Sirtuin functions and modulation: from chemistry to the clinic

SIRT2-mediated ACSS2 K271 deacetylation suppresses lipogenesis under nutrient stress

De novo lipogenesis is associated with the development of human diseases such as cancer, diabetes, and obesity. At the core of lipogenesis lies acetyl coenzyme A (CoA), a metabolite that plays a crucial role in fatty acid synthesis. One of the pathways contributing to the production of cytosolic acetyl-CoA is mediated by acetyl-CoA synthetase 2 (ACSS2). Here, we reveal that when cells encounter nutrient stress, particularly a deficiency in amino acids, Sirtuin 2 (SIRT2) catalyzes the deacetylation of ACSS2 at the lysine residue K271. This results in K271 ubiquitination and subsequently proteasomal degradation of ACSS2. Substitution of K271 leads to decreased ubiquitination of ACSS2, increased ACSS2 protein level, and thus increased lipogenesis. Our study uncovers a mechanism that cells employ to efficiently manage lipogenesis during periods of nutrient stress.

Dexmedetomidine mitigation of renal ischaemia-reperfusion injury: comprehensive insights from cellular mechanisms to clinical application

Renal ischaemia-reperfusion injury (IRI) is a critical cause of acute kidney injury (AKI) after major surgery, leading to elevated morbidity, mortality, and long-term renal dysfunction. Despite advances in perioperative care, the occurrence of IRI remains high. The renoprotective properties of dexmedetomidine (DEX), a selective α2-adrenergic receptor agonist, have been demonstrated, reducing oxidative stress, inflammation, apoptosis, ferroptosis, cellular senescence, and renal fibrosis while enhancing mitochondrial function and autophagy. From cellular studies to clinical applications, DEX has been effective in mitigating renal IRI, enhancing postoperative renal outcomes, and lowering the incidence of AKI in various surgical settings. This review comprehensively discusses and summarises the renoprotective effects and the underlying mechanisms of DEX, with a focus on its application across various surgical and clinical scenarios. In conclusion, DEX effectively mitigates renal IRI, as evidenced by robust in vitro, in vivo, and clinical studies. It significantly reduces kidney damage and improves surgical outcomes. However, its efficacy is less pronounced in kidney transplantation, suggesting that its renoprotective effects vary depending on the clinical context.

SIRTUINS MODULATORS MITIGATE HYPOXIA-INDUCED CELL DEATH DUE TO CHANGES IN HISTONE 3 ACETYLATION, AND MITOCHONDRIAL FUNCTION, DYNAMICS, AND CONTENT

Hypoxia is a key environmental factor linked to neurodevelopmental complications, primarily through its impact on mitochondrial dysfunction. Given that sirtuins regulate mitochondrial and cellular metabolism, we aimed to investigate whether pharmacological modulation of sirtuins could protect neurons from hypoxia-induced mitochondrial dysfunction and cell death. To explore this, primary cortical neurons from male Wistar rats (control) and Spontaneously Hypertensive Rats (a model for neonatal hypoxia and schizophrenia) were exposed to cobalt chloride (CoCl2) to chemically induce hypoxia. Neurons were also treated with Nicotinamide (50 μM), Resveratrol (0.5 μM), and Sirtinol (5 μM) to modulate sirtuin activity. We first assessed histone deacetylation, cell death, mitochondrial calcium retention capacity, mitochondrial membrane potential, and levels of reactive oxygen species (ROS). In addition, we analysed the expression of genes related to mitochondrial metabolism, dynamics, and biogenesis, as well as high-energy compound levels. Our data indicate that both chemical and neonatal hypoxia caused mitochondrial depolarization, reduced calcium retention, increased ROS levels, and elevated Nfe2l2 expression in primary cortical neurons. Hypoxia also led to increased expression of genes associated with mitochondrial biogenesis and fission, as well as reduced ATP levels and elevated pyruvate and lactate levels. Importantly, treatment with sirtuin modulators enhanced neuron viability, likely by further increasing Nfe2l2 expression and reducing ROS production. These modulators also improved metabolic outcomes, including higher ATP levels, and normalized pyruvate and lactate production, as well as mitochondrial fusion gene expression. Collectively, our findings suggest that sirtuin modulators could mitigate hypoxia-induced damage and may represent a potential therapeutic strategy for managing neurodevelopmental disorders.

Maternal exercise before and during pregnancy protects against genotoxicity and promotes offspring hippocampal health in mice prenatally exposed to high fructose

The fetal brain is susceptible to programming effects during pregnancy, potentially leading to long-term consequences for offspring's cognitive health. Fructose (FRU) intake is thought to adversely affect fetal brain development, whereas physical exercise before and during pregnancy may be protective. Therefore, this study aimed to assess biochemical and genotoxic changes in maternal hippocampi and behavioral, genotoxic, and biochemical alterations in offspring hippocampi. Seventy female mice were exposed to FRU (20%/L) and/or voluntary physical exercise (VPE) pre-pregnancy for eight weeks, and then mated and exposure was continued until weaning. Offspring were evaluated at 60 days old using behavioral test, genotoxic, and biochemical markers. FRU-induced long-term memory impairment in male offspring, which was alleviated by VPE. VPE mitigated DNA damage from maternal FRU consumption in both maternal and offspring hippocampi in female offspring, VPE increased levels of apurine/apyrimidinic endonuclease 1, erythroid nuclear factor 2, and cAMP response element binding proteins, whereas in males, 8-oxoguanine DNA glycosylase-1 levels upregulate. FRU consumption led to oxidative stress and antioxidant defense alterations in offspring, while VPE mitigated these effects. Telomere shortening was observed in male offspring from mothers who consumed FRU during pregnancy. Our findings suggest that exposure to FRU during (pre)pregnancy and lactation has adverse effects on offspring's hippocampi later in life, and VPE has a protective effect. Overall, the study underscores the significance of maternal dietary and physical habits on long-term offspring health, with an emphasis on implications for adult cognitive function.

A bibliometric and visual analysis of the impact of senescence on tumor immunotherapy

Background

Recently, many studies have focused on the relationship between senescence and immunotherapy in cancer treatment. However, relatively few studies have examined the intrinsic links between the three. Whether these studies can act synergistically in the fight against cancer and the specific links between them are still unclear.

Methods

We extracted, quantified, and visualized data from the literature (n = 2396) for the period 2004-2023 after rigorous quality control using citespace, GraphPad Prism, the R software package, and VOSviewer.

Results

Linear fit analyses were generated to predict the number of annual publications and citations as a function of the top-performing authors, journals, countries, and affiliations academically over the past two decades such as Weiwei, Aging-us, China, and the UT MD Anderson Cancer Center. Vosviewer-based hierarchical clustering further categorized study characteristics into six clusters, including two major clusters of immunotherapy research, immunosenescence-related research factors, and timeline distributions suggesting that cellular senescence and tumor progression is a relatively new research cluster that warrants further exploration and development. Study characterization bursts and linear regression analyses further confirmed these findings and revealed other important results, such as aging (a = 1.964, R² = 0.6803) and immunotherapy (a = 16.38, R² = 0.8812). Furthermore, gene frequency analysis in this study revealed the most abundant gene, APOE, and SIRT1-7 proteins.

Conclusion

The combination of aging therapies with tumor immunotherapies is currently in its preliminary stages. Although senescence has the greatest impact on ICB therapies, mechanistic investigations, and drug development for APOE and sirt1-7 (Sirtuins family) targets may be the key to combining senescence therapies with immunotherapies in the treatment of tumors.

Lead-Structure-Based Rigidization Approach to Optimize SirReal-Type Sirt2 Inhibitors

Sirtuins are involved in cellular processes in multiple ways. Therefore, the development of potent and selective Sirt2 inhibitors provides an important contribution to understanding physiological and pathophysiological mechanisms, particularly for the research and treatment of cancer and neurodegenerative diseases. Based on established SirReal-type lead inhibitors, further selective Sirt2 inhibitors were synthesized in a docking-guided rigidization approach, and the knowledge regarding requirements and properties of the Sirt2-binding pocket was expanded by means of a comprehensive SAR study. Naphthalene derivative FM69 emerged from the screening as the most potent rigidized inhibitor, which, with an IC50 value of 0.15 µM against Sirt2, represents a promising foundation for the further development of novel potent and selective Sirt2 inhibitors based on the presented rigidization strategy.

Sirtuin 2 inhibitor AGK2 exerts antiviral effects by inducing epigenetic suppression of hepatitis B virus covalently closed circular DNA through recruitment of repressive histone lysine methyltransferases and reduction of cccDNA

Chronic hepatitis B virus (HBV) infection continues to be a global health concern because current treatments such as interferon-α and nucleos(t)ide analogs cannot fully eliminate the virus due to persistence of covalently closed circular DNA (cccDNA) and integrated HBV DNA. Earlier research suggests that AGK2, a selective SIRT2 inhibitor, suppresses HBV replication by modifying key signaling pathways. This study aimed to further explore the anti-HBV effects of AKG2, particularly its effects on the epigenetic landscape of cccDNA. HBV-transfected and -infected cells were used to assess the impact of AGK2 on viral replication. Changes in SIRT2 expression and α-tubulin acetylation (SDS-PAGE-immunoblotting), core particle formation (native agarose gel electrophoresis and immunoblotting), HBV RNA (northern blotting) and DNA (Southern blotting) synthesis, and cccDNA levels (Southern blotting) were measured. Chromatin immunoprecipitation assays were performed to examine deposition of transcriptionally repressive epigenetic markers on cccDNA. AGK2 reduced expression of SIRT2, increased acetylated α-tubulin levels, and reduced synthesis of HBV RNA and DNA. Importantly, AGK2 also reduced cccDNA levels and increased deposition of repressive histone markers H4K20me1, H3K27me3, and H3K9me3 on cccDNA, mediated by histone lysine methyltransferases such as PR-Set7, EZH2, SETDB1, and SUV39H1. Additionally, there was a reduction in recruitment of RNA polymerase II and acetylated H3 to cccDNA, indicating that AGK2 enhances transcriptional repression. AGK2 suppresses HBV replication through direct antiviral actions, and by epigenetic modulation of cccDNA, indicating that using AGK2 to target SIRT2 and associated epigenetic regulators shows promise as a functional cure for chronic hepatitis B.

The role of autophagy in fibrosis: Mechanisms, progression and therapeutic potential (Review)

Various forms of tissue damage can lead to fibrosis, an abnormal reparative reaction. In the industrialized countries, 45% of deaths are attributable to fibrotic disorders. Autophagy is a highly preserved process. Lysosomes break down organelles and cytoplasmic components during autophagy. The cytoplasm is cleared of pathogens and dysfunctional organelles, and its constituent components are recycled. With the growing body of research on autophagy, it is becoming clear that autophagy and its associated mechanisms may have a role in the development of numerous fibrotic disorders. However, a comprehensive understanding of autophagy in fibrosis is still lacking and the progression of fibrotic disease has not yet been thoroughly investigated in relation to autophagy‑associated processes. The present review focused on the latest findings and most comprehensive understanding of macrophage autophagy, endoplasmic reticulum stress‑mediated autophagy and autophagy‑mediated endothelial‑to‑mesenchymal transition in the initiation, progression and treatment of fibrosis. The article also discusses treatment strategies for fibrotic diseases and highlights recent developments in autophagy‑targeted therapies.

Activation and inhibition of sirtuins: From bench to bedside

The sirtuin family comprises seven NAD+-dependent enzymes which catalyze protein lysine deacylation and mono ADP-ribosylation. Sirtuins act as central regulators of genomic stability and gene expression and control key processes, including energetic metabolism, cell cycle, differentiation, apoptosis, and aging. As a result, all sirtuins play critical roles in cellular homeostasis and organism wellness, and their dysregulation has been linked to metabolic, cardiovascular, and neurological diseases. Furthermore, sirtuins have shown dichotomous roles in cancer, acting as context-dependent tumor suppressors or promoters. Given their central role in different cellular processes, sirtuins have attracted increasing research interest aimed at developing both activators and inhibitors. Indeed, sirtuin modulation may have therapeutic effects in many age-related diseases, including diabetes, cardiovascular and neurodegenerative disorders, and cancer. Moreover, isoform selective modulators may increase our knowledge of sirtuin biology and aid to develop better therapies. Through this review, we provide critical insights into sirtuin pharmacology and illustrate their enzymatic activities and biological functions. Furthermore, we outline the most relevant sirtuin modulators in terms of their modes of action, structure-activity relationships, pharmacological effects, and clinical applications.

The curious case of mitochondrial sirtuin in rewiring breast cancer metabolism: Mr Hyde or Dr Jekyll?

Mammalian sirtuins are class III histone deacetylases involved in the regulation of multiple biological processes including senescence, DNA repair, apoptosis, proliferation, caloric restriction, and metabolism. Among the mammalian sirtuins, SIRT3, SIRT4, and SIRT5 are localized in the mitochondria and collectively termed the mitochondrial sirtuins. Mitochondrial sirtuins are NAD+-dependent deacetylases that play a central role in cellular metabolism and function as epigenetic regulators by performing post-translational modification of cellular proteins. Several studies have identified the role of mitochondrial sirtuins in age-related pathologies and the rewiring of cancer metabolism. Mitochondrial sirtuins regulate cellular functions by contributing to post-translational modifications, including deacetylation, ADP-ribosylation, demalonylation, and desuccinylation of diverse cellular proteins to maintain cellular homeostasis. Here, we review and discuss the structure and function of the mitochondrial sirtuins and their role as metabolic regulators in breast cancer. Altered breast cancer metabolism may promote tumor progression and has been an essential target for therapy. Further, we discuss the potential role of targeting mitochondrial sirtuin and its impact on breast cancer progression using sirtuin inhibitors and activators as anticancer agents.

Total Astragalus saponins promote ferroptosis in gastric cancer cells by upregulating SIRT3

Background

Gastric cancer (GC) is a malignant tumor of the digestive tract originating from the epithelial cells of the gastric mucosa, which is highly invasive and heterogeneous, posing a serious threat to human health. In recent years, ferroptosis, as a novel mode of programmed cell death, has shown potential anticancer effects in tumor therapy. Total Astragalus saponins (TAS), a natural product derived from Astragalus membranaceus, have been shown to possess various pharmacological activities, including anticancer effects. This study aimed to investigate the effects of TAS on GC cells, focusing on the mechanism of action of its regulation of the silent information regulator 3 (SIRT3) in inducing ferroptosis in GC cells.

Methods

We treated SGC-7901 cells with TAS at concentrations of 50, 100, and 200 µg/mL. After TAS treatment, the SGC-7901 cells were transfected with a vector designed to knock down SIRT3 expression. We assessed cell proliferation, viability, and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay), colony formation assay, and flow cytometry. SIRT3 expression was measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Fe2+, malondialdehyde (MDA), lactate dehydrogenase (LDH), and superoxide dismutase assay kits were used to detect the level of reactive oxygen species (ROS) by fluorescent probe assay. Western blot was used to detect apoptosis-related proteins and SIRT3 protein expression.

Results

TAS dose-dependently inhibited SGC-7901 cell proliferation and viability (P<0.05) and induced apoptosis (P<0.05). TAS promoted the expression of SIRT3 and ACSL4 proteins (P<0.05), inhibited the expression of SLC7A11 and GPX4 proteins (P<0.05), and induced ferroptosis of SGC-7901 cells (P<0.05). Knockdown of the SIRT3 gene attenuated the effect of TAS treatment on ferroptosis (P<0.05).

Conclusions

TAS has therapeutic potential for GC and can effectively inhibit the proliferation and viability of SGC-7901 cells, and the mechanism may be that TAS upregulates SIRT3 to promote the ferroptosis of SGC-7901 cells.

Exercise in Diabetic Cardiomyopathy: Its Protective Effects and Molecular Mechanism

Diabetic cardiomyopathy (DCM) is one of the cardiovascular complications of diabetes, characterized by the development of ventricular systolic and diastolic dysfunction due to factors such as inflammation, oxidative stress, fibrosis, and disordered glucose metabolism. As a sustainable therapeutic approach, exercise has been reported in numerous studies to regulate blood glucose and improve abnormal energy metabolism through various mechanisms, thereby ameliorating left ventricular diastolic dysfunction and mitigating DCM. This review summarizes the positive impacts of exercise on DCM and explores its underlying molecular mechanisms, providing new insights and paving the way for the development of tailored exercise programs for the prophylaxis and therapy of DCM.

Advancements in understanding the role and mechanism of sirtuin family (SIRT1-7) in breast cancer management

Breast cancer (BC) is the most prevalent type of cancer in women worldwide and it is classified into a few distinct molecular subtypes based on the expression of growth factor and hormone receptors. Though significant progress has been achieved in the search for novel medications through traditional and advanced approaches, still we need more efficacious and reliable treatment options to treat different types and stages of BC. Sirtuins (SIRT1-7) a class III histone deacetylase play a major role in combating various cancers including BC. Studies reveal thateach sirtuin has a unique and well-balanced biology, indicating that it regulates a variety of biological processes that result in the initiation, progression,and metastasis of BC. SIRT also plays a major role in numerous vital biological functions, including apoptosis, axonal protection, transcriptional silencing, DNA recombination and repair, fat mobilization, and aging. As per the current demand, we wish to outline the structural insights into sirtuin's catalytic site, substantial variations among all SIRT types, and their mechanism in BC management. Additionally, this review will focus on the application of SIRT modulators along with their clinical significance, hurdles, and future perspective to develop successful SIRT-based drug candidates to conquer the BC problem.

Treating Metabolic Dysregulation and Senescence by Caloric Restriction: Killing Two Birds with One Stone?

Cellular senescence is a state of permanent cell cycle arrest accompanied by metabolic activity and characteristic phenotypic changes. This process is crucial for developing age-related diseases, where excessive calorie intake accelerates metabolic dysfunction and aging. Overnutrition disturbs key metabolic pathways, including insulin/insulin-like growth factor signaling (IIS), the mammalian target of rapamycin (mTOR), and AMP-activated protein kinase. The dysregulation of these pathways contributes to insulin resistance, impaired autophagy, exacerbated oxidative stress, and mitochondrial dysfunction, further enhancing cellular senescence and systemic metabolic derangements. On the other hand, dysfunctional endothelial cells and adipocytes contribute to systemic inflammation, reduced nitric oxide production, and altered lipid metabolism. Numerous factors, including extracellular vesicles, mediate pathological communication between the vascular system and adipose tissue, amplifying metabolic imbalances. Meanwhile, caloric restriction (CR) emerges as a potent intervention to counteract overnutrition effects, improve mitochondrial function, reduce oxidative stress, and restore metabolic balance. CR modulates pathways such as IIS, mTOR, and sirtuins, enhancing glucose and lipid metabolism, reducing inflammation, and promoting autophagy. CR can extend the health span and mitigate age-related diseases by delaying cellular senescence and improving healthy endothelial-adipocyte interactions. This review highlights the crosstalk between endothelial cells and adipocytes, emphasizing CR potential in counteracting overnutrition-induced senescence and restoring vascular homeostasis.

Design, synthesis, and biological evaluation of novel 3-naphthylthiophene derivatives as potent SIRT2 inhibitors for the treatment of myocardial fibrosis

SIRT2 (sirtuin2) is a NAD+-dependent deacetylase implicated in fibrosis and inflammation of the liver, kidney, and heart. In this study, we designed and synthesized a series of 3-naphthylthiophene derivatives and evaluated their inhibitory activity against the SIRT2 enzyme. Among them, Z18 demonstrated outstanding SIRT2 inhibitory activity and selectivity. It significantly inhibited both the proliferation of cardiac fibroblasts (CFs) and the activity and expression of SIRT2 in CFs. Moreover, compound Z18 effectively suppressed TGF-β1-induced increases in α-SMA and CoL-1A1 protein expression, as well as hydroxyproline levels. Pharmacological mechanism tests demonstrated that Z18 inhibited SIRT2, thereby suppressing the TGF-β1-induced autocrine production of TGF-β1 and the phosphorylation of Smad2/3 in CFs. In MTT assays, Z18 exhibited a significant inhibitory effect on the proliferation of CFs induced by TGF-β1. In vivo, Z18 effectively ameliorated TAC- and ISO-induced declines in cardiac function, histopathological morphological changes, and collagen deposition. It also inhibited SIRT2 activity and reduced the expression of α-SMA and p-Smad2/3. In hepatorenal toxicity assays, Z18 exhibited an excellent safety profile. These results support the further development of the selective SIRT2 inhibitor Z18 as a potential lead compound for the treatment of myocardial fibrosis.

A Narrative Review of Signaling Pathway and Treatment Options for Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy is a progressive kidney disease that frequently results in end-stage renal disorders and is characterized by proteinuria, albuminuria, decreased filtration, and renal fibrosis. Despite the fact that there are a number of therapeutic alternatives available, DN continues to be the main contributor to end-stage renal disease. Therefore, significant innovation is required to enhance outcomes in DN patients.

METHODS

Information was collected from online search engines like, Google Scholar, Web of Science, PubMed, Scopus, and Sci-Hub databases using keywords like diabetes, nephropathy, kidney disease, autophagy, etc. Results: Natural compounds have anti-inflammatory and antioxidant properties and impact various signaling pathways. They ameliorate kidney damage by decreasing oxidative stress, inflammatory process, and fibrosis and enhance the antioxidant system, most likely by activating and deactivating several signaling pathways. This review focuses on the role of metabolic memory and various signaling pathways involved in the pathogenesis of DN and therapeutic approaches available for the management of DN. Special attention is given to the various pathways modulated by the phytoconstituents.

Molecular Sentinels: Unveiling the Role of Sirtuins in Prostate Cancer Progression

Prostate cancer (PCa) remains a critical global health challenge, with high mortality rates and significant heterogeneity, particularly in advanced stages. While early-stage PCa is often manageable with conventional treatments, metastatic PCa is notoriously resistant, highlighting an urgent need for precise biomarkers and innovative therapeutic strategies. This review focuses on the dualistic roles of sirtuins, a family of NAD+-dependent histone deacetylases, dissecting their unique contributions to tumor suppression or progression in PCa depending on the cellular context. It reveals their multifaceted impact on hallmark cancer processes, including sustaining proliferative signaling, evading growth suppressors, activating invasion and metastasis, resisting cell death, inducing angiogenesis, and enabling replicative immortality. SIRT1, for example, fosters chemoresistance and castration-resistant prostate cancer through metabolic reprogramming, immune modulation, androgen receptor signaling, and enhanced DNA repair. SIRT3 and SIRT4 suppress oncogenic pathways by regulating cancer metabolism, while SIRT2 and SIRT6 influence tumor aggressiveness and androgen receptor sensitivity, with SIRT6 promoting metastatic potential. Notably, SIRT5 oscillates between oncogenic and tumor-suppressive roles by regulating key metabolic enzymes; whereas, SIRT7 drives PCa proliferation and metabolic stress adaptation through its chromatin and nucleolar regulatory functions. Furthermore, we provide a comprehensive summary of the roles of individual sirtuins, highlighting their potential as biomarkers in PCa and exploring their therapeutic implications. By examining each of these specific mechanisms through which sirtuins impact PCa, this review underscores the potential of sirtuin modulation to address gaps in managing advanced PCa. Understanding sirtuins' regulatory effects could redefine therapeutic approaches, promoting precision strategies that enhance treatment efficacy and improve outcomes for patients with aggressive disease.

Decoding NAD+ Metabolism in COVID-19: Implications for Immune Modulation and Therapy

The persistent threat of COVID-19, particularly with the emergence of new variants, underscores the urgency for innovative therapeutic strategies beyond conventional antiviral treatments. Current immunotherapies, including IL-6/IL-6R monoclonal antibodies and JAK inhibitors, exhibit suboptimal efficacy, necessitating alternative approaches. Our review delves into the significance of NAD+ metabolism in COVID-19 pathology, marked by decreased NAD+ levels and upregulated NAD+-consuming enzymes such as CD38 and poly (ADP-ribose) polymerases (PARPs). Recognizing NAD+'s pivotal role in energy metabolism and immune modulation, we propose modulating NAD+ homeostasis could bolster the host's defensive capabilities against the virus. The article reviews the scientific rationale behind targeting NAD+ pathways for therapeutic benefit, utilizing strategies such as NAD+ precursor supplementation and enzyme inhibition to modulate immune function. While preliminary data are encouraging, the challenge lies in optimizing these interventions for clinical use. Future research should aim to unravel the intricate roles of key metabolites and enzymes in NAD+ metabolism and to elucidate their specific mechanisms of action. This will be essential for developing targeted NAD+ therapies, potentially transforming the management of COVID-19 and setting a precedent for addressing other infectious diseases.

Silent Information Regulator 1/Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α Axis: A Promising Target for Parkinson's and Alzheimer's Disease Therapies

One of the key challenges in medical research is developing safe medications to treat neurodegenerative disorders. Increased oxidative stress, mitochondrial dysfunction, and neuroinflammation are common features of Alzheimer's disease (AD) and Parkinson's disease (PD). Silent information regulator 1 (SIRT-1), part of the sirtuin family, plays a critical role in various physiological processes by binding to histones and nonhistone proteins. SIRT-1 primarily mitigates oxidative stress and regulates mitochondrial activity by maintaining the deacetylated form of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), ensuring stable PGC-1α levels. Research has shown reduced SIRT-1/PGC-1α expression in AD and PD models. Targeting this pathway presents a promising therapeutic approach for managing AD and PD, potentially leading to disease-modifying treatments and improved outcomes. This review highlights the findings of various studies suggesting that the SIRT-1/PGC-1α pathway promotes mitochondrial biogenesis, synaptic plasticity, and cognitive function, as well as exerts antioxidant, anti-inflammatory, and anti-apoptotic effects, offering a potential method for AD and PD treatment.

Role of SIRT1 in Potentially Toxic Trace Elements (Lead, Fluoride, Aluminum and Cadmium) Associated Neurodevelopmental Toxicity

The formation of the central nervous system is a meticulously planned and intricate process. Any modification to this process has the potential to disrupt the structure and operation of the brain, which could result in deficiencies in neurological growth. When neurotoxic substances are present during the early stages of development, they can be exceptionally dangerous. Prenatally, the immature brain is extremely vulnerable and is therefore at high risk in pregnant women associated with occupational exposures. Lead, fluoride, aluminum, and cadmium are examples of possibly toxic trace elements that have been identified as an environmental concern in the aetiology of a number of neurological and neurodegenerative illnesses. SIRT1, a member of the sirtuin family has received most attention for its potential neuroprotective properties. SIRT1 is an intriguing therapeutic target since it demonstrates important functions to increase neurogenesis and cellular lifespan by modulating multiple pathways. It promotes axonal extension, neurite growth, and dendritic branching during the development of neurons. Additionally, it contributes to neurogenesis, synaptic plasticity, memory development, and neuroprotection. This review summarizes the possible role of SIRT1 signalling pathway in potentially toxic trace elements -induced neurodevelopmental toxicity, highlighting some molecular pathways such as mitochondrial biogenesis, CREB/BDNF and PGC-1α/NRF1/TFAM.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Sirtuin Proteins and Memory: A Promising Target in Alzheimer's Disease Therapy?

Sirtuins (SIRTs), nicotine adenine dinucleotide (+)-dependent histone deacetylases, have emerged as critical regulators in many signalling pathways involved in a wide range of biological processes. Currently, seven mammalian SIRTs have been characterized and are found across a number of cellular compartments. There has been considerable interest in the role of SIRTs in the brain due to their role in a plethora of metabolic- and age-related diseases, including their involvement in learning and memory function in physiological and pathophysiological conditions. Although cognitive function declines over the course of healthy ageing, neurological disorders including Alzheimer's disease (AD) can be associated with progressive cognitive impairments. This review aimed to report and integrate recent advances in the understanding of the role of SIRTs in cognitive function and dysfunction in the context of AD. We have also reviewed the use of selective and/or natural SIRT activators as potential therapeutic agents and/or adjuvants for AD.

NAD+ enhancers as therapeutic agents in the cardiorenal axis

Cardiorenal diseases represent a complex interplay between heart failure and renal dysfunction, being clinically classified as cardiorenal syndromes (CRS). Recently, the contributions of altered nicotinamide adenine dinucleotide (NAD+) metabolism, through deficient NAD+ synthesis and/or elevated consumption, have proved to be decisive in the onset and progress of cardiorenal disease. NAD+ is a pivotal coenzyme in cellular metabolism, being significant in various signaling pathways, such as energy metabolism, DNA damage repair, gene expression, and stress response. Convincing evidence suggests that strategies designed to boost cellular NAD+ levels are a promising therapeutic option to address cardiovascular and renal disorders. Here, we review and discuss the implications of NAD+ metabolism in cardiorenal diseases, focusing on the propitious NAD+ boosting therapeutic strategies, based on the use of NAD+ precursors, poly(ADP-ribose) polymerase inhibitors, sirtuin activators, and other alternative approaches, such as CD38 blockade, nicotinamide phosphoribosyltransferase activation and combined interventions.

The new function of FaSRT2-1 protein in energy metabolism: Promoting strawberry fruit quality and ripening

Sirtuins (SRTs) are nicotinamide adenine dinucleotide (NAD+) dependent II histone deacetylases (HDACs) that have been understudied in horticultural crops. However, their functions in regulating mitochondrial energy metabolism and influencing fruit development and quality formation remain unclear. In this study, we found that FaSRT2-1 exhibits diverse subcellular localizations. Overexpression of FaSRT2-1 promoted strawberry fruit quality formation (soluble sugars, organic acids, anthocyanins) and accelerated ripening. Conversely, knockout of FaSRT2-1 yielded opposite results. During fruit ripening, ATP content and ATP/ADP ratio gradually increased, and FaSRT2-1 promoted ATP accumulation and decreased before and after the deep red stage, respectively, indicating its role in fruit ripening and senescence. FaSRT2-1 interacted with energy-related proteins (FaRPT4a, FaATPβ and FaATPγ) to increase ATP content and the ATP/ADP ratio. Additionally, FaSRT2-1 collaborated with FaGDH2 and FaWDR5B to increase the accumulation of soluble sugars, organic acids and anthocyanins. Meanwhile, FaRPT4a, FaATPγ, FaGDH2 and FaWDR5B were co-localized with FaSRT2-1, while FaATPβ was localized in both the cytoplasm and mitochondria. Transient overexpression experiments further highlight the roles of FaRPT4a and FaGDH2/FaWDR5B in modulating ATP accumulation and fruit ripening, respectively. In summary, FaSRT2-1 plays important roles in promoting strawberry fruit ripening, senescence and quality formation by regulating energy metabolism.

Targeting sirtuins for cancer therapy: epigenetics modifications and beyond

Sirtuins (SIRTs) are well-known as nicotinic adenine dinucleotide+(NAD+)-dependent histone deacetylases, which are important epigenetic enzymes consisting of seven family members (SIRT1-7). Of note, SIRT1 and SIRT2 are distributed in the nucleus and cytoplasm, while SIRT3, SIRT4 and SIRT5 are localized in the mitochondria. SIRT6 and SIRT7 are distributed in the nucleus. SIRTs catalyze the deacetylation of various substrate proteins, thereby modulating numerous biological processes, including transcription, DNA repair and genome stability, metabolism, and signal transduction. Notably, accumulating evidence has recently underscored the multi-faceted roles of SIRTs in both the suppression and progression of various types of human cancers. Crucially, SIRTs have been emerging as promising therapeutic targets for cancer therapy. Thus, in this review, we not only present an overview of the molecular structure and function of SIRTs, but elucidate their intricate associations with oncogenesis. Additionally, we discuss the current landscape of small-molecule activators and inhibitors targeting SIRTs in the contexts of cancer and further elaborate their combination therapies, especially highlighting their prospective utility for future cancer drug development.

The role of Klotho and sirtuins in sleep-related cardiovascular diseases: a review study

The prevalence of sleep disorders has been reported from 1.6% to 56.0%, worldwide. Sleep deprivation causes cardiovascular diseases (CVDs) including atherosclerosis, vascular aging, hypertension, heart dysfunction, reduced heart rate variability, and cardiac arrhythmia. Reduced tissue oxygen causes various CVDs by activating pro-inflammatory factors and increasing oxidative stress. Sleep disorders are more important and prevalent in older people and cause more severe cardiovascular complications. On the other hand, the reduction of Klotho level, an age-dependent protein whose expression decreases with age, is associated with age-related diseases. Sirtuins, class III histone deacetylases, also are among the essential factors in postponing cellular aging and increasing the lifespan of organisms, and they do this by regulating different pathways in the cell. Sirtuins and Klotho play an important role in the pathophysiology of CVDS and both have anti-oxidative stress and anti-inflammatory activity. Studies have shown that the levels of Klotho and sirtuins are altered in sleep disorders. In this article, alterations of Klotho and sirtuins in sleep disorders and in the development of sleep-related CVDs were reviewed and the possible signaling pathways were discussed. The inclusion criteria were studies with keywords of different types of sleep disorders and CVDs, klotho, SIRT1-7, and sirtuins in PubMed, Scopus, Embase، Science Direct، Web of Sciences and Google Scholar by the end of 2023. The studies revealed there is a bidirectional relationship between sleep disorders and the serum and tissue levels of Klotho and sirtuins and sleep related-CVDs.

The role of histone deacetylases in inflammatory respiratory diseases: an update

INTRODUCTION

Histone deacetylases (HDACs) catalyze the removal of acetyl groups from lysine residues of histones and other proteins, generally leading to a closed chromosomal configuration and transcriptional repression. Different HDACs have distinct substrate specificities and functions in different biological processes. Accumulating evidence indicates that HDACs play a key role in the pathogenesis of multiple respiratory diseases.

AREAS COVERED

After an extensive search of the PubMed database, Web of Science and ClinicalTrials.gov, covering the period from 1992 to 2024, this review summarizes recent advances in understanding the role of HDACs in inflammatory respiratory diseases, including allergic rhinitis (AR), chronic rhinosinusitis (CRS), asthma and chronic obstructive pulmonary disease (COPD). We also examine recent progress on the efficacy and potential use of histone deacetylase inhibitors (HDACi) for the treatment of these diseases.

EXPERT OPINION

Available data indicate that HDACs play an important role in the development of common inflammatory respiratory diseases, and HDACi have shown promise as treatments for these diseases. However, the exact roles and underlying mechanisms of specific HDACs in disease pathogenesis require further study. Additional work is necessary to develop novel potent HDACi with high isoform selectivity.

The Role of SIRT1 in Leukemia

OPINION STATEMENT

Leukemia is a type of hematological malignancy (HM) caused by uncontrolled proliferation, apoptosis, and differentiation of hematopoietic stem cells (HSCs). Leukemia cells proliferate greatly in the bone marrow (BM), infiltrate other tissues and organs, and affect the normal hematopoietic function. Although the emergence of new targeted agents and immune agents has improved the prognosis of patients, due to the complex pathogenic factors and heterogeneity of leukemia, there are still some patients with poor prognosis. Recent studies have shown that silent information regulator 1 (SIRT1) is involved in the proliferation, apoptosis, metabolism, and senescence of leukemia cells. As a double-edged sword in leukemia cells, SIRT1 can both promote and inhibit the growth of leukemia cells. Since its mechanism of action has not been elucidated, it is urgent to explore the regulatory mechanism of SIRT1 in leukemia. In this review, we discussed the mechanisms of SIRT1 in different aspects of leukemia, providing a theoretical basis for the treatment of patients with leukemia.

Role of sirtuins in sepsis and sepsis-induced organ dysfunction: A review

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis causes a high mortality rate and current treatment focuses on supportive therapies but lacks specific therapeutic targets. Notably, sirtuins (SIRTs) shows potential clinical application in the treatment of sepsis. It has been demonstrated that SIRTs, the nicotinamide adenine dinucleotide+(NAD+)-dependent deacetylases that regulate key signaling pathways in eukaryotes and prokaryotes, are involved in a variety of biological processes. To date, seven mammalian yeast Sir2 homologs have been identified. SIRTs can regulate inflammation, oxidative stress, apoptosis, autophagy, and other pathways that play important roles in sepsis-induced organ dysfunction. However, the existing studies on SIRTs in sepsis are too scattered, and there is no relevant literature to integrate them. This review innovatively summarizes the different mechanisms of SIRTs in sepsis organ dysfunction according to the different systems, and focuses on SIRT agonists, inhibitors, and targeted drugs that have been proved to be effective in the treatment of sepsis, so as to integrate the clinical research and basic research closely. We searched PubMed for all literature related to SIRTs and sepsis since its inception using the following medical subject headings: sirtuins, SIRTs, and sepsis. Data on the mechanisms of SIRTs in sepsis-induced organ damage and their potential as targets for disease treatment were extracted.

Is SIRT3 and Mitochondria a Reliable Target for Parkinson's Disease and Aging? A Narrative Review

Aging is a complicated degenerative process that has been thoroughly researched in a variety of taxa, including mammals, worms, yeast, and flies. One important controller of organismal lifetime is the conserved deacetylase protein known as silencing information regulator 2 (SIR2). It has been demonstrated that overexpressing SIR2 lengthens the life span in worms, flies, and yeast, demonstrating its function in enhancing longevity. SIRT3 is a member of the sirtuin protein family, identified as a major regulator of longevity and aging. Sirtuin 3 (SIRT3), a possible mitochondrial tumor suppressor, has been explicitly linked to the control of cellular reactive oxygen species (ROS) levels, the Warburg effect, and carcinogenesis. SIRT3 plays a significant part in neurodegenerative illnesses such as Parkinson's and Alzheimer's disease by decreasing the oxidative stress in mitochondria and reducing the ROS levels. Furthermore, SIRT3 has been linked to metabolic and cardiovascular disorders, indicating its wider role in the pathophysiology of disease and possible therapeutic applications.

Adolescent co-exposure to environmental cadmium and high-fat diet induces cognitive decline via Larp7 m6A-mediated SIRT6 inhibition

The effects and underlying mechanisms of adolescent exposure to combined environmental hazards on cognitive function remain unclear. Here, using a combined exposure model, we found significant cognitive decline, hippocampal neuronal damage, and neuronal senescence in mice exposed to cadmium (Cd) and high-fat diet (HFD) during adolescence. Furthermore, we observed a significant downregulation of Sirtuin 6 (SIRT6) expression in the hippocampi of co-exposed mice. UBCS039, a specific SIRT6 activator, markedly reversed the above adverse effects. Further investigation revealed that co-exposure obviously reduced the levels of La ribonucleoprotein 7 (LARP7), disrupted the interaction between LARP7 and SIRT6, ultimately decreasing SIRT6 expression in mouse hippocampal neuronal cells. Overexpression of Larp7 reversed the combined exposure-induced SIRT6 decrease and senescence in mouse hippocampal neuronal cells. Additionally, the results showed notably elevated levels of Larp7 m6A and YTH domain family protein 2 (YTHDF2) in mouse hippocampal neuronal cells treated with the combined hazards. Ythdf2 short interfering RNA, RNA immunoprecipitation, and RNA stability assays further demonstrated that YTHDF2 mediated the degradation of Larp7 mRNA under combined exposure. Collectively, adolescent co-exposure to Cd and HFD causes hippocampal senescence and cognitive decline in mice by inhibiting LARP7-mediated SIRT6 expression in an m6A-dependent manner.

A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models

Mutations in the lipoyltransferase 1 (LIPT1) gene are rare inborn errors of metabolism leading to a fatal condition characterized by lipoylation defects of the 2-ketoacid dehydrogenase complexes causing early-onset seizures, psychomotor retardation, abnormal muscle tone, severe lactic acidosis, and increased urine lactate, ketoglutarate, and 2-oxoacid levels. In this article, we characterized the disease pathophysiology using fibroblasts and induced neurons derived from a patient bearing a compound heterozygous mutation in LIPT1. A Western blot analysis revealed a reduced expression of LIPT1 and absent expression of lipoylated pyruvate dehydrogenase E2 (PDH E2) and alpha-ketoglutarate dehydrogenase E2 (α-KGDH E2) subunits. Accordingly, activities of PDH and α-KGDH were markedly reduced, associated with cell bioenergetics failure, iron accumulation, and lipid peroxidation. In addition, using a pharmacological screening, we identified a cocktail of antioxidants and mitochondrial boosting agents consisting of pantothenate, nicotinamide, vitamin E, thiamine, biotin, and α-lipoic acid, which is capable of rescuing LIPT1 pathophysiology, increasing the LIPT1 expression and lipoylation of mitochondrial proteins, improving cell bioenergetics, and eliminating iron overload and lipid peroxidation. Furthermore, our data suggest that the beneficial effect of the treatment is mainly mediated by SIRT3 activation. In conclusion, we have identified a promising therapeutic approach for correcting LIPT1 mutations.

MicroRNAs Modulating Neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is one of the most frequent age-associated neurodegenerative disorder. Presence of α-synuclein-containing aggregates in the substantia nigra pars compacta (SNpc) and loss of dopaminergic (DA) neurons are among the characteristic of PD. One of the hallmarks of PD pathophysiology is chronic neuroinflammation. Activation of glial cells and elevated levels of pro-inflammatory factors are confirmed as frequent features of the PD brain. Chronic secretion of pro-inflammatory cytokines by activated astrocytes and microglia exacerbates DA neuron degeneration in the SNpc. MicroRNAs (miRNAs) are among endogenous non-coding small RNA with the ability to perform post-transcriptional regulation in target genes. In that regard, the capability of miRNAs for modulating inflammatory signaling is the center of attention in many investigations. MiRNAs could enhance or limit inflammatory signaling, exacerbating or ameliorating the pathological consequences of extreme neuroinflammation. This review summarizes the importance of inflammation in the pathophysiology of PD. Besides, we discuss the role of miRNAs in promoting or protecting neural cell injury in the PD model by controlling the inflammatory pathway. Modifying the neuroinflammation by miRNAs could be considered a primary therapeutic strategy for PD.

AtSRT1 regulates flowering by regulating flowering integrators and energy signals in Arabidopsis

Epigenetic modifications, such as histone alterations, play crucial roles in regulating the flowering process in Arabidopsis, a typical long-day model plant. Histone modifications are notably involved in the intricate regulation of FLC, a key inhibitor of flowering. Although sirtuin-like protein and NAD+-dependent deacetylases play an important role in regulating energy metabolism, plant stress responses, and hormonal signal transduction, the mechanisms underlying their developmental transitions remain unclear. Thus, this study aimed to reveal how Arabidopsis NAD + -dependent deacetylase AtSRT1 affects flowering by regulating the expression of flowering integrators. Genetic and molecular evidence demonstrated that AtSRT1 mediates histone deacetylation by directly binding near the transcriptional start sites (TSS) of the flowering integrator genes FT and SOC1 and negatively regulating their expression by modulating the expression of the downstream gene LFY to inhibit flowering. Additionally, AtSRT1 directly down-regulates the expression of TOR, a glucose-driven central hub of energy signaling, which controls cell metabolism and growth in response to nutritional and environmental factors. This down-regulation occurs through binding near the TSS of TOR, facilitating the addition of H3K27me3 marks on FLC via the TOR-FIE-PRC2 pathway, further repressing flowering. These results uncover a multi-pathway regulatory network involving deacetylase AtSRT1 during the flowering process, highlighting its interaction with TOR as a hub for the coordinated regulation of energy metabolism and flowering initiation. These findings significantly enhance understanding of the complexity of histone modifications in the regulation of flowering.

Targeting histone modifiers in bladder cancer therapy - preclinical and clinical evidence

Bladder cancer in the most advanced, muscle-invasive stage is lethal, and very limited therapeutic advances have been reported for decades. To date, cisplatin-based chemotherapy remains the first-line therapy for advanced bladder cancer. Late-line options have historically been limited. In the past few years, next-generation sequencing technology has enabled chromatin remodelling gene mutations to be characterized, showing that these alterations are more frequent in urothelial bladder carcinoma than in other cancer types. Histone modifiers have functional roles in tumour progression by modulating the expression of tumour suppressors and oncogenes and, therefore, have been considered as novel drug targets for cancer therapy. The roles of epigenetic reprogramming through histone modifications have been increasingly studied in bladder cancer, and the therapeutic efficacy of targeting those histone modifiers genetically or chemically is being assessed in preclinical studies. Results from preclinical studies in bladder cancer encouraged the investigation of some of these drugs in clinical trials, which yield mixed results. Further understanding of how alterations of histone modification mechanistically contribute to bladder cancer progression, drug resistance and tumour microenvironment remodelling will be required to facilitate clinical application of epigenetic drugs in bladder cancer.

Metformin prevents the onset and progression of intervertebral disc degeneration: New insights and potential mechanisms (Review)

Metformin has been the go‑to medical treatment for addressing type 2 diabetes mellitus (T2DM) as a frontline oral antidiabetic. Obesity, cancer and bone deterioration are linked to T2DM, which is considered a metabolic illness. Numerous diseases associated with T2DM, such as tumours, cardiovascular disease and bone deterioration, may be treated with metformin. Intervertebral disc degeneration (IVDD) is distinguished by degeneration of the spinal disc, accompanied by the gradual depletion of proteoglycans and water in the nucleus pulposus (NP) of the IVD, resulting in lower back pain. The therapeutic effect of metformin on IVDD has also attracted much attention. By stimulating AMP‑activated kinase, metformin could enhance autophagy and suppress cell senescence, apoptosis and inflammation, thus effectively delaying IVDD. The present review aimed to systematically explain the development of IVDD and mechanism of metformin in the treatment and prevention of IVDD to provide a reference for the clinical application of metformin as adjuvant therapy in the treatment of IVDD.

Reactivity-Tunable Fluorescent Platform for Selective and Biocompatible Modification of Cysteine or Lysine

Chemoselective modification of specific residues within a given protein poses a significant challenge, as the microenvironment of amino acid residues in proteins is variable. Developing a universal molecular platform with tunable chemical warheads can provide powerful tools for precisely labeling specific amino acids in proteins. Cysteine and lysine are hot targets for chemoselective modification, but current cysteine/lysine-selective warheads face challenges due to cross-reactivity and unstable reaction products. In this study, a versatile fluorescent platform is developed for highly selective modification of cysteine/lysine under biocompatible conditions. Chloro- or phenoxy-substituted NBSe derivatives effectively labeled cysteine residues in the cellular proteome with high specificity. This finding also led to the development of phenoxy-NBSe phototheragnostic for the diagnosis and activatable photodynamic therapy of GSH-overexpressed cancer cells. Conversely, alkoxy-NBSe derivatives are engineered to selectively react with lysine residues in the cellular environment, exhibiting excellent anti-interfering ability against thiols. Leveraging a proximity-driven approach, alkoxy-NBSe probes are successfully designed to demonstrate their utility in bioimaging of lysine deacetylase activity. This study also achieves integrating a small photosensitizer into lysine residues of proteins in a regioselective manner, achieving photoablation of cancer cells activated by overexpressed proteins.

Decreased AMPK/SIRT1/PDK4 induced by androgen excess inhibits human endometrial stromal cell decidualization in PCOS

Polycystic ovary syndrome (PCOS) is a complex common endocrine disorder affecting women of reproductive age. Ovulatory dysfunction is recognized as a primary infertile factor, however, even when ovulation is medically induced and restored, PCOS patients continue to experience reduced cumulative pregnancy rates and a higher spontaneous miscarriage rate. Hyperandrogenism, a hallmark feature of PCOS, affects ovarian folliculogenesis, endometrial receptivity, and the establishment and maintenance of pregnancy. Decidualization denotes the transformation that the stromal compart of the endometrium must undergo to accommodate pregnancy, driven by the rising progesterone levels and local cAMP production. However, studies on the impact of hyperandrogenism on decidualization are limited. In this study, we observed that primary endometrial stromal cells from women with PCOS exhibit abnormal responses to progesterone during in vitro decidualization. A high concentration of testosterone inhibits human endometrial stromal cells (HESCs) decidualization. RNA-Seq analysis demonstrated that pyruvate dehydrogenase kinase 4 (PDK4) expression was significantly lower in the endometrium of PCOS patients with hyperandrogenism compared to those without hyperandrogenism. We also characterized that the expression of PDK4 is elevated in the endometrium stroma at the mid-secretory phase. Artificial decidualization could enhance PDK4 expression, while downregulation of PDK4 leads to abnormal decidualization both in vivo and in vitro. Mechanistically, testosterone excess inhibits IGFBP1 and PRL expression, followed by phosphorylating of AMPK that stimulates PDK4 expression. Based on co-immunoprecipitation analysis, we observed an interaction between SIRT1 and PDK4, promoting glycolysis to facilitate decidualization. Restrain of AR activation resumes the AMPK/SIRT1/PDK4 pathway suppressed by testosterone excess, indicating that testosterone primarily acts on decidualization through AR stimulation. Androgen excess in the endometrium inhibits decidualization by disrupting the AMPK/SIRT1/PDK4 signaling pathway. These data demonstrate the critical roles of endometrial PDK4 in regulating decidualization and provide valuable information for understanding the underlying mechanism during decidualization.

SIRT7 Inhibits Melanin Synthesis of PIG1 and PIG3V by Suppressing the Succinylation of EZR

Background

Vitiligo is an autoimmune disease characterized by loss of skin pigmentation and currently has no effective treatment. This study aimed to investigate the function of SIRT7, being an important desuccinylase mediating multiple disease progression, and its mechanism in vitiligo progression.

Methods

Normal human melanocytes (NHM) PIG1 and vitiligo human melanocytes (VHM) PIG3V were utilized in this research. The role of sirtuin 7 (SIRT7) and Ezrin (EZR) on melanin synthesis was investigated by detecting tyrosinase activity, melanin content, α-MSH levels, and the protein levels of melanin-related markers. The function of EZR was identified via rescue experiments, while the underlying mechanism was investigated via bioinformatic analysis, co-immunoprecipitation (co-IP), immunoprecipitation (IP), and Western blot techniques.

Results

Results showed that only SIRT7 was highly expressed in vitiligo human melanocytes, where knockingdown SIRT7 translated into increased melanin synthesis in melanocytes. Mechanistically, SIRT7 knockdown promoted the succinylation of EZR at the Lys (K)60 site. Moreover, overexpressing EZR induced higher melanin synthesis in melanocytes, while its knocking down exerted the opposite effect by inhibiting SIRT7 knockdown-induced melanin synthesis.

Conclusion

SIRT7 inhibited melanin synthesis in melanocytes by suppressing the succinylation of EZR. These findings are envisaged to provide a novel theoretical basis for vitiligo treatment.

Recent advances in the therapeutic applications of selenium nanoparticles

Selenium nanoparticles (SeNPs) are an appealing carrier for the targeted delivery. The selenium nanoparticles are gaining global attention because of the potential therapeutic applications in several diseases e.g., rheumatoid arthritis (RA), inflammatory bowel disease (IBD), asthma, liver, and various autoimmune disorders like psoriasis, cancer, diabetes, and a variety of infectious diseases. Despite the fact still there is no recent literature that summarises the therapeutic applications of SeNPs. There are some challenges that need to be addressed like finding targets for SeNPs in various diseases, and the various functionalization techniques utilized to increase SeNP's stability while facilitating wide drug-loaded SeNP distribution to tumor areas and preventing off-target impacts need to focus on understanding more about the therapeutic aspects for better understanding the science behind it. Keeping that in mind we have focused on this gap and try to summarize all recent key targeted therapies for SeNPs in cancer treatment and the numerous functionalization strategies. We have also focused on recent advancements in SeNP functionalization methodologies and mechanisms for biomedical applications, particularly in anticancer, anti-inflammatory, and anti-infection therapeutics. Based on our observation we found that SeNPs could potentially be useful in suppressing viral epidemics, like the ongoing COVID-19 pandemic, in complement to their antibacterial and antiparasitic uses. SeNPs are significant nanoplatforms with numerous desirable properties for clinical translation.

Mitochondrial Sirtuins in Cancer: A Revisited Review from Molecular Mechanisms to Therapeutic Strategies

The sirtuin (SIRT) family is well-known as a group of deacetylase enzymes that rely on nicotinamide adenine dinucleotide (NAD+). Among them, mitochondrial SIRTs (SIRT3, SIRT4, and SIRT5) are deacetylases located in mitochondria that regulate the acetylation levels of several key proteins to maintain mitochondrial function and redox homeostasis. Mitochondrial SIRTs are reported to have the Janus role in tumorigenesis, either tumor suppressive or oncogenic functions. Although the multi-faceted roles of mitochondrial SIRTs with tumor-type specificity in tumorigenesis, their critical functions have aroused a rising interest in discovering some small-molecule compounds, including inhibitors and activators for cancer therapy. Herein, we describe the molecular structures of mitochondrial SIRTs, focusing on elucidating their regulatory mechanisms in carcinogenesis, and further discuss the recent advances in developing their targeted small-molecule compounds for cancer therapy. Together, these findings provide a comprehensive understanding of the crucial roles of mitochondrial SIRTs in cancer and potential new therapeutic strategies.

Sirtfood intake in relation to the 10-year risk of major adverse cardiovascular events: a population-based cohort study

BACKGROUND

Sirtuins have an important role in the regulation of metabolic and biological processess. Thus, we hypothesized that foods that could activate sirtuins, known as "sirtfood", may improve health status. So, this study was aimed at investigating the association between the amount of sirtfood intake and the risk of major adverse cardiovascular events (MACE).

METHODS

In this cohort study, 2918 adults who had no history of MACE at the start of the study (2006-2008) participated and were followed up on until 2018. The amount of sirtfoods intake (servings per week) was computed using a validated food frequency questionnaire. Each patient's medical records were evaluated to detect MACE. The Cox proportional hazards model was applied to assess the association between the amount of sirtfood intake and the risk of MACE.

RESULTS

The median duration of the study was 10.6 years. The hazard ratio (HR) for the risk of MACE was 0.70 for the second (95% CI: 0.50, 0.98) and 0.60 (95% CI: 0.42, 0.86) for the third tertile of sirtfoods intake compared with the first tertile. This association was nonlinear, and sirtfoods consumption of more than five servings per week did not result in a lower risk of MACE. In addition, there was a significant interaction between age (P-interaction < 0.001) and sirtfoods intake in relation to MACE occurrence. When assessing sirtfood components, compared with the lowest intake, the highest amount of soy (HR: 0.74, 95% CI: 0.56, 0.99) and parsley (HR: 0.62, 95% CI: 0.47, 0.83) intake was related to a lower risk of MACE.

CONCLUSION

Our results indicated an inverse association between a higher amount of sirtfood intake and a lower risk of MACE incidents. This association was nonlinear, and having more than five servings of sirtfood per week did not reduce the risk of MACE any further.

Exploring the therapeutic potential of quercetin: A focus on its sirtuin-mediated benefits

As the global population ages, preventing lifestyle- and aging-related diseases is increasing, necessitating the search for safe and affordable therapeutic interventions. Among nutraceuticals, quercetin, a flavonoid ubiquitously present in various plants, has garnered considerable interest. This review aimed to collate and analyze existing literature on the therapeutic potentials of quercetin, especially its interactions with SIRTs and its clinical applicability based on its bioavailability and safety. This narrative review was based on a literature survey spanning from 2015 to 2023 using PUBMED. The keywords and MeSH terms used were: "quercetin" AND "bioavailability" OR "metabolism" OR "metabolites" as well as "quercetin" AND "SIRTuin" OR "SIRT*" AND "cellular effects" OR "pathway" OR "signaling" OR "neuroprotective" OR "cardioprotective" OR "nephroprotective" OR "antiatherosclerosis" OR "diabetes" OR "antidiabetic" OR "dyslipidemia" AND "mice" OR "rats". Quercetin demonstrates multiple therapeutic activities, including neuroprotective, cardioprotective, and anti-atherosclerotic effects. Its antioxidant, anti-inflammatory, antiviral, and immunomodulatory properties are well-established. At a molecular level, it majorly interacts with SIRTs, particularly SIRT1 and SIRT6, and modulates numerous signaling pathways, contributing to its therapeutic effects. These pathways play roles in reducing oxidative stress, inflammation, autophagy regulation, mitochondrial biogenesis, glucose utilization, fatty acid oxidation, and genome stability. However, clinical trials on quercetin's effectiveness in humans are scarce. Quercetin exhibits a wide range of SIRT-mediated therapeutic effects. Despite the compelling preclinical data, more standardized clinical trials are needed to fully understand its therapeutic potential. Future research should focus on addressing its bioavailability and safety concerns.

Sirtuin 3 ameliorates inflammatory bowel disease via inhibiting intestinal inflammation and oxidative stress

Sirtuin 3 involved in development of various diseases, but its role in inflammatory bowel disease is still unknown. We used inflammatory bowel disease biopsies, colitis animal model, and vitro cells RAW264.7 to study the role of Sirtuin 3 in the pathophysiology of inflammatory bowel disease. Sirtuin 3 negatively correlated with intestinal TNF-α. Sirt3 was less pronounced in pediatric and adult inflammatory bowel disease patients compared with corresponding control group. Sirtuin 3 activator Honokiol suppressed dextran sulfate sodium induced colonic manifestations, while Sirt3 inhibitor caused opposite results. Honokiol inhibited colonic oxidative stress by and reduced intestinal permeability. Honokiol repressed inflammatory response by reducing macrophage infiltration, pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 levels, and inhibiting activation of NF-κB p65 in the colitis mice. However, Sirt3 inhibitor amplified colonic oxidative stress and inflammatory response. In vitro study, Sirt3 inhibitor or siRNA Sirtuin 3 activated NF-κB p65 and enhanced TNF-α, IL-1β, and IL-6 secretion from LPS stimulated RAW264.7, while Honokiol remarkably attenuated these pro-inflammatory cytokines secretion. Finally, knockdown of Sirt3 in Caco-2 cells enhanced TNF-α induced intestinal barrier integrity injury. Sirtuin 3 negatively regulates inflammatory bowel disease progression via reducing colonic inflammation and oxidative stress. Sirtuin 3 is a promising therapeutic target in clinical application for inflammatory bowel disease therapy.

Understanding the Impact of the Sirtuin 1 (SIRT1) Gene on Age-related Macular Degeneration: A Comprehensive Study

Age-related macular degeneration (AMD) is a prevalent and incurable condition affecting the central retina and posing a significant risk to vision, particularly in individuals over the age of 60. As the global population ages, the prevalence of AMD is expected to rise, leading to substantial socioeconomic impacts and increased healthcare costs. The disease manifests primarily in two forms, neovascular and non-neovascular, with genetic, environmental and lifestyle factors playing a pivotal role in disease susceptibility and progression. This review article involved conducting an extensive search across various databases, including Google Scholar, PubMed, Web of Science, ScienceDirect, Scopus and EMBASE, to compile relevant case-control studies and literature reviews from online published articles extracted using search terms related to the work. SIRT1, a key member of the sirtuin family, influences cellular processes such as ageing, metabolism, DNA repair and stress response. Its dysregulation is linked to retinal ageing and ocular conditions like AMD. This review discusses the role of SIRT1 in AMD pathology, its association with genetic variants and its potential as a biomarker, paving the way for targeted interventions and personalised treatment strategies. In addition, it highlights the findings of case-control studies investigating the relationship between SIRT1 gene polymorphisms and AMD risk. These studies collectively revealed a significant association between certain SIRT1 gene variants and AMD risk. Further studies with larger sample sizes are required to validate these findings. As the prevalence of AMD grows, understanding the role of SIRT1 and other biomarkers becomes increasingly vital for improving diagnosis, treatment and, ultimately, patient outcomes.

SIRT6 activates PPARα to improve doxorubicin-induced myocardial cell aging and damage

The Sirtuins family, formally known as the Silent Information Regulator Factors, constitutes a highly conserved group of histone deacetylases. Recent studies have illuminated SIRT6's role in doxorubicin (DOX)-induced oxidative stress and apoptosis within myocardial cells. Nevertheless, the extent of SIRT6's impact on DOX-triggered myocardial cell aging and damage remains uncertain, with the associated mechanisms yet to be fully understood. In our research, we examined the influence of SIRT6 on DOX-induced cardiomyocyte senescence using β-galactosidase and γ-H2AX staining. Additionally, we gauged the mRNA expression of senescence-associated genes, namely p16, p21, and p53, through Real-time PCR. Employing ELISA assay kits, MDA, and total SOD activity assay kits, we measured inflammatory factors TNF-α, IL-6, and IL-1β, alongside oxidative stress-related indicators. The results unequivocally indicated that SIRT6 overexpression robustly inhibited DOX-induced cardiomyocyte senescence. Furthermore, we established that SIRT6 overexpression suppressed the inflammatory response and oxidative stress induced by DOX in cardiomyocytes. Conversely, silencing SIRT6 exacerbated DOX-induced cardiomyocyte injury. Our investigations further unveiled that SIRT6 upregulated the expression of genes CD36, CPT1, LCAD, MCAD associated with fatty acid oxidation through its interaction with PPARα, thereby exerting anti-aging effects. In vivo, the overexpression of SIRT6 was observed to restore DOX-induced declines in EF and FS to normal levels in mice. Echocardiography and HE staining revealed the restoration of cardiomyocyte alignment, affording protection against DOX-induced myocardial senescence and injury. The findings from this study suggest that SIRT6 holds significant promise as a therapeutic target for mitigating DOX-induced cardiomyopathy.

Leucine regulates lipid metabolism in adipose tissue through adipokine-mTOR-SIRT1 signaling pathway and bile acid-microbe axis in a finishing pig model

This study was conducted to explore the regulatory mechanism of leucine (Leu) on lipid metabolism of finishing pigs. Twenty-four Duroc × Landrace × Large cross pigs with an average body weight of 68.33 ± 0.97 kg were randomly allocated into 3 treatment groups with 8 replicates per group (1 pig per replicate). The dietary treatments were as follows: control group (CON), 0.25% Leu group and 0.50% Leu group. The experimental period was 42 d. The results showed as follows. (1) Compared with the CON, 0.25% and 0.50% Leu increased (P < 0.01) the average daily gain (ADG), while the average backfat thickness (ABT) and the ratio of feed intake to body weight gain (F:G ratio) were decreased (P < 0.05). (2) In the 0.25% Leu group, the relative mRNA expression levels of sterol regulatory element binding protein-1c (SREBP1c), recombinant fatty acid transport protein 1 (FATP1), chemerin and peroxisome proliferator-activated receptor γ (PPARγ) were decreased but the level of fatty acid binding protein 4 (FABP4) and fatty acid translocase (FAT/CD36) were increased in backfat tissue. In the 0.25% Leu group, the protein levels of p-Rictor, p-Raptor, p-eIF4E-binding protein 1 (p-4EBP1), p-silent mating type information regulator 2 homolog 1 (p-SIRT1) and acetylation ribosome s6 protein kinase 1 (Ac-S6K1) were increased (P < 0.05). (3) Compared to the CON, the diversity of gut microbiota in the 0.25% Leu group was increased. Principal component analysis showed that the relative abundance of Bacteroidetes, Lactobacillus and Desulfovibrio was higher in the 0.25% Leu group than the CON, but the relative abundance of Firmicutes, Treponema and Shigella was lower than in the CON (P < 0.05). (4) Four different metabolites were screened out from the serum of finishing pigs including allolithocholic acid (alloLCA), isolithocholic acid (isoLCA), ursodeoxycholic acid (UDCA) and hyodeoxycholic acid (HDCA), which correlate to various degrees with the above microorganisms. In conclusion, Leu could promote adipose tissue lipolysis of finishing pigs through the mTOR-SIRT1 signaling pathway, and S6K1 is acetylated at the same time, and the interaction between gut microbiota and bile acid metabolism is also involved.

Novel xanthone derivatives as potent sirtuin 2 inhibitors

Six amino derivatives of xanthone were obtained via chemical synthesis. Biochemical studies revealed their SIRT2 inhibitory activity ranging from 48.5 % (compound 4, 5-chloro-2-((4-(3-methoxyphenyl)piperazin-1-yl)methyl)-9H-xanthen-9-one hydrochloride) to 93.2 % (compound 3, 5-chloro-2-(((2-methoxyphenethyl)amino)methyl)-9H-xanthen-9-one hydrochloride). The structure-activity analysis showed favourable properties of secondary amines relative to tertiary piperazine derivatives. The tested compounds do not possess additional SIRT1 activating activity and no antioxidant activity (DPPH in vitro assay). Comprehensive analysis of the lipophilicity of the obtained compounds was also performed. For compound 3 potential molecular targets and similar active compounds were predicted in order to facilitate further research in this group of compounds.

Nuclear Nicotinamide Adenine Dinucleotide Deficiency by Nmnat1 Deletion Impaired Hepatic Insulin Signaling, Mitochondrial Function, and Hepatokine Expression in Mice Fed a High-Fat Diet

Metabolic syndrome (MetS) is a worldwide challenge that is closely associated with obesity, nonalcoholic liver disease, insulin resistance, and type 2 diabetes. Boosting nicotinamide adenine dinucleotide (NAD+) presents great potential in preventing MetS. However, the function of nuclear NAD+ in the development of MetS remains poorly understood. In this study, hepatocyte-specific Nmnat1 knockout mice were used to determine a possible link between nuclear NAD+ and high-fat diet (HFD)-induced MetS. We found that Nmnat1 knockout significantly reduced hepatic nuclear NAD+ levels but did not exacerbate HFD-induced obesity and hepatic triglycerides accumulation. Interestingly, loss of Nmnat1 caused insulin resistance. Further analysis revealed that Nmnat1 deletion promoted gluconeogenesis but inhibited glycogen synthesis in the liver. Moreover, Nmnat1 deficiency induced mitochondrial dysfunction by decreasing mitochondrial DNA (mtDNA)-encoded complexes Ⅰ and Ⅳ, suppressing mtDNA replication and mtRNA transcription and reducing mtDNA copy number. In addition, Nmnat1 depletion affected the expression of hepatokines in the liver, particularly downregulating the expression of follistatin. These findings highlight the importance of nuclear NAD+ in maintaining insulin sensitivity and provide insights into the mechanisms underlying HFD-induced insulin resistance.

Strain background of Candida albicans interacts with SIR2 to alter phenotypic switching

The genetic background between strains of a single species and within a single strain lineage can significantly impact the expression of biological traits. This genetic variation may also reshape epigenetic mechanisms of cell identity and environmental responses that are controlled by interconnected transcriptional networks and chromatin-modifying enzymes. Histone deacetylases, including sirtuins, are critical regulators of chromatin state and have been directly implicated in governing the phenotypic transition between the 'sterile' white state and the mating-competent opaque state in Candida albicans, a common fungal commensal and pathogen of humans. Here, we found that a previously ambiguous role for the sirtuin SIR2 in C. albicans phenotypic switching is likely linked to the genetic background of mutant strains produced in the RM lineage of SC5314. SIR2 mutants in a specific lineage of BWP17 displayed increased frequencies of switching to the opaque state compared to the wild-type. Loss of SIR2 in other SC5314-derived backgrounds, including newly constructed BWP17 sir2Δ/Δ mutants, failed to recapitulate the increased white-opaque switching frequencies observed in the original BWP17 sir2Δ/Δ mutant background. Whole-genome sequencing revealed the presence of multiple imbalanced chromosomes and large loss of heterozygosity tracts that likely interact with SIR2 to increase phenotypic switching in this BWP17 sir2Δ/Δ mutant lineage. These genomic changes are not found in other SC5314-derived sir2Δ/Δ mutants that do not display increased opaque cell formation. Thus, complex karyotypes can emerge during strain construction that modify mutant phenotypes and highlight the importance of validating strain background when interpreting phenotypes.