Association of SIRT6 circulating levels with urinary and glycometabolic markers in pre-diabetes and diabetes

The role of sirtuins in the regulatin of oxidative stress during the progress and therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and impaired glucose homeostasis. Oxidative stress, arising from an imbalance between reactive oxygen species (ROS) production and antioxidant defense systems, plays a significant role in the development and progression of T2DM. The sirtuin family, particularly Sirt1, Sirt3, and Sirt6, have emerged as key regulators of oxidative stress in various cellular processes. This review aims to explore the role of the sirtuin family in oxidative stress during the progression of T2DM and their potential as therapeutic targets. We discussed the mechanisms through which sirtuins modulate oxidative stress, their impact on insulin sensitivity, and beta-cell function involved in T2DM. Furthermore, we highlight drugs targeting sirtuin activation and related complications in T2DM. This review summarizes the role as well as mechanism of sirtuins in the regulation of oxidative stress in T2DM and available drugs targeting sirtuins in clinic, which may provide novel insights into the mechanism and therapy of T2DM.

SIRT6's function in controlling the metabolism of lipids and glucose in diabetic nephropathy

Diabetic nephropathy (DN) is a complication of diabetes mellitus (DM) and the main cause of excess mortality in patients with type 2 DM. The pathogenesis and progression of DN are closely associated with disorders of glucose and lipid metabolism. As a member of the sirtuin family, SIRT6 has deacetylation, defatty-acylation, and adenosine diphosphate-ribosylation enzyme activities as well as anti-aging and anticancer activities. SIRT6 plays an important role in glucose and lipid metabolism and signaling, especially in DN. SIRT6 improves glucose and lipid metabolism by controlling glycolysis and gluconeogenesis, affecting insulin secretion and transmission and regulating lipid decomposition, transport, and synthesis. Targeting SIRT6 may provide a new therapeutic strategy for DN by improving glucose and lipid metabolism. This review elaborates on the important role of SIRT6 in glucose and lipid metabolism, discusses the potential of SIRT6 as a therapeutic target to improve glucose and lipid metabolism and alleviate DN occurrence and progression of DN, and describes the prospects for future research.

Overexpressed SIRT6 ameliorates doxorubicin-induced cardiotoxicity and potentiates the therapeutic efficacy through metabolic remodeling

Since the utilization of anthracyclines in cancer therapy, severe cardiotoxicity has become a major obstacle. The major challenge in treating cancer patients with anthracyclines is minimizing cardiotoxicity without compromising antitumor efficacy. Herein, histone deacetylase SIRT6 expression was reduced in plasma of patients treated with anthracyclines-based chemotherapy regimens. Furthermore, overexpression of SIRT6 alleviated doxorubicin-induced cytotoxicity in cardiomyocytes, and potentiated cytotoxicity of doxorubicin in multiple cancer cell lines. Moreover, SIRT6 overexpression ameliorated doxorubicin-induced cardiotoxicity and potentiated antitumor efficacy of doxorubicin in mice, suggesting that SIRT6 overexpression could be an adjunctive therapeutic strategy during doxorubicin treatment. Mechanistically, doxorubicin-impaired mitochondria led to decreased mitochondrial respiration and ATP production. And SIRT6 enhanced mitochondrial biogenesis and mitophagy by deacetylating and inhibiting Sgk1. Thus, SIRT6 overexpression coordinated metabolic remodeling from glycolysis to mitochondrial respiration during doxorubicin treatment, which was more conducive to cardiomyocyte metabolism, thus protecting cardiomyocytes but not cancer cells against doxorubicin-induced energy deficiency. In addition, ellagic acid, a natural compound that activates SIRT6, alleviated doxorubicin-induced cardiotoxicity and enhanced doxorubicin-mediated tumor regression in tumor-bearing mice. These findings provide a preclinical rationale for preventing cardiotoxicity by activating SIRT6 in cancer patients undergoing chemotherapy, but also advancing the understanding of the crucial role of SIRT6 in mitochondrial homeostasis.

Role of sirtuins in metabolic disease-related renal injury

Poor control of metabolic diseases induces kidney injury, resulting in microalbuminuria, renal insufficiency and, ultimately, chronic kidney disease. The potential pathogenetic mechanisms of renal injury caused by metabolic diseases remain unclear. Tubular cells and podocytes of the kidney show high expression of histone deacetylases known as sirtuins (SIRT1-7). Available evidence has shown that SIRTs participate in pathogenic processes of renal disorders caused by metabolic diseases. The present review addresses the regulatory roles of SIRTs and their implications for the initiation and development of kidney damage due to metabolic diseases. SIRTs are commonly dysregulated in renal disorders induced by metabolic diseases such as hypertensive nephropathy and diabetic nephropathy. This dysregulation is associated with disease progression. Previous literature has also suggested that abnormal expression of SIRTs affects cellular biology, such as oxidative stress, metabolism, inflammation, and apoptosis of renal cells, resulting in the promotion of invasive diseases. This literature reviews the research progress made in understanding the roles of dysregulated SIRTs in the pathogenesis of metabolic disease-related kidney disorders and describes the potential of SIRTs serve as biomarkers for early screening and diagnosis of these diseases and as therapeutic targets for their treatment.

Serum SIRT6 Levels Are Associated with Frailty in Older Adults

OBJECTIVES

Frailty is one of the major health problems facing aging societies worldwide. We investigated the association between serum SIRT6 and frailty in older adults.

DESIGN

Cross-sectional analysis of associations of serum SIRT6 and frailty in older people.

SETTING

Enrolled community-dwelling and hospital outpatient clinic adults older than 65 years old in Wuhan City, Hubei Province, China.

PARTICIPANTS

A total of 540 community-dwelling older adults (age ≥ 65 years) in Wuhan were included in the study.

MEASURES

We used Frailty Phenotype criteria for classifying participants based on their frailty status. Serum SIRT6 was measured using an ELISA kit.

RESULTS

A total of 540 older adults were included in this cross-sectional study. Serum SIRT6 was lower in the slowness group (7.23±1.81 vs 5.89±1.74, p<0.001), weakness group (6.87±1.88 vs 5.68±1.64, p<0.001), and exhaustion group (6.73±1.90 vs 5.88±1.74, p<0.001) compare with the normal group. ROC curves were used to assess the efficiency of SIRT6 in predicting frailty in older adults. The AUC for SIRT6 was 0.792 (95% CI: 0.7514 to 0.8325), with the highest sensitivity of 68.0% and the specificity of 91.9%, and the optimal critical value of 4.65ng/ml according to Youden's index. Multivariate logistic regression analysis showed that serum SIRT6 level was independently associated with frailty in older people.

CONCLUSION

In conclusion, serum SIRT6 was decreased in frailty compared with robust older adults. A decreased serum SIRT6 was independently associated with an increased risk of frailty. SIRT6 may be a potential target for the treatment of patients with frailty.

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.

The correlation of serum sirt6 with clinical outcome and prognosis in patients with gastric cancer

BACKGROUND

We aimed to evaluate the correlation between serum sirtuin 6 (sirt6) level and clinicopathological characteristics and prognosis of gastric cancer (GC) patients.

METHODS

The serum sirt6 levels of subjects (135 cases of GC, 68 cases of atrophic gastritis, 60 cases of healthy controls) were analyzed by enzyme-linked immunosorbent assay. The predictive and prognostic values of sirt6 serum level for GC were determined by performing receiver operating characteristic curve (ROC), Kaplan-Meier analysis, as well as univariate and multivariate Cox regression, respectively.

RESULTS

GC patients showed lower sirt6 serum levels than that of atrophic gastritis patients and healthy control. Taking the healthy control as a reference, the area under the ROC curve (AUC) of sirt6 serum level for diagnosing GC was 0.955 with a sensitivity of 91.85% and a specificity of 90.0%. Based on ROC analysis using atrophic gastritis as the state variable, serum sirt6 had a high diagnostic efficiency for GC (AUC = 0.754). Serum sirt6 was related to the clinicopathological features (tumor size, Lauren's classification, tumor node metastasis staging, lymph node metastasis) and overall survival (log-rank χ2 = 12.22, P < .001). The AUC of serum sirt6 predicting death in GC patients was 0.731. At the optimal cutoff value (16.83 ng/mL), the sensitivity and specificity of sirt6 were 59.57% and 79.55%, respectively. Moreover, lower sirt6 level as independent risk factor was revealed to affect prognosis of GC patients (P = .018).

CONCLUSION

Serum sirt6 level was positively associated with the tumor stage and metastasis conditions, which could be served as diagnostic and predictive biomarkers in GC.

Sirtuin 6 affects glucose reabsorption and gluconeogenesis in type 1 diabetes via FoxO1

AIM

The purpose of this study was to explore the expression changes of Sirtuin 6 in diabetic renal tissues and the molecular mechanisms affecting renal tubular gluconeogenesis and reabsorption.

METHODS

The type 1 diabetic C57BL/6 mice model as well as high glucose cultured proximal tubular cells and cell lines were established. Sirt6 siRNA, the SGLT2 inhibitor (dapagliflozin), and insulin were pre-treated to make Sirtuin 6 levels, gluconeogenesis, and reabsorption changes. Immunofluorescence was used for Sirtuin 6 renal localization, and molecular biological detection was adopted for transcription factors, FoxO1, transporters (SGLT2 and GLUT2) as well as rate-limiting enzyme. Nuclear/plasma proteins were extracted to detect Sirtuin 6 and FoxO1 levels in the subcellular structure.

RESULTS

Sirtuin 6 was decreased in STZ-induced diabetic renal outer medulla, and lower both in high glucose-induced primary proximal tubular cells and cell lines. Sirtuin 6 reversed the glucose reabsorption and gluconeogenesis effect via regulating FoxO1 and affecting nuclear translocation of FoxO1 in high glucose-induced proximal tubular cells.

CONCLUSION

Sirtuin 6 affects renal glucose reabsorption and gluconeogenesis in type 1 diabetes by regulating FoxO1 nuclear import.

SIRT1-SIRT7 in Diabetic Kidney Disease: Biological Functions and Molecular Mechanisms

Diabetic kidney disease (DKD) is a severe microvascular complication in patients with diabetes and is one of the main causes of renal failure. The current clinical treatment methods for DKD are not completely effective, and further exploration of the molecular mechanisms underlying the pathology of DKD is necessary to improve and promote the treatment strategy. Sirtuins are class III histone deacetylases, which play an important role in many biological functions, including DNA repair, apoptosis, cell cycle, oxidative stress, mitochondrial function, energy metabolism, lifespan, and aging. In the last decade, research on sirtuins and DKD has gained increasing attention, and it is important to summarize the relationship between DKD and sirtuins to increase the awareness of DKD and improve the cure rates. We have found that miRNAs, lncRNAs, compounds, or drugs that up-regulate the activity and expression of sirtuins play protective roles in renal function. Therefore, in this review, we summarize the biological functions, molecular targets, mechanisms, and signaling pathways of SIRT1-SIRT7 in DKD models. Existing research has shown that sirtuins have the potential as effective targets for the clinical treatment of DKD. This review aims to lay a solid foundation for clinical research and provide a theoretical basis to slow the development of DKD in patients.

Sirtuin Family and Diabetic Kidney Disease

Diabetes mellitus (DM) is gradually attacking the health and life of people all over the world. Diabetic kidney disease (DKD) is one of the most common chronic microvascular complications of DM, whose mechanism is complex and still lacks research. Sirtuin family is a class III histone deacetylase with highly conserved NAD⁺ binding domain and catalytic functional domain, while different N-terminal and C-terminal structures enable them to bind different deacetylated substrates to participate in the cellular NAD⁺ metabolism. The kidney is an organ rich in NAD⁺ and database exploration of literature shows that the Sirtuin family has different expression localization in renal, cellular, and subcellular structures. With the progress of modern technology, a variety of animal models and reagents for the Sirtuin family and DKD emerged. Machine learning in the literature shows that the Sirtuin family can regulate pathophysiological injury mainly in the glomerular filtration membrane, renal tubular absorption, and immune inflammation through various mechanisms such as epigenetics, multiple signaling pathways, and mitochondrial function. These mechanisms are the key nodes participating in DKD. Thus, it is of great significance for target therapy to study biological functions of the Sirtuin family and DKD regulation mechanism in-depth.