Stress-dependent regulation of FOXO transcription factors by the SIRT1 deacetylase

Garcinia flavonoids for healthy aging: Anti-senescence mechanisms and cosmeceutical applications in skin care

Cellular senescence, the irreversible arrest of cell division, is a hallmark of aging and a key contributor to age-related disorders. Targeting senescent cells represents a promising therapeutic approach to combat these ailments. This review explores the potential of Garcinia species, a genus rich in flavonoids with established antioxidant and anti-inflammatory properties, as a source of natural anti-senescence agents. We investigate the intricate connections between aging, cellular senescence, and oxidative stress, highlighting the detrimental effects of free radicals on cellular health. Furthermore, we analyze the diverse array of flavonoids identified within Garcinia and their established cellular mechanisms. We critically evaluate the emerging evidence for the anti-senescence potential of flavonoids in general and the limited research on Garcinia flavonoids in this context. By identifying existing knowledge gaps and paving the way for future research, this review underscores the exciting potential of Garcinia flavonoids as natural anti-senescence agents. These agents hold promise for not only promoting healthy aging but also for the development of cosmeceutical products that combat the visible signs of aging.

S6K2 in Focus: Signaling Pathways, Post-Translational Modifications, and Computational Analysis

S6 Kinase 2 (S6K2) is a key regulator of cellular signaling and is crucial for cell growth, proliferation, and survival. This review is divided into two parts: the first focuses on the complex network of upstream effectors, downstream modulators, and post-translational modifications (PTMs) that regulate S6K2 activity. We emphasize the dynamic nature of S6K2 regulation, highlighting its critical role in cellular homeostasis and its potential as a therapeutic target in diseases like cancer. The second part utilizes in silico analyses, employing computational tools to model S6K2's three-dimensional structure and predict its interaction networks. Molecular dynamics simulations and docking studies reveal potential binding sites and interactions with novel known inhibitors. We also examine the effects of environmental contaminants that potentially disrupt S6K2 function and provide insights into the role of external factors that could impact its regulatory mechanisms. These computational findings provide a deeper understanding of the conformational dynamics of S6K2 and its interactions with its inhibitors. Together, this integrated biochemical and computational approach enhances our understanding of S6K2 regulation and identifies potential new therapeutic strategies targeting S6K2 in the oncology setting.

Molecular pathways involved in the control of contractile and metabolic properties of skeletal muscle fibers as potential therapeutic targets for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin, a subsarcolemmal protein whose absence results in increased susceptibility of the muscle fiber membrane to contraction-induced injury. This results in increased calcium influx, oxidative stress, and mitochondrial dysfunction, leading to chronic inflammation, myofiber degeneration, and reduced muscle regenerative capacity. Fast glycolytic muscle fibers have been shown to be more vulnerable to mechanical stress than slow oxidative fibers in both DMD patients and DMD mouse models. Therefore, remodeling skeletal muscle toward a slower, more oxidative phenotype may represent a relevant therapeutic approach to protect dystrophic muscles from deterioration and improve the effectiveness of gene and cell-based therapies. The resistance of slow, oxidative myofibers to DMD pathology is attributed, in part, to their higher expression of Utrophin; there are, however, other characteristics of slow, oxidative fibers that might contribute to their enhanced resistance to injury, including reduced contractile speed, resistance to fatigue, increased capillary density, higher mitochondrial activity, decreased cellular energy requirements. This review focuses on signaling pathways and regulatory factors whose genetic or pharmacologic modulation has been shown to ameliorate the dystrophic pathology in preclinical models of DMD while promoting skeletal muscle fiber transition towards a slower more oxidative phenotype.

SIRT1-FOXOs signaling pathway: A potential target for attenuating cardiomyopathy

Cardiomyopathy constitutes a global health burden. It refers to myocardial injury that causes alterations in cardiac structure and function, ultimately leading to heart failure. Currently, there is no definitive treatment for cardiomyopathy. This is because existing treatments primarily focus on drug interventions to attenuate symptoms rather than addressing the underlying causes of the disease. Notably, the cardiomyocyte loss is one of the key risk factors for cardiomyopathy. This loss can occur through various mechanisms such as metabolic disturbances, cardiac stress (e.g., oxidative stress), apoptosis as well as cell death resulting from disorders in autophagic flux, etc. Sirtuins (SIRTs) are categorized as class III histone deacetylases, with their enzyme activity primarily reliant on the substrate nicotinamide adenine dinucleotide (NAD (+)). Among them, Sirtuin 1 (SIRT1) is the most intensively studied in the cardiovascular system. Forkhead O transcription factors (FOXOs) are the downstream effectors of SIRT1. Several reports have shown that SIRT1 can form a signaling pathway with FOXOs in myocardial tissue, and this pathway plays a key regulatory role in cell loss. Thus, this review describes the basic mechanism of SIRT1-FOXOs in inhibiting cardiomyocyte loss and its favorable role in cardiomyopathy. Additionally, we summarized the SIRT1-FOXOs related regulation factor and prospects the SIRT1-FOXOs potential clinical application, which provide reference for the development of cardiomyopathy 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.

Resveratrol and p53: How are they involved in CRC plasticity and apoptosis?

BACKGROUND

Colorectal cancer (CRC), which is mainly caused by epigenetic and lifestyle factors, is very often associated with functional plasticity during its development. In addition, the malignant plasticity of CRC cells underscores one of their survival abilities to functionally adapt to specific stresses, including inflammation, that occur during carcinogenesis. This leads to the generation of various subsets of cancer cells with phenotypic diversity and promotes epithelial-mesenchymal transition (EMT), formation of cancer cell stem cells (CSCs) and metabolic reprogramming. This can enhance cancer cell differentiation and facilitate tumorigenic potential, drug resistance and metastasis.

AIM OF REVIEW

The tumor protein p53 acts as one of the central suppressors of carcinogenesis by regulating its target genes, whose proteins are involved in the plasticity of cancer cells, autophagy, cell cycle, apoptosis, DNA repair. The aim of this review is to summarize the latest published research on resveratrol's effect in the prevention of CRC, its regulatory actions, specifically on the p53 pathway, and its treatment options.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Resveratrol, a naturally occurring polyphenol, is a potent inducer of a variety of tumor-controlling. However, the underlying mechanisms linking the p53 signaling pathway to the functional anti-plasticity effect of resveratrol in CRC are still poorly understood. Therefore, this review discusses novel relationships between anti-cellular plasticity/heterogeneity, pro-apoptosis and modulation of tumor protein p53 signaling in CRC oncogenesis, as one of the crucial mechanisms by which resveratrol prevents malignant phenotypic changes leading to cell migration and drug resistance, thus improving the ongoing treatment of CRC.

The relationship between SIRT1 and inflammation: a systematic review and meta-analysis

Recent studies underscore the anti-inflammatory role of SIRT1; however, its levels during inflammatory states remain ambiguous. We synthesized relevant studies up to 20 March 2024 to evaluate the relationship between SIRT1 and inflammation, using data from three major databases. Employing a random-effects model, we analyzed both cross-sectional and longitudinal studies, calculating weighted mean differences (WMDs) for pooled effect sizes. Subgroup and sensitivity analyses, along with a risk of bias assessment, were also conducted. We reviewed 13 publications, encompassing 21 datasets and 2,028 participants. The meta-analysis indicated higher SIRT1 levels in inflammatory groups compared to control groups pre-adjustment (WMD, 3.18 ng/ml; 95% CI 2.30, 4.06 ng/ml; P<0.001; I²= 99.7%) and post-adjustment (WMD, 0.88 ng/ml; 95% CI 0.14, 1.62 ng/ml; P<0.001; I²= 99.5%). Notably, middle-aged patients with inflammation exhibited lower SIRT1 levels (WMD, -0.85 ng/ml; 95% CI -1.47, -0.22 ng/ml; P= 0.008; I²= 95.4%), while groups characterized by East Asian descent, plasma studies, autoimmune conditions, and musculoskeletal disorders showed higher levels. The findings suggest that inflammation generally upregulates SIRT1, potentially elucidating its role in immunobiological processes. However, the significant heterogeneity observed, partly due to the cross-sectional nature of some data, limits insights into the duration of disease progression, which remains highly variable.

Dual-edged role of SIRT1 in energy metabolism and cardiovascular disease

Regulation of energy metabolism is pivotal in the development of cardiovascular diseases. Dysregulation in mitochondrial fatty acid oxidation has been linked to cardiac lipid accumulation and diabetic cardiomyopathy. Sirtuin 1 (SIRT1) is a deacetylase that regulates the acetylation of various proteins involved in mitochondrial energy metabolism. SIRT1 mediates energy metabolism by directly and indirectly affecting multiple aspects of mitochondrial processes, such as mitochondrial biogenesis. SIRT1 interacts with essential mitochondrial energy regulators such as peroxisome proliferator-activated receptor-α (PPARα), PPARγ coactivator-1α, estrogen-related receptor-α, and their downstream targets. Apart from that, SIRT1 regulates additional proteins, including forkhead box protein O1 and AMP-activated protein kinase in cardiac disease. Interestingly, studies have also shown that the expression of SIRT1 plays a dual-edged role in energy metabolism. Depending on the physiological state, SIRT1 expression can be detrimental or protective. This review focuses on the molecular pathways through which SIRT1 regulates energy metabolism in cardiovascular diseases. We will review SIRT1 and discuss its role in cardiac energy metabolism and its benefits and detrimental effects in heart disease.

A novel treatment strategy targeting cellular pathways with natural products to alleviate sarcopenia

Sarcopenia is a condition marked by a significant reduction in muscle mass and strength, primarily due to the aging process, which critically impacts muscle protein dynamics, metabolic functions, and overall physical functionality. This condition leads to increased body fat and reduced daily activity, contributing to severe health issues and a lower quality of life among the elderly. Recognized in the ICD-10-CM only in 2016, sarcopenia lacks definitive treatment options despite its growing prevalence and substantial social and economic implications. Given the aging global population, addressing sarcopenia has become increasingly relevant and necessary. The primary causes include aging, cachexia, diabetes, and nutritional deficiencies, leading to imbalances in protein synthesis and degradation, mitochondrial dysfunction, and hormonal changes. Exercise remains the most effective intervention, but it is often impractical for individuals with limited mobility, and pharmacological options such as anabolic steroids and myostatin inhibitors are not FDA-approved and are still under investigation. This review is crucial as it examines the potential of natural products as a novel treatment strategy for sarcopenia, targeting multiple mechanisms involved in its pathogenesis. By exploring natural products' multi-targeted effects, this study aims to provide innovative and practical solutions for sarcopenia management. Therefore, this review indicates significant improvements in muscle mass and function with the use of specific natural compounds, suggesting promising alternatives for those unable to engage in regular physical activity.

Anti-aging effects of Lacticaseibacillus paracasei PS117 on cognitive and intestinal health in naturally-aged mice: A focus on senescence-related proteins and microbiota composition

The rising global aging population underscores the urgency of maintaining the health and well-being of the elderly while reducing the healthcare burden. Anti-aging probiotics have emerged as a promising strategy. This study identified a novel anti-senescence probiotic, Lacticaseibacillus paracasei PS117 (PS117). The effects of PS117 and heat-treated PS117 (HT-PS117) supplementation on cognitive function of naturally-aged male mice were investigated. It was found that PS117 supplementation improved the cognitive performance of aged mice in the Y-maze test. Furthermore, the level of senescence-related protein p16INK4a (p16) were reduced, while anti-senescence protein sirtuin 1 (Sirt1) were increased in the hippocampus. In addition, there was an overall improvement in the intestinal function. Distinct changes in the gut microbiota were also identified, suggesting a potential contribution to the beneficial effects of PS117 supplementation. In conclusion, these results suggest that PS117 supplements could improve cognitive and intestinal functions in naturally-aged mice, while HT-117 improves only intestinal function, possibly by improving the gut microbiota composition.

Activation of AMPK/SIRT1/FOXO3a signaling by BMS-477118 (saxagliptin) mitigates chronic colitis in rats: uncovering new anti-inflammatory and antifibrotic roles

Ulcerative colitis (UC) is a debilitating chronic disease marked by persistent inflammation and intestinal fibrosis. Despite the availability of various treatments, many patients fail to achieve long-term remission, underscoring a significant unmet therapeutic need. BMS-477118, a reversible inhibitor of dipeptidyl peptidase 4 (DPP4), has demonstrated anti-inflammatory properties in preclinical and clinical studies with minimal adverse effects compared to other antidiabetic agents. However, the potential benefits of BMS-477118 in chronic UC have not yet been explored. In this study, we aimed to investigate the effects of BMS-477118 in rats subjected to chronic dextran sodium sulfate (DSS) administration. Our findings indicate that BMS-477118 activates the interconnected positive feedback loop involving AMPK, SIRT1, and FOXO3a, improving histological appearance in injured rat colons. BMS-477118 also reduced fibrotic changes associated with the chronic nature of the animal model, alleviated macroscopic damage and disease severity, and improved the colon weight-to-length ratio. Additionally, BMS-477118 prevented DSS-induced weight loss and enhanced tight junction proteins. These effects, in conjunction with reduced oxidative stress and its potential anti-inflammatory, antiapoptotic, and autophagy-inducing properties, fostered prolonged survival in rats with chronic UC. To conclude, BMS-477118 has the potential to activate the AMPK/SIRT1/FOXO3a signaling pathway in inflamed colons. These results suggest that the AMPK/SIRT1/FOXO3a pathway could be a new therapeutic target for UC. Further research is mandatory to explore the therapeutic possibilities of this pathway. Additionally, continued studies on the therapeutic potential of BMS-477118 and other DPP4 inhibitors are promising for creating new treatments for various conditions, including UC in diabetic patients.

Preconditioning with β-hydroxybutyrate attenuates lung ischemia-reperfusion injury by suppressing alveolar macrophage pyroptosis through the SIRT1-FOXO3 signaling pathway

The complex pathogenesis of lung ischemia-reperfusion injury (LIRI) was examined in a murine model, focusing on the role of pyroptosis and its exacerbation of lung injury. We specifically examined the levels and cellular localization of pyroptosis within the lung, which revealed alveolar macrophages as the primary site. The inhibition of pyroptosis by VX-765 reduced the severity of lung injury, underscoring its significant role in LIRI. Furthermore, the therapeutic potential of β-hydroxybutyrate (β-OHB) in ameliorating LIRI was examined. Modulation of β-OHB levels was evaluated by ketone ester supplementation and 3-hydroxybutyrate dehydrogenase 1 (BDH-1) gene knockout, along with the manipulation of the SIRT1-FOXO3 signaling pathway using EX-527 and pCMV-SIRT1 plasmid transfection. This revealed that β-OHB exerts lung-protective and anti-pyroptotic effects, which were mediated through the upregulation of SIRT1 and the enhancement of FOXO3 deacetylation, leading to decreased pyroptosis markers and lung injury. In addition, β-OHB treatment of MH-S cells in vitro showed a concentration-dependent improvement in pyroptosis, linking its therapeutic benefits to specific cell mechanisms. Overall, this study highlights the significance of alveolar macrophage pyroptosis in the exacerbation of LIRI and indicates the potential of β-OHB in mitigating injury by modulating the SIRT1-FOXO3 signaling pathway.

The Role of Molecular and Cellular Aging Pathways on Age-Related Hearing Loss

Aging, a complex process marked by molecular and cellular changes, inevitably influences tissue and organ homeostasis and leads to an increased onset or progression of many chronic diseases and conditions, one of which is age-related hearing loss (ARHL). ARHL, known as presbycusis, is characterized by the gradual and irreversible decline in auditory sensitivity, accompanied by the loss of auditory sensory cells and neurons, and the decline in auditory processing abilities associated with aging. The extended human lifespan achieved by modern medicine simultaneously exposes a rising prevalence of age-related conditions, with ARHL being one of the most significant. While our understanding of the molecular basis for aging has increased over the past three decades, a further understanding of the interrelationship between the key pathways controlling the aging process and the development of ARHL is needed to identify novel targets for the treatment of AHRL. The dysregulation of molecular pathways (AMPK, mTOR, insulin/IGF-1, and sirtuins) and cellular pathways (senescence, autophagy, and oxidative stress) have been shown to contribute to ARHL. However, the mechanistic basis for these pathways in the initiation and progression of ARHL needs to be clarified. Therefore, understanding how longevity pathways are associated with ARHL will directly influence the development of therapeutic strategies to treat or prevent ARHL. This review explores our current understanding of the molecular and cellular mechanisms of aging and hearing loss and their potential to provide new approaches for early diagnosis, prevention, and treatment of ARHL.

Hypothalamic circuits and aging: keeping the circadian clock updated

Over the past century, age-related diseases, such as cancer, type-2 diabetes, obesity, and mental illness, have shown a significant increase, negatively impacting overall quality of life. Studies on aged animal models have unveiled a progressive discoordination at multiple regulatory levels, including transcriptional, translational, and post-translational processes, resulting from cellular stress and circadian derangements. The circadian clock emerges as a key regulator, sustaining physiological homeostasis and promoting healthy aging through timely molecular coordination of pivotal cellular processes, such as stem-cell function, cellular stress responses, and inter-tissue communication, which become disrupted during aging. Given the crucial role of hypothalamic circuits in regulating organismal physiology, metabolic control, sleep homeostasis, and circadian rhythms, and their dependence on these processes, strategies aimed at enhancing hypothalamic and circadian function, including pharmacological and non-pharmacological approaches, offer systemic benefits for healthy aging. Intranasal brain-directed drug administration represents a promising avenue for effectively targeting specific brain regions, like the hypothalamus, while reducing side effects associated with systemic drug delivery, thereby presenting new therapeutic possibilities for diverse age-related conditions.

The Multifaceted Role of Endothelial Sirt1 in Vascular Aging: An Update

NAD+-dependent deacetylase sirtuin-1 (Sirt1) belongs to the sirtuins family, known to be longevity regulators, and exerts a key role in the prevention of vascular aging. By aging, the expression levels of Sirt1 decline with a severe impact on vascular function, such as the rise of endothelial dysfunction, which in turn promotes the development of cardiovascular diseases. In this context, the impact of Sirt1 activity in preventing endothelial senescence is particularly important. Given the key role of Sirt1 in counteracting endothelial senescence, great efforts have been made to deepen the knowledge about the intricate cross-talks and interactions of Sirt1 with other molecules, in order to set up possible strategies to boost Sirt1 activity to prevent or treat vascular aging. The aim of this review is to provide a proper background on the regulation and function of Sirt1 in the vascular endothelium and to discuss the recent advances regarding the therapeutic strategies of targeting Sirt1 to counteract vascular aging.

Reactive Oxygen Species Mechanisms that Regulate Protein-Protein Interactions in Cancer

Reactive oxygen species (ROS) are produced during cellular metabolism and in response to environmental stress. While low levels of ROS play essential physiological roles, excess ROS can damage cellular components, leading to cell death or transformation. ROS can also regulate protein interactions in cancer cells, thereby affecting processes such as cell growth, migration, and angiogenesis. Dysregulated interactions occur via various mechanisms, including amino acid modifications, conformational changes, and alterations in complex stability. Understanding ROS-mediated changes in protein interactions is crucial for targeted cancer therapies. In this review, we examine the role that ROS mechanisms in regulating pathways through protein-protein interactions.

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

Gene, Protein, and in Silico Analyses of FoxO, an Evolutionary Conserved Transcription Factor in the Sea Urchin Paracentrotus lividus

FoxO is a member of the evolutionary conserved family of transcription factors containing a Forkhead box, involved in many signaling pathways of physiological and pathological processes. In mammals, mutations or dysfunctions of the FoxO gene have been implicated in diverse diseases. FoxO homologs have been found in some invertebrates, including echinoderms. We have isolated the FoxO cDNA from the sea urchin Paracentrotus lividus (Pl-foxo) and characterized the corresponding gene and mRNA. In silico studies showed that secondary and tertiary structures of Pl-foxo protein corresponded to the vertebrate FoxO3 isoform, with highly conserved regions, especially in the DNA-binding domain. A phylogenetic analysis compared the Pl-foxo deduced protein with proteins from different animal species and confirmed its evolutionary conservation between vertebrates and invertebrates. The increased expression of Pl-foxo mRNA following the inhibition of the PI3K signaling pathway paralleled the upregulation of Pl-foxo target genes involved in apoptosis or cell-cycle arrest events (BI-1, Bax, MnSod). In silico studies comparing molecular data from sea urchins and other organisms predicted a network of Pl-foxo protein-protein interactions, as well as identified potential miRNAs involved in Pl-foxo gene regulation. Our data may provide new perspectives on the knowledge of the signaling pathways underlying sea urchin development.

Allosteric Activation of SIRT1 by 2,4-Dihydroxy-azaflavanone Averts MPP+-Mediated Dysfunction in Mitochondrial Biogenesis and Bioenergetics: Implications for Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder that affects dopamine neurons of the substantia nigra pars compacta (SNpc), resulting in motor dysfunction. Among the pathways examined, mitochondria and α-synuclein were found to play a major role in the disease progression. Hence, several attempts are being made to restore mitochondrial bioenergetics or protein aggregation pathways as disease-modifying strategies. Our earlier studies reported the protective effect of 2,4-dihydroxy-azaflavanone (azaflavanone) in a transgenic Drosophila fly model of PD. In the present study, we found that azaflavanone acts as an allosteric activator of SIRT1 in both cell-free and cell-based systems and the effects were more pronounced as compared to resveratrol. Also, azaflavanone appears to interact selectively with SIRT1 as other SIRTs such as SIRT3 and SIRT6 did not exhibit any gross changes in cellular thermal shift assay (CETSA). Molecular docking studies depicted a higher docking score with azaflavanone than with resveratrol. Further, N27 cells treated with azaflavanone exhibited a dose-dependent increase in the mitotracker staining, mtDNA/nuclear DNA ratio, and also mitochondrial bioenergetics. The observed effects appear to be due to the activation of SIRT1, as evidenced by an increase in the expression of PGC-1α and TFAM, which are the downstream targets of SIRT1. Lastly, the Parkinsonian mimic MPP+-induced disturbance in the mitochondrial membrane potential, mitochondrial bioenergetics, and biogenesis were ameliorated by azaflavanone. Overall, our findings indicate that azaflavanone, being an antioxidant and an allosteric activator of SIRT1, is a promising compound for ameliorating the pathophysiology of PD.

A role for sirtuin 1 in FGF23 activation following β-glycerophosphate treatment

Phosphate homeostasis is vital for many biological processes and disruptions in circulating levels can be detrimental. While the mechanisms behind FGF23 regulation have been regularly studied, the role of extracellular phosphate sensing and its impact on fibroblast growth factor 23 (FGF23) expression remains unclear. This study aimed to investigate the involvement of reactive oxygen species (ROS), silent information regulator 1 (SIRT1), and Hairy and Enhancer of Split-1 (HES1) in regulating FGF23 in FGF23 expressing MC3T3-E1 cells. MC3T3-E1 cells treated with β-glycerophosphate (BGP) resulted in increased Fgf23 expression. Inhibition of ROS formation by inhibition of NADPH oxidase, which is essential for ROS production, did not affect this response to BGP, suggesting ROS is not involved in this process. Moreover, treatment with tert-butyl hydroperoxide (TBHP), a ROS-inducing agent, did not increase Fgf23 expression. This suggests that ROS machinery is not involved in FGF23 stimulation as previously suggested. Nonetheless, inhibition of SIRT1 using Ex527 eliminated the Fgf23 response to BGP, indicating its involvement in FGF23 regulation after BGP treatment. Indeed, activation of SIRT1 using SRT1720 increased Fgf23 expression. Moreover, transcription factor Hes1 was upregulated by BGP treatment, which was diminished when cells were treated with Ex527 implying it is also regulated through SIRT1. These findings suggest the existence of an upstream SIRT1-HES1 axis in the regulation of FGF23 by phosphate, though we were unable to find a role for ROS in this process. Further research should provide insights into phosphate homeostasis and potential therapeutic targets for phosphate-related disorders.

SIRT1 and FOXO1 role on MASLD risk: effects of DHA-rich n-3 PUFA supplementation and exercise in aged obese female mice and in post-menopausal overweight/obese women

Sirtuins 1 (SIRT1) and Forkhead box protein O1 (FOXO1) expression have been associated with obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). Exercise and/or docosahexaenoic acid (DHA) supplementation have shown beneficial effects on MASLD. The current study aims to assess the relationships between Sirt1, Foxo1 mRNA levels and several MASLD biomarkers, as well as the effects of DHA-rich n-3 PUFA supplementation and/or exercise in the steatotic liver of aged obese female mice, and in peripheral blood mononuclear cells (PBMCs) of postmenopausal women with overweight/obesity. In the liver of 18-month-old mice, Sirt1 levels positively correlated with the expression of genes related to fatty acid oxidation, and negatively correlated with lipogenic and proinflammatory genes. Exercise (long-term treadmill training), especially when combined with DHA, upregulated hepatic Sirt1 mRNA levels. Liver Foxo1 mRNA levels positively associated with hepatic triglycerides (TG) content and the expression of lipogenic and pro-inflammatory genes, while negatively correlated with the lipolytic gene Hsl. In PBMCs of postmenopausal women with overweight/obesity, FOXO1 mRNA expression negatively correlated with the hepatic steatosis index (HSI) and the Zhejiang University index (ZJU). After 16-weeks of DHA-rich PUFA supplementation and/or progressive resistance training (RT), most groups exhibited reduced MASLD biomarkers and risk indexes accompanying with body fat mass reduction, but no significant changes were found between the intervention groups. However, in PBMCs n-3 supplementation upregulated FOXO1 expression, and the RT groups exhibited higher SIRT1 expression. In summary, SIRT1 and FOXO1 could be involved in the beneficial mechanisms of exercise and n-3 PUFA supplementation related to MASLD manifestation.

SIRT1 signaling pathways in sarcopenia: Novel mechanisms and potential therapeutic targets

Sarcopenia is an aging-related skeletal disease characterized by decreased muscle mass, strength, and physical function, severely affecting the quality of life (QoL) of the elderly population. Sirtuin 1 (SIRT1), as a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, has been reported to participate in various aging-related signaling pathways and exert protective effect on many human diseases. SIRT1 functioned as an important role in the occurrence and progression of sarcopenia through regulating key pathways related to protein homeostasis, apoptosis, mitochondrial dysfunction, insulin resistance and autophagy in skeletal muscle, including SIRT1/Forkhead Box O (FoxO), AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor κB (NF-κB), SIRT1/p53, AMPK/SIRT1/peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), and SIRT1/live kinase B1 (LKB1)/AMPK pathways. However, the specific mechanisms of these processes have not been fully illuminated. Currently, several SIRT1-mediated interventions on sarcopenia have been preliminarily developed, such as SIRT1 activator polyphenolic compounds, exercising and calorie restriction. In this review, we summarized the predominant mechanisms of SIRT1 involved in sarcopenia and therapeutic modalities targeting the SIRT1 signaling pathways for the prevention and prognosis of sarcopenia.

Ethnicity-related differences in mitochondrial regulation by insulin stimulation in diabetes

Mitochondrial dysfunction has long been implicated in the development of insulin resistance, which is a hallmark of type 2 diabetes. However, recent studies reveal ethnicity-related differences in mitochondrial processes, underscoring the need for nuance in studying mitochondrial dysfunction and insulin sensitivity. Furthermore, the higher prevalence of type 2 diabetes among African Americans and individuals of African descent has brought attention to the role of ethnicity in disease susceptibility. In this review, which covers existing literature, genetic studies, and clinical data, we aim to elucidate the complex relationship between mitochondrial alterations and insulin stimulation by considering how mitochondrial dynamics, contact sites, pathways, and metabolomics may be differentially regulated across ethnicities, through mechanisms such as single nucleotide polymorphisms (SNPs). In addition to achieving a better understanding of insulin stimulation, future studies identifying novel regulators of mitochondrial structure and function could provide valuable insights into ethnicity-dependent insulin signaling and personalized care.

Acetylation of FOXO1 activates Bim expression involved in CVB3 induced cardiomyocyte apoptosis

Viral myocarditis (VMC) is the major reason for sudden cardiac death among both children and young adults. Of these, coxsackievirus B3 (CVB3) is the most common causative agent of myocarditis. Recently, the role of signaling pathways in the pathogenesis of VMC has been evaluated in several studies, which has provided a new perspective on identifying potential therapeutic targets for this hitherto incurable disease. In the present study, in vivo and in vitro experiments showed that CVB3 infection leads to increased Bim expression and triggers apoptosis. In addition, by knocking down Bim using RNAi, we further confirmed the biological function of Bim in apoptosis induced by CVB3 infection. We additionally found that Bim and forkhead box O1 class (FOXO1) inhibition significantly increased the viability of CVB3-infected cells while blocking viral replication and viral release. Moreover, CVB3-induced Bim expression was directly dependent on FOXO1 acetylation, which is catalyzed by the co-regulation of CBP and SirTs. Furthermore, the acetylation of FOXO1 was an important step in Bim activation and apoptosis induced by CVB3 infection. The findings of this study suggest that CVB3 infection induces apoptosis through the FOXO1 acetylation-Bim pathway, thus providing new insights for developing potential therapeutic targets for enteroviral myocarditis.

Longevity factor FOXO3a: A potential therapeutic target for age-related ocular diseases

The forkhead box protein O3 (FOXO3a) belongs to the subgroup O of the forkhead transcription factor family and plays an important role in regulating the aging process by participating in the regulation of various life processes, including cell cycle arrest, apoptosis, autophagy, oxidative stress, and DNA repair. The eye is an organ that is affected by aging earlier. However, the functional role and potential clinical applications of FOXO3a in age-related eye diseases have not received widespread attention and lacked comprehensive and clear clarification. In this review, we demonstrated the relationship between FOXO3a and visual system health, summarized the functional roles of FOXO3a in various eye diseases, and potential ocular-related therapies and drugs targeting FOXO3a in visual system diseases through a review and summary of relevant literature. This review indicates that FOXO3a is an important factor in maintaining the normal function of various tissues in the eye, and is closely related to the occurrence and development of ophthalmic-related diseases. Based on its vital role in the normal function of the visual system, FOXO3a has potential clinical application value in related ophthalmic diseases. At present, multiple molecules and drugs targeting FOXO3a have been reported to have the potential for the treatment of related ophthalmic diseases, but further clinical trials are needed. In conclusion, this review can facilitate us to grasp the role of FOXO3a in the visual system and provide new views and bases for the treatment strategy research of age-related eye diseases.

Fe3O4-Coated CNTs-Gum Arabic Nano-Hybrid Composites Exhibit Enhanced Anti-Leukemia Potency Against AML Cells via ROS-Mediated Signaling

Background

Prior studies on magnetite (Fe3O4) NPs and carbon nanotubes (CNTs) cytotoxic effects against acute myeloid leukemia (AML) are inconclusive rather than definitive.

Purpose

Investigation of the effects of Gum Arabic (GA)-stabilized/destabilized Fe3O4 NPs and CNTs, alone or in combination, on AML cell proliferation.

Methods

Hybrid NPs were synthesized, characterized, and assessed for their cytotoxicity against Kasumi-1, HL-60, and THP-1 in comparison to normal primary bone marrow CD34+ cells. The molecular pathways of nanostructures' cytotoxicity were also investigated.

Results

The Fe3O4 NPs were effectively synthesized and attached to the surface of the CNTs, resulting in the formation of a novel hybrid through their interaction with the GA colloidal solution in an aqueous media. Although the evaluated nanostructured nanoparticles had significant growth suppression ability against the leukemia cell lines, with IC50 values ranging from 42.437 to 189.842 μg/mL, they exhibited comparatively modest toxicity towards normal hematopoietic cells (IC50: 113.529‒162.656 μg/mL). The incorporation of Fe3O4 NPs with CNTs in a hybrid nanocomposite significantly improved their effectiveness against leukemia cells, with the extent of improvement varying depending on the specific cell type. The nanostructured particles were stabilized by GA, which enhances their ability to inhibit cell proliferation in a manner that depends on the specific cell type. Also, nanoparticles exhibit cytotoxicity due to their capacity to stimulate the production of intracellular ROS, halt the cell cycle at the G1 phase, and induce apoptosis. This is supported by the activation of p53, BAX, cytochrome C, and caspase-3, which are triggered by ROS. The nanostructures lead to an increase in the expression of genes encoding proteins related to oxidative stress (SIRT1, FOXO3, NFE2L2, and MAP3K5) and cyclin-dependent kinase inhibitors (CDKN1A and CDKN1B) in response to ROS.

Conclusion

We provide an effective Fe3O4 NPs/CNTs nano-hybrid composite that induces apoptosis and has strong anti-leukemic capabilities. This hybrid nanocomposite is promising for in vivo testing and validation.

Preventing loss of sirt1 lowers mitochondrial oxidative stress and preserves C2C12 myotube diameter in an in vitro model of cancer cachexia

Cancer cachexia is a multifactorial syndrome associated with advanced cancer that contributes to mortality. Cachexia is characterized by loss of body weight and muscle atrophy. Increased skeletal muscle mitochondrial reactive oxygen species (ROS) is a contributing factor to loss of muscle mass in cachectic patients. Mice inoculated with Lewis lung carcinoma (LLC) cells lose weight, muscle mass, and have lower muscle sirtuin-1 (sirt1) expression. Nicotinic acid (NA) is a precursor to nicotinamide dinucleotide (NAD+) which is exhausted in cachectic muscle and is a direct activator of sirt1. Mice lost body and muscle weight and exhibited reduced skeletal muscle sirt1 expression after inoculation with LLC cells. C2C12 myotubes treated with LLC-conditioned media (LCM) had lower myotube diameter. We treated C2C12 myotubes with LCM for 24 h with or without NA for 24 h. C2C12 myotubes treated with NA maintained myotube diameter, sirt1 expression, and had lower mitochondrial superoxide. We then used a sirt1-specific small molecule activator SRT1720 to increase sirt1 activity. C2C12 myotubes treated with SRT1720 maintained myotube diameter, prevented loss of sirt1 expression, and attenuated mitochondrial superoxide production. Our data provides evidence that NA may be beneficial in combating cancer cachexia by maintaining sirt1 expression and decreasing mitochondrial superoxide production.

The dual role of sirtuins in cancer: biological functions and implications

Sirtuins are pivotal in orchestrating numerous cellular pathways, critically influencing cell metabolism, DNA repair, aging processes, and oxidative stress. In recent years, the involvement of sirtuins in tumor biology has garnered substantial attention, with a growing body of evidence underscoring their regulatory roles in various aberrant cellular processes within tumor environments. This article delves into the sirtuin family and its biological functions, shedding light on their dual roles-either as promoters or inhibitors-in various cancers including oral, breast, hepatocellular, lung, and gastric cancers. It further explores potential anti-tumor agents targeting sirtuins, unraveling the complex interplay between sirtuins, miRNAs, and chemotherapeutic drugs. The dual roles of sirtuins in cancer biology reflect the complexity of targeting these enzymes but also highlight the immense therapeutic potential. These advancements hold significant promise for enhancing clinical outcomes, marking a pivotal step forward in the ongoing battle against cancer.

Wogonin alleviates sepsis-induced acute lung injury by modulating macrophage polarization through the SIRT1-FOXO1 pathways

Sepsis-induced acute lung injury is a common and severe complication of sepsis, for which effective treatments are currently lacking. Previous studies have demonstrated the influence of wogonin in treating acute lung injury (ALI). However, its precise mechanism of action remains unclear. To delve deeper into the mechanisms underlying wogonin's impacts in sepsis-induced acute lung injury, we established a mouse sepsis model through cecal ligation and puncture and conducted further cell experiments using lipopolysaccharide-treated MH-S and MLE-12 cells to explore wogonin's potential mechanisms of action in treating ALI. Our results revealed that wogonin significantly increased the survival rate of mice, alleviated pulmonary pathological damage and inflammatory cell infiltration, and activated the SIRT1-FOXO1 pathway. Additionally, wogonin suppressed the release of pro-inflammatory factors by M1 macrophages and induced the activation of M2 anti-inflammatory factors. Further in vitro studies confirmed that wogonin effectively inhibited M1 macrophage polarization through the activation of the SIRT1-FOXO1 pathway, thereby mitigating lung pathological changes caused by ALI. In summary, our study demonstrated that wogonin regulated macrophage M1/M2 polarization through the activation of the SIRT1-FOXO1 pathway, thereby attenuating the inflammatory response and improving pulmonary pathological changes induced by sepsis-induced ALI. This discovery provided a solid mechanistic foundation for the therapeutic use of wogonin in sepsis-induced ALI, shedding new light on potential strategies for the treatment of sepsis-induced ALI.

Obesity and male fertility disorders

Often associated with obesity, male infertility represents a widespread condition that challenges the wellbeing of the couple. In this article, we provide a comprehensive and critical analysis of studies exploring the association between obesity and male reproductive function, to evaluate the frequency of this association, and establish the effects of increased body weight on conventional and biofunctional sperm parameters and infertility. In an attempt to find possible molecular markers of infertility in obese male patients, the numerous mechanisms responsible for infertility in overweight/obese patients are reviewed in depth. These include obesity-related functional hypogonadism, insulin resistance, hyperinsulinemia, chronic inflammation, adipokines, irisin, gut hormones, gut microbiome, and sperm transcriptome. According to meta-analytic evidence, excessive body weight negatively influences male reproductive health. This can occurr through a broad array of molecular mechanisms. Some of these are not yet fully understood and need to be further elucidated in the future. A better understanding of the effects of metabolic disorders on spermatogenesis and sperm fertilizing capacity is very useful for identifying new diagnostic markers and designing therapeutic strategies for better clinical management of male infertility.

Effect of MEHP on testosterone synthesis via Sirt1/Foxo1/Rab7 signaling pathway inhibition of lipophagy in TM3 cells

Mono-2-ethylhexyl phthalic acid (MEHP) is the most toxic metabolite of the plasticizer di-2-ethylhexyl phthalic acid (DEHP), and studies have shown that MEHP causes serious reproductive effects. However, its exact mechanisms of action remain elusive. In this study, we aimed to investigate the reproductive effects of MEHP and preliminarily explore its underlying molecular mechanisms. We found that TM3 cells gradually secreted less testosterone and intracellular free cholesterol with increasing MEHP exposure. MEHP exposure inhibited lipophagy and the Sirt1/Foxo1/Rab7 signaling pathway in TM3 cells, causing aberrant accumulation of intracellular lipid droplets. Addition of the Sirt1 agonist SRT1720 and Rab7 agonist ML-098 alleviated the inhibition of lipophagy and increased free cholesterol and testosterone contents in TM3 cells. SRT1720 alleviated the inhibitory effect of MEHP on the Sirt1/Foxo1/Rab7 signaling pathway, whereas ML-098 only alleviated the inhibition of Rab7 protein expression by MEHP and had no effect on Sirt1 and Foxo1 protein expression. This suggests that MEHP inhibits lipophagy in TM3 cells by suppressing the Sirt1/Foxo1/Rab7 signaling pathway, ultimately leading to a further decrease in cellular testosterone secretion. This study improves our current understanding of the toxicity and molecular mechanisms of action of MEHP and provides new insights into the reproductive effects of phthalic acid esters.

Cardiovascular Disease and miRNAs: Possible Oxidative Stress-Regulating Roles of miRNAs

MicroRNAs (miRNAs) have been highlighted as key players in numerous diseases, and accumulating evidence indicates that pathological expressions of miRNAs contribute to both the development and progression of cardiovascular diseases (CVD), as well. Another important factor affecting the development and progression of CVD is reactive oxygen species (ROS), as well as the oxidative stress they may impose on the cells. Considering miRNAs are involved in virtually every biological process, it is not unreasonable to assume that miRNAs also play critical roles in the regulation of oxidative stress. This narrative review aims to provide mechanistic insights on possible oxidative stress-regulating roles of miRNAs in cardiovascular diseases based on differentially expressed miRNAs reported in various cardiovascular diseases and their empirically validated targets that have been implicated in the regulation of oxidative stress.

Recruitment of CTCF to the SIRT1 promoter after Oxidative Stress mediates Cardioprotective Transcription

Because most DNA-binding transcription factors (dbTFs), including the architectural regulator CTCF, bind RNA and exhibit di-/multimerization, a central conundrum is whether these distinct properties are regulated post-transcriptionally to modulate transcriptional programs. Here, investigating stress-dependent activation of SIRT1, encoding an evolutionarily-conserved protein deacetylase, we show that induced phosphorylation of CTCF acts as a rheostat to permit CTCF occupancy of low-affinity promoter DNA sites to precisely the levels necessary. This CTCF recruitment to the SIRT1 promoter is eliciting a cardioprotective cardiomyocyte transcriptional activation program and provides resilience against the stress of the beating heart in vivo . Mice harboring a mutation in the conserved low-affinity CTCF promoter binding site exhibit an altered, cardiomyocyte-specific transcriptional program and a systolic heart failure phenotype. This transcriptional role for CTCF reveals that a covalent dbTF modification regulating signal-dependent transcription serves as a previously unsuspected component of the oxidative stress response.

Redox signaling and skeletal muscle adaptation during aerobic exercise

Redox regulation is a fundamental physiological phenomenon related to oxygen-dependent metabolism, and skeletal muscle is mainly regarded as a primary site for oxidative phosphorylation. Several studies have revealed the importance of reactive oxygen and nitrogen species (RONS) in the signaling process relating to muscle adaptation during exercise. To date, improving knowledge of redox signaling in modulating exercise adaptation has been the subject of comprehensive work and scientific inquiry. The primary aim of this review is to elucidate the molecular and biochemical pathways aligned to RONS as activators of skeletal muscle adaptation and to further identify the interconnecting mechanisms controlling redox balance. We also discuss the RONS-mediated pathways during the muscle adaptive process, including mitochondrial biogenesis, muscle remodeling, vascular angiogenesis, neuron regeneration, and the role of exogenous antioxidants.

SIRT1: An Intermediator of Key Pathways Regulating Pulmonary Diseases

Silent information regulator type-1 (SIRT1), a nicotinamide adenine dinucleotide+-dependent deacetylase, is a member of the sirtuins family and has unique protein deacetylase activity. SIRT1 participates in physiological as well as pathophysiological processes by targeting a wide range of protein substrates and signalings. In this review, we described the latest progress of SIRT1 in pulmonary diseases. We have introduced the basic information and summarized the prominent role of SIRT1 in several lung diseases, such as acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, lung cancer, and aging-related diseases.

Aspirin-Mediated Acetylation of SIRT1 Maintains Intestinal Immune Homeostasis

Aspirin, also named acetylsalicylate, can directly acetylate the side-chain of lysine in protein, which leads to the possibility of unexplained drug effects. Here, the study used isotopic-labeling aspirin-d3 with mass spectrometry analysis to discover that aspirin directly acetylates 10 HDACs proteins, including SIRT1, the most studied NAD+-dependent deacetylase. SIRT1 is also acetylated by aspirin in vitro. It is also identified that aspirin directly acetylates lysine 408 of SIRT1, which abolishes SIRT1 deacetylation activity by impairing the substrates binding affinity. Interestingly, the lysine 408 of SIRT1 can be acetylated by CBP acetyltransferase in cells without aspirin supplement. Aspirin can inhibit SIRT1 to increase the levels of acetylated p53 and promote p53-dependent apoptosis. Moreover, the knock-in mice of the acetylation-mimic mutant of SIRT1 show the decreased production of pro-inflammatory cytokines and maintain intestinal immune homeostasis. The study indicates the importance of the acetylated internal functional site of SIRT1 in maintaining intestinal immune homeostasis.

How calorie restriction slows aging: an epigenetic perspective

Genomic instability and epigenetic alterations are some of the prominent factors affecting aging. Age-related heterochromatin loss and decreased whole-genome DNA methylation are associated with abnormal gene expression, leading to diseases and genomic instability. Modulation of these epigenetic changes is crucial for preserving genomic integrity and controlling cellular identity is important for slowing the aging process. Numerous studies have shown that caloric restriction is the gold standard for promoting longevity and healthy aging in various species ranging from rodents to primates. It can be inferred that delaying of aging through the main effector such as calorie restriction is involved in cellular identity and epigenetic modification. Thus, an understanding of aging through calorie restriction may seek a more in-depth understanding. In this review, we discuss how caloric restriction promotes longevity and healthy aging through genomic stability and epigenetic alterations. We have also highlighted how the effectors of caloric restriction are involved in modulating the chromatin-based barriers.

Emerging roles of FOXK2 in cancers and metabolic disorders

FOXK2, a member of the Forkhead box K (FOXK) transcription factor family, is widely expressed in various tissues and organs throughout the body. FOXK2 plays crucial roles in cell proliferation, differentiation, autophagy, de novo nucleotide biosynthesis, DNA damage response, and aerobic glycolysis. Although FOXK2 is recognized as an oncogene in colorectal cancer and hepatocellular carcinoma, it acts as a tumor suppressor in breast cancer, cervical cancer, and non-small cell lung cancer (NSCLC). This review provides an overview of the recent progress in understanding the regulatory mechanisms of FOXK2 and its downstream targets, highlights the significant impact of FOXK2 dysregulation on cancer etiology, and discusses the potential of targeting FOXK2 for cancer treatment.

Oxidative Stress and FOXO-1 Relationship in Stage III Periodontitis

OBJECTIVES

8-Hydroxideoxyguanosine (8-OHdG) is a marker of oxidative stress, and Forkhead Box-O1 (FOXO1) is a transcription factor and signaling integrator in cell and tissue homeostasis. This study aims to determine FOXO1 and 8-OHdG levels in serum and saliva samples of periodontitis patients and to evaluate their relationship with clinical periodontal parameters.

MATERIALS AND METHODS

Twenty healthy individuals, twenty generalized Stage III Grade B periodontitis patients, and nineteen generalized Stage III Grade C periodontitis patients were included in the study. Clinical periodontal parameters (plaque index (PI), probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL)) were recorded. Salivary and serum 8-OHdG and FOX-O1 levels were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Clinical periodontal parameters showed a statistically significant increase in periodontitis groups compared to the control group (p < 0.05). 8-OHdG salivary levels were significantly higher in both periodontitis groups compared to the control group. The salivary FOXO1 levels were significantly lower in both periodontitis groups compared to the control group. Salivary FOXO1 level had a low-grade negative correlation with BOP and salivary 8-OHdG level.

CONCLUSIONS

While reactive oxygen species increase in periodontal inflammation, low expression of FOXO1, an important transcription factor for antioxidant enzymes, supports that this molecule plays a vital role in tissue destruction, and FOXO1 can be seen as a potential immune modulator.

CLINICAL RELEVANCE

The role of FOXO1 in supporting antioxidant defense may suggest that FOXO1 is a candidate target for periodontitis treatment.

Aspartame Causes Developmental Defects and Teratogenicity in Zebra Fish Embryo: Role of Impaired SIRT1/FOXO3a Axis in Neuron Cells

Aspartame, a widely used artificial sweetener, is present in many food products and beverages worldwide. It has been linked to potential neurotoxicity and developmental defects. However, its teratogenic effect on embryonic development and the underlying potential mechanisms need to be elucidated. We investigated the concentration- and time-dependent effects of aspartame on zebrafish development and teratogenicity. We focused on the role of sirtuin 1 (SIRT1) and Forkhead-box transcription factor (FOXO), two proteins that play key roles in neurodevelopment. It was found that aspartame exposure reduced the formation of larvae and the development of cartilage in zebrafish. It also delayed post-fertilization development by altering the head length and locomotor behavior of zebrafish. RNA-sequencing-based DEG analysis showed that SIRT1 and FOXO3a are involved in neurodevelopment. In silico and in vitro analyses showed that aspartame could target and reduce the expression of SIRT1 and FOXO3a proteins in neuron cells. Additionally, aspartame triggered the reduction of autophagy flux by inhibiting the nuclear translocation of SIRT1 in neuronal cells. The findings suggest that aspartame can cause developmental defects and teratogenicity in zebrafish embryos and reduce autophagy by impairing the SIRT1/FOXO3a axis in neuron cells.

A MiR181/Sirtuin1 regulatory circuit modulates drug response in biliary cancers

Despite recent advances, biliary tract cancer (BTC) remains one of the most lethal tumor worldwide due to late diagnosis, limited therapeutic strategies and resistance to conventional therapies. In recent years, high-throughput technologies have enabled extensive genome, and transcriptome sequencing unveiling, among others, the regulatory potential of microRNAs (miRNAs). Compelling evidence shown that miRNA are attractive therapeutic targets and promising candidates as biomarkers for various therapy-resistant tumors. The analysis of miRNA profile successfully identified miR-181c and -181d as significantly downregulated in BTC patients. Low miR-181c and -181d expression levels were correlated with worse prognosis and poor treatment efficacy. In fact, progression-free survival analysis indicated poor survival rates in miR-181c and -181d low expressing patients. The expression profile of miR-181c and -181d in BTC cell lines revealed that both miRNAs were dysregulated. Functional in vitro experiments in BTC cell lines showed that overexpression of miR-181c and -181d affected cell viability and increased sensitivity to chemotherapy compared to controls. In addition, by using bioinformatic tools we showed that the miR-181c/d functional role is determined by binding to their target SIRT1 (Sirtuin 1). Moreover, BTC patients expressing high levels of miR-181 and low SIRT1 shown an improved survival and treatment response. An integrative network analysis demonstrated that, miR-181/SIRT1 circuit had a regulatory effect on several important metabolic tumor-related processes. Our study demonstrated that miR-181c and -181d act as tumor suppressor miRNA in BTC, suggesting the potential use as therapeutic strategy in resistant cancers and as predictive biomarker in the precision medicine of BTC.

Role of sirtuins in epigenetic regulation and aging control

Advances in modern healthcare in developed countries make it possible to extend the human lifespan, which is why maintaining active longevity is becoming increasingly important. After the sirtuin (SIRT) protein family was discovered, it started to be considered as a significant regulator of the physiological processes associated with aging. SIRT has deacetylase, deacylase, and ADP-ribosyltransferase activity and modifies a variety of protein substrates, including chromatin components and regulatory proteins. This multifactorial regulatory system affects many processes: cellular metabolism, mitochondrial functions, epigenetic regulation, DNA repair and more. As is expected, the activity of sirtuin proteins affects the manifestation of classic signs of aging in the body, such as cellular senescence, metabolic disorders, mitochondrial dysfunction, genomic instability, and the disruption of epigenetic regulation. Changes in the SIRT activity in human cells can also be considered a marker of aging and are involved in the genesis of various age-dependent disorders. Additionally, experimental data obtained in animal models, as well as data from population genomic studies, suggest a SIRT effect on life expectancy. At the same time, the diversity of sirtuin functions and biochemical substrates makes it extremely complicated to identify cause-and-effect relationships and the direct role of SIRT in controlling the functional state of the body. However, the SIRT influence on the epigenetic regulation of gene expression during the aging process and the development of disorders is one of the most important aspects of maintaining the homeostasis of organs and tissues. The presented review centers on the diversity of SIRT in humans and model animals. In addition to a brief description of the main SIRT enzymatic and biological activity, the review discusses its role in the epigenetic regulation of chromatin structure, including the context of the development of genome instability associated with aging. Studies on the functional connection between SIRT and longevity, as well as its effect on pathological processes associated with aging, such as chronic inflammation, fibrosis, and neuroinflammation, have been critically analyzed.

Inhibitory protein-protein interactions of the SIRT1 deacetylase are choreographed by post-translational modification

Regulation of SIRT1 activity is vital to energy homeostasis and plays important roles in many diseases. We previously showed that insulin triggers the epigenetic regulator DBC1 to prime SIRT1 for repression by the multifunctional trafficking protein PACS-2. Here, we show that liver DBC1/PACS-2 regulates the diurnal inhibition of SIRT1, which is critically important for insulin-dependent switch in fuel metabolism from fat to glucose oxidation. We present the x-ray structure of the DBC1 S1-like domain that binds SIRT1 and an NMR characterization of how the SIRT1 N-terminal region engages DBC1. This interaction is inhibited by acetylation of K112 of DBC1 and stimulated by the insulin-dependent phosphorylation of human SIRT1 at S162 and S172, catalyzed sequentially by CK2 and GSK3, resulting in the PACS-2-dependent inhibition of nuclear SIRT1 enzymatic activity and translocation of the deacetylase in the cytoplasm. Finally, we discuss how defects in the DBC1/PACS-2-controlled SIRT1 inhibitory pathway are associated with disease, including obesity and non-alcoholic fatty liver disease.

Sirtuins in intervertebral disc degeneration: current understanding

BACKGROUND

Intervertebral disc degeneration (IVDD) is one of the etiologic factors of degenerative spinal diseases, which can lead to a variety of pathological spinal conditions such as disc herniation, spinal stenosis, and scoliosis. IVDD is a leading cause of lower back pain, the prevalence of which increases with age. Recently, Sirtuins/SIRTs and their related activators have received attention for their activity in the treatment of IVDD. In this paper, a comprehensive systematic review of the literature on the role of SIRTs and their activators on IVDD in recent years is presented. The molecular pathways involved in the regulation of IVDD by SIRTs are summarized, and the effects of SIRTs on senescence, inflammatory responses, oxidative stress, and mitochondrial dysfunction in myeloid cells are discussed with a view to suggesting possible solutions for the current treatment of IVDD.

PURPOSE

This paper focuses on the molecular mechanisms by which SIRTs and their activators act on IVDD.

METHODS

A literature search was conducted in Pubmed and Web of Science databases over a 13-year period from 2011 to 2024 for the terms "SIRT", "Sirtuin", "IVDD", "IDD", "IVD", "NP", "Intervertebral disc degeneration", "Intervertebral disc" and "Nucleus pulposus".

RESULTS

According to the results, SIRTs and a large number of activators showed positive effects against IVDD.SIRTs modulate autophagy, myeloid apoptosis, oxidative stress and extracellular matrix degradation. In addition, they attenuate inflammatory factor-induced disc damage and maintain homeostasis during disc degeneration. Several clinical studies have reported the protective effects of some SIRTs activators (e.g., resveratrol, melatonin, honokiol, and 1,4-dihydropyridine) against IVDD.

CONCLUSION

The fact that SIRTs and their activators play a hundred different roles in IVDD helps to better understand their potential to develop further treatments for IVDD.

NOVELTY

This review summarizes current information on the mechanisms of action of SIRTs in IVDD and the challenges and limitations of translating their basic research into therapy.

Loss of FoxO1 activates an alternate mechanism of mitochondrial quality control for healthy adipose browning

Browning of white adipose tissue is hallmarked by increased mitochondrial density and metabolic improvements. However, it remains largely unknown how mitochondrial turnover and quality control are regulated during adipose browning. In the present study, we found that mice lacking adipocyte FoxO1, a transcription factor that regulates autophagy, adopted an alternate mechanism of mitophagy to maintain mitochondrial turnover and quality control during adipose browning. Post-developmental deletion of adipocyte FoxO1 (adO1KO) suppressed Bnip3 but activated Fundc1/Drp1/OPA1 cascade, concurrent with up-regulation of Atg7 and CTSL. In addition, mitochondrial biogenesis was stimulated via the Pgc1α/Tfam pathway in adO1KO mice. These changes were associated with enhanced mitochondrial homeostasis and metabolic health (e.g., improved glucose tolerance and insulin sensitivity). By contrast, silencing Fundc1 or Pgc1α reversed the changes induced by silencing FoxO1, which impaired mitochondrial quality control and function. Ablation of Atg7 suppressed mitochondrial turnover and function, causing metabolic disorder (e.g., impaired glucose tolerance and insulin sensitivity), regardless of elevated markers of adipose browning. Consistently, suppression of autophagy via CTSL by high-fat diet was associated with a reversal of adO1KO-induced benefits. Our data reveal a unique role of FoxO1 in coordinating mitophagy receptors (Bnip3 and Fundc1) for a fine-tuned mitochondrial turnover and quality control, underscoring autophagic clearance of mitochondria as a prerequisite for healthy browning of adipose tissue.

BNC1 deficiency induces mitochondrial dysfunction-triggered spermatogonia apoptosis through the CREB/SIRT1/FOXO3 pathway: the therapeutic potential of nicotinamide riboside and metformin†

Male infertility is a global health problem that disturbs numerous couples worldwide. Basonuclin 1 (BNC1) is a transcription factor mainly expressed in proliferative keratinocytes and germ cells. A frameshift mutation of BNC1 was identified in a large Chinese primary ovarian insufficiency pedigree. The expression of BNC1 was significantly decreased in the testis biopsies of infertile patients with nonobstructive azoospermia. Previous studies have revealed that mice with BNC1 deficiency are generally subfertile and undergo gradual spermatogenic failure. We observed that apoptosis of spermatogonia is tightly related to spermatogenic failure in mice with a Bnc1 truncation mutation. Such impairment is related to mitochondrial dysfunction causing lower mitochondrial membrane potential and higher reactive oxygen species. We showed that downregulation of CREB/SIRT1/FOXO3 signaling participates in the above impairment. Administration of nicotinamide riboside or metformin reversed mitochondrial dysfunction and inhibited apoptosis in Bnc1-knockdown spermatogonia by stimulating CREB/SIRT1/FOXO3 signaling. Dietary supplementation with nicotinamide riboside or metformin in mutated mice increased SIRT1 signaling, improved the architecture of spermatogenic tubules, inhibited apoptosis of the testis, and improved the fertility of mice with a Bnc1 truncation mutation. Our data establish that oral nicotinamide riboside or metformin can be useful for the treatment of spermatogenic failure induced by Bnc1 mutation.

Forkhead box O proteins: steering the course of stem cell fate

Stem cells are pivotal players in the intricate dance of embryonic development, tissue maintenance, and regeneration. Their behavior is delicately balanced between maintaining their pluripotency and differentiating as needed. Disruptions in this balance can lead to a spectrum of diseases, underscoring the importance of unraveling the complex molecular mechanisms that govern stem cell fate. Forkhead box O (FOXO) proteins, a family of transcription factors, are at the heart of this intricate regulation, influencing a myriad of cellular processes such as survival, metabolism, and DNA repair. Their multifaceted role in steering the destiny of stem cells is evident, as they wield influence over self-renewal, quiescence, and lineage-specific differentiation in both embryonic and adult stem cells. This review delves into the structural and regulatory intricacies of FOXO transcription factors, shedding light on their pivotal roles in shaping the fate of stem cells. By providing insights into the specific functions of FOXO in determining stem cell fate, this review aims to pave the way for targeted interventions that could modulate stem cell behavior and potentially revolutionize the treatment and prevention of diseases.

Emerging roles of SIRT1 activator, SRT2104, in disease treatment

Silent information regulator 1 (SIRT1) is a NAD+-dependent class III deacetylase that plays important roles in the pathogenesis of numerous diseases, positioning it as a prime candidate for therapeutic intervention. Among its modulators, SRT2104 emerges as the most specific small molecule activator of SIRT1, currently advancing into the clinical translation phase. The primary objective of this review is to evaluate the emerging roles of SRT2104, and to explore its potential as a therapeutic agent in various diseases. In the present review, we systematically summarized the findings from an extensive array of literature sources including the progress of its application in disease treatment and its potential molecular mechanisms by reviewing the literature published in databases such as PubMed, Web of Science, and the World Health Organization International Clinical Trials Registry Platform. We focuses on the strides made in employing SRT2104 for disease treatment, elucidating its potential molecular underpinnings based on preclinical and clinical research data. The findings reveal that SRT2104, as a potent SIRT1 activator, holds considerable therapeutic potential, particularly in modulating metabolic and longevity-related pathways. This review establishes SRT2104 as a leading SIRT1 activator with significant therapeutic promise.

Microphysiological systems for human aging research

Recent advances in microphysiological systems (MPS), also known as organs-on-a-chip (OoC), enable the recapitulation of more complex organ and tissue functions on a smaller scale in vitro. MPS therefore provide the potential to better understand human diseases and physiology. To date, numerous MPS platforms have been developed for various tissues and organs, including the heart, liver, kidney, blood vessels, muscle, and adipose tissue. However, only a few studies have explored using MPS platforms to unravel the effects of aging on human physiology and the pathogenesis of age-related diseases. Age is one of the risk factors for many diseases, and enormous interest has been devoted to aging research. As such, a human MPS aging model could provide a more predictive tool to understand the molecular and cellular mechanisms underlying human aging and age-related diseases. These models can also be used to evaluate preclinical drugs for age-related diseases and translate them into clinical settings. Here, we provide a review on the application of MPS in aging research. First, we offer an overview of the molecular, cellular, and physiological changes with age in several tissues or organs. Next, we discuss previous aging models and the current state of MPS for studying human aging and age-related conditions. Lastly, we address the limitations of current MPS and present future directions on the potential of MPS platforms for human aging research.

Mechanistic regulation of FOXO transcription factors in the nucleus

FOXO proteins represent evolutionarily conserved transcription factors (TFs) that play critical roles in responding to various physiological signals or pathological stimuli, either through transcription-dependent or -independent mechanisms. Dysfunction of these proteins have been implicated in numerous diseases, including cancer. Although the regulation of FOXO TFs shuttling between the cytoplasm and the nucleus has been extensively studied and reviewed, there's still a lack of a comprehensive review focusing on the intricate interactions between FOXO, DNA, and cofactors in the regulation of gene expression. In this review, we aim to summarize recent advances and provide a detailed understanding of the mechanism underlying FOXO proteins binding to target DNA. Additionally, we will discuss the challenges associated with pharmacological approaches in modulating FOXO function, and explore the dynamic association between TF, DNA, and RNA on chromatin. This review will contribute to a better understanding of mechanistic regulations of eukaryotic TFs within the nucleus.