Research progress on sirtuins family members and cell senescence

Analysis of the Expression and Prognostic Value of SIRTs in Hepatocellular Carcinoma

Purpose

This study contributes to the evolving understanding of the pivotal involvement of Sirtuins (SIRTs) in various human cancers, with a particular focus on elucidating their expression patterns and clinical relevance within the context of hepatocellular carcinoma (HCC). The investigation involves a comprehensive analysis of mRNA expression and prognostic implications associated with distinct SIRTs in HCC.

Patients and Methods

Initial data pertaining to SIRT expression in HCC patients were collated from publicly accessible databases. Subsequently, the expression levels of select members of the SIRT family were validated using clinicopathological specimens from HCC patients. Additionally, HCC tissue microarray was employed to scrutinize the correlation between SIRT7 expression and HCC prognosis.

Results

The findings indicated a substantial upregulation of SIRT2, SIRT3, SIRT4, SIRT6, and SIRT7 in HCC tissues. Survival analysis underscored a pronounced association between elevated mRNA levels of SIRT3, SIRT6, and SIRT7 and an adverse prognosis for HCC patients. Particularly, SIRT7 emerged as a potential independent risk factor for poor prognosis in HCC patients. Examination of the HCC tissue microarray revealed heightened expression of SIRT7 in 68 cases (54.8%) of HCC tissues. Multivariate analysis established high SIRT7 expression as an independent risk factor for diminished Disease-Free Survival (DFS) and Overall Survival (OS) in HCC patients.

Conclusion

The aberrant expression of SIRT7 presents itself may be as a novel biomarker for predicting the prognosis of HCC patients.

Ginsenoside Rb2 Inhibits the Pyroptosis in Myocardial Ischemia Progression Through Regulating the SIRT1 Mediated Deacetylation of ASC

Myocardial ischemic (MI) injury is a common cardiovascular disease, and the potential therapeutic effects of ginsenoside Rb2 (Rb2) have been lately the focus of interest. Therefore, this study aimed to investigate the effects of Rb2 on pyroptosis of cardiomyocytes in MI progression. An in vitro MI model was developed by subjecting rat's cardiomyocytes (H9c2) to hypoxia/reoxygenation (H/R). The cell viability was determined by CCK-8 assay, while cell death was analyzed by propidium iodide staining. Similarly, pyroptosis-related protein levels and acetylation levels of apoptosis-associated speck-like protein containing a CARD (ASC) were detected by western blotting, and the relationship between Sirtuin 1 (SIRT1) and ASC was confirmed by co-immunoprecipitation (Co-IP) assay. Moreover, hematoxylin-eosin (H&E) and triphenyl tetrazolium chloride staining were used to study pathological structure and infarct size. It was found that post-Rb2 treatment significantly increased the cell viability and decreased the cell death and lactic dehydrogenase release, while the increased gasdermin D-N, NOD-like receptor thermal protein domain-associated protein 3, ASC, and cleaved-caspase-1 protein levels were significantly decreased in H/R-stimulated H9c2 cells. Moreover, the acetylation levels of H92c cells were decreased post-Rb2 treatment via increasing SIRT1 levels, while knocking down SIRT1, translated into an increase in ASC acetylation levels, leading to the increase in ASC protein stability and expressions. Additionally, the Rb2 effects on pyroptosis in H/R-stimulated H92c cells were reversed by overexpressing ASC, while reduced myocardial tissue damage was observed in MI rats following in vivo Rb2 treatment. Rb2 treatment inhibited pyroptosis in MI progression by decreasing the ASC levels. Mechanistically, Rb2 treatment increased the SIRT1 levels, further increasing the acetylation levels of ASC and decreasing the protein stability of ASC.

Resveratrol Attenuates Hyperoxia Lung Injury in Neonatal Rats by Activating SIRT1/PGC-1α Signaling Pathway

OBJECTIVES

 Our previous study showed that resveratrol (Res) attenuates apoptosis and mitochondrial dysfunction in alveolar epithelial cell injury induced by hyperoxia by activating the SIRT1/PGC-1α signaling pathway. In the present study, we investigated whether Res protects against hyperoxia-induced lung injury in neonatal rats by activating SIRT1/PGC-1α signaling pathway.

METHODS

 Naturally delivered neonatal rats were randomly divided into six groups: normoxia + normal saline, normoxia + dimethyl sulfoxide (DMSO), normoxia + Res, hyperoxia + normal saline, hyperoxia + DMSO, and hyperoxia + Res. Lung tissue samples were collected on postnatal days 1, 7, and 14. Hematoxylin and eosin staining was used to evaluate lung development. Dual-immunofluorescence staining, real-time polymerase chain reaction, and western blotting were used to evaluate the levels of silencing information regulator 2-related enzyme 1 (SIRT1), peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), nuclear respiratory factor 1 (Nrf1), Nrf2, transcription factor A (TFAM) and citrate synthase, the number of mitochondrial DNA (mtDNA) and mitochondria, the integrity of mtDNA, and the expression of TFAM in mitochondria.

RESULTS

 We found that hyperoxia insulted lung development, whereas Res attenuated the hyperoxia lung injury. Res significantly upregulated the levels of SIRT1, PGC-1α, Nrf1, Nrf2, TFAM, and citrate synthase; promoted TFAM expression in the mitochondria; and increased the copy number of ND1 and the ratio of ND4/ND1.

CONCLUSION

 Our data suggest that Res attenuates hyperoxia-induced lung injury in neonatal rats, and this was achieved, in part, by activating the SIRT1/PGC-1α signaling pathway to promote mitochondrial biogenesis.

KEY POINTS

· Hyperoxia insulted lung development in neonatal rats.. · Resveratrol promoted mitochondrial biogenesis to attenuate hyperoxia lung injury in neonatal rats.. · Resveratrol, at least in part, promoted mitochondrial biogenesis by activating the SIRT1/PGC-1α signaling pathway..

Molecular mechanisms involved in doxorubicin-induced cardiotoxicity: A bibliometrics analysis by VOSviewer

Doxorubicin is a potent chemotherapeutic agent that can cause cardiotoxicity. Many documents (more than 14,000) have been published in the area of doxorubicin-induced cardiotoxicity (DIC) since 1970. A comprehensive bibliographic analysis of author keywords was used to describe better and understand the molecular mechanisms involved in DIC. The objective was to consider the state of the author keywords of research on the molecular mechanisms involved in DIC based on a bibliometrics study of articles published over the past fifty years. A bibliometrics analysis was conducted using VOSviewer with data collected from the Web of Science Core Collection database of over 14,000 documents (from 1970 to July 19, 2023). Using scientific publications retrieved about DIC, author keywords were assessed at the scientific field level. The current study showed that the annual number of DIC-related publications has increased over the past 50 years. The Journal of Clinical Oncology is the leading journal in this field. The top cited DIC document was published in 2004. The top keywords with high frequency were "doxorubicin," "cardiotoxicity," and "adriamycin." According to the results of this study, the most common mechanisms involved in DIC were as follows oxidative stress, apoptosis, inflammation, autophagy, mitophagy, endoplasmic reticulum stress, pyroptosis, and ferroptosis. The highest occurrences of regulators-related author keywords were "AKT," "Sirt1," and "AMPK." Based on the findings, oxidative stress, apoptosis, inflammation, autophagy, mitophagy, endoplasmic reticulum stress, pyroptosis, and ferroptosis were hot research mechanisms of DIC from 1970 to July 19, 2023.

Potential molecular mechanisms underlying the ameliorative effect of Cola nitida (Vent.) Schott & Endl. on insulin resistance in rat skeletal muscles

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida (Vent.) Schott & Endl. are among the common medicinal plants employed in traditional medicine for treating diabetes and its complications.

AIM OF THE STUDY

The present study investigated the effect of Cola nitida infusion on the expression of key genes involved in insulin signaling vis-à-vis Insulin receptor substrate 1 (IRS-1), tumor protein P53 gene, glucose transporter type 4 (GLUT4), phosphoinositide 3-kinases (PI3K) and B-cell lymphoma-2 (BCL2) in skeletal muscles of type 2 diabetic (T2D) rats.

METHODS

Type 2 diabetic rats were administered C. nitida infusion at low and high doses (150 and 300 mg/kg bodyweight, respectively), while a high dose of the infusion was also administered to a normal toxicological group. Metformin served as the standard antidiabetic drug. The rats were sacrificed at the end of the experimental period. Their psoas muscles were harvested and assayed for the expressions of IRS1, p53, GLUT4, PI3K and BCL2. The studied genes were further subjected to enrichment analysis using the ShinyGO 0.76 online software.

RESULTS

Induction of T2D upregulated the expressions of IRS-1, p53, PI3K and BCL2 in psoas muscles, while concomitantly downregulating GLUT4 expression. These expressions were significantly reversed in type 2 diabetic rats treated with C. nitida infusion, and the results were statistically significant compared to metformin. Gene enrichment analysis revealed that the genes were linked to intrinsic pathways and biological processes involved in insulin resistance. The infusion further improved muscle glucose uptake, ex vivo. Molecular docking and molecular dynamics stimulation of C. nitida infusion phytoconstituents, caffeine and theobromine with IRS-1, p53, GLUT4, PI3K and BCL2 revealed a strong binding affinity as evident by the RMSD and RMSF values.

CONCLUSION

These results indicate the potentials of C. nitida infusion to improve glucose homeostasis in skeletal muscles of type 2 diabetic rats.

SIRT6 Knockdown in Buffalo Fetal Fibroblasts Exacerbates Premature Senescence Caused by DNA and Telomere Damage

As a gene with antiaging functions, sirtuin6 (SIRT6) belonging to the sirtuin family plays a vital role in DNA repair, telomerase function, and cellular senescence, as well as maintains epigenomic stability and promotes longevity. However, its role in cell senescence in large animals, such as buffaloes, remains unknown. Fibroblasts are commonly used for somatic reprogramming, and their physiological characteristics affect the efficiency of this process. We aimed to elucidate the role of SIRT6 in cellular senescence and proliferation and analyze its effect on the biological function of buffalo fibroblasts to help improve the efficiency of buffalo somatic cell reprogramming. The expression of SIRT6 and related DNA damage was measured in buffalo fibroblasts obtained at different developmental stages (in the fetus and at 3 and 10 years of age), and the effect of SIRT6 knockdown on the senescence of buffalo fetal fibroblast was investigated. An inverse relationship was observed between SIRT6 expression and senescence in buffalo fibroblasts obtained from animals of various ages. This was accompanied by decreased cell growth, viability, and increased DNA damage. Short hairpin RNA-mediated SIRT6 knockdown accelerated the senescence of buffalo fetal fibroblasts. It blocked the cell cycle during in vitro cell culture, which further enhanced DNA damage, particularly with respect to the telomeres. Collectively, our findings suggest that SIRT6 expression was closely associated with buffalo senescence in fibroblasts. These findings serve as a foundation to better understand the cellular functions of SIRT6 and also aid in selecting donor cells for buffalo somatic cell reprogramming.

Therapeutic application of traditional Chinese medicine in kidney disease: Sirtuins as potential targets

Sirtuins are a family of NAD+ III-dependent histone deacetylases that consists of seven family members, Sirt1-Sirt7, which regulate various signalling pathways and are involved in many critical biological processes of kidney diseases. Traditional Chinese medicine (TCM), as an essential part of the global healthcare system, has multi-component and multi-pathway therapeutic characteristics and plays a role in preventing and controlling various diseases. Through ongoing collaboration with modern medicine, TCM has recently achieved many remarkable advancements in theoretical investigation, mechanistic research, and clinical applications related to kidney diseases. Therefore, a comprehensive and systematic summary of TCM that focuses on sirtuins as the intervention target for kidney diseases is necessary. This review introduces the relationship between abnormal sirtuins levels and common kidney diseases, such as diabetic kidney disease and acute kidney injury. Based on the standard biological processes, such as inflammation, oxidative stress, autophagy, mitochondrial homeostasis, and fibrosis, which are underlying kidney diseases, comprehensively describes the roles and regulatory effects of TCM targeting the sirtuins family in various kidney diseases.

The activation of SIRT1 ameliorates BPDE-induced inflammatory damage in BEAS-2B cells via HMGB1/TLR4/NF-κB pathway

Benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), the metabolite of environmental pollutant benzo(a)pyrene (B(a)P) could induce pulmonary toxicity and inflammation. SIRT1, an NAD+ -dependent histone deacetylase, is known to regulate inflammation in the occurrence and development of various diseases, but its effects on BPDE-induced acute lung injury are still unknown. The present study aimed to explore the role of SIRT1 in BPDE-induced acute lung injury. Here, human bronchial epithelial (HBE) cells (BEAS-2B) cells were stimulated with BPDE at different concentrations (0.50, 0.75, and 1.00 μmol/L) for 24 h, we found that the levels of cytokines in the supernatant were increased and the expression of SIRT1 in cells was down-regulated, at the same time, BPDE stimulation up-regulated the protein expression of HMGB1, TLR4, and p-NF-κBp65 in BEAS-2B cells. Then the activator and inhibitor of SIRT1 were used before BPDE exposure, it was shown that the activation of SIRT1 significantly attenuated the levels of inflammatory cytokines and HMGB1, and reduced the expression of HMGB1, AC-HMGB1, TLR4, and p-NF-κBp65 protein; while these results were reversed by the inhibition of SIRT1. This study revealed that the SIRT1 activation may protect against BPDE-induced inflammatory damage in BEAS-2B cells by regulating the HMGB1/TLR4/NF-κB pathway.

Role of hypoxia in cellular senescence

Senescent cells persist and continuously secrete proinflammatory and tissue-remodeling molecules that poison surrounding cells, leading to various age-related diseases, including diabetes, atherosclerosis, and Alzheimer's disease. The underlying mechanism of cellular senescence has not yet been fully explored. Emerging evidence indicates that hypoxia is involved in the regulation of cellular senescence. Hypoxia-inducible factor (HIF)- 1α accumulates under hypoxic conditions and regulates cellular senescence by modulating the levels of the senescence markers p16, p53, lamin B1, and cyclin D1. Hypoxia is a critical condition for maintaining tumor immune evasion, which is promoted by driving the expression of genetic factors (such as p53 and CD47) while triggering immunosenescence. Under hypoxic conditions, autophagy is activated by targeting BCL-2/adenovirus E1B 19-kDa interacting protein 3, which subsequently induces p21WAF1/CIP1 as well as p16Ink4a and increases β-galactosidase (β-gal) activity, thereby inducing cellular senescence. Deletion of the p21 gene increases the activity of the hypoxia response regulator poly (ADP-ribose) polymerase-1 (PARP-1) and the level of nonhomologous end joining (NHEJ) proteins, repairs DNA double-strand breaks, and alleviates cellular senescence. Moreover, cellular senescence is associated with intestinal dysbiosis and an accumulation of D-galactose derived from the gut microbiota. Chronic hypoxia leads to a striking reduction in the amount of Lactobacillus and D-galactose-degrading enzymes in the gut, producing excess reactive oxygen species (ROS) and inducing senescence in bone marrow mesenchymal stem cells. Exosomal microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play important roles in cellular senescence. miR-424-5p levels are decreased under hypoxia, whereas lncRNA-MALAT1 levels are increased, both of which induce cellular senescence. The present review focuses on recent advances in understanding the role of hypoxia in cellular senescence. The effects of HIFs, immune evasion, PARP-1, gut microbiota, and exosomal mRNA in hypoxia-mediated cell senescence are specifically discussed. This review increases our understanding of the mechanism of hypoxia-mediated cellular senescence and provides new clues for anti-aging processes and the treatment of aging-related diseases.

Epigenetic modifications of inflammation in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common cause of joint-related chronic disability in elderly individuals worldwide. It seriously impacts the quality of life and inflicts a substantial social and economic burden. The pathological mechanisms underlying IDD have not been fully revealed, leading to less satisfactory clinical treatment outcomes. More studies are urgently needed to reveal its precise pathological mechanisms. Numerous studies have revealed that inflammation is closely related to various pathological processes of IDD, including the continuous loss of extracellular matrix, cell apoptosis, and senescence, indicating the important role of inflammation in the pathological mechanism of IDD. Epigenetic modifications affect the functions and characteristics of genes mainly through DNA methylation, histone modification, non-coding RNA regulation, and other mechanisms, thus having a major effect on the survival state of the body. Recently, the role of epigenetic modifications in inflammation during IDD has been attracting research interest. In this review, we summarize the roles of different types of epigenetic modifications in inflammation during IDD in recent years, to improve our understanding of the etiology of IDD and to transform basic research strategy into a clinically effective treatment for joint-related chronic disability in elderly individuals.

The role of Sirt3-induced autophagy in renal structural damage caused by periodontitis in rats

OBJECTIVE

This research aimed to explore the effect of periodontitis on renal tissues injury in rats and the role of Sirtuin3 (Sirt3) and its regulation of autophagy in this progression.

MATERIAL AND METHODS

Thirty Wistar rats were assigned into three groups: control, periodontitis (P), and periodontitis with gavage administration of Sirt3 activator resveratrol (P + RSV). To induce periodontitis, the wire ligature was placed around the cervical region of the rat maxillary first molar. After 8 weeks, micro-computed tomography (Micro-CT) and hematoxylin and eosin (HE) were used to evaluate the alveolar bone resorption and periodontal inflammation. Serum and urine biochemical indicators were measured to assess renal function. The pathological changes of the kidney were observed via HE and periodic acid Schiff (PAS) staining. Autophagosome was viewed by transmission electron microscopy (TEM). Real-time PCR and western blot were used to test expressions of Sirt3 and autophagy indicators in renal and periodontal tissues, including mammalian target of rapamycin (mTOR), phosphor-mTOR (p-mTOR), BECN1 (Beclin-1), and microtubule-associated protein 1 light chain 3 (LC3).

RESULTS

Alveolar bone destruction, resorption, and periodontal inflammation were observed in the P group (compared with the control group), and the above indexes were significantly improved after RSV intervention; the obvious changes in renal tissue structure in the P group were partially recovered after RSV intervention, while renal functional status was not affected (among the three groups); in addition, the levels of Sirt3 and autophagy in kidney and periodontal tissues of P group were inhibited, manifested as a decrease in the number of autophagosomes (renal tissue) and expressions of autophagy marker Beclin-1 and LC3 conversion rate and an increase in the expression of p-mTOR. After Sirt3 activation (RSV), the above indicators were significantly improved.

CONCLUSION

Periodontitis causes renal structural damage in rats, which may be connected to the effect of Sirt3-induced autophagy.

New Insights into the Genetics and Epigenetics of Aging Plasticity

Biological aging is characterized by irreversible cell cycle blockade, a decreased capacity for tissue regeneration, and an increased risk of age-related diseases and mortality. A variety of genetic and epigenetic factors regulate aging, including the abnormal expression of aging-related genes, increased DNA methylation levels, altered histone modifications, and unbalanced protein translation homeostasis. The epitranscriptome is also closely associated with aging. Aging is regulated by both genetic and epigenetic factors, with significant variability, heterogeneity, and plasticity. Understanding the complex genetic and epigenetic mechanisms of aging will aid the identification of aging-related markers, which may in turn aid the development of effective interventions against this process. This review summarizes the latest research in the field of aging from a genetic and epigenetic perspective. We analyze the relationships between aging-related genes, examine the possibility of reversing the aging process by altering epigenetic age.

Caloric restriction induced epigenetic effects on aging

Aging is the subject of many studies, facilitating the discovery of many interventions. Epigenetic influences numerous life processes by regulating gene expression and also plays a crucial role in aging regulation. Increasing data suggests that dietary changes can alter epigenetic marks associated with aging. Caloric restriction (CR)is considered an intervention to regulate aging and prolong life span. At present, CR has made some progress by regulating signaling pathways associated with aging as well as the mechanism of action of intercellular signaling molecules against aging. In this review, we will focus on autophagy and epigenetic modifications to elaborate the molecular mechanisms by which CR delays aging by triggering autophagy, epigenetic modifications, and the interaction between the two in caloric restriction. In order to provide new ideas for the study of the mechanism of aging and delaying aging.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Senescence in osteoarthritis: from mechanism to potential treatment

Osteoarthritis (OA) is an age-related cartilage degenerative disease, and chondrocyte senescence has been extensively studied in recent years. Increased numbers of senescent chondrocytes are found in OA cartilage. Selective clearance of senescent chondrocytes in a post-traumatic osteoarthritis (PTOA) mouse model ameliorated OA development, while intraarticular injection of senescent cells induced mouse OA. However, the means and extent to which senescence affects OA remain unclear. Here, we review the latent mechanism of senescence in OA and propose potential therapeutic methods to target OA-related senescence, with an emphasis on immunotherapies. Natural killer (NK) cells participate in the elimination of senescent cells in multiple organs. A relatively comprehensive discussion is presented in that section. Risk factors for OA are ageing, obesity, metabolic disorders and mechanical overload. Determining the relationship between known risk factors and senescence will help elucidate OA pathogenesis and identify optimal treatments.

Sirtuins functions in central nervous system cells under neurological disorders

The sirtuins (SIRTs), a class of NAD+ -dependent deacylases, contain seven SIRT family members in mammals, from SIRT1 to SIRT7. Extensive studies have revealed that SIRT proteins regulate virous cell functions. Central nervous system (CNS) decline resulted in progressive cognitive impairment, social and physical abilities dysfunction. Therefore, it is of vital importance to have a better understanding of potential target to promote homeostasis of CNS. SIRTs have merged as the underlying regulating factors of the process of neurological disorders. In this review, we profile multiple functions of SIRT proteins in different cells during brain function and under CNS injury.

The prognostic implications of SIRTs expression in breast cancer: a systematic review and meta-analysis

BACKGROUND

Sirtuins (SIRTs) have key roles in cancer progression. However, the prognostic implications of SIRTs in breast cancer (BC) remains a subject of debate and controversy. Thus, we performed a meta-analysis to identify the precise prognostic value of SIRTs in BC patients.

METHODS

Systematic literature searching was conducted in PubMed, Cochrane Library, Web of Science, and Embase databases. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to estimate the association of SIRTs expression and survival outcomes in BC patients.

RESULTS

A total of 22 original studies with 6317 patients were eligible for this meta-analysis. The results showed that in patients with BC, elevated SIRTs levels were associated with shorter overall survival (OS) and disease-free survival (DFS) both in univariate (HR = 1.56, 95% CI 1.21-2.00; HR = 1.67, 95% CI 1.32-2.12, respectively) and multivariate analysis models (HR = 2.11, 95% CI 1.48-3.00; HR = 1.70, 95% CI 1.20-2.39, respectively). Notably, further subgroup analysis revealed that overexpression of SIRT1 and SIRT6 predicted poor OS (HR = 2.65, 95% CI 1.54-4.56; HR = 2.53, 95% CI 1.64-3.90, respectively) and DFS (HR = 1.65, 95% CI 1.07-2.56; HR = 2.74; 95% CI 1.88-4.01, respectively) in BC.

CONCLUSIONS

Our data has elucidated that SIRT1 and SIRT6 could serve as prognostic biomarkers for patients with BC and may contribute to refined patient management.

SIRT2 Is Critical for Sheep Oocyte Maturation through Regulating Function of Surrounding Granulosa Cells

Oocyte in vitro maturation is crucial for in vitro embryo production technology, which provides oocytes resources for in vitro fertilization and somatic cell nuclear transfer. Previous studies proved that SIRT2, a member of the sirtuin family, plays a role in oocyte meiosis, but its role in sheep oocyte maturation and its regulating mechanism remains unknown. Firstly, we confirmed the role of Sirt2 in sheep oocytes maturation by supplementation of SIRT2 inhibitor and activator. To further explore the specific mechanism, we performed knockdown of Sirt2 in granulosa cells and then cocultured them with oocytes. Moreover, we determined the effects of Sirt2 on granulosa cell oxidative apoptosis, cell migration, and diffusion, and examined its effects on granulosa cell mitochondrial function, mitophagy, and steroid hormone levels. The results showed that supplementation of SIRT2 inhibitor decreased the oocytes maturation rate (69.28% ± 1.28 vs. 45.74% ± 4.74, p < 0.05), while resveratrol, a SIRT2 activator, increased its maturation rate (67.44% ± 1.68 vs. 78.52 ± 1.28, p < 0.05). Knockdown of Sirt2 in sheep granulosa cells also reduced the oocytes maturation rate (47.98% ± 1.43 vs. 33.60% ± 1.77, p < 0.05), and led to decreased cell migration and expansion ability, oxidative apoptosis, abnormal mitochondrial gene expression, decreased mitochondrial membrane potential and ATP level, and increased mitophagy level. Overexpression of Sirt2 improved mitochondrial membrane potential and ATP level and improved mitochondrial function. Furthermore, we found that Sirt2 knockdown in granulosa cells promotes the secretion of P4 through regulating p-ERK1/2. In conclusion the present study showed that SIRT2 is critical for sheep oocyte maturation through regulating the function of ovarian granulosa cells, especially affecting its mitochondrial function.

Redox signaling at the crossroads of human health and disease

Redox biology is at the core of life sciences, accompanied by the close correlation of redox processes with biological activities. Redox homeostasis is a prerequisite for human health, in which the physiological levels of nonradical reactive oxygen species (ROS) function as the primary second messengers to modulate physiological redox signaling by orchestrating multiple redox sensors. However, excessive ROS accumulation, termed oxidative stress (OS), leads to biomolecule damage and subsequent occurrence of various diseases such as type 2 diabetes, atherosclerosis, and cancer. Herein, starting with the evolution of redox biology, we reveal the roles of ROS as multifaceted physiological modulators to mediate redox signaling and sustain redox homeostasis. In addition, we also emphasize the detailed OS mechanisms involved in the initiation and development of several important diseases. ROS as a double‐edged sword in disease progression suggest two different therapeutic strategies to treat redox‐relevant diseases, in which targeting ROS sources and redox‐related effectors to manipulate redox homeostasis will largely promote precision medicine. Therefore, a comprehensive understanding of the redox signaling networks under physiological and pathological conditions will facilitate the development of redox medicine and benefit patients with redox‐relevant diseases.

Regulation of lung epithelial cell senescence in smoking-induced COPD/emphysema by microR-125a-5p via Sp1 mediation of SIRT1/HIF-1a

Chronic obstructive pulmonary disease (COPD) affects the health of more than 300 million people worldwide; at present, there is no effective drug to treat COPD. Smoking is the most important risk factor, but the molecular mechanism by which smoking causes the disease is unclear. The senescence of lung epithelial cells is related to development of COPD. Regulation of miRNAs is the main epigenetic mechanism related to aging. β-Galactose staining showed that the lung tissues of smokers have a higher degree of cellular senescence, and the expression of miR-125a-5p is high. This effect is obvious for smokers with COPD/emphysema, and there is a negative correlation between miR-125a-5p levels and values for forced expiratory volume in one second (FEV1)/forced vital capacity (FVC). After Balb/c mice were chronically exposed to various concentrations of cigarette smoke (CS), plethysmography showed that lung function was impaired, lung tissue senescence was increased, and the senescence-associated secretory phenotype (SASP) in bronchoalveolar lavage fluid was increased. For mouse lung epithelial (MLE)-12 cells treated with cigarette smoke extract (CSE), Sp1 and SIRT1 levels were low, HIF-1α acetylation levels were high, and cell senescence and secretion of SASP factors were elevated. Down-regulation of miR-125a-5p or up-regulation of Sp1 reversed these effects. In addition, compared with mice exposed to CS, knockdown of miR-125a-5p reduced lung epithelial cell senescence and COPD/emphysema. Therefore, in smoking-induced COPD, elevated miR-125a-5p participates in the senescence of lung epithelial cells through Sp1/SIRT1/HIF-1α. These findings provide evidence related to the pathogenesis of COPD/emphysema caused by chronic smoking.

Sirtuins at the Crossroads between Mitochondrial Quality Control and Neurodegenerative Diseases: Structure, Regulation, Modifications, and Modulators

Sirtuins (SIRT1-SIRT7), a family of nicotinamide adenine dinucleotide (NAD⁺)-dependent enzymes, are key regulators of life span and metabolism. In addition to acting as deacetylates, some sirtuins have the properties of deacylase, decrotonylase, adenosine diphosphate (ADP)-ribosyltransferase, lipoamidase, desuccinylase, demalonylase, deglutarylase, and demyristolyase. Mitochondrial dysfunction occurs early on and acts causally in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Sirtuins are implicated in the regulation of mitochondrial quality control, which is highly associated with the pathogenesis of neurodegenerative diseases. There is growing evidence indicating that sirtuins are promising and well-documented molecular targets for the treatment of mitochondrial dysfunction and neurodegenerative disorders by regulating mitochondrial quality control, including mitochondrial biogenesis, mitophagy, mitochondrial fission/fusion dynamics, and mitochondrial unfolded protein responses (mtUPR). Therefore, elucidation of the molecular etiology of sirtuin-mediated mitochondrial quality control points to new prospects for the treatment of neurodegenerative diseases. However, the mechanisms underlying sirtuin-mediated mitochondrial quality control remain obscure. In this review, we update and summarize the current understanding of the structure, function, and regulation of sirtuins with an emphasis on the cumulative and putative effects of sirtuins on mitochondrial biology and neurodegenerative diseases, particularly their roles in mitochondrial quality control. In addition, we outline the potential therapeutic applications for neurodegenerative diseases of targeting sirtuin-mediated mitochondrial quality control through exercise training, calorie restriction, and sirtuin modulators in neurodegenerative diseases.

SIRT1: A Potential Therapeutic Target in Autoimmune Diseases

The morbidity and mortality of autoimmune diseases (Ads) have been increasing worldwide, and the identification of novel therapeutic strategies for prevention and treatment is urgently needed. Sirtuin 1 (SIRT1), a member of the class III family of nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylases, has been reported to participate in the progression of several diseases. SIRT1 also regulates inflammation, oxidative stress, mitochondrial function, immune responses, cellular differentiation, proliferation and metabolism, and its altered functions are likely involved in Ads. Several inhibitors and activators have been shown to affect the development of Ads. SIRT1 may represent a novel therapeutic target in these diseases, and small molecules or natural products that modulate the functions of SIRT1 are potential therapeutic agents. In the present review, we summarize current studies of the biological functions of SIRT1 and its role in the pathogenesis and treatment of Ads.

SIRT3 affects mitochondrial metabolic reprogramming via the AMPK-PGC-1α axis in the development of benign prostatic hyperplasia

BACKGROUND

Sirtuin 3 (SIRT3) has been reported to share an association with mitochondrial metabolic reprogramming. However, the molecular mechanism underlying is not well understood, especially in benign prostatic hyperplasia (BPH). Therefore, the purpose of this study was to research whether SIRT3 can affect the progression of BPH via the regulation of mitochondrial metabolic reprogramming.

METHODS

Following the development of a rat model of BPH using testosterone propionate (TP), we extracted prostate tissues from sham-operated and BPH rats. Subsequently, bioinformatics prediction was used to screen the genes differentially expressed in BPH. To verify the role played by SIRT3 in BPH, we injected AAV9-SIRT3 into rats, followed by TP treatment. Prostate epithelial cells (PEC) were treated with TP to assess the mitochondrial morphology, mitochondrial membrane potential, and expression of enzymes related to the oxidative phosphorylation pathway after SIRT3 expression alteration. Finally, we examined the expression of AMPK-PGC-1α pathway in tissues and cells.

RESULTS

SIRT3 was reduced in the prostate tissues of BPH rats. After overexpression of SIRT3, mitochondrial morphology was more stable in prostate tissues of BPH rats and in TP-treated PEC, with significant increases in mitochondrial membrane potential and in the expression of oxidative phosphorylation-related enzymes in the cytoplasm. Moreover, SIRT3 significantly activated the AMPK-PGC-1α signaling pathway, which maintained the stability of mitochondrial membrane potential as well as mitochondrial structure, thus alleviating the symptoms of BPH.

CONCLUSION

SIRT3 maintained the stability of mitochondrial membrane potential as well as mitochondrial structure by activating the AMPK-PGC-1α pathway, thereby alleviating the symptoms of BPH.

An Adipose-Derived Injectable Sustained-Release Collagen Scaffold of Adipokines Prepared Through a Fast Mechanical Processing Technique for Preventing Skin Photoaging in Mice

Ultraviolet A (UVA) radiation is the major contributor to skin photoaging, associated with increased collagen degradation and reactive oxygen species (ROS) expression. Adipokines have been proven as promising therapeutic agents for skin photoaging. However, adipokine therapy is generally limited by the short in vivo release duration and biological instability. Therefore, developing a treatment that provides a sustained release of adipokines and enhanced therapeutic effects is desirable. In this study, we developed a novel mechanical processing technique to extract adipose tissue-derived ECM components, named the “adipose collagen fragment” (ACF). The physical characterization, injectability, collagen components, residual DNA/RNA and adipokine release pattern of ACF were identified in vitro. L929 cells were treated with ACF or phosphate-buffered saline for 24 h after UVA irradiation in vitro. The expression of senescence-associated xβ-galactosidase (SA-β-gal), ROS and antioxidase were investigated. Then, we evaluated its therapeutic efficacy by injecting ACF and phosphate-buffered saline, as a control, into the dermis of photoaging nude mice and harvesting skin samples at weeks 1, 2, and 4 after treatment for assessment. The content of adipokines released from ACF was identified in vivo. The collagen synthesis and collagen degradation in ACF implants were evaluated by immune staining. Dermal thickness, fibroblast expression, collagen synthesis, ROS level, antioxidase expression, capillary density, and apoptotic cell number were evaluated by histological assessment, immune staining, and polymerase chain reaction in the skin samples. We demonstrated that ACF is the concentrated adipose extracellular matrix collagen fragment without viable cells and can be injected through fine needles. The lower expression of SA-β-gal, ROS and higher expression of antioxidase were observed in the ACF-treated group. ACF undergoes collagen degradation and promotes neocollagen synthesis in ACF implants. Meanwhile, ACF serves as a sustained-release system of adipokines and exhibits a significantly higher therapeutic effect on mouse skin photoaging by enhancing angiogenesis, antioxidant abilities, antiapoptotic activities, and collagen synthesis through sustainedly releasing adipokines. To sum up, ACF is an adipokines-enriched, sustained-release extracellular matrix collagen scaffold that can prevent UVA-induced skin photoaging in mice. ACF may serve as a novel autologous skin filler for skin rejuvenation applications in the clinic.

Hydrogen Sulfide Attenuates Angiotensin II-Induced Cardiac Fibroblast Proliferation and Transverse Aortic Constriction-Induced Myocardial Fibrosis through Oxidative Stress Inhibition via Sirtuin 3

Sirtuin 3 (SIRT3) is critical in mitochondrial function and oxidative stress. Our present study investigates whether hydrogen sulfide (H₂S) attenuated myocardial fibrosis and explores the possible role of SIRT3 on the protective effects. Neonatal rat cardiac fibroblasts were pretreated with NaHS followed by angiotensin II (Ang II) stimulation. SIRT3 was knocked down with siRNA technology. SIRT3 promoter activity and expression, as well as mitochondrial function, were measured. Male wild-type (WT) and SIRT3 knockout (KO) mice were intraperitoneally injected with NaHS followed by transverse aortic constriction (TAC). Myocardium sections were stained with Sirius red. Hydroxyproline content, collagen I and collagen III, α-smooth muscle actin (α-SMA), and dynamin-related protein 1 (DRP1) expression were measured both in vitro and in vivo. We found that NaHS enhanced SIRT3 promoter activity and increased SIRT3 mRNA expression. NaHS inhibited cell proliferation and hydroxyproline secretion, decreased collagen I, collagen III, α-SMA, and DRP1 expression, alleviated oxidative stress, and improved mitochondrial respiration function and membrane potential in Ang II-stimulated cardiac fibroblasts, which were unavailable after SIRT3 was silenced. In vivo, NaHS reduced hydroxyproline content, ameliorated perivascular and interstitial collagen deposition, and inhibited collagen I, collagen III, and DRP1 expression in the myocardium of WT mice but not SIRT3 KO mice with TAC. Altogether, NaHS attenuated myocardial fibrosis through oxidative stress inhibition via a SIRT3-dependent manner.

Jaridon 6, a new diterpene from Rabdosia rubescens (Hemsl.) Hara, can display anti-gastric cancer resistance by inhibiting SIRT1 and inducing autophagy

Tumor resistance is the main cause of treatment failure and is associated with many tumor factors. Jaridon 6, a new diterpene extracted from Rabdosia rubescens (Hemsl.) Hara, which has been previously extracted by our research team, has been tested having more obvious advantages in resistant tumor cells. However, its mechanism is unclear. In this study, we studied the effect and the specific mechanism of Jaridon 6 in resistant gastric cancer cells. Cytotoxicity test, colony test, western blotting, and nude test verified the anti-drug resistance ability of Jaridon 6 in the MGC803/PTX and MGC803/5-Fu cells. Jaridon 6 has shown obvious inhibitory effects in the sirtuin 1 (SIRT1) enzyme test. Transmission electron microscopy and immunofluorescence tests further proved the autophagic action of Jaridon 6. Jaridon 6 could inhibit the proliferation of the resistant gastric cancer cell in vivo and in vitro. Jaridon 6 inhibited SIRT1 enzyme and induced autophagy by inhibiting the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway. Thus, it may be considered for treating gastric cancer resistance by individual or combined administration, as an SIRT1 inhibitor and autophagy inducer.

Age-related changes of human serum Sirtuin6 in adults

Background

Aging is a natural life process and with an aging population, age-related diseases (e.g. type 2 diabetes mellitus (T2DM), atherosclerosis-based cardiovascular diseases) are the primary mortality cause in older adults. Telomerase is often used as an aging biomarker. Detection and characterization of novel biomarkers can help in a more specific and sensitive identification of a person’s aging status. Also, this could help in age-related diseases early prevent, ultimately prolonging the population’s life span. Sirtuin 6 (Sirt6) - a member of the Sirtuins NAD⁺-dependent histone deacetylases family - is mainly intracellularly expressed, and is reported to be involved in the regulation of aging and aging-related diseases. Whether serum Sirt6 is correlated with aging and could be used as an aging biomarker is unknown. In the present study, we aimed to investigate the age-related Sirt6 changes in the serum of human adults.

Methods

Participants were divided into three groups according to age: 20–30 years (Young); 45–55 years (Middle-aged); and ≥ 70 years (Old). The Sirt6 and telomerase serum concentrations were determined by ELISA. The Sirt6 and human telomerase reverse transcriptase (hTERT) expression in vessels from amputated human lower limbs were analyzed using real-time quantitative PCR (RT-qPCR) and immunohistochemical staining. The relationships between variables were evaluated by Pearson correlation analysis.

Results

The Sirt6 and telomerase serum levels reduced with an increase in age. A similar tendency was observed for Sirt6 and hTERT in the vessel. Serum levels of Sirt6 were higher in females compared with males. Pearson’s regression analysis revealed that the Sirt6 serum level positively correlated with telomerase (r = 0.5743) and both were significantly negatively correlated with age (r = − 0.5830 and r = − 0.5993, respectively).

Conclusions

We reported a negative correlation between serum Sirt6 concentration and aging in human beings. Therefore, the Sirt6 serum level is a potential sex-specific aging marker.

SIRT1-Related Signaling Pathways and Their Association With Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic and debilitating disease that can exert serious and overwhelming effects on the physical and mental health of premature infants, predominantly due to intractable short- and long-term complications. Oxidative stress is one of the most predominant causes of BPD. Hyperoxia activates a cascade of hazardous events, including mitochondrial dysfunction, uncontrolled inflammation, reduced autophagy, increased apoptosis, and the induction of fibrosis. These events may involve, to varying degrees, alterations in SIRT1 and its associated targets. In the present review, we describe SIRT1-related signaling pathways and their association with BPD. Our intention is to provide new insights into the molecular mechanisms that regulate BPD and identify potential therapeutic targets for this debilitating condition.

Epigallocatechin Gallate Effectively Affects Senescence and Anti-SASP via SIRT3 in 3T3-L1 Preadipocytes in Comparison with Other Bioactive Substances

AIM

We investigated different bioactive compounds including epigallocatechin gallate (EGCG), anthocyanidin, resveratrol, phloretin, spermidine, butyrate, and β-hydroxybutyrate with regard to their effect on SIRT3 via NRF2 and modulation of the proinflammatory senescence-associated secretory phenotype (SASP) in senescence induced 3T3-L1 preadipocytes.

METHODS

For induction of senescence, 3T3-L1 preadipocytes were incubated with bromodeoxyuridine (BrdU) for 8 days. Cell cycle inhibition was observed, and β-galactosidase activity was measured. After BrdU treatment, cells were treated with different bioactive compounds in various concentrations for 96 h. ELISA was used for determining proinflammatory cytokine IL6 in SASP cells.

RESULTS

CDKN1a increased significantly after BrdU incubation compared to untreated control (p < 0.01). All secondary plant ingredients used for treatment, but not anthocyanidin 50 μM, decrease CDKN1a expression (p < 0.05), whereas most endogenous substances did not attenuate CDKN1a. IL6 secretion positively correlated with CDKN1a (p < 0.01), whereas EGCG could diminish both, IL6 and CDKN1a with the strongest effect (p < 0.01). Although NRF2 positively correlated with SIRT3 activation (p < 0.05), only resveratrol (p < 0.01) and anthocyanidin (p < 0.05) could activate NRF2 significantly. Solely anthocyanidin 50 μM (p < 0.05) and 100 μM (p < 0.01) and EGCG 50 μM (p < 0.01) could increase SIRT3 expression. Activation of SIRT3 with EGCG correlated with lowered IL6 secretion significantly (p < 0.05) but not with anthocyanidin.

CONCLUSION

Accumulation of senescent cells in adipose tissue plays an important role in obesity and age-related diseases. SIRT3, located in the mitochondria, can regulate ROS via different pathways. Thus, targeting SIRT3 activating compounds such as EGCG may delay senescence of cells and senescence induced inflammatory processes.

Molecular characterization and expression of sirtuin 2, sirtuin 3, and sirtuin 5 in the Wuchang bream (Megalobrama amblycephala) in response to acute temperature and ammonia nitrogen stress

This study sought to characterize sirtuin 2 (sirt2), sirtuin 3 (sirt3), and sirtuin 5 (sirt5) in Megalobrama amblycephala (M. amblycephala) by cloning the open reading frame (ORF) of sirt2, sirt3, and sirt5. The full-lengths of the resulting M. amblycephala sirt2, sirt3, and sirt5 cDNA sequences were 1845, 1534, and 1920 bp, respectively, with 92%, 98%, and 91% similarities to Danio rerio sequences. Based on our bioinformatic analyses and predictions, the sirt2 and sirt3 genes of M. amblycephala were classified within the Sir2 I family, whereas sirt5 belonged to the Sir2 III family. Furthermore, sirt2, sirt3, and sirt5 were widely distributed in different M. amblycephala tissues. Particularly, sirt2 and sirt5 were highly expressed in gills, intestines, and liver (P < 0.05), whereas sirt3 was highly expressed in gills, kidney, liver, and spleen (P < 0.05). A 2 × 2 factorial experiment was also conducted to analyze sirt2, sirt3, and sirt5 expression patterns in response to acute temperature (25 and 32 °C) and ammonia nitrogen (0 and 20 mg/L) stress. Notably, these two stressors were found to interactively affect sirt2, sirt3, and sirt5 expression patterns in M. amblycephala liver. At the higher water temperature (32 °C) and ammonia nitrogen concentration (20 mg/L) tested herein, sirt2, sirt3, and sirt5 had similar expression levels and exhibited a down-regulation trend at 6 and 48 h post-stress but became up-regulated thereafter to counteract the stressors at 96 h post-stress.

SIRT1/SIRT3 Modulates Redox Homeostasis during Ischemia/Reperfusion in the Aging Heart

Ischemia/reperfusion (I/R) injury is the central cause of global death in cardiovascular diseases, which is characterized by disorders such as angina, stroke, and peripheral vascular disease, finally causing severe debilitating diseases and death. The increased rates of morbidity and mortality caused by I/R are parallel with aging. Aging-associated cardiac physiological structural and functional deterioration were found to contribute to abnormal reactive oxygen species (ROS) production during I/R stress. Disturbed redox homeostasis could further trigger the related signaling pathways that lead to cardiac irreversible damages with mitochondria dysfunction and cell death. It is notable that sirtuin proteins are impaired in aged hearts and are critical to maintaining redox homeostasis via regulating substrate metabolism and inflammation and thus preserving cardiac function under stress. This review discussed the cellular and functional alterations upon I/R especially in aging hearts. We propose that mitochondria are the primary source of reactive oxygen species (ROS) that contribute to I/R injury in aged hearts. Then, we highlight the cardiomyocyte protection of the age-related proteins Sirtuin1 (SIRT1) and Sirtuin1 (SIRT3) in response to I/R injury, and we discuss their modulation of cardiac metabolism and the inflammatory reaction that is involved in ROS formation.