Association of SIRT1 gene polymorphism and its expression for the risk of alcoholic fatty liver disease in the Han population

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

SIRT1 regulates endoplasmic reticulum stress-related organ damage

Endoplasmic reticulum (ER) stress plays a key role in the pathogenesis of several organ damages. Studies show that excessive ER stress (ERS) can destroy cellular homeostasis, causing cell damage and physiological dysfunction in various organs. In recent years, Sirtuin1 (SIRT1) has become a research hotspot on ERS. Increasing evidence suggests that SIRT1 plays a positive role in various ERS-induced organ damage via multiple mechanisms, including inhibiting cellular apoptosis and promoting autophagy. SIRT1 can also alleviate liver, heart, lung, kidney, and intestinal damage by inhibiting ERS. We discuss the possible mechanism of SIRT1, explore potential therapeutic targets of diseases, and provide a theoretical basis for treating ERS-related diseases.

A Potential Role for Sirtuin-1 in Alzheimer's Disease: Reviewing the Biological and Environmental Evidence

Sirtuin-1 (Sirt1), encoded by the SIRT1 gene, is a conserved Nicotinamide adenine dinucleotide (NAD+) dependent deacetylase enzyme, considered as the master regulator of metabolism in humans. Sirt1 contributes to a wide range of biological pathways via several mechanisms influenced by lifestyle, such as diet and exercise. The importance of a healthy lifestyle is of relevance to highly prevalent modern chronic diseases, such as Alzheimer's disease (AD). There is growing evidence at multiple levels for a role of Sirt1/SIRT1 in AD pathological mechanisms. As such, this review will explore the relevance of Sirt1 to AD pathological mechanisms, by describing the involvement of Sirt1/SIRT1 in the development of AD pathological hallmarks, through its impact on the metabolism of amyloid-β and degradation of phosphorylated tau. We then explore the involvement of Sirt1/SIRT1 across different AD-relevant biological processes, including cholesterol metabolism, inflammation, circadian rhythm, and gut microbiome, before discussing the interplay between Sirt1 and AD-related lifestyle factors, such as diet, physical activity, and smoking, as well as depression, a common comorbidity. Genome-wide association studies have explored potential associations between SIRT1 and AD, as well as AD risk factors and co-morbidities. We summarize this evidence at the genetic level to highlight links between SIRT1 and AD, particularly associations with AD-related risk factors, such as heart disease. Finally, we review the current literature of potential interactions between SIRT1 genetic variants and lifestyle factors and how this evidence supports the need for further research to determine the relevance of these interactions with respect to AD and dementia.

Resveratrol promotes bone mass in ovariectomized rats and the SIRT1 rs7896005 SNP is associated with bone mass in women during perimenopause and early postmenopause

OBJECTIVE

This study aimed to examine the effects of SIRT1 agonist resveratrol on bone mass in ovariectomized (OVX) rats and the SIRT1 single-nucleotide polymorphism (SNP) rs7896005 on bone mass in women during menopause and early postmenopause.

METHODS

An animal experiment was conducted on rats that were sham-operated (SHAM), OVX or OVX and different administered doses of resveratrol. Serum markers and femur microstructure and staining were assessed. A cross-sectional study was conducted in women undergoing menopause. SIRT1 protein and SIRT1 SNP rs7896005 were evaluated.

RESULTS

OVX rats administered resveratrol, especially high doses, showed lower bone loss than OVX rats. Serum osteoprotegerin (OPG) and femur SIRT1, β-catenin and bone mineral density (BMD) were significantly increased, whereas receptor activator of NF-κB ligand (RANKL) was significantly decreased. Serum SIRT1 levels were significantly lower in women with low bone mass (p < 0.01). Women with the CA genotype of rs7896005 had lower bone mass than those with the CC genotype. The A allele showed a significant negative effect on bone loss risk (odds ratio = 3.48; p = 0.025).

CONCLUSIONS

Resveratrol stimulated SIRT1 expression and Wnt/β-catenin signaling to promote bone mass in rat femurs. Among women in perimenopause and early postmenopause, SIRT1 protected bone mass, and the A allele of SIRT1 rs7896005 was a risk factor for reduced bone mass.

The Ameliorating Effects of Apple Polyphenol Extract on High-Fat-Diet-Induced Hepatic Steatosis Are SIRT1-Dependent: Evidence from Hepatic-Specific SIRT1 Heterozygous Mutant C57BL/6 Mice

Apple polyphenol extract (APE) has been reported to possess protective effects against hepatic steatosis. To explore whether APE-induced alleviation of hepatic steatosis is SIRT1-dependent, the present study was carried out using wild-type and hepatic SIRT1 heterozygous mutant (Sirt1^+/-) C57BL/6 mice. On consideration of the sex disparity related to hepatic steatosis morbidity, both male and female mice were included in the study. Six to eight week old mice were fed a high-fat diet (HFD) and randomly assigned to one of the following groups: (1) wild-type mice (wt+HFD), (2) Sirt1^+/- mice (Sirt1^+/-+HFD), and (3) Sirt1^+/- mice with 500 mg/(kg·bw·d) APE intragastric administration (Sirt1^+/-+HAP). HFD-induced weight gain and triglyceride accumulation was more prominent in Sirt1^+/- mice in comparison to wild-type mice. Following APE treatment, these effects were significantly reduced along with the alleviation of hepatic steatosis via upregulated expression of SIRT1 at the protein and mRNA levels in both male and female mice. However, APE differentially regulated the genes related to lipid metabolism (Lkb1, Ampk, Hsl, Srebp-1c, Abcg1, and Cd36) in a sex-specific manner. Moreover, APE treatment altered gut microbiota composition, with an increased relative abundance of Akkermansia and a decreased Firmicutes/Bacterodetes ratio. Thus, our study provided new evidence supporting our hypothesis that APE-induced alleviation of hepatic steatosis is SIRT1-dependent.

Protective effects of tea extracts against alcoholic fatty liver disease in mice via modulating cytochrome P450 2E1 expression and ameliorating oxidative damage

The alcoholic fatty liver disease (AFLD) has been a severe public health problem. Oxidative stress is involved in the initiation and progression of AFLD. Tea is a popular beverage worldwide with strong antioxidant activity. In this research, our purpose is to explore and compare the effects of 12 selected teas on AFLD. The ethanol liquid diet was used to feed the mice, and 12 tea extracts were administrated at 200 mg/kg body weight every day for 4 weeks. The results showed that the application of several tea extracts exhibited different inhibitory effects on lipid accumulation induced by sub-acute alcohol consumption based on the determination of triglyceride concentration and the histological alteration in the liver. In addition, several teas significantly decreased serum alanine aminotransferase and aspartate aminotransferase activities, inhibited the cytochrome P450 2E1 expression, and promoted alcohol metabolism (p < .05). Besides, compared with the model group, several teas obviously elevated superoxide dismutase and glutathione peroxidase activities as well as glutathione content, and remarkably decreased malondialdehyde level (p < .05). In general, Fried Green Tea, Fenghuang Narcissus Oolong Tea, and Pu-erh Dark Tea possessed potential preventive effects on AFLD. Moreover, the main phytochemicals in the three tea extracts were determined and quantified via high-performance liquid chromatography, and the most commonly detected ingredients were catechins and caffeine, which could exert the protective effects on AFLD.

Complement C3 activation regulates the production of tRNA-derived fragments Gly-tRFs and promotes alcohol-induced liver injury and steatosis

Complement is known to play a role in alcoholic fatty liver disease (AFLD), but the underlying mechanisms are poorly understood, thereby constraining the development of a rational approach for therapeutic intervention in the complement system. C3 deficiency has been shown to impart protective effects against ethanol-induced hepatic steatosis and inflammation. Here we demonstrate a protection effect in wild-type mice by treatment with CR2-Crry, a specific inhibitor of C3 activation. The expression of glycine transfer (t) RNA-derived fragments (Gly-tRFs) is upregulated in ethanol-fed mice and inhibition of Gly-tRFs in vivo decreases chronic ethanol feeding-induced hepatosteatosis without affecting inflammation. The expression of Gly-tRF was downregulated in C3-deficient or CR2-Crry-treated mice, but not in C5-deficient mice; Gly-tRF expression was restored by the C3 activation products C3a or Asp (C3a-des-Arg) via the regulation of CYP2E1. Transcriptome profiling of hepatic tissues showed that Gly-tRF inhibitors upregulate the expression of sirtuin1 (Sirt1) and subsequently affect downstream lipogenesis and β-oxidation pathways. Mechanistically, Gly-tRF interacts with AGO3 to downregulate Sirt1 expression via sequence complementarity in the 3' UTR. Notably, the expression levels of C3d, CYP2E1 and Gly-tRF are upregulated, whereas Sirt1 is decreased in AFLD patients compared to healthy controls. Collectively, our findings suggest that C3 activation products contribute to hepatosteatosis by regulating the expression of Gly-tRF. Complement inhibition at the C3 activation step and treatment with Gly-tRF inhibitors may be potential and precise therapeutic approaches for AFLD.

Growing burden of alcoholic liver disease in China: A review

Explosive economic growth and increasing social openness in China over the last 30 years have significantly boosted alcohol consumption, and consequently, the incidence of alcoholic liver disease (ALD) in China has increased. Because the epidemiologic and clinical features of ALD in the Chinese population may differ from those of the Caucasian population, this review describes the epidemiology, pathogenesis, genetic polymorphisms, diagnosis, and treatment of ALD in the Chinese population. This updated knowledge of ALD in China provides information needed for a global understanding of ALD and may help in the development of useful strategies for reducing the global ALD burden.