Repression of P66Shc expression by SIRT1 contributes to the prevention of hyperglycemia-induced endothelial dysfunction

The role of neurovascular coupling dysfunction in cognitive decline of diabetes patients

Neurovascular coupling (NVC) is an important mechanism to ensure adequate blood supply to active neurons in the brain. NVC damage can lead to chronic impairment of neuronal function. Diabetes is characterized by high blood sugar and is considered an important risk factor for cognitive impairment. In this review, we provide fMRI evidence of NVC damage in diabetic patients with cognitive decline. Combined with the exploration of the major mechanisms and signaling pathways of NVC, we discuss the effects of chronic hyperglycemia on the cellular structure of NVC signaling, including key receptors, ion channels, and intercellular connections. Studying these diabetes-related changes in cell structure will help us understand the underlying causes behind diabetes-induced NVC damage and early cognitive decline, ultimately helping to identify the most effective drug targets for treatment.

The p66Shc Redox Protein and the Emerging Complications of Diabetes

Diabetes mellitus is a chronic metabolic disease, the prevalence of which is constantly increasing worldwide. It is often burdened by disabling comorbidities that reduce the quality and expectancy of life of the affected individuals. The traditional complications of diabetes are generally described as macrovascular complications (e.g., coronary heart disease, peripheral arterial disease, and stroke), and microvascular complications (e.g., diabetic kidney disease, retinopathy, and neuropathy). Recently, due to advances in diabetes management and the increased life expectancy of diabetic patients, a strong correlation between diabetes and other pathological conditions (such as liver diseases, cancer, neurodegenerative diseases, cognitive impairments, and sleep disorders) has emerged. Therefore, these comorbidities have been proposed as emerging complications of diabetes. P66Shc is a redox protein that plays a role in oxidative stress, apoptosis, glucose metabolism, and cellular aging. It can be regulated by various stressful stimuli typical of the diabetic milieu and is involved in various types of organ and tissue damage under diabetic conditions. Although its role in the pathogenesis of diabetes remains controversial, there is strong evidence regarding the involvement of p66Shc in the traditional complications of diabetes. In this review, we will summarize the evidence supporting the role of p66Shc in the pathogenesis of diabetes and its complications, focusing for the first time on the emerging complications of diabetes.

Oxidative Stress and Its Regulation in Diabetic Retinopathy

Diabetic retinopathy is the retinal disease associated with hyperglycemia in patients who suffer from type 1 or type 2 diabetes. It includes maculopathy, involving the central retina and characterized by ischemia and/or edema, and peripheral retinopathy that progresses to a proliferative stage with neovascularization. Approximately 10% of the global population is estimated to suffer from diabetes, and around one in 5 of these individuals have diabetic retinopathy. One of the major effects of hyperglycemia is oxidative stress, the pathological state in which elevated production of reactive oxygen species damages tissues, cells, and macromolecules. The retina is relatively prone to oxidative stress due to its high metabolic activity. This review provides a summary of the role of oxidative stress in diabetic retinopathy, including a description of the retinal cell players and the molecular mechanisms. It discusses pathological processes, including the formation and effects of advanced glycation end-products, the impact of metabolic memory, and involvements of non-coding RNA. The opportunities for the therapeutic blockade of oxidative stress in diabetic retinopathy are also considered.

Sirtuin 2 deficiency aggravates ageing-induced vascular remodelling in humans and mice

AIMS

The mechanisms underlying ageing-induced vascular remodelling remain unclear. This study investigates the role and underlying mechanisms of the cytoplasmic deacetylase sirtuin 2 (SIRT2) in ageing-induced vascular remodelling.

METHODS AND RESULTS

Transcriptome and quantitative real-time PCR data were used to analyse sirtuin expression. Young and old wild-type and Sirt2 knockout mice were used to explore vascular function and pathological remodelling. RNA-seq, histochemical staining, and biochemical assays were used to evaluate the effects of Sirt2 knockout on the vascular transcriptome and pathological remodelling and explore the underlying biochemical mechanisms. Among the sirtuins, SIRT2 had the highest levels in human and mouse aortas. Sirtuin 2 activity was reduced in aged aortas, and loss of SIRT2 accelerated vascular ageing. In old mice, SIRT2 deficiency aggravated ageing-induced arterial stiffness and constriction-relaxation dysfunction, accompanied by aortic remodelling (thickened vascular medial layers, breakage of elastin fibres, collagen deposition, and inflammation). Transcriptome and biochemical analyses revealed that the ageing-controlling protein p66Shc and metabolism of mitochondrial reactive oxygen species (mROS) contributed to SIRT2 function in vascular ageing. Sirtuin 2 repressed p66Shc activation and mROS production by deacetylating p66Shc at lysine 81. Elimination of reactive oxygen species by MnTBAP repressed the SIRT2 deficiency-mediated aggravation of vascular remodelling and dysfunction in angiotensin II-challenged and aged mice. The SIRT2 coexpression module in aortas was reduced with ageing across species and was a significant predictor of age-related aortic diseases in humans.

CONCLUSION

The deacetylase SIRT2 is a response to ageing that delays vascular ageing, and the cytoplasm-mitochondria axis (SIRT2-p66Shc-mROS) is important for vascular ageing. Therefore, SIRT2 may serve as a potential therapeutic target for vascular rejuvenation.

Exploring Edible Mushrooms for Diabetes: Unveiling Their Role in Prevention and Treatment

Diabetes mellitus is a complex illness in which the body does not create enough insulin to control blood glucose levels. Worldwide, this disease is life-threatening and requires low-cost, side-effect-free medicine. Due to adverse effects, many synthetic hypoglycemic medications for diabetes fail. Mushrooms are known to contain natural bioactive components that may be anti-diabetic; thus, scientists are now targeting them. Mushroom extracts, which improve immune function and fight cancer, are becoming more popular. Mushroom-derived functional foods and dietary supplements can delay the onset of potentially fatal diseases and help treat pre-existing conditions, which leads to the successful prevention and treatment of type 2 diabetes, which is restricted to the breakdown of complex polysaccharides by pancreatic-amylase and the suppression of intestinal-glucosidase. Many mushroom species are particularly helpful in lowering blood glucose levels and alleviating diabetes symptoms. Hypoglycaemic effects have been observed in investigations on Agaricussu brufescens, Agaricus bisporus, Cordyceps sinensis, Inonotus obliqus, Coprinus comatus, Ganoderma lucidum, Phellinus linteus, Pleurotus spp., Poria cocos, and Sparassis crispa. For diabetics, edible mushrooms are high in protein, vitamins, and minerals and low in fat and cholesterol. The study found that bioactive metabolites isolated from mushrooms, such as polysaccharides, proteins, dietary fibers, and many pharmacologically active compounds, as well as solvent extracts of mushrooms with unknown metabolites, have anti-diabetic potential in vivo and in vitro, though few are in clinical trials.

Phosphoglycerate dehydrogenase activates PKM2 to phosphorylate histone H3T11 and attenuate cellular senescence

Vascular endothelial cells (ECs) senescence correlates with the increase of cardiovascular diseases in ageing population. Although ECs rely on glycolysis for energy production, little is known about the role of glycolysis in ECs senescence. Here, we report a critical role for glycolysis-derived serine biosynthesis in preventing ECs senescence. During senescence, the expression of serine biosynthetic enzyme PHGDH is significantly reduced due to decreased transcription of the activating transcription factor ATF4, which leads to reduction of intracellular serine. PHGDH prevents premature senescence primarily by enhancing the stability and activity of pyruvate kinase M2 (PKM2). Mechanistically, PHGDH interacts with PKM2, which prevents PCAF-catalyzed PKM2 K305 acetylation and subsequent degradation by autophagy. In addition, PHGDH facilitates p300-catalyzed PKM2 K433 acetylation, which promotes PKM2 nuclear translocation and stimulates its activity to phosphorylate H3T11 and regulate the transcription of senescence-associated genes. Vascular endothelium-targeted expression of PHGDH and PKM2 ameliorates ageing in mice. Our findings reveal that enhancing serine biosynthesis could become a therapy to promote healthy ageing.

Endothelial Dysfunction and Chronic Inflammation: The Cornerstones of Vascular Alterations in Age-Related Diseases

Vascular diseases of the elderly are a topic of enormous interest in clinical practice, as they have great epidemiological significance and lead to ever-increasing healthcare expenditures. The mechanisms underlying these pathologies have been increasingly characterized over the years. It has emerged that endothelial dysfunction and chronic inflammation play a diriment role among the most relevant pathophysiological mechanisms. As one can easily imagine, various processes occur during aging, and several pathways undergo irreversible alterations that can promote the decline and aberrations that trigger the diseases above. Endothelial dysfunction and aging of circulating and resident cells are the main characteristics of the aged organism; they represent the framework within which an enormous array of molecular abnormalities occur and contribute to accelerating and perpetuating the decline of organs and tissues. Recognizing and detailing each of these dysfunctional pathways is helpful for therapeutic purposes, as it allows one to hypothesize the possibility of tailoring interventions to the damaged mechanism and hypothetically limiting the cascade of events that drive the onset of these diseases. With this paper, we have reviewed the scientific literature, analysing the pathophysiological basis of the vascular diseases of the elderly and pausing to reflect on attempts to interrupt the vicious cycle that connotes the diseases of aging, laying the groundwork for therapeutic reasoning and expanding the field of scientific research by moving from a solid foundation.

USP15 regulates p66Shc stability associated with Drp1 activation in liver ischemia/reperfusion

Liver ischemia/reperfusion (I/R) injury is a major clinical concern of liver transplantation, which accounts for organ rejection and liver dysfunction. The adaptor protein p66Shc acts as a crucial redox enzyme and is implicated in liver I/R. Elevated p66Shc expression is associated with hepatocellular apoptosis in liver I/R, but the molecular mechanisms of p66Shc responsible for its aberrant expression and function remain unknown. In the present study, hepatocyte-specific p66Shc-knockdown mice exhibited clear inhibition in hepatocellular apoptosis and oxidative stress under liver I/R, while hepatocyte-specific p66Shc overexpression mice displayed the deteriorative impairment. Mechanistically, p66Shc-triggered mitochondrial fission and apoptosis in liver I/R by mediating ROS-driven Drp1 activation. Furthermore, a screening for p66Shc-interacting proteins identified ubiquitin-specific protease 15 (USP15) as a mediator critical for abnormal p66Shc expression. Specifically, USP15 interacted with the SH2 domain of p66Shc and maintained its stabilization by removing ubiquitin. In vivo, p66Shc knockdown abrogated USP15-driven hepatocellular apoptosis, whereas p66Shc overexpression counteracted the antiapoptotic effect of USP15 silencing in response to liver I/R. There was clinical evidence for the positive association between p66Shc and USP15 in patients undergoing liver transplantation. In summary, p66Shc contributes to mitochondrial fission and apoptosis associated with Drp1 activation, and abnormal p66Shc expression relies on the activity of USP15 deubiquitination under liver I/R. The current study sheds new light on the molecular mechanism of p66Shc, and identifies USP15 as a novel mediator of p66Shc to facilitate better therapeutics against liver I/R.

Factors and Pathways Modulating Endothelial Cell Senescence in Vascular Aging

Aging causes a progressive decline in the structure and function of organs. With advancing age, an accumulation of senescent endothelial cells (ECs) contributes to the risk of developing vascular dysfunction and cardiovascular diseases, including hypertension, diabetes, atherosclerosis, and neurodegeneration. Senescent ECs undergo phenotypic changes that alter the pattern of expressed proteins, as well as their morphologies and functions, and have been linked to vascular impairments, such as aortic stiffness, enhanced inflammation, and dysregulated vascular tone. Numerous molecules and pathways, including sirtuins, Klotho, RAAS, IGFBP, NRF2, and mTOR, have been implicated in promoting EC senescence. This review summarizes the molecular players and signaling pathways driving EC senescence and identifies targets with possible therapeutic value in age-related vascular diseases.

Targeting SIRT1 Rescues Age- and Obesity-Induced Microvascular Dysfunction in Ex Vivo Human Vessels

BACKGROUND

Experimental evidence suggests a key role of SIRT1 (silent information regulator 1) in age- and metabolic-related vascular dysfunction. Whether these effects hold true in the human microvasculature is unknown. We aimed to investigate the SIRT1 role in very early stages of age- and obesity-related microvascular dysfunction in humans.

METHODS

Ninety-five subjects undergoing elective laparoscopic surgery were recruited and stratified based on their body mass index status (above or below 30 kg/m²) and age (above or below 40 years) in 4 groups: Young Nonobese, Young Obese, Old Nonobese, and Old Obese. We measured small resistance arteries' endothelial function by pressurized micromyography before and after incubation with a SIRT1 agonist (SRT1720) and a mitochondria reactive oxygen species (mtROS) scavenger (MitoTEMPO). We assessed vascular levels of mtROS and nitric oxide availability by confocal microscopy and vascular gene expression of SIRT1 and mitochondrial proteins by qPCR. Chromatin immunoprecipitation assay was employed to investigate SIRT1-dependent epigenetic regulation of mitochondrial proteins.

RESULTS

Compared with Young Nonobese, obese and older patients showed lower vascular expression of SIRT1 and antioxidant proteins (FOXO3 [forkhead box protein O3] and SOD2) and higher expression of pro-oxidant and aging mitochondria proteins p66^Shc and Arginase II. Old Obese, Young Obese and Old Nonobese groups endothelial dysfunction was rescued by SRT1720. The restoration was comparable to the one obtained with mitoTEMPO. These effects were explained by SIRT1-dependent chromatin changes leading to reduced p66^Shc expression and upregulation of proteins involved in mitochondria respiratory chain.

CONCLUSIONS

SIRT1 is a novel central modulator of the earliest microvascular damage induced by age and obesity. Through a complex epigenetic control mainly involving p66^Shc and Arginase II, it influences mtROS levels, NO availability, and the expression of proteins of the mitochondria respiratory chain. Therapeutic modulation of SIRT1 restores obesity- and age-related endothelial dysfunction. Early targeting of SIRT1 might represent a crucial strategy to prevent age- and obesity-related microvascular dysfunction.

The mechanisms of glycolipid metabolism disorder on vascular injury in type 2 diabetes

Patients with diabetes have severe vascular complications, such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, and neuropathy. Devastating vascular complications lead to increased mortality, blindness, kidney failure, and decreased overall quality of life in people with type 2 diabetes (T2D). Glycolipid metabolism disorder plays a vital role in the vascular complications of T2D. However, the specific mechanism of action remains to be elucidated. In T2D patients, vascular damage begins to develop before insulin resistance and clinical diagnosis. Endothelial dysregulation is a significant cause of vascular complications and the early event of vascular injury. Hyperglycemia and hyperlipidemia can trigger inflammation and oxidative stress, which impair endothelial function. Furthermore, during the pathogenesis of T2D, epigenetic modifications are aberrant and activate various biological processes, resulting in endothelial dysregulation. In the present review, we provide an overview and discussion of the roles of hyperglycemia- and hyperlipidemia-induced endothelial dysfunction, inflammatory response, oxidative stress, and epigenetic modification in the pathogenesis of T2D. Understanding the connections of glucotoxicity and lipotoxicity with vascular injury may reveal a novel potential therapeutic target for diabetic vascular complications.

Oxidative stress and inflammation regulation of sirtuins: New insights into common oral diseases

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)⁺-dependent histone deacetylases, comprising seven members SIRT1-SIRT7. Sirtuins have been extensively studied in regulating ageing and age-related diseases. Sirtuins are also pivotal modulators in oxidative stress and inflammation, as they can regulate the expression and activation of downstream transcriptional factors (such as Forkhead box protein O3 (FOXO3a), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB)) as well as antioxidant enzymes, through epigenetic modification and post-translational modification. Most importantly, studies have shown that aberrant sirtuins are involved in the pathogenesis of infectious and inflammatory oral diseases, and oral cancer. In this review, we provide a comprehensive overview of the regulatory patterns of sirtuins at multiple levels, and the essential roles of sirtuins in regulating inflammation, oxidative stress, and bone metabolism. We summarize the involvement of sirtuins in several oral diseases such as periodontitis, apical periodontitis, pulpitis, oral candidiasis, oral herpesvirus infections, dental fluorosis, and oral cancer. At last, we discuss the potential utilization of sirtuins as therapeutic targets in oral diseases.

Theories and Molecular Basis of Vascular Aging: A Review of the Literature from VascAgeNet Group on Pathophysiological Mechanisms of Vascular Aging

Vascular aging, characterized by structural and functional alterations of the vascular wall, is a hallmark of aging and is tightly related to the development of cardiovascular mortality and age-associated vascular pathologies. Over the last years, extensive and ongoing research has highlighted several sophisticated molecular mechanisms that are involved in the pathophysiology of vascular aging. A more thorough understanding of these mechanisms could help to provide a new insight into the complex biology of this non-reversible vascular process and direct future interventions to improve longevity. In this review, we discuss the role of the most important molecular pathways involved in vascular ageing including oxidative stress, vascular inflammation, extracellular matrix metalloproteinases activity, epigenetic regulation, telomere shortening, senescence and autophagy.

Epigenetic modifications in metabolic memory: What are the memories, and can we erase them?

Inherent and acquired abnormalities in gene regulation due to the influence of genetics and epigenetics (traits related to environment rather than genetic factors) underly many diseases including diabetes. Diabetes could lead to multiple complications including retinopathy, nephropathy and cardiovascular disease that greatly increase morbidity and mortality. Epigenetic changes have also been linked to diabetes-related complications. Genes associated with many pathophysiological features of these vascular complications (e.g., inflammation, fibrosis, and oxidative stress) can be regulated by epigenetic mechanisms involving histone posttranslational modifications, DNA methylation, changes in chromatin structure/remodeling and noncoding RNAs. Intriguingly, these epigenetic changes triggered during early periods of hyperglycemic exposure and uncontrolled diabetes are not immediately corrected even after restoration of normoglycemia and metabolic balance. This latency in effect across time and conditions is associated with persistent development of complications in diabetes with prior history of poor glycemic control, termed as metabolic memory or legacy effect. Epigenetic modifications are generally reversible and provide a window of therapeutic opportunity to ameliorate cellular dysfunction and mitigate or 'erase' metabolic memory. Notably, trained immunity and related epigenetic changes transmitted from hematopoietic stem cells to innate immune cells have also been implicated in metabolic memory. Hence, identification of epigenetic variations at candidate genes, or epigenetic signatures genome-wide by epigenome-wide association studies can aid in prompt diagnosis to prevent progression of complications and identification of much-needed new therapeutic targets. Herein, we provide a review of epigenetics and epigenomics in metabolic memory of diabetic complications covering the current basic research, clinical data, and translational implications.

p66Shc in Cardiovascular Pathology

p66Shc is a widely expressed protein that governs a variety of cardiovascular pathologies by generating, and exacerbating, pro-apoptotic ROS signals. Here, we review p66Shc’s connections to reactive oxygen species, expression, localization, and discuss p66Shc signaling and mitochondrial functions. Emphasis is placed on recent p66Shc mitochondrial function discoveries including structure/function relationships, ROS identity and regulation, mechanistic insights, and how p66Shc-cyt c interactions can influence p66Shc mitochondrial function. Based on recent findings, a new p66Shc mitochondrial function model is also put forth wherein p66Shc acts as a rheostat that can promote or antagonize apoptosis. A discussion of how the revised p66Shc model fits previous findings in p66Shc-mediated cardiovascular pathology follows.

Effect of exercise and curcumin on cardiomyocyte molecular mediators associated with oxidative stress and autophagy in aged male rats

AIM

Aging can origin changes in the heart that may increase risk of developing cardiovascular disease. This study aimed to characterize autophagy alterations and related molecular mediators in the heart tissue in the aging alone or in combination with exercise and curcumin treatment.

METHODS

Seven young and twenty-eight elderly male Wistar rats were assigned into five groups, namely: young control, age, exercise, curcumin, and curcumin+exercise. Aged rats in exercise group run on treadmill (17 m/min) and in the curcumin group received curcumin (50 mg/kg) by gavage daily for 8 weeks for 2 months. At the end, heart samples were collected and used for determination of autophagy by immunostaining for LC3-phosphatidylethanolamine conjugate (LC3-II), apoptosis by TUNEL assay, Malondialdehyde (MDA) level by enzymatic assay and determination of mediators' molecules by ELISA for NADPH Oxidase 4 (NOX4), sirtuin 1 (SIRT-1), phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-Ƙb) protein levels and Sequestosome-1 (P62). Also, histological changes such as fibrosis evaluated by Masson trichrome staining.

RESULTS

Our results showed that autophagy, SIRT-1 level were significantly decreased and MDA, NOX4, p-NF-Ƙb and P62 levels were significantly increased in heart of aged group compared to young group. Also, significant increased apoptosis and fibrosis levels in the heart of aged rats were observed compared with young rats, whereas, these undesirable changes were improved by exercise and curcumin. Also, combination therapy of aged rats with curcumin and exercise showed more significant prominent effect on molecular mediators and histological changes in the heart compared with monotherapy.

CONCLUSION

These findings indicate that stress oxidative increase and autophagy decrease in the heart tissue of aged rats. The age induced the mentioned changes in the heart may in part be associated with down-expression of SIRT-1 and overexpression of NOX4 proteins. It was also showed that these age induced effects can be alleviated by treatment with exercise and curcumin. Since NF-Ƙb increased in both the age and treatment groups, it seems the age heart increased NF-Ƙb to be due to a compensatory mechanism.

Cerebral Microvascular Senescence and Inflammation in Diabetes

Stress-induced premature senescence can contribute to the accelerated metabolic aging process in diabetes. Progressive accumulation of senescent cells in the brain, especially those displaying the harmful inflammatory senescence-associated secretory phenotype (SASP), may lead to cognitive impairment linked with metabolic disturbances. In this context, the senescence within the neurovascular unit (NVU) should be studied as much as in the neurons as emerging evidence shows that neurogliovascular communication is critical for brain health. It is also known that cerebrovascular dysfunction and decreased cerebral blood flow (CBF) precede the occurrence of neuronal pathologies and overt cognitive impairment. Various studies have shown that endothelial cells, the major component of the NVU, acquire a senescent phenotype via various molecular mediators and pathways upon exposure to high glucose and other conditions mimicking metabolic disturbances. In addition, senescence in the other cells that are part of the NVU, like pericytes and vascular smooth cells, was also triggered upon exposure to diabetic conditions. The senescence within the NVU may compromise functional and trophic coupling among glial, vascular, and neuronal cells and the resulting SASP may contribute to the chronic neurovascular inflammation observed in Alzheimer's Disease and Related Dementias (ADRD). The link between diabetes-mediated cerebral microvascular dysfunction, NVU senescence, inflammation, and cognitive impairment must be widely studied to design therapeutic strategies.

Epigenetic Modifications and Non-Coding RNA in Diabetes-Mellitus-Induced Coronary Artery Disease: Pathophysiological Link and New Therapeutic Frontiers

Diabetes mellitus (DM) is a glucose metabolism disorder characterized by chronic hyperglycemia resulting from a deficit of insulin production and/or action. DM affects more than 1 in 10 adults, and it is associated with an increased risk of cardiovascular morbidity and mortality. Cardiovascular disease (CVD) accounts for two thirds of the overall deaths in diabetic patients, with coronary artery disease (CAD) and ischemic cardiomyopathy as the main contributors. Hyperglycemic damage on vascular endothelial cells leading to endothelial dysfunction represents the main initiating factor in the pathogenesis of diabetic vascular complications; however, the underlying pathophysiological mechanisms are still not entirely understood. This review addresses the current knowledge on the pathophysiological links between DM and CAD with a focus on the role of epigenetic modifications, including DNA methylation, histone modifications and noncoding RNA control. Increased knowledge of epigenetic mechanisms has contributed to the development of new pharmacological treatments (“epidrugs”) with epigenetic targets, although these approaches present several challenges. Specific epigenetic biomarkers may also be used to predict or detect the development and progression of diabetes complications. Further studies on diabetes and CAD epigenetics are needed in order to identify possible new therapeutic targets and advance personalized medicine with the prediction of individual drug responses and minimization of adverse effects.

Melatonin alleviates hydrogen peroxide induced oxidative damage in MC3T3-E1 cells and promotes osteogenesis by activating SIRT1

Oxidative stress is an important contributor to the development of osteoporosis. Melatonin, an indoleamine secreted by the pineal gland, has antioxidant properties. This study aims to explore whether melatonin can promote bone formation and elucidate the mechanisms underlying this process. In this study, we used an in vitro hydrogen peroxide (H₂O₂)-induced oxidative stress model in MC3T3-E1 cells and an in vivo ovariectomized osteoporotic bone defect model in rats to explore the protective effects of melatonin against osteoporotic bone defects along with the mechanism underlying these effects. We found that melatonin significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of BMP2, RUNX2, and OPN in MC3T3-E1 cells treated with H₂O₂. Furthermore, melatonin was found to activate SIRT1, SIRT3 and inhibit p66Shc, reduce the intracellular reactive oxygen species levels, stabilize mitochondria, reduce malondialdehyde levels, increase superoxide dismutase activity, and reduce apoptosis in MC3T3-E1 cells treated with H₂O₂. Intriguingly, these effects could be reversed by the SIRT1 inhibitor EX527. In vivo experiments confirmed that melatonin improves the microstructure and bone mineral density of the distal femoral bone trabecula and promotes bone formation. Meanwhile, melatonin activated SIRT1, inhibited p66Shc and increased SIRT3 expression. Taken together, our findings showed that melatonin can restrain oxidative damage in MC3T3-E1 cells and promote osteogenesis by activating SIRT1 which regulate the activity of SIRT3 and inhibit the expression of p66Shc, suggesting that melatonin could be a potential therapeutic agent for osteoporosis-related bone metabolic diseases.

The Role of p66Shc in Diabetes: A Comprehensive Review from Bench to Bedside

It is well-documented that diabetes is an inflammatory and oxidative disease, with an escalating global burden. Still, there is no definite treatment for diabetes or even prevention of its harmful complications. Therefore, understanding the molecular pathways associated with diabetes might help in finding a solution. p66Shc is a member of Shc family proteins, and it is considered as an oxidative stress sensor and regulator in cells. There are inconsistent data about the role of p66Shc in inducing diabetes, but accumulating evidence supports its role in the pathogenesis of diabetes-related complications, including macro and microangiopathies. There is growing hope that by understanding and targeting molecular pathways involved in this network, prevention of diabetes or its complications would be achievable. This review provides an overview about the role of p66Shc in the development of diabetes and its complications.

SIRT6 in Vascular Diseases, from Bench to Bedside

Aging is a key risk factor for angiogenic dysfunction and cardiovascular diseases, including heart failure, hypertension, atherosclerosis, diabetes, and stroke. Members of the NAD⁺-dependent class III histone deacetylase family, sirtuins, are conserved regulators of aging and cardiovascular and cerebrovascular diseases. The sirtuin SIRT6 is predominantly located in the nucleus and shows deacetylase activity for acetylated histone 3 lysine 56 and lysine 9 as well as for some non-histone proteins. Over the past decade, experimental analyses in rodents and non-human primates have demonstrated the critical role of SIRT6 in extending lifespan. Recent studies highlighted the pleiotropic protective actions of SIRT6 in angiogenesis and cardiovascular diseases, including atherosclerosis, hypertension, heart failure, and stroke. Mechanistically, SIRT6 participates in vascular diseases via epigenetic regulation of endothelial cells, vascular smooth muscle cells, and immune cells. Importantly, SIRT6 activators (e.g., MDL-800/MDL-811) have provided therapeutic value for treating age-related vascular disorders. Here, we summarized the roles of sirtuins in cardiovascular diseases; reviewed recent advances in the understanding of SIRT6 in vascular biology, cardiovascular aging, and diseases; highlighted its therapeutic potential; and discussed future perspectives.

Epigenetics in the pathogenesis of diabetic nephropathy

Diabetic nephropathy (DN), which is a common microvascular complication with a high incidence in diabetic patients, greatly increases the mortality of patients. With further study on DN, it is found that epigenetics plays a crucial role in the pathophysiological process of DN. Epigenetics has an important impact on the development of DN through a variety of mechanisms, and promotes the generation and maintenance of metabolic memory, thus ultimately leading to a poor prognosis. In this review we discuss the methylation of DNA, modification of histone, and regulation of non-coding RNA involved in the progress of cell dysfunction, inflammation and fibrosis in the kidney, which ultimately lead to the deterioration of DN.

Dysfunctional Vascular Endothelium as a Driver of Atherosclerosis: Emerging Insights Into Pathogenesis and Treatment

Atherosclerosis, the chronic accumulation of cholesterol-rich plaque within arteries, is associated with a broad spectrum of cardiovascular diseases including myocardial infarction, aortic aneurysm, peripheral vascular disease, and stroke. Atherosclerotic cardiovascular disease remains a leading cause of mortality in high-income countries and recent years have witnessed a notable increase in prevalence within low- and middle-income regions of the world. Considering this prominent and evolving global burden, there is a need to identify the cellular mechanisms that underlie the pathogenesis of atherosclerosis to discover novel therapeutic targets for preventing or mitigating its clinical sequelae. Despite decades of research, we still do not fully understand the complex cell-cell interactions that drive atherosclerosis, but new investigative approaches are rapidly shedding light on these essential mechanisms. The vascular endothelium resides at the interface of systemic circulation and the underlying vessel wall and plays an essential role in governing pathophysiological processes during atherogenesis. In this review, we present emerging evidence that implicates the activated endothelium as a driver of atherosclerosis by directing site-specificity of plaque formation and by promoting plaque development through intracellular processes, which regulate endothelial cell proliferation and turnover, metabolism, permeability, and plasticity. Moreover, we highlight novel mechanisms of intercellular communication by which endothelial cells modulate the activity of key vascular cell populations involved in atherogenesis, and discuss how endothelial cells contribute to resolution biology - a process that is dysregulated in advanced plaques. Finally, we describe important future directions for preclinical atherosclerosis research, including epigenetic and targeted therapies, to limit the progression of atherosclerosis in at-risk or affected patients.

Therapeutic potential of resveratrol in diabetic nephropathy according to molecular signaling

BACKGROUND

Diabetic nephropathy (DN) as a severe complication of diabetes mellitus (DM), is a crucial menace for human health and survival and remarkably elevates the healthcare systems' costs. Therefore, it is worth noting to identify novel preventive and therapeutic strategies to alleviate the disease conditions. Resveratrol, as a well-defined anti-diabetic/ antioxidant agent has capabilities to counteract diabetic complications. It has been predicted that resveratrol will be a fantastic natural polyphenol for diabetes therapy in the next few years.

OBJECTIVE

Accordingly, the current review aims to depict the role of resveratrol in the regulation of different signaling pathways that are involved in the reactive oxygen species (ROS) production, inflammatory processes, autophagy, and mitochondrial dysfunction, as critical contributors to DN pathophysiology.

RESULTS

The pathogenesis of DN can be multifactorial; hyperglycemia is one of the prominent risk factors of DN development that is closely related to oxidative stress. Resveratrol, as a well-defined polyphenol, has various biological and medicinal properties, including anti-diabetic, anti-inflammatory, and anti-oxidative effects.

CONCLUSION

Resveratrol prevents kidney damages that are caused by oxidative stress, enhances antioxidant capacity, and attenuates the inflammatory and fibrotic responses. For this reason, resveratrol is considered an interesting target in DN research due to its therapeutic possibilities during diabetic disorders and renal protection.

Endothelial SIRT1 as a Target for the Prevention of Arterial Aging: Promises and Challenges

ABSTRACT

SIRT1, a member of the sirtuin family of longevity regulators, possesses potent activities preventing vascular aging. The expression and function of SIRT1 in endothelial cells are downregulated with age, in turn causing early vascular aging and predisposing various vascular abnormalities. Overexpression of SIRT1 in the vascular endothelium prevents aging-associated endothelial dysfunction and senescence, thus the development of hypertension and atherosclerosis. Numerous efforts have been directed to increase SIRT1 signaling as a potential strategy for different aging-associated diseases. However, the complex mechanisms underlying the regulation of SIRT1 have posed a significant challenge toward the design of specific and effective therapeutics. This review aimed to provide a summary on the regulation and function of SIRT1 in the vascular endothelium and to discuss the different approaches targeting this molecule for the prevention and treatment of age-related cardiovascular and cerebrovascular diseases.

Up-regulation of GLP-1R improved the dysfunction of late EPCs under hyperglycemia by regulating SIRT1 expression

The dysfunction of endothelial progenitor cells (EPCs) is closely associated with diabetic vascular complications. Both glucagonlike peptide-1 receptor (GLP-1R) and silent information regulator 1 (SIRT1) can control systemic glucose homeostasis and protect endothelial cells against hyperglycemia-induced oxidative stress. In this study, we mainly assessed the role played by SIRT1 and GLP-1R and their relationship in regulating the function of late EPCs under hyperglycemia stimulation. Human peripheral blood mononuclear cells (PBMCs) were cultured in EGM-2 medium and induced to differentiate into EPCs and 25 mM glucose was used to stimulate EPCs to obtain a hyperglycemia condition. Subsequently, the expression and location of GLP-1R and SIRT1 in EPCs were detected. After GLP-1R or SIRT1 knockdown, or the treatment by GLP-1R agonist and/or SIRT1 agonist/inhibitor, the effects of SIRT1 and GLP-1R and their relationship in regulating the function of late EPCs under hyperglycemia stimulation was studied by detecting the apoptosis, migration, adhesion and angiogenicity abilities of EPCs. Results demonstrated that, in high-glucose stimulated EPCs, the expression of GLP-1R and SIRT1 was down-regulated. The knockdown of either GLP-1R or SIRT1 could increase EPCs apoptosis and weaken the migration, adhesion and angiogenicity abilities of EPCs. In addition, the improvement effects of Exendin-4 or GLP-1R over-expression on EPCs dysfunction could be weakened to some degree under SIRT1 knockdown. In conclusion, both GLP-1R and SIRT1 expression played important roles in regulating EPCs dysfunction under hyperglycemia and the up-regulation of GLP-1R improved the dysfunction of late EPCs by regulating SIRT1 expression.

p66Shc-mediated oxidative stress is involved in gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a heightened level of oxidative stress, which is characterized by the overproduction of reactive oxygen species (ROS) from mitochondria. Previous studies showed that mitochondrial dysfunction is regulated by dynamin-related protein 1 (Drp1) and p66Shc in GDM.

AIM

The aim was to investigate the expression of Drp1 and p66Shc and their possible mechanisms in the pathogenesis of GDM.

METHODS

A total of 30 pregnant women, 15 with GDM and 15 without GDM, were enrolled. Peripheral blood mononuclear cells and placental tissue were collected. The human JEG3 trophoblast cell line was cultivated in 5.5 mmol/L or 30 mmol/L glucose and transfected with wild-type (wt)-p66Shc and p66Shc siRNA. P66Shc and Drp1 mRNA levels were detected by quantitative real-time polymerase chain reaction. The expression of p66Shc and Drp1 was assayed by immunohistochemistry and western blotting. ROS was assayed by dihydroethidium staining.

RESULTS

The p66Shc mRNA level was increased in the serum (P < 0.01) and placentas (P < 0.01) of women with GDM, and the expression of Drp1 mRNA and protein were also increased in placentas (P < 0.05). In JEG3 cells treated with 30 mmol/L glucose, the mRNA and protein expression of p66Shc and Drp1 were increased at 24 h (both P < 0.05), 48 h (both P < 0.01) and 72 h (both P < 0.001). ROS expression was also increased. High levels of Drp1 and ROS expression were detected in JEG3 cells transfected with wt-p66Shc (P < 0.01), and low levels were detected in JEG3 cells transfected with p66Shc siRNA (P < 0.05).

CONCLUSION

The upregulated expression of Drp1 and p66shc may contribute to the occurrence and development of GDM. Regulation of the mitochondrial fusion-fission balance could be a novel strategy for GDM treatment.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Sirtuin1 in vascular endothelial function, an overview

Sirtuin1 is a nutrient-sensitive class III histone deacetylase which is a well-known regulator of organismal lifespan. It has been extensively studied for its role in metabolic regulation as well. Along with its involvement in ageing and metabolism, Sirtuin1 directly deacetylates many critical proteins controlling cardiovascular pathophysiology. Studies using conditional expression and deletion of Sirtuin1 have revealed that it functions in a highly tissue/organ-specific manner. In the vasculature, Sirtuin1 controls endothelial homoeostasis by governing the expression of inflammatory mediators, oxidants and essential transcription factors. Adding to this complexity, Sirtuin1 expression and/or function is also governed by some of these target proteins. Therefore, the importance of better understanding the organ and tissue specificity of Sirtuin1 is highly desirable. Considering the huge volume of research done in this field, this review focuses on Sirtuin1 targets regulating vascular endothelial function. Here, we summarize the discovery of Sirtuin1 as a transcription controller and the further identification of direct target proteins involved in the vascular physiology. Overall, this review presents a holistic picture of the complex cross-talk involved in the molecular regulation of vascular physiology by Sirtuin1.

Lower p66Shc promoter methylation in subjects with chronic renal failure

Objective

To determine the correlation between DNA methylation of p66Shc promoter and some markers of inflammatory and oxidative stress in chronic renal failure (CRF) patients compared with healthy subjects.

Methods

An observational cross-sectional study was conducted in the nephrology department at Sidi Bouzid Regional Hospital (Tunisia). In total, 39 patients with CRF and 37 healthy subjects were included. Several biochemical parameters were measured. Furthermore, markers of the oxidative and inflammatory status (MDA, TAS, SOD, and CRP) were evaluated. The p66Shc methylation status was determined using the methylation-specific PCR.

Results

Our results showed that levels of blood glucose, urea, creatinine, uric acid, ChT, TG, albuminuria, CRP and MDA were significantly elevated in CRF patients compared to controls. Furthermore, p66Shc promoter region was highly demethylated in CRF patients compared to healthy controls (84% vs 4%). Our data showed a positive correlation between p66Shc hypomethylation and levels of MDA (r = 0.93; p<0, 05) and CRP (r = 0.89; P <0, 05), as well as a significant negative correlation between p66Shc hypomethylation, TAS (r = -0.76; P <0, 05) and SOD (r = -0.77; p<0, 05) levels. Similarly, there was a positive correlation between p66Shc hypomethylation and the disease stages. Importantly, multiple regression analysis showed that p66shc DNA hypomethylation remains strongly correlated with MDA, CRP and stages of CRF.

Conclusion

This study indicates that the DNA hypomethylation of p66shc promoter was correlated with oxidative and inflammatory stress and the disease stages in CRF patients.

Sirtuins and Renal Oxidative Stress

Renal failure is a major health problem that is increasing worldwide. To improve clinical outcomes, we need to understand the basic mechanisms of kidney disease. Aging is a risk factor for the development and progression of kidney disease. Cells develop an imbalance of oxidants and antioxidants as they age, resulting in oxidative stress and the development of kidney damage. Calorie restriction (CR) is recognized as a dietary approach that promotes longevity, reduces oxidative stress, and delays the onset of age-related diseases. Sirtuins, a type of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, are considered to be anti-aging molecules, and CR induces their expression. The sirtuin family consists of seven enzymes (Sirt1–7) that are involved in processes and functions related to antioxidant and oxidative stress, such as DNA damage repair and metabolism through histone and protein deacetylation. In fact, a role for sirtuins in the regulation of antioxidants and redox substances has been suggested. Therefore, the activation of sirtuins in the kidney may represent a novel therapeutic strategy to enhancing resistance to many causative factors in kidney disease through the reduction of oxidative stress. In this review, we discuss the relationship between sirtuins and oxidative stress in renal disease.

Exendin-4 inhibits high glucose-induced oxidative stress in retinal pigment epithelial cells by modulating the expression and activation of p66Shc

PURPOSE

Activation of p⁶⁶Sch, an adaptor protein, is associated with oxidative stress and apoptosis and has been implicated in the pathogenesis of diabetes-induced retinal pigment epithelial cell damage and diabetic retinopathy. Exendin-4 is a glucagon-like protein that protects against diabetic retinopathy, but the mechanism of action is not well understood. This study aimed to investigate whether Exendin-4 could protect against high glucose-induced oxidative stress and apoptosis in the adult human retinal pigment epithelial-19 cell line by modulating levels and activation of p⁶⁶Shc and to study the underlying mechanisms.

MATERIALS AND METHODS

Adult human retinal pigment epithelial-19 cells were cultured under low (5 µM) or high glucose (100 µM) conditions in the presence or absence of Exendin-4 and with or without pre-incubation with Exendin-9-39, a glucagon-like peptide-1 receptor antagonist.

RESULTS

In a dose-dependent manner, Exendin-4 inhibited high glucose-induced cell death and decreased levels of reactive oxygen species, lactate dehydrogenase release, and single single-stranded DNA. At the most effective concentration (100 µM), Exendin-4 reduced mitochondrial levels of phospho-p⁶⁶Shc (Ser³⁶), cytoplasmic levels of cleaved caspase-3 and cytochrome-c, and NADPH oxidase levels in high glucose-treated cells. It also increased levels of glutathione and magnesium superoxide dismutase and protein levels of magnesium superoxide dismutase but downregulated total protein levels of protein kinase-β and p⁶⁶Shc and inhibited c-Jun N-terminal kinase phosphorylation in both low- and high glucose-treated cells. All these Exendin-4 effects, however, were inhibited by Exendin-9-39.

CONCLUSIONS

Exendin-4 protects against high glucose-induced adult human retinal pigment epithelial-19 cell damage by increasing antioxidants, downregulating NADPH, and inhibiting mitochondria-mediated apoptosis, effects that are associated with the inhibition of c-Jun N-terminal kinase and downregulation of protein kinase-β and p⁶⁶Shc.

The Emerging Role of HDACs: Pathology and Therapeutic Targets in Diabetes Mellitus

Diabetes mellitus (DM) is one of the principal manifestations of metabolic syndrome and its prevalence with modern lifestyle is increasing incessantly. Chronic hyperglycemia can induce several vascular complications that were referred to be the major cause of morbidity and mortality in DM. Although several therapeutic targets have been identified and accessed clinically, the imminent risk of DM and its prevalence are still ascending. Substantial pieces of evidence revealed that histone deacetylase (HDAC) isoforms can regulate various molecular activities in DM via epigenetic and post-translational regulation of several transcription factors. To date, 18 HDAC isoforms have been identified in mammals that were categorized into four different classes. Classes I, II, and IV are regarded as classical HDACs, which operate through a Zn-based mechanism. In contrast, class III HDACs or Sirtuins depend on nicotinamide adenine dinucleotide (NAD+) for their molecular activity. Functionally, most of the HDAC isoforms can regulate β cell fate, insulin release, insulin expression and signaling, and glucose metabolism. Moreover, the roles of HDAC members have been implicated in the regulation of oxidative stress, inflammation, apoptosis, fibrosis, and other pathological events, which substantially contribute to diabetes-related vascular dysfunctions. Therefore, HDACs could serve as the potential therapeutic target in DM towards developing novel intervention strategies. This review sheds light on the emerging role of HDACs/isoforms in diabetic pathophysiology and emphasized the scope of their targeting in DM for constituting novel interventional strategies for metabolic disorders/complications.

Prenatal nicotine exposure leads to decreased histone H3 lysine 9 (H3K9) methylation and increased p66shc expression in the neonatal pancreas

Prenatal exposure to nicotine, tobacco's major addictive constituent, has been shown to reduce birth weight and increases apoptosis, oxidative stress, and mitochondrial dysfunction in the postnatal pancreas. Given that upregulated levels of the pro-oxidative adapter protein p66shc is observed in growth-restricted offspring and is linked to beta-cell apoptosis, the goal of this study was to investigate whether alterations in p66shc expression underlie the pancreatic deficits in nicotine-exposed offspring. Maternal administration of nicotine in rats increased p66shc expression in the neonatal pancreas. Similarly, nicotine treatment augmented p66shc expression in INS-1E pancreatic beta cells. Increased p66shc expression was also associated with decreased histone H3 lysine 9 methylation. Finally, nicotine increased the expression of Kdm4c, a key histone lysine demethylase, and decreased Suv39h1, a critical histone lysine methyltransferase. Collectively, these results suggest that upregulation of p66shc through posttranslational histone modifications may underlie the reported adverse outcomes of nicotine exposure on pancreatic function.

Epigenetic Remodeling in Obesity-Related Vascular Disease

Significance: The prevalence of obesity and cardiometabolic phenotypes is alarmingly increasing across the globe and is associated with atherosclerotic vascular complications and high mortality. In spite of multifactorial interventions, vascular residual risk remains high in this patient population, suggesting the need for breakthrough therapies. The mechanisms underpinning obesity-related vascular disease remain elusive and represent an intense area of investigation. Recent Advances: Epigenetic modifications-defined as environmentally induced chemical changes of DNA and histones that do not affect DNA sequence-are emerging as a potent modulator of gene transcription in the vasculature and might significantly contribute to the development of obesity-induced endothelial dysfunction. DNA methylation and histone post-translational modifications cooperate to build complex epigenetic signals, altering transcriptional networks that are implicated in redox homeostasis, mitochondrial function, vascular inflammation, and perivascular fat homeostasis in patients with cardiometabolic disturbances. Critical Issues: Deciphering the epigenetic landscape in the vasculature is extremely challenging due to the complexity of epigenetic signals and their function in regulating transcription. An overview of the most important epigenetic pathways is required to identify potential molecular targets to treat or prevent obesity-related endothelial dysfunction and atherosclerotic disease. This would enable the employment of precision medicine approaches in this setting. Future Directions: Current and future research efforts in this field entail a better definition of the vascular epigenome in obese patients as well as the unveiling of novel, cell-specific chromatin-modifying drugs that are able to erase specific epigenetic signals that are responsible for maladaptive transcriptional alterations and vascular dysfunction in obese patients. Antioxid. Redox Signal. 34, 1165-1199.

The Role of Histone Protein Acetylation in Regulating Endothelial Function

Endothelial cell (EC), consisting of the innermost cellular layer of all types of vessels, is not only a barrier composer but also performing multiple functions in physiological processes. It actively controls the vascular tone and the extravasation of water, solutes, and macromolecules; modulates circulating immune cells as well as platelet and leukocyte recruitment/adhesion and activation. In addition, EC also tightly keeps coagulation/fibrinolysis balance and plays a major role in angiogenesis. Therefore, endothelial dysfunction contributes to the pathogenesis of many diseases. Growing pieces of evidence suggest that histone protein acetylation, an epigenetic mark, is altered in ECs under different conditions, and the acetylation status change at different lysine sites on histone protein plays a key role in endothelial dysfunction and involved in hyperglycemia, hypertension, inflammatory disease, cancer and so on. In this review, we highlight the importance of histone acetylation in regulating endothelial functions and discuss the roles of histone acetylation across the transcriptional unit of protein-coding genes in ECs under different disease-related pathophysiological processes. Since histone acetylation changes are conserved and reversible, the knowledge of histone acetylation in endothelial function regulation could provide insights to develop epigenetic interventions in preventing or treating endothelial dysfunction-related diseases.

Molecular mechanisms of doxorubicin-induced cardiotoxicity: novel roles of sirtuin 1-mediated signaling pathways

Doxorubicin (DOX) is an anthracycline chemotherapy drug used in the treatment of various types of cancer. However, short-term and long-term cardiotoxicity limits the clinical application of DOX. Currently, dexrazoxane is the only approved treatment by the United States Food and Drug Administration to prevent DOX-induced cardiotoxicity. However, a recent study found that pre-treatment with dexrazoxane could not fully improve myocardial toxicity of DOX. Therefore, further targeted cardioprotective prophylaxis and treatment strategies are an urgent requirement for cancer patients receiving DOX treatment to reduce the occurrence of cardiotoxicity. Accumulating evidence manifested that Sirtuin 1 (SIRT1) could play a crucially protective role in heart diseases. Recently, numerous studies have concentrated on the role of SIRT1 in DOX-induced cardiotoxicity, which might be related to the activity and deacetylation of SIRT1 downstream targets. Therefore, the aim of this review was to summarize the recent advances related to the protective effects, mechanisms, and deficiencies in clinical application of SIRT1 in DOX-induced cardiotoxicity. Also, the pharmaceutical preparations that activate SIRT1 and affect DOX-induced cardiotoxicity have been listed in this review.

Mushroom-Derived Medicine? Preclinical Studies Suggest Potential Benefits of Ergothioneine for Cardiometabolic Health

Medicinal use of mushrooms has been documented since ancient times, and in the modern world, mushrooms have a longstanding history of use in Eastern medicine. Recent interest in plant-based diets in Westernized countries has brought increasing attention to the use of mushrooms and mushroom-derived compounds in the prevention and treatment of chronic diseases. Edible mushrooms are the most abundant food sources of the modified amino acid, ergothioneine. This compound has been shown to accumulate in almost all cells and tissues, but preferentially in those exposed to oxidative stress and injury. The demonstrated cytoprotectant effect of ergothioneine has led many to suggest a potential therapeutic role for this compound in chronic conditions that involve ongoing oxidative stress and inflammation, including cardiovascular and metabolic diseases. However, the in vivo effects of ergothioneine and its underlying therapeutic mechanisms in the whole organism are not as clear. Moreover, there are no well-defined, clinical prevention and intervention trials of ergothioneine in chronic disease. This review highlights the cellular and molecular mechanisms of action of ergothioneine and its potential as a Traditional, Complementary and Alternative Medicine for the promotion of cardiometabolic health and the management of the most common manifestations of cardiometabolic disease.

Noncoding RNAs involved in DNA methylation and histone methylation, and acetylation in diabetic vascular complications

Diabetes is a metabolic disorder and its incidence is still increasing. Diabetic vascular complications cause major diabetic mobility and include accelerated atherosclerosis, nephropathy, retinopathy, and neuropathy. Hyperglycemia contributes to the pathogenesis of diabetic vascular complications via numerous mechanisms including the induction of oxidative stress, inflammation, metabolic alterations, and abnormal proliferation of EC and angiogenesis. In the past decade, epigenetic modifications have attracted more attention as they participate in the progression of diabetic vascular complications despite controlled glucose levels and regulate gene expression without altering the genomic sequence. DNA methylation and histone methylation, and acetylation are vital epigenetic modifications and their underlying mechanisms in diabetic vascular complication are still urgently needed to be investigated. Non-coding RNAs (nc RNAs) such as micro RNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNAs (circ RNAs) were found to exert transcriptional regulation in diabetic vascular complication. Although nc RNAs are not considered as epigenetic components, they are involved in epigenetic modifications. In this review, we summarized the investigations of non-coding RNAs involved in DNA methylation and histone methylation and acetylation. Their cross-talks might offer novel insights into the pathology of diabetic vascular complications.

Arsenic suppresses GDF1 expression via ROS-dependent downregulation of specificity protein 1

Inorganic arsenic, an environmental contaminant, has adverse health outcomes. Our previous studies showed that arsenic causes abnormal cardiac development in zebrafish embryos by downregulating Dvr1/GDF1 expression and that folic acid protects against these effects. However, the mechanism by which arsenic represses Dvr1/GDF1 expression remains unknown. Herein, we demonstrate that specificity protein 1 (Sp1) acts as a transcriptional activator of GDF1. Arsenic treatment downregulated Sp1 at both the mRNA and protein level and its downstream targets GDF1 and SIRT1. Chromatin immunoprecipitation analysis showed that the occupancy of Sp1 on the GDF1 or SIRT1 promoter was significantly reduced in response to arsenite. Further investigation showed that Sp1 overexpression inhibited the arsenic-mediated decrease in GDF1 and SIRT1, while Sp1 knockdown had the opposite effect. We found that expression of the oxidative adaptor p66shc was inversely related to that of SIRT1 and that the binding of SIRT1 to the p66shc promoter was sharply attenuated by arsenite treatment. SIRT1 overexpression attenuated p66shc expression but enhanced GDF1 protein expression, while SIRT1 depletion exerted the opposite effect. Both the antioxidants N-acetylcysteine and folic acid reversed the arsenic-mediated repression of Sp1, GDF1 and SIRT1. Moreover, wild-type p66shc overexpression enhanced the arsenic-mediated repression of Sp1, GDF1 and SIRT1, which was accompanied by an increase in intracellular reactive oxygen species (ROS) levels, while both overexpression of a dominant negative p66shcSer36Ala mutant and deficiency in p66shc reversed these effects. Taken together, our results revealed that arsenic suppresses GDF1 expression via the ROS-dependent downregulation of the Sp1/SIRT1 axis, which forms a negative feedback loop with p66shc to regulate oxidative stress. Our findings reveal a novel molecular mechanism underlying arsenic toxicity and provide new insight into the protective effect of folic acid in arsenic-mediated toxicity.

The Endothelium as a Target for Anti-Atherogenic Therapy: A Focus on the Epigenetic Enzymes EZH2 and SIRT1

Endothelial cell inflammatory activation and dysfunction are key events in the pathophysiology of atherosclerosis, and are associated with an elevated risk of cardiovascular events. Yet, therapies specifically targeting the endothelium and atherosclerosis are lacking. Here, we review how endothelial behaviour affects atherogenesis and pose that the endothelium may be an efficacious cellular target for antiatherogenic therapies. We discuss the contribution of endothelial inflammatory activation and dysfunction to atherogenesis and postulate that the dysregulation of specific epigenetic enzymes, EZH2 and SIRT1, aggravate endothelial dysfunction in a pleiotropic fashion. Moreover, we propose that commercially available drugs are available to clinically explore this postulation.

The Epigenome in Atherosclerosis

Emerging evidence suggests the growing importance of "nongenetic factors" in the pathogenesis of atherosclerotic vascular disease. Indeed, the inherited genome determines only part of the risk profile as genomic approaches do not take into account additional layers of biological regulation by "epi"-genetic changes. Epigenetic modifications are defined as plastic chemical changes of DNA/histone complexes which critically affect gene activity without altering the DNA sequence. These modifications include DNA methylation, histone posttranslational modifications, and non-coding RNAs and have the ability to modulate gene expression at both transcriptional and posttranscriptional level. Notably, epigenetic signals are mainly induced by environmental factors (i.e., pollution, smoking, noise) and, once acquired, may be transmitted to the offspring. The inheritance of adverse epigenetic changes may lead to premature deregulation of pathways involved in vascular damage and endothelial dysfunction. Here, we describe the emerging role of epigenetic modifications as fine-tuners of gene transcription in atherosclerosis. Specifically, the following aspects are described in detail: (1) discovery and impact of the epigenome in cardiovascular disease, (2) the epigenetic landscape in atherosclerosis; (3) inheritance of epigenetic signals and premature vascular disease; (4) epigenetic control of lipid metabolism, vascular oxidative stress, inflammation, autophagy, and apoptosis; (5) epigenetic biomarkers in patients with atherosclerosis; (6) novel therapeutic strategies to modulate epigenetic marks. Understanding the individual epigenetic profile may pave the way for new approaches to determine cardiovascular risk and to develop personalized therapies to treat atherosclerosis and its complications.

The Role of Fibroblast Growth Factor 21 in Diabetic Cardiovascular Complications and Related Epigenetic Mechanisms

Fibroblast growth factor 21 (FGF21), is an emerging metabolic regulator mediates multiple beneficial effects in the treatment of metabolic disorders and related complications. Recent studies showed that FGF21 acts as an important inhibitor in the onset and progression of cardiovascular complications of diabetes mellitus (DM). Furthermore, evidences discussed so far demonstrate that epigenetic modifications exert a crucial role in the initiation and development of DM-related cardiovascular complications. Thus, epigenetic modifications may involve in the function of FGF21 on DM-induced cardiovascular complications. Therefore, this review mainly interprets and delineates the recent advances of role of FGF21 in DM cardiovascular complications. Then, the possible changes of epigenetics related to the role of FGF21 on DM-induced cardiovascular complications are discussed. Thus, this article not only implies deeper understanding of the pathological mechanism of DM-related cardiovascular complications, but also provides the possible novel therapeutic strategy for DM-induced cardiovascular complications by targeting FGF21 and related epigenetic mechanism.

Hyperglycemia-reduced NAD+ biosynthesis impairs corneal epithelial wound healing in diabetic mice

OBJECTIVE

Nicotinamide adenine dinucleotide (NAD) is an essential molecule participating in multiple physiological and pathophysiological processes. In diabetic cornea, the NAD⁺-consuming enzyme SIRT1 was down-regulated and contributed to the delayed wound healing. However, the impact of hyperglycemia on corneal NAD⁺ biosynthesis remained elusive. This study was to investigate the relationship of NAD⁺ biosynthesis and the delayed corneal wound healing in diabetic mice.

METHODS

Type 1 diabetes mellitus (DM) mice were induced by streptozotocin and corneal epithelial wound healing models were constructed by epithelial scraping. The NAD⁺ contents of corneal epithelium were measured using the NAD/NADH quantification kit. Expression of key enzymes involved in the NAD⁺ biosynthesis in type 1 DM mice and type 2 DM patients were analyzed. The nicotinamide phosphoribosyltransferase (NAMPT)-specific siRNA and the selective inhibitor FK866 were used to achieve the blockade of NAMPT, whereas exogenous NAD⁺ and its precursors were replenished to the corneal epithelial cells and DM mice.

RESULTS

Hyperglycemia attenuated NAD⁺ content and NAMPT expression in the corneal epithelium of both type 1 DM mice and type 2 DM patients. Local knockdown of NAMPT by siRNA or FK866 consistently recapitulated the delayed corneal epithelial wound healing in normal mice. Moreover, NAD⁺ replenishment recovered the impaired proliferation and migration capacity by either FK866 or high glucose treatment in cultured corneal epithelial cells. Furthermore, in DM mice, NAD⁺ and its precursors nicotinamide mononucleotide and nicotinamide riboside also facilitated corneal epithelial and nerve regeneration, accompanied with the recovered expression of SIRT1 and phosphorylated EGFR, AKT, and ERK1/2 in epithelium and corneal sensitivity.

CONCLUSION

Hyperglycemia-reduced NAD⁺ biosynthesis and contributed to the impaired epithelial wound healing in DM mice. The replenishment of NAD⁺ and its precursors facilitated diabetic corneal wound healing and nerve regeneration, which may provide a novel therapeutic strategy for the treatment of diabetic corneal complications.

DPPC-coated lipid nanoparticles as an inhalable carrier for accumulation of resveratrol in the pulmonary vasculature, a new strategy for pulmonary arterial hypertension treatment

In this study, we investigated the feasibility of dipalmitoylphosphatidylcholine-coated lipid nanoparticles (DPPC-LNs) as a carrier for preferential accumulation into lungs of Resveratrol (Res), a potentially promising drug for the treatment of pulmonary arterial hypertension (PAH). Res-loaded DPPC-LNs were prepared following a thin film hydration-ultrasonic dispersion technique using glyceryl monostearate as lipid core. DPPC can reduce the interactions between nanoparticles and pulmonary surfactant. The optimal formulation was prepared and characterized for physicochemical properties, storage stability and in vitro release profiles. The optimal formulation was evaluated for uptake by pulmonary arterial smooth muscle cells (PASMCs) using fluorescence microscopy. The efficacy of Res-loaded DPPC-LNs in reducing hyperplasia was tested in 5-HT induced proliferated PASMCs. The drug absorption profiles upon intratracheal administration were monitored in healthy rats. Optimized spherical DPPC-LNs - with mean size of 123.7 nm, zeta potential of -19.4 mV and entrapment efficiency of 94.40% - exhibited an 80% cumulative drug release over 48 h. Fluorescence microscopic study revealed an time-dependent enhancement of cellular uptake of Rh123-labeled DPPC-LNs by PASMCs. PASMC proliferation induced by 5-HT was significantly inhibited by Res-loaded DPPC-LNs. Optimized DPPC-LNs appeared to be safe when incubated with PASMCs. Besides, plasma and lung tissue data analysis indicated higher value of accumulation after intratracheal administration of Res-loaded DPPC-LNs in comparison with the intravenously dosed Res solution, indicating longer retention of Res in the lungs and their slower entry to the systemic blood circulation. DPPC-LNs could be a viable delivery system for site-specific treatment of PAH.

Smooth Muscle Sirtuin 1 Blocks Thoracic Aortic Aneurysm/Dissection Development in Mice

PURPOSE

Advancing age is the major risk factor for thoracic aortic aneurysm/dissection (TAAD). However, the causative link between age-related molecules and TAAD remains elusive. Here, we investigated the role of Sirtuin 1 (SIRT1, also known as class III histone deacetylase), the best studied member of the longevity-related Sirtuin family, in TAAD development in vivo.

METHODS

We used male smooth muscle-specific SIRT1 transgenic (ST-Tg) mice, smooth muscle-specific SIRT1 knockout (ST-KO) mice, and their wild-type (WT) littermates on a C57BL/6J background to establish a TAAD model induced by oral administration of 3-aminopropionitrile fumarate (BAPN). We analyzed the incidence and fatality rates of TAAD in the groups. We examined matrix metallopeptidase 2 (MMP2) and MMP9 expression in aortas or cultured A7r5 cells via western blotting and real-time polymerase chain reaction (PCR). We performed chromatin immunoprecipitation (ChIP) to clarify the epigenetic mechanism of SIRT1-regulated MMP2 expression in vascular smooth muscle cells (VSMCs).

RESULTS

BAPN treatment markedly increased the incidence of TAAD in WT mice but caused less disease in ST-Tg mice. Moreover, ST-KO mice had the highest BAPN-induced TAAD fatality rate of all the groups. Mechanistically, SIRT1 overexpression resulted in lower MMP2 and MMP9 expression after BAPN treatment in both mouse aortas and cultured A7r5 cells. The downregulation of BAPN-induced MMP2 expression by SIRT1 was mediated by deacetylation of histone H3 lysine 9 (H3K9) on the Mmp2 promoter in the A7r5 cells.

CONCLUSION

Our findings suggest that SIRT1 expression in SMCs protects against TAAD and could be a novel therapeutic target for TAAD management.

High glucose-induced PRDX3 acetylation contributes to glucotoxicity in pancreatic β-cells: Prevention by Teneligliptin

Chronic hyperglycemia has deleterious effects on pancreatic β-cell function and survival in type 2 diabetes (T2D) due to the low expression level of endogenous antioxidants in the β-cells. Peroxiredoxin-3 (PRDX3) is a mitochondria specific H202 scavenger and protects the cell from mitochondrial damage. However, nothing is known about how glucotoxicity influences PRDX3 function in the pancreatic beta cells. Exposure of rat insulinoma INS-1 cells and human beta cells (1.1B4) to high glucose conditions (30mM) stimulated acetylation of PRDX3 which facilitates its hyper-oxidation causing mitochondrial dysfunction by SIRT1 degradation. SIRT1 deficiency induces beta cell apoptosis via NOX-JNK-p66Shc signalosome activation. Herein we investigated the direct effect of Teneligliptin, a newer DPP-4 inhibitor on beta-cell function and survival in response to high glucose conditions. Teneligliptin treatment enhances SIRT1 protein levels and activity by USP22, an ubiquitin specific peptidase. Activated SIRT1 prevents high glucose-induced PRDX3 acetylation by SIRT3 resulted in inhibition of PRDX3 hyper-oxidation thereby strengthening the mitochondrial antioxidant defense. Notably, we identify PRDX3 as a novel SIRT3 target and show their physical interaction. Intriguingly, inhibition of SIRT1 activity by EX-527 or SIRT1 siRNA knockdown exacerbated the SIRT3 mediated PRDX3 deacetylation which leads to peroxiredoxin-3 hyper-oxidation and beta-cell apoptosis by the activation of NOX-JNK-p66Shc signalosome. Collectively, our results unveil a novel and first direct effect of high glucose on PRDX3 acetylation on beta-cell dysfunction by impaired antioxidant defense and SIRT1 mediated SIRT3-PRDX3 activation by Teneligliptin suppresses high glucose-mediated mitochondrial dysfunction.

Emerging roles of microRNAs in intestinal ischemia/reperfusion-induced injury: a review

Intestinal ischemia/reperfusion (II/R) injury is a serious pathological phenomenon in underlying hemorrhagic shock, trauma, strangulated intestinal obstruction, and acute mesenteric ischemia which associated with high morbidity and mortality. MicroRNAs (miRNAs, miRs) are endogenous non-coding RNAs that regulate post-transcriptionally target mRNA translation via degrading it and/or suppressing protein synthesis. This review discusses on the role of some miRNAs in underlying II/R injury. Some of these miRNAs can have protective action through agomiR or specific antagomiR, and others can have destructive effects in the basal level of II/R insult. Based on these literature reviews, II/R injury affects several miRNAs and their specific target genes. Some miRNAs upregulate under condition of II/R injury, and multiple miRNAs downregulate following II/R damage. Data of this review have been collected from the scientific articles published in databases such as Science Direct, Scopus, PubMed, Web of Science, and Scientific Information Database from 2000 to 2020. It is shown a correlation between changes in the expression of miRNAs and autophagy, inflammation, oxidative stress, apoptosis, and epithelial barrier function. Taken together, agomiR or antagomiR of some miRNAs can be considered as one new target for the research and development of innovative drugs to the prevention or treatment of II/R damage.