirtuin 1 (SIRT1) in Neurodegeneration

Sirtuins (SIRT) are a class of histone deacetylases that regulate important metabolic pathways and play a role in several disease processes. Of the seven mammalian homologs currently identified, sirtuin 1 (SIRT1) is the best understood and most studied. It has been associated with several neurodegenerative diseases and cancers. As such, it has been further investigated as a therapeutic target in the treatment of disorders such as Parkinson's disease (PD), Huntington's disease (HD), and Alzheimer's disease (AD). SIRT1 deacetylates histones such as H1 lysine 26, H3 lysine 9, H3 lysine 56, and H4 lysine 16 to regulate chromatin remodeling and gene transcription. The homolog has also been observed to express contradictory responses to tumor suppression and tumor promotion. Studies have shown that SIRT1 may have anti-inflammatory properties by inhibiting the effects of NF-κB, as well as stimulating upregulation of autophagy. The SIRT1 activators resveratrol and cilostazol have been shown to improve Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) scores in AD patients. In this review, we aim to explore the various roles of SIRT1 with regard to neuroprotection and neurodegeneration.

Effect of Resveratrol on Markers of Oxidative Stress and Sirtuin 1 in Elderly Adults with Type 2 Diabetes

Type 2 diabetes (T2D) affects a large part of the adult population and impairs its quality of life. Because of this, natural compounds with antioxidant, anti-inflammatory and hypoglycemic properties have been used as adjuvants. Among these compounds, resveratrol (RV) stands out, a polyphenol that has been studied in several clinical trials, the results of which are controversial. We conducted a randomized clinical trial on 97 older adults with T2D to evaluate the effect of RV on oxidative stress markers and sirtuin 1, using doses of 1000 mg/day (EG1000, n = 37) and 500 mg/day (EG500, n = 32) compared with a placebo (PG, n = 28). Biochemical markers, oxidative stress and sirtuin 1 levels were measured at baseline and after six months. We observed a statistically significant increase (p < 0.05) in total antioxidant capacity, antioxidant gap, the percentage of subjects without oxidant stress and sirtuin 1 levels in EG1000. In the PG, we observed a significant increase (p < 0.05) in lipoperoxides, isoprostanes and C-reactive protein levels. An increase in the oxidative stress score and in the percentage of subjects with mild and moderate oxidative stress was observed too. Our findings suggest that 1000 mg/day of RV exerts a more efficient antioxidant effect than 500 mg/day.

Protective Effects Against Brucella abortus 544 Infection in a Murine Macrophage Cell Line and in a Mouse Model via Treatment with Sirtuin 1 Activators Resveratrol, Piceatannol and Ginsenoside Rg3

Brucellosis is a contagious zoonotic disease that infects millions of people annually with hundreds of millions more being exposed. It is caused by Brucella, a highly infectious bacterial species capable of infecting humans with an estimated dose of 10-100 organisms. Sirtuin 1 (SIRT1) has been reported to contribute to prevention of viral diseases as well as a chronic infection caused by Mycobacterium bovis. Here, we investigated the role of SIRT1 in the establishment of Brucella abortus infection in both in vitro and in vivo systems using the reported SIRT1 activators resveratrol (RES), piceatannol (PIC), and ginsenoside Rg3 (Rg3). In RAW264.7 cells, SIRT1 activators did not alter the adherence of Brucella or Salmonella Typhimurium. However, reduced uptake of Brucella was observed in cells treated with PIC and Rg3, and survival of Brucella within the cells was only observed to decrease in cells that were treated with Rg3, while PIC treatment reduced the intracellular survival of Salmonella. SIRT1 treatment in mice via oral route resulted in augmented Brucella resistance for PIC and Rg3, but not RES. PIC treatment favors Th2 immune response despite reduced serum proinflammatory cytokine production, while Rg3-treated mice displayed high IL-12 and IFN-γ serum production. Overall, our findings encourage further investigation into the complete mechanisms of action of the different SIRT1 activators used as well as their potential benefit as an effective alternative approach against intracellular and extracellular pathogens.

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.

Sirtuin 1 activator alleviated lethal inflammatory injury via promotion of autophagic degradation of pyruvate kinase M2

Upregulation of pyruvate kinase M2 (PKM2) is critical for the orchestration of metabolism and inflammation in critical illness, while autophagic degradation is a recently revealed mechanism that counter-regulates PKM2. Accumulating evidence suggests that sirtuin 1 (SIRT1) function as a crucial regulator in autophagy. The present study investigated whether SIRT1 activator would downregulate PKM2 in lethal endotoxemia via promotion of its autophagic degradation. The results indicated that lethal dose of lipopolysaccharide (LPS) exposure decreased the level of SIRT1. Treatment with SRT2104, a SIRT1 activator, reversed LPS-induced downregulation of LC3B-II and upregulation of p62, which was associated with reduced level of PKM2. Activation of autophagy by rapamycin also resulted in reduction of PKM2. The decline of PKM2 in SRT2104-treated mice was accompanied with compromised inflammatory response, alleviated lung injury, suppressed elevation of blood urea nitrogen (BUN) and brain natriuretic peptide (BNP), and improved survival of the experimental animals. In addition, co-administration of 3-methyladenine, an autophagy inhibitor, or Bafilomycin A1, a lysosome inhibitor, abolished the suppressive effects of SRT2104 on PKM2 abundance, inflammatory response and multiple organ injury. Therefore, promotion of autophagic degradation of PKM2 might be a novel mechanism underlying the anti-inflammatory benefits of SIRT1 activator.

Leptin alleviated ovarian ischemia-reperfusion injury in rats via modulation of Sirt-1/Nrf2 and TLR4/NF-kB/caspase-3 signaling pathways

Objective. Ovarian torsion is a gynecological emergency that occurs mostly during the female reproductive years due to ovarian masses or surgical manipulation. This work aims to explore the probable protective effect of leptin on rat ovaries due to ischemia-reperfusion (IR) injury. Methods. Wistar albino rats were divided into four groups: 1) control group; 2) ovarian IR group (OVIR); 3) leptin group I [OVIR + leptin (10 µg/kg body weight, b.w.)]; and 4) leptin group II (OVIR + leptin (100 µg/kg b.w.)]. Serum levels of estradiol and anti-Mullerian hormone (AMH) were measured. Levels of oxidative stress and inflammatory markers in ovarian tissue were determined along with the expression of sirtuin 1 (Sirt1), nuclear erythroid factor-2 (Nrf2), cyclooxygenase-2 (COX-2), nuclear factor kappa (NF-κB), toll like receptor-4 (TLR4), and caspase-3. Results. Serum estradiol and AMH levels were decreased with increased expression of COX-2, TLR4, caspase-3, and NF-κB and decreased expression of Sirt1and Nrf2 in ovary of the OVIR group, which were improved by exogenous administration of both leptin doses. Conclusion. Leptin administration dose-dependently reduced the severity of OVIR injury via modulation of Sirt-1/Nrf2 and TLR4/NF-kB/caspase-3 signaling pathways. Thus, leptin may be used as an adjuvant measure to prevent ovarian damage and improve the outcomes. However, clinical studies are needed to evaluate these results in humans.

Role of the AMPK/SIRT1 pathway in non‑alcoholic fatty liver disease (Review)

Non‑alcoholic fatty liver disease (NAFLD) is an increasingly prevalent ailment worldwide. Moreover, de novo lipogenesis (DNL) is considered a critical factor in the development of NAFLD; hence, its inhibition is a promising target for the prevention of fatty liver disease. There is evidence to indicate that AMP‑activated protein kinase (AMPK) and sirtuin 1 (SIRT1) may play a crucial role in DNL and are the regulatory proteins in type 2 diabetes mellitus, obesity and cardiovascular disease. Therefore, AMPK and SIRT1 may be promising targets for the treatment of NAFLD. The present review article thus aimed to summarize the findings of clinical studies published during the past decade that suggested the beneficial effects of AMPK and SIRT1, using their specific activators and their combined effects on fatty liver disease.

Resveratrol-like Compounds as SIRT1 Activators

The sirtuin 1 (SIRT1) activator resveratrol has emerged as a promising candidate for the prevention of vascular oxidative stress, which is a trigger for endothelial dysfunction. However, its clinical use is limited by low oral bioavailability. In this work, we have applied a previously developed computational protocol to identify the most promising derivatives from our in-house chemical library of resveratrol derivatives. The most promising compounds in terms of SIRT1 activation and oral bioavailability, predicted in silico, were evaluated for their ability to activate the isolated SIRT1 enzyme. Then, we assessed the antioxidant effects of the most effective derivative, compound 3d, in human umbilical vein endothelial cells (HUVECs) injured with H₂O₂ 100 µM. The SIRT1 activator 3d significantly preserved cell viability and prevented an intracellular reactive oxygen species increase in HUVECs exposed to the oxidative stimulus. Such effects were partially reduced in the presence of a sirtuin inhibitor, sirtinol, confirming the potential role of sirtuins in the activity of resveratrol and its derivatives. Although 3d appeared less effective than resveratrol in activating the isolated enzyme, the effects exhibited by both compounds in HUVECs were almost superimposable, suggesting a higher ability of 3d to cross cell membranes and activate the intracellular target SIRT1.

Protects against Premature Senescence in Human Endothelial Cells

The senescence of vascular endothelial cells (EC) leads to vascular dysfunction. However, the molecular mechanisms of EC senescence and its associated pathophysiological changes have not yet been clearly studied. This study sought to inspect the Chrysanthemum coronarium L. (CC) extract's mechanism in preventing premature senescence of EC. A senescent endothelial cell model was created in human umbilical vein endothelial cells (HUVECs) with 100 µmol/L H₂O₂ treatment for 24 h. The effect of CC on senescent HUVECs was elucidated by measuring the activity of β-galactosidase (SA-β-gal), which exhibits an aging-related phenotype. SA-β-gal activity increased to 13.2 ± 2.85% in H₂O₂-treated HUVECs, whereas this activity was attenuated in the CC group. Immunoblot analyses revealed that p21, p53, and PAI-1 levels increased in the senescent HUVECs; however, the levels decreased in the HUVECs treated with various concentrations of CC (10, 20, and 50 μg/mL). The CC extract reduced the production of reactive oxygen species and reversed the decrease in NO production. Additionally, pretreatment with an Nω-nitro-l-arginine methyl ester (eNOS inhibitor) and nicotinamide (sirtuin 1 inhibitor) inhibited the anti-senescent effect of CC extract in HUVECs. Taken together, this study validated the novel endothelial protective effect of CC extract and its prevention of senescence in HUVECs through the mechanism regulated by eNOS and SIRT1 expression.

Stemness of Normal and Cancer Cells: The Influence of Methionine Needs and SIRT1/PGC-1α/PPAR-α Players

Stem cells are a population of undifferentiated cells with self-renewal and differentiation capacities. Normal and cancer stem cells share similar characteristics in relation to their stemness properties. One-carbon metabolism (OCM), a network of interconnected reactions, plays an important role in this dependence through its role in the endogenous synthesis of methionine and S-adenosylmethionine (SAM), the universal donor of methyl groups in eukaryotic cells. OCM genes are differentially expressed in stem cells, compared to their differentiated counterparts. Furthermore, cultivating stem cells in methionine-restricted conditions hinders their stemness capacities through decreased SAM levels with a subsequent decrease in histone methylation, notably H3K4me3, with a decrease in stem cell markers. Stem cells' reliance on methionine is linked to several mechanisms, including high methionine flux or low endogenous methionine biosynthesis. In this review, we provide an overview of the recent discoveries concerning this metabolic dependence and we discuss the mechanisms behind them. We highlight the influence of SIRT1 on SAM synthesis and suggest a role of PGC-1α/PPAR-α in impaired stemness produced by methionine deprivation. In addition, we discuss the potential interest of methionine restriction in regenerative medicine and cancer treatment.

miR‑141 impairs mitochondrial function in cardiomyocytes subjected to hypoxia/reoxygenation by targeting Sirt1 and MFN2

Mitochondrial oxidative stress and dysfunction are major pathogenic features of cardiac injury induced by ischemia/reperfusion (I/R). MicroRNA-141 (miR-141) has been implicated in the mitochondrial dysfunction in cell-based models of oxidant stress. Thus, the main aim of the present study was to systematically assess the role of miR-141 in cardiomyocyte injury induced by simulated I/R. The challenge of HL-1 cardiomyocytes with hypoxia/reoxygenation (H/R) decreased cell viability, which was also associated with an increase in miR-141 expression. The H/R-induced cell injury was mitigated by a miR-141 inhibitor and exacerbated by a miR-141 mimic. Furthermore, H/R induced mitochondrial superoxide production, dysfunction (decreased oxygen utilization and membrane depolarization), as well as ultrastructural damage. These mitochondrial effects were mitigated by a miR-141 inhibitor and intensified by a miR-141 mimic. Luciferase reporter assay, reverse transcription-quantitative PCR, and western blot analyses identified sirtuin-1 (Sirt1) and mitofusin-2 (MFN2) as targets of miR-141. The silencing of Sirt1 reduced the MFN2 cardiomyocyte levels and reversed the alleviating effects of miR-141 inhibitor on mitochondrial function during H/R. Collectively, these findings suggest that miR-141 functions as a causative agent in cardiomyocyte injury induced by I/R, primarily by interfering with two mitochondrial regulatory proteins, Sirt1 and MFN2.

The Value of Myocardium and Kidney Histopathological and Immunohistochemical Findings in Accidental Hypothermia-Related Fatalities

Background and Objectives: The post-mortem diagnosis of hypothermia is challenging in forensics. The aim of our study was to detect the kidney and heart histopathological changes that occurred in a group of hypothermia-related fatalities. Materials and Methods: The cohort included 107 cases identified in the database of our department between 2007 and 2021, which have been associated with extreme cold stress. Demographic and clinicopathological data were collected from the medico-legal reports. Archived tissue samples were evaluated to identify the histopathological features, in routine haematoxylin-eosin (H&E), Periodic acid-Schiff (PAS), and Masson's trichrome stainings, while cardiac sirtuin1 (SIRT1) and renal ubiquitin (Ub) immunostaining have been performed. Results: The majority of cases exposed to low temperatures were males (76%) from rural regions (68.2%) during the cold season. Paradoxical undressing was documented in 9.3% of cases. The common comorbidities included alcoholism (50.5%), neuropsychiatric diseases (10.3%), diabetes mellitus (3.7%), and lung tuberculosis (4.7%). The microscopic heart exam revealed areas of myocardial degeneration (100%), contraction bands (95.3%), fatty change (13.1%) and focal wavy contractile myocardial cells. Basal vacuolisation of renal tubular epithelial cells (Armanni-Ebstein lesions) (21.5%), focal tubular necrosis (7.5%), tubular renal cysts (7.5%), interstitial haemorrhages (5.6%), diabetic kidney disease (3.7%), background benign nephroangiosclerosis (42.1%), variable thickening of tubules and corpuscles basement membranes, capsular space amorphous material, and intratubular casts were identified in kidney tissue samples. Myocardial cells displayed SIRT1 weak expression, with a loss of immunopositivity correlated with areas with contraction bands, while a variable Ub expression was observed in renal corpuscles capsules, proximal, distal, and collecting renal tubules, Henle's loops, urothelium, and intratubular casts. Conclusions: In the context of the current concept that death associated with hypothermia is still a diagnosis of exclusion, our findings suggest that the microscopic exam provides relevant data that support the diagnosis of hypothermia-related fatalities in appropriate circumstances of death. A deeper insight into the histopathologic findings in hypothermic patients may lead to new therapeutic approaches in these cases.

Sirtuin 1 in Host Defense during Infection

Sirtuins (SIRTs) are members of the class III histone deacetylase family and epigenetically control multiple target genes to modulate diverse biological responses in cells. Among the SIRTs, SIRT1 is the most well-studied, with a role in the modulation of immune and inflammatory responses following infection. The functions of SIRT1 include orchestrating immune, inflammatory, metabolic, and autophagic responses, all of which are required in establishing and controlling host defenses during infection. In this review, we summarize recent information on the roles of SIRT1 and its regulatory mechanisms during bacterial, viral, and parasitic infections. We also discuss several SIRT1 modulators, as potential antimicrobial treatments. Understanding the function of SIRT1 in balancing immune homeostasis will contribute to the development of new therapeutics for the treatment of infection and inflammatory disease.

SIRT1 suppresses pituitary tumor progression by downregulating PTTG1 expression

Although pituitary tumors are among the most common types of brain tumor, the underlying molecular mechanism of this disease remains obscure. To this end, the role of sirtuin 1 (SIRT1) in pituitary tumors was reported. The results of reverse transcription‑quantitative PCR and immunohistochemistry revealed that sirtuin 1 (SIRT1) expression was downregulated in the tumor tissues of patients with pituitary tumors. In vitro experiments of the present study demonstrated that SIRT1 upregulation suppressed pituitary tumor cell line growth, while SIRT1 downregulation demonstrated the opposite effect. Additionally, it was determined that the enzymatic activity of SIRT1 was required for its cellular function. A mechanistic experiment determined that SIRT1 negatively regulated pituitary tumor‑transforming gene 1 (PTTG1) expression through the deacetylation of histone (H)3 lysine (K)9ac at the promoter region of PTTG1. Moreover, H3K9ac levels at the PTTG1 promoter were determined to be an essential regulatory element for PTTG1 expression. Thus, it was concluded that the SIRT1/H3K9ac/PTTG1 axis contributed to pituitary tumor formation and may represent a potential therapeutic strategy.

Downregulation of miR-34c-5p alleviates chronic intermittent hypoxia-induced myocardial damage by targeting sirtuin 1

Numerous microRNAs (miRs) are abnormally expressed in response to hypoxia-induced myocardial damage. Herein, miR-34c-5p as a potential pharmaco-target was investigated in a mouse model of chronic intermittent hypoxia (CIH)-induced myocardial damage. A mouse model of myocardial damage was established using CIH with 7% or 21% O₂ alternating 60 s for 12 h/day, 21% O₂ for 12 h/day. AntagomiR-34c-5p (20 nM/0.1 ml; once a week for 12 weeks) was used as a miR-34c-5p inhibitor in a mouse model with tail-vein injection. In another experiment, mice were administrated with Sirt1 activator SRT1720 (50 mg/kg/day) by intraperitoneal injection. Gene Expression Omnibus database showed a significant upregulation of miR-34c-5p expression in the ischemic myocardium of male mice. In CIH-stimulated mice, miR-34c-5p expression was also significantly increased compared with normal mice. Treatment of antagomiR-34c-5p significantly restrained CIH-triggered myocardial apoptosis. After administration of antagomiR-34c-5p or Sirt1 activator SRT1720, cardiac hypertrophy and oxidative stress were attenuated in CIH-stimulated mice. We also found sirtuin 1 (Sirt1) as a direct target of miR-34c-5p, which was able to mediate Sirt1 protein expression in cardiomyocytes. AntagomiR-34c-5p injection markedly elevated Sirt1 protein expression in CIH-stimulated mice. AntagomiR-34c-5p or Sirt1 activator SRT1720 administration exhibited the antioxidative activity and cardioprotective roles in CIH-stimulated mice.

Ferulic Acid, Pterostilbene, and Tyrosol Protect the Heart from ER-Stress-Induced Injury by Activating SIRT1-Dependent Deacetylation of eIF2α

Disturbances in Endoplasmic Reticulum (ER) homeostasis induce ER stress, which has been involved in the development and progression of various heart diseases, including arrhythmias, cardiac hypertrophy, ischemic heart diseases, dilated cardiomyopathy, and heart failure. A mild-to-moderate ER stress is considered beneficial and adaptative for heart functioning by engaging the pro-survival unfolded protein response (UPR) to restore normal ER function. By contrast, a severe or prolonged ER stress is detrimental by promoting cardiomyocyte apoptosis through hyperactivation of the UPR pathways. Previously, we have demonstrated that the NAD⁺-dependent deacetylase SIRT1 is cardioprotective in response to severe ER stress by regulating the PERK pathway of the UPR, suggesting that activation of SIRT1 could protect against ER-stress-induced cardiac damage. The purpose of this study was to identify natural molecules able to alleviate ER stress and inhibit cardiomyocyte cell death through SIRT1 activation. Several phenolic compounds, abundant in vegetables, fruits, cereals, wine, and tea, were reported to stimulate the deacetylase activity of SIRT1. Here, we evaluated the cardioprotective effect of ten of these phenolic compounds against severe ER stress using cardiomyoblast cells and mice. Among the molecules tested, we showed that ferulic acid, pterostilbene, and tyrosol significantly protect cardiomyocytes and mice heart from cardiac alterations induced by severe ER stress. By studying the mechanisms involved, we showed that the activation of the PERK/eIF2α/ATF4/CHOP pathway of the UPR was reduced by ferulic acid, pterostilbene, and tyrosol under ER stress conditions, leading to a reduction in cardiomyocyte apoptosis. The protection afforded by these phenolic compounds was not directly related to their antioxidant activity but rather to their ability to increase SIRT1-mediated deacetylation of eIF2α. Taken together, our results suggest that ferulic acid, pterostilbene, and tyrosol are promising molecules to activate SIRT1 to protect the heart from the adverse effects of ER stress.

SIRT1: A promising therapeutic target for chronic pain

Chronic pain remains an unresolved problem. Current treatments have limited efficacy. Thus, novel therapeutic targets are urgently required for the development of more effective analgesics. An increasing number of studies have proved that sirtuin 1 (SIRT1) agonists can relieve chronic pain. In this review, we summarize recent progress in understanding the roles and mechanisms of SIRT1 in mediating chronic pain associated with peripheral nerve injury, chemotherapy‐induced peripheral neuropathy, spinal cord injury, bone cancer, and complete Freund's adjuvant injection. Emerging studies have indicated that SIRT1 activation may exert positive effects on chronic pain relief by regulating inflammation, oxidative stress, and mitochondrial dysfunction. Therefore, SIRT1 agonists may serve as potential therapeutic drugs for chronic pain.

Transcriptional factor 3 binds to sirtuin 1 to activate the Wnt/β-catenin signaling in cervical cancer

Transcriptional factor 3 (TCF3, also termed E2A), first reported to exert crucial functions during lymphocyte development, has been revealed to participate in the pathogenesis of human cancers. The aim of this work was to investigate the function of TCF3 in cervical cancer (CC) and the molecular interactions. The bioinformatics prediction suggested that TCF3 was highly expressed in CC and linked to poor prognosis. Increased TCF3 expression was identified in CC cell lines, and its downregulation reduced proliferation and migration of CC cells in vitro as well as growth of xenograft tumors in vivo. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that the TCF-3-related genes and genes showed differential expression between CC and normal tissues were mainly enriched in the Wnt/β-catenin pathway. TCF3 bound to sirtuin 1 (SIRT1) promoter for transcriptional activation, and SIRT1 promoted deacetylation and nuclear translocation of β-catenin in CC. SIRT1 overexpression blocked the role of TCF3 silencing and restored cell proliferation in vitro and tumor growth in vivo. Treatment with XAV-939, a β-catenin inhibitor, significantly suppressed the cell proliferation and tumor growth induced by SIRT1 overexpression. In conclusion, this study demonstrates that TCF3 augments progression of CC by activating SIRT1-mediated β-catenin signaling.

A novel resveratrol analog upregulates sirtuin 1 and inhibits inflammatory cell infiltration in acute pancreatitis

Acute pancreatitis (AP), an inflammatory disorder of the pancreas, is a complicated disease without specific drug therapy. (R)-4,6-dimethoxy-3-(4-methoxy phenyl)-2,3-dihydro-1H-indanone [(R)-TML104] is a synthesized analog of the natural product resveratrol sesquiterpenes (±) -isopaucifloral F. This study aimed to investigate the effect and underlying mechanism of (R)-TML104 on AP. The experimental AP model was induced by caerulein hyperstimulation in BALB/c mice. (R)-TML104 markedly attenuated caerulein-induced AP, as evidenced by decreased pancreatic edema, serum amylase levels, serum lipase levels, and pancreatic myeloperoxidase activity. In addition, (R)-TML104 significantly inhibited the expression of pancreatic chemokines C-C motif chemokine ligand 2 and macrophage inflammatory protein-2 and the infiltration of neutrophils and macrophages. Mechanistically, (R)-TML104 activated AMP-activated protein kinase and induced sirtuin 1 (SIRT1) expression. (R)-TML104 treatment markedly induced the SIRT1-signal transducer and activator of transcription 3 (STAT3) interaction and reduced acetylation of STAT3, thus inhibiting the inflammatory response mediated by the interleukin 6-STAT3 pathway. The effect of (R)-TML104 on SIRT1-STAT3 interaction was reversed by treatment with a SIRT1 inhibitor selisistat (EX527). Together, our findings indicate that (R)-TML104 alleviates experimental pancreatitis by reducing the infiltration of inflammatory cells through modulating SIRT1.

Role of sirtuin 1 in the brain development in congenital hypothyroidism rats via the regulation of p53 signaling pathway

The present study aimed to investigate the expression, role, and underlying mechanism of action of sirtuin 1 (SIRT1) in congenital hypothyroidism (CH). A CH model was established in rats, and neuronal cells were isolated from the hippocampal tissues of normal rats. Free thyroxine (fT4) and thyroid-Stimulating hormone (TSH) concentrations were determined to confirm CH model conduction. The cognitive behavior of rats with CH was examined using open field and forced swimming tests. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to detect the expression levels of SIRT1, p53, B-cell lymphoma-extra-large (Bcl-xl), Bcl-2-associated X (Bax), and cytochrome c in the hippocampal tissues and neuronal cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and flow cytometry were performed to evaluate cell viability and apoptosis, respectively. The results revealed that SIRT1 was expressed at low levels in the hippocampal tissues of rats with CH. Moreover, overexpression of SIRT1 in the hippocampal tissues of rats with CH and improved rat behavior, while reducing the CH-induced nerve cell apoptosis. In addition, this overexpression increased the viability, inhibited apoptosis, and reduced the expression of p53, Bax, and cytochrome c, while increasing the expression of Bcl-xl in cultured neurons. In contrast, SIRT1-small interfering RNA exhibited the opposite effects in cultured neurons. In conclusion, SIRT1 plays a role in the occurrence and development of CH by regulating nerve cell apoptosis.

DHA-Enriched Phospholipids and EPA-Enriched Phospholipids Alleviate Lipopolysaccharide-Induced Intestinal Barrier Injury in Mice via a Sirtuin 1-Dependent Mechanism

Intestinal barrier dysfunction has emerged as a potential contributor to the development of several severe diseases. Herein, the effect and underlying mechanism of DHA-enriched phospholipids (DHA-PL) and EPA-enriched phospholipids (EPA-PL) on protecting against lipopolysaccharide (LPS)-induced intestinal barrier injury were elucidated. C57BL/6J male mice were fed an AIN-93G diet containing 1% DHA-PL or EPA-PL for 4 weeks and then were intraperitoneally injected with LPS (10 mg/kg) to cause intestinal barrier injury. The results manifested that DHA-PL and EPA-PL pretreatment balanced apoptosis and autophagy in intestinal epithelial cells and maintained intestinal tight junction integrity. Our findings also demonstrated that cotreatment with EX-527, a sirtuin 1 specific inhibitor, hindered the role of DHA-PL and EPA-PL against LPS-evoked intestinal barrier injury through reversing the inhibitory action of them on NF-κB and MAPKs activation as well as their potentiating actions on Nrf2 nuclear translocation. Overall, DHA-PL and EPA-PL alleviated LPS-mediated intestinal barrier injury via inactivation of the NF-κB and MAPKs pathways as well as activating the Nrf2 antioxidant pathway via up-regulating sirtuin 1.

Paeonol inhibits inflammatory response and protects chondrocytes by upregulating sirtuin 1

Paeonol is the bioactive component in Paeonia lactiflora Pall., Cynanchum paniculatum and Paeonia × suffruticosa Andr. Paeonol has been previously demonstrated to inhibit the release of tumor necrosis factor α (TNF-α) and interluekin 6 (IL-6) in chondrocytes. Sirtuin 1 (SIRT1) is downregulated in degraded cartilage and paeonol could induce nuclear accumulation of SIRT1. Therefore, the present study aims to investigate the possible role of paeonol in chondrocyte inflammation and cartilage protection in osteoarthritis (OA) as well as its regulation of SIRT1. Primary chondrocytes from rat knee joints were transfected with short hairpin (sh) - SIRT1 and (or) paeonol prior to IL-1β exposure, and then inflammatory response, apoptosis, and extracellular matrix (ECM) degradation in the cells were evaluated concurrent with the activation of the nuclear factor κβ (NF-κβ) signaling pathway. Increased levels of TNF-α, IL-17, IL-6, matrix metalloproteinase 1 (MMP-1), MMP-3, and MMP-13 along with decreased tissue inhibitor of metalloproteinases 1 and type II collagen levels were found in IL-1β-stimulated chondrocytes. Chondrocyte apoptosis was elevated and the NF-κβ signaling pathway was activated in response to IL-1β treatment. Paeonol enhanced SIRT1 expression to inactivate the NF-κβ signaling pathway, thereby ameliorating inflammatory cytokine secretion, ECM degradation, and chondrocyte apoptosis. In conclusion, the results of the present study confirm the potential of paeonol as a candidate OA drug.

Resveratrol inhibits the progression of premature senescence partially by regulating v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1)

Objective

To explore the effect of resveratrol in premature senescence and reveal its anti-premature senescence mechanisms through network pharmacology.

Methods

In this study, the H₂O₂-induced bone marrow mesenchymal stem cells (BMMSCs) premature senescence model is applied. Cell counting kit-8 assay, β-galactosidase staining and flow cytometry are conducted to detect the proliferation, senescence and apoptosis of BMMSCs. Bioinformatics analyses are used to screen and validate molecular targets of resveratrol acting on premature senescence. Dual-luciferase reporter assay is conducted to verify the interaction between v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1). RT-qPCR and western blot are adopted to detect mRNA and protein levels of RELA, SIRT1, senescence-related genes and apoptosis-related genes.

Results

First, we proved that resveratrol alleviated the H₂O₂-induced senescence of BMMSCs. Then, bioinformatics analysis revealed that RELA was the downstream target of resveratrol and SIRT1 was the downstream target of RELA, respectively, involved in premature aging. RELA/SIRT1 may be the potential target of resveratrol for premature senescence. Notably, rescue experiments indicated that resveratrol inhibited premature senescence partially through targeting regulation RELA/SIRT1.

Conclusion

In our study, we confirm the functional role of the resveratrol-RELA- SIRT1 axis in the progression of premature senescence, which provides a latent target for premature senescence treatment.

Decreased Systemic and Airway Sirtuin 1 Expression in Adults With Bronchiectasis

Aim: Whether accelerated aging, reflected by sirtuin 1 (SIRT1) expression, is implicated in bronchiectasis remains largely unknown. We sought to determine the patterns of SIRT1 and other aging markers in systemic circulation and airways and their expression levels associated with bronchiectasis severity and exacerbation.

Methods: We enrolled 132 patients with bronchiectasis and 50 healthy subjects in a prospective cohort study to profile aging markers in systemic circulation and recruited 36 patients with bronchiectasis and 32 disease controls (idiopathic pulmonary fibrosis or tumors) in a cross-sectional study to profile aging markers in bronchial epithelium of both large-to-medium and small airways. We profiled aging marker expression from peripheral blood mononuclear cells and enumerated the positively stained cells for detection of aging marker expression in bronchial epithelium.

Results: Compared with healthy controls, the relative telomere length (median: 0.88 vs. 0.99, p = 0.009), SIRT1 (median: 0.89 vs. 0.99, p = 0.002), and Ku80 (median: 0.87 vs. 0.96, p < 0.001) expression levels were consistently lower in the peripheral blood mononuclear cells among patients with bronchiectasis and modestly discriminated patients with bronchiectasis from healthy controls. No remarkable changes in SIRT1, telomere length, or Ku70 were identified at onset of exacerbation. Within the bronchial epithelium, the percentage of positively stained cells was lower for SIRT1 (median: 25.1 vs. 57.2%, p < 0.05) and numerically lower for p16 (median: 40.0 vs. 45.1%) and p21 (median: 28.9 vs. 35.9%) in patients with bronchiectasis than in disease controls (p > 0.05).

Conclusion: SIRT1 was downregulated in systemic circulation and bronchiectatic airways, which was independent of disease severity and lung function impairment.

Fibroblast Growth Factor 21 Modulates Microglial Polarization That Attenuates Neurodegeneration in Mice and Cellular Models of Parkinson's Disease

Microglial polarization and the subsequent neuroinflammatory response were identified as key contributors to the progress of Parkinson's disease (PD). Researchers have shown that fibroblast growth factor 21 (FGF21) plays multiple biological functions, including anti-inflammation and neuroprotection. However, the knowledge of FGF21 on microglial polarization in PD in vivo is far from completion. In this study, both in vivo and in vitro models were used to investigate whether FGF21 enhances the brain function by modulating microglial polarization in PD. The protective effects of FGF21 in vivo were conducted using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced PD mice model alongside intraperitoneally received FGF21. A behavioral test battery and tyrosine hydroxylase (TH) immunohistochemistry were conducted to evaluate the neuronal function and nigrostriatal tract integrity. Immunofluorescence assay and Western blot were used to examine M1/M2 microglial polarization. Then, a microglia-neuron co-culture system was adopted in vitro to identify the underlying molecular mechanisms of FGF21. The results showed that FGF21 significantly alleviated motor and cognitive impairment in mice with PD. FGF21 also protected TH-positive neuron cells in the striatum and midbrain. Mechanistically, FGF21 suppressed M1 microglial polarization and the subsequent mRNA expression of pro-inflammatory factors while promoting M2 microglial polarization with increasing anti-inflammatory factors in mice with PD. Furthermore, sirtuin 1 (SIRT1) and the nuclear factor-kappa B (NF-κB) pathway were involved in the FGF21-induced M2 microglial polarization. Conversely, SIRT1 inhibitor EX527 significantly prevented both the FGF21-induced SIRT1 expression and M2 microglial polarization. Moreover, FGF21 pretreatment of microglia significantly prevented neuronal cell apoptosis in a microglia-neuron co-culture system. In conclusion, our data demonstrate that FGF21 exerted its protective effects in the pathology of PD through SIRT1/NF-κB pathway-mediated microglial polarization. Given the safety record of human clinical trials, FGF21 could be a promising therapy for clinical trials to ameliorate motor and nonmotor deficits in patients with PD.

Bazedoxifene activates the angiotensin II-induced HUVEC hypertension model by targeting SIRT1

The shift in vascular function to vasoconstriction, pro-inflammatory state, oxidative stress and carbon monoxide deficiency may to endothelial dysfunction and injury, which is the key event in hypertension. Estrogen receptor modulators play a protective role in blood vessels. The present study aimed to investigate the effect of bazedoxifene, a selective estrogen receptor modulator, on human umbilical vein endothelial cells (HUVECs) and its potential underlying mechanism of action. The present study treated endothelial cells with different concentrations of bazedoxifene and determined cell viability using Cell Counting Kit-8 to screen for the optimal working concentration of bazedoxifene. Subsequently, an angiotensin II (AngII)-induced vascular endothelial cell model was established to observe the effect of bazedoxifene on AngII-induced endothelial cells. The concentrations of nitric oxide (NO) and reactive oxygen species (ROS) were detected using NO and ROS kits, respectively. The protein expression of sirtuin 1 (SIRT1), oxidative stress-related proteins and apoptosis-related proteins was detected using western blotting, and apoptosis was detected using a TUNEL assay. The results demonstrated that bazedoxifene promoted AngII-induced HUVEC viability, reduced the expression of stress-related proteins and inhibited apoptosis. Furthermore, bazedoxifene activated SIRT1 to promote the proliferation and inhibit the oxidative stress and apoptosis of AngII-induced HUVECs. These findings suggested that bazedoxifene could effectively promote AngII-induced HUVEC proliferation and inhibit cell apoptosis and oxidative stress. In addition, bazedoxifene protected HUVEC dysfunction induced by AngII by targeting the activation of SIRT1. In summary, bazedoxifene could improve the protective role against hypertension induced by AngII.

Inhibition of ATG3 ameliorates liver steatosis by increasing mitochondrial function

BACKGROUND & AIMS

Autophagy-related gene 3 (ATG3) is an enzyme mainly known for its actions in the LC3 lipidation process, which is essential for autophagy. Whether ATG3 plays a role in lipid metabolism or contributes to non-alcoholic fatty liver disease (NAFLD) remains unknown.

METHODS

By performing proteomic analysis on livers from mice with genetic manipulation of hepatic p63, a regulator of fatty acid metabolism, we identified ATG3 as a new target downstream of p63. ATG3 was evaluated in liver samples from patients with NAFLD. Further, genetic manipulation of ATG3 was performed in human hepatocyte cell lines, primary hepatocytes and in the livers of mice.

RESULTS

ATG3 expression is induced in the liver of animal models and patients with NAFLD (both steatosis and non-alcoholic steatohepatitis) compared with those without liver disease. Moreover, genetic knockdown of ATG3 in mice and human hepatocytes ameliorates p63- and diet-induced steatosis, while its overexpression increases the lipid load in hepatocytes. The inhibition of hepatic ATG3 improves fatty acid metabolism by reducing c-Jun N-terminal protein kinase 1 (JNK1), which increases sirtuin 1 (SIRT1), carnitine palmitoyltransferase 1a (CPT1a), and mitochondrial function. Hepatic knockdown of SIRT1 and CPT1a blunts the effects of ATG3 on mitochondrial activity. Unexpectedly, these effects are independent of an autophagic action.

CONCLUSIONS

Collectively, these findings indicate that ATG3 is a novel protein implicated in the development of steatosis.

LAY SUMMARY

We show that autophagy-related gene 3 (ATG3) contributes to the progression of non-alcoholic fatty liver disease in humans and mice. Hepatic knockdown of ATG3 ameliorates the development of NAFLD by stimulating mitochondrial function. Thus, ATG3 is an important factor implicated in steatosis.