High glucose induced alteration of SIRTs in endothelial cells causes rapid aging in a p300 and FOXO regulated pathway

Role of FoxO transcription factors in aging-associated cardiovascular diseases

Aging constitutes a major risk factor toward the development of cardiovascular diseases (CVDs). The aging heart undergoes several changes at the molecular, cellular and physiological levels, which diminishes its contractile function and weakens stress tolerance. Further, old age increases the exposure to risk factors such as hypertension, diabetes and hypercholesterolemia. Notably, research in the past decades have identified FoxO subfamily of the forkhead transcription factors as key players in regulating diverse cellular processes linked to cardiac aging and diseases. In the present chapter, we discuss the important role of FoxO in the development of various aging-associated cardiovascular complications such as cardiac hypertrophy, cardiac fibrosis, heart failure, vascular dysfunction, atherosclerosis, hypertension and myocardial ischemia. Besides, we will also discuss the role of FoxO in cardiometabolic alterations, autophagy and proteasomal degradation, which are implicated in aging-associated cardiac dysfunction.

SET8 suppression mediates high glucose-induced vascular endothelial inflammation via the upregulation of PTEN

Hyperglycemia-mediated endothelial inflammation participates in the pathogenesis of cardiovascular complications in subjects with diabetes. Previous studies reported that phosphatase and tensin homolog deleted on chromosome ten (PTEN) and SET8 participate in high glucose-mediated endothelial inflammation. In this study, we hypothesize that SET8 regulates PTEN expression, thus contributing to high glucose-mediated vascular endothelial inflammation. Our data indicated that plasma soluble intercellular adhesion molecule-1 (sICAM-1) and endothelial selectin (e-selectin) were increased in patients with diabetes and diabetic rats. PTEN expression was augmented in the peripheral blood mononuclear cells of patients with diabetes and in the aortic tissues of diabetic rats. Our in vitro study indicated that high glucose increased monocyte/endothelial adhesion, endothelial adhesion molecule expression and p65 phosphorylation in human umbilical vein endothelial cells (HUVECs). Moreover, high glucose led to endothelial inflammation via upregulation of PTEN. Furthermore, high glucose inhibited SET8 expression and histone H4 lysine 20 methylation (H4K20me1), a downstream target of SET8. SET8 overexpression reversed the effects of high-glucose treatment. shSET8-mediated endothelial inflammation was counteracted by siPTEN. Furthermore, SET8 was found to interact with FOXO1. siFOXO1 attenuated high glucose-mediated endothelial inflammation. FOXO1 overexpression-mediated endothelial inflammation was counteracted by siPTEN. H4K20me1 and FOXO1 were enriched in the PTEN promoter region. shSET8 increased PTEN promoter activity and augmented the positive effect of FOXO1 overexpression on PTEN promoter activity. Our in vivo study indicated that SET8 was downregulated and FOXO1 was upregulated in the peripheral blood mononuclear cells of patients with diabetes and the aortic tissues of diabetic rats. In conclusion, SET8 interacted with FOXO1 to modulate PTEN expression in vascular endothelial cells, thus contributing to hyperglycemia-mediated endothelial inflammation.

High glucose levels in patients with diabetes trigger vascular inflammation by affecting the expression of key proteins in blood vessel linings. Elevated glucose causes inflammation of the endothelium, a thin layer of cells that lines blood and lymph vessels, leading to cardiovascular complications. The phosphatase and tensin homolog protein (PTEN) contributes to endothelial inflammation, but the precise mechanisms are unclear. Xuefang Shen at Fudan University in Shanghai, China, and co-workers demonstrated that elevated glucose increases PTEN expression, with increased levels of the protein found in peripheral blood cells of diabetic patients and aortic tissues of diabetic rats. In further experiments on rats, the researchers found that glucose also suppressed another protein called SET8, which contributed to increased PTEN levels. This suggests that SET8 is involved in PTEN modulation, and that both proteins influence vascular inflammation.

Panax notoginseng saponins alleviates advanced glycation end product-induced apoptosis by upregulating SIRT1 and antioxidant expression levels in HUVECs

The present study examined whether Panax notoginseng saponins (PNS) alleviated advanced glycation end product (AGE)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were incubated with 300 µg/ml AGEs alone or AGEs and PNS (0.05, 0.5 or 1 mg/ml) for 48 h. The results of the present study demonstrated that PNS effectively promoted cell viability, inhibited apoptosis and suppressed the activity of caspase-3 in AGE-induced HUVECs. The activities of monocyte chemoattractant protein-1 and malondialdehyde were reduced, and superoxide dismutase activity was increased following treatment with PNS. Furthermore, PNS significantly increased the expression of silent information regulator 1 (SIRT1) and transforming growth factor (TGF)-β1 proteins, and suppressed the expression of inducible nitric oxide synthase and cyclooxyggenase-2 proteins in AGE-induced HUVECs. Therefore, the present study demonstrated that PNS reduced AGE-induced apoptosis by upregulating SIRT1 and antioxidants in HUVECs. The present findings suggest that the PNS may as an important pharmacological agent for AGE-induced cardiovascular injury.

High glucose concentration produces a short-term increase in pERK1/2 and p85 proteins, having a direct angiogenetic effect by an action similar to VEGF

AIMS

Excessive glucose serum concentration, endothelial dysfunction and microangiopathy are key features of diabetes mellitus, being both diagnostic parameters and pathogenetic mechanisms. Vascular endothelial growth factor (VEGF) is importantly implicated in the physiology and pathology of blood vessels, including diabetic vascular damage.

METHODS

These factors certainly affect endothelial cells, and to evaluate mechanisms involved, we took advantage of telomerase-immortalized human microvascular endothelial (TIME) cells. TIME cells were exposed to different glucose concentrations and to VEGF treatments. Culture conditions also included the use of basement membrane extract, as an in vitro differentiation model. Cell morphology was then evaluated in the different conditions, and cellular proteins were extracted to analyze specific protein products by Western blot.

RESULTS

High glucose concentrations and VEGF did substantially affect neither morphology nor growth of cultured TIME cells, while both considerably increased differentiation into "capillary-like" structures when cells were cultured on basement membrane extract.

CONCLUSIONS

Under these conditions, high glucose concentration and VEGF also produced a short-term increase in pERK1/2 and p85 proteins, while total and phosphorylated AKT were not affected. These data suggest a direct angiogenetic effect of glucose, affecting intracellular transduction mechanisms with an action similar to that of VEGF. This effect on endothelial cell proliferation and differentiation could be part of pathogenetic mechanisms producing diabetic microvascular alterations.

Protective effect of isoliquiritigenin on experimental diabetic nephropathy in rats: Impact on Sirt-1/NFκB balance and NLRP3 expression

The prevalence of diabetes mellitus (DM) drastically increases worldwide. Persistent hyperglycemia affects body microvasculature causing injuries to kidney producing diabetic nephropathy (DNE). Manifestation of these microvascular complications is associated with disturbed redox homeostasis. The current study evaluated the effect of isoliquiritigenin (ISLQ), a bioactive chalcone found in licorice which is known for its antioxidant effect, on diabetes-induced renal injury. DM was prompted in male rats by streptozotocin (STZ, 50 mg/kg, intraperitoneally). ISLQ was administrated by oral gavage for 8 weeks at a dose (20 mg/kg/day). Features of renal injury were observed in kidneys of diabetic rats including, albuminuria and deteriorated renal function. Renal dysfunction was associated with reduced sirtuin-1 (Sirt-1) expression, increased renal oxidative stress, nucleotide-binding domain and leucine-rich repeat containing protein-3 (NLRP3), nuclear factor-κB (NFκB) and inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Moreover, there was significant downregulation of anti-inflammatory cytokine interleukin-10 (IL-10), glomerular and tubular injury and collagen accumulation. ISLQ administration preserved renal function and architecture, restored Sirt1 and renal oxidant-antioxidant balance, dampened inflammation and attenuated collagen accumulation. It can be inferred that ISLQ possess a protective effect and could have a potential as a food supplement to halt development and progression of DNE.

Glucose-induced, duration-dependent genome-wide DNA methylation changes in human endothelial cells

DNA methylation, a critical epigenetic mechanism, plays an important role in governing gene expressions during biological processes such as aging, which is well known to be accelerated in hyperglycemia (diabetes). In the present study, we investigated the effects of glucose on whole genome DNA methylation in small [human retinal microvascular endothelial cells (HRECs)] and large [human umbilical vein endothelial cells (HUVECs)] vessel endothelial cell (EC) lines exposed to basal or high glucose-containing media for variable lengths of time. Using the Infinium EPIC array, we obtained 773,133 CpG sites (probes) for analysis. Unsupervised clustering of the top 5% probes identified four distinct clusters within EC groups, with significant methylation differences attributed to EC types and the duration of cell culture rather than glucose stimuli alone. When comparing the ECs incubated for 2 days versus 7 days, hierarchical clustering analyses [methylation change >10% and false discovery rate (FDR) <0.05] identified 17,354 and 128 differentially methylated CpGs for HUVECs and HRECs, respectively. Predominant DNA hypermethylation was associated with the length of culture and was enriched for gene enhancer elements and regions surrounding CpG shores and shelves. We identified 88 differentially methylated regions (DMRs) for HUVECs and 8 DMRs for HRECs (all FDR <0.05). Pathway enrichment analyses of DMRs highlighted involvement of regulators of embryonic development (i.e., HOX genes) and cellular differentiation [transforming growth factor-β (TGF-β) family members]. Collectively, our findings suggest that DNA methylation is a complex process that involves tightly coordinated, cell-specific mechanisms. Such changes in methylation overlap genes critical for cellular differentiation and embryonic development.

Melatonin inhibits Müller cell activation and pro-inflammatory cytokine production via upregulating the MEG3/miR-204/Sirt1 axis in experimental diabetic retinopathy

Diabetic retinopathy (DR) is the most common ocular complication caused by diabetes mellitus and is the main cause of visual impairment in working-age people. Reactive gliosis and pro-inflammatory cytokine production by Müller cells contribute to the progression of DR. Melatonin is a strong anti-inflammatory hormone, mediating the cytoprotective effect of a variety of retinal cells against hyperglycemia. In this study, melatonin inhibited the gliosis activation and inflammatory cytokine production of Müller cells in both in vitro and in vivo models of DR. The melatonin membrane blocker, Luzindole, invalidated the melatonin-mediated protective effect on Müller cells. Furthermore, melatonin inhibited Müller cell activation and pro-inflammatory cytokine production by upregulating the long noncoding RNA maternally expressed gene 3/miR-204/sirtuin 1 axis. In conclusion, our study suggested that melatonin treatment could be a novel therapeutic strategy for DR.

A review of pharmacological and pharmacokinetic properties of stachydrine

Stachydrine is extracted from the leaves of Leonurus japonicus Houtt (or Motherwort, "Yi Mu Cao" in Traditional Chinese Medicine) and is the major bioactive ingredient. So far, stachydrine has demonstrated various bioactivities for the treatment of fibrosis, cardiovascular diseases, cancers, uterine diseases, brain injuries, and inflammation. The pharmacological and pharmacokinetic properties of stachydrine up to 2019 have been comprehensively searched and summarized. This review provides an updated summary of recent studies on the pharmacological activities of stachydrine. Many studies have demonstrated that stachydrine has strong anti-fibrotic properties (on various types of fibrosis) by inhibiting ECM deposition and decreasing inflammatory and oxidative stress through multiple molecular mechanisms (including TGF-β, ERS-mediated apoptosis, MMPs/TIMPs, NF-κB, and JAK/STAT). The cardioprotective and vasoprotective activities of stachydrine are related to its inhibition of β-MHC, excessive autophagy, SIRT1, eNOS uncoupling and TF, promotion of SERCA, and angiogenesis. In addition to its anticancer action, regulation of the uterus, neuroprotective effects, etc. the pharmacokinetic properties of stachydrine are also discussed.

Research progress on sirtuins family members and cell senescence

Human aging is a phenomenon of gradual decline and loss of cell, tissue, organ and other functions under the action of external environment and internal factors. It is mainly related to genomic instability, telomere wear, mitochondrial dysfunction, protein balance disorder, antioxidant damage, microRNA expression disorder and so on. Sirtuins protein is a kind of deacetylase which can regulate cell metabolism and participate in a variety of cell physiological functions. It has been found that sirtuins family can prolong the lifespan of yeast. Sirtuins can inhibit human aging through many signaling pathways, including apoptosis signaling pathway, mTOR signaling pathway, sirtuins signaling pathway, AMPK signaling pathway, phosphatidylinositol 3 kinase (PI3K) signaling pathway and so on. Based on this, this paper reviews the action principle of anti-aging star members of sirtuins family Sirt1, Sirt3 and Sirt6 on anti-aging related signaling pathways and typical compounds, in order to provide ideas for the screening of anti-aging compounds of sirtuins family members.

Glucose-induced oxidative stress and accelerated aging in endothelial cells are mediated by the depletion of mitochondrial SIRTs

Diabetic complications cause significant morbidity and mortality. Dysfunction of vascular endothelial cells (ECs), caused by oxidative stress, is a main mechanism of cellular damage. Oxidative stress accelerates EC senescence and DNA damage. In this study, we examined the role of mitochondrial sirtuins (SIRTs) in glucose-induced oxidative stress, EC senescence, and their regulation by miRNAs. Human retinal microvascular endothelial cells (HRECs) were exposed to 5 mmol/L (normoglycemia; NG) or 25 mmol/L glucose (hyperglycemia; HG) with or without transfection of miRNA antagomirs (miRNA-1, miRNA-19b, and miRNA-320; specific SIRT-targeting miRNAs). Expressions of SIRT3, 4 and 5 and their targeting miRNAs were examined using qRT-PCR and ELISAs were used to study SIRT proteins. Cellular senescence was investigated using senescence-associated β-gal stain; while, oxidative stress and mitochondrial alterations were examined using 8-OHdG staining and cytochrome B expressions, respectively. A streptozotocin-induced diabetic mouse model was also used and animal retinas and hearts were collected at 2 months of diabetes. In HRECs, HG downregulated the mRNAs of SIRTs, while SIRT-targeting miRNAs were upregulated. ELISA analyses confirmed such downregulation of SIRTs at the protein level. HG additionally caused early senescence, endothelial-to-mesenchymal transition and oxidative DNA damage in ECs. These changes were prevented by the transfection of specific miRNA antagomirs and by resveratrol. Retinal and cardiac tissues from diabetic mice also showed similar reductions of mitochondrial SIRTs. Collectively, these findings demonstrate a novel mechanism in which mitochondrial SIRTs regulate glucose-induced cellular aging through oxidative stress and how these SIRTs are regulated by specific miRNAs. Identifying such mechanisms may lead to the discovery of novel treatments for diabetic complications.

FOXO1 inhibition prevents renal ischemia-reperfusion injury via cAMP-response element binding protein/PPAR-γ coactivator-1α-mediated mitochondrial biogenesis

BACKGROUND AND PURPOSE

Growing evidence indicates targeting mitochondrial dynamics and biogenesis could accelerate recovery from renal ischemia-reperfusion (I/R) injury, but the underlying mechanisms remain elusive. Transcription factor forkhead box O1 (FOXO1) is a key regulator of mitochondrial homeostasis and plays a pathological role in the progression of renal disease.

EXPERIMENTAL APPROACH

A mouse model of renal I/R injury and a hypoxia/reoxygenation (H/R) injury model for human renal tubular epithelial cells were used.

KEY RESULTS

I/R injury up-regulated renal expression of FOXO1 and treatment with FOXO1-selective inhibitor AS1842856 prior to I/R injury decreased serum urea nitrogen, serum creatinine and the tubular damage score after injury. Post-I/R injury AS1842856 treatment could also ameliorate renal function and improve the survival rate of mice following injury. AS1842856 administration reduced mitochondrial-mediated apoptosis, suppressed the overproduction of mitochondrial ROS and accelerated recovery of ATP both in vivo and in vitro. Additionally, FOXO1 inhibition improved mitochondrial biogenesis and suppressed mitophagy. Expression of PPAR-γ coactivator 1α (PGC-1α), a master regulator of mitochondrial biogenesis, was down-regulated in both I/R and H/R injury, which could be abrogated by FOXO1 inhibition. Experiments using integrated bioinformatics analysis and coimmunoprecipitation established that FOXO1 inhibited PGC-1α transcription by competing with cAMP-response element binding protein (CREB) for its binding to transcriptional coactivators CREBBP/EP300 (CBP/P300).

CONCLUSION AND IMPLICATIONS

These findings suggested that FOXO1 was critical to maintain mitochondrial function in renal tubular epithelial cells and FOXO1 may serve as a therapeutic target for pharmacological intervention in renal I/R injury.

The Mediterranean Diet Slows Down the Progression of Aging and Helps to Prevent the Onset of Frailty: A Narrative Review

The aging population is rapidly increasing all over the world. This results in significant implications for the planning and provision of health and social care. Aging is physiologically characterized by a decrease in lean mass, bone mineral density and, to a lesser extent, fat mass. The onset of sarcopenia leads to weakness and a further decrease in physical activity. An insufficient protein intake, which we often observe in patients of advanced age, certainly accelerates the progression of sarcopenia. In addition, many other factors (e.g., insulin resistance, impaired protein digestion and absorption of amino acids) reduce the stimulation of muscle protein synthesis in the elderly, even if the protein intake is adequate. Inadequate intake of foods can also cause micronutrient deficiencies that contribute to the development of frailty. We know that a healthy eating style in middle age predisposes to so-called "healthy and successful" aging, which is the condition of the absence of serious chronic diseases or of an important decline in cognitive or physical functions, or mental health. The Mediterranean diet is recognized to be a "healthy food" dietary pattern; high adherence to this dietary pattern is associated with a lower incidence of chronic diseases and lower physical impairment in old age. The aim of our review was to analyze observational studies (cohort and case-control studies) that investigated the effects of following a healthy diet, and especially the effect of adherence to a Mediterranean diet (MD), on the progression of aging and on onset of frailty.

SIRT1-Mediated Protective Effect of Aralia elata (Miq.) Seem against High-Glucose-Induced Senescence in Human Umbilical Vein Endothelial Cells

Aralia elata (Miq.) Seem (AS) is widely been for treating many diseases, enhancing energy, and boosting immunity; however, its protective effects against high-glucose (HG)-triggered endothelial dysfunction and the potential underlying mechanisms have not been investigated. In this study, we determined the effect of AS on senescence in human umbilical vein endothelial cells (HUVECs) and elucidated the mechanisms underlying its anti-aging effects. The senescence model of endothelial cells (ECs) was established by culturing HUVECs in media containing HG (30 mM). We found that the proportion of senescent (senescence-associated β-galactosidase+) cells in the HG group was significantly higher than that in the control group; however, this increase was suppressed by AS treatment. Moreover, cell cycle analysis revealed that AS (20 μg/mL) significantly recovered HG-induced cell cycle arrest in ECs, and Western blot revealed that AS prevented HG-induced decreases in silent information regulator 1 (SIRT1) level and endothelial nitric oxide synthase (eNOS) phosphorylation. These results show that AS delayed HG-induced senescence in ECs by modulation of the SIRT1/5′ AMP-activated protein kinase and AKT/eNOS pathways.

Role of liraglutide in brain repair promotion through Sirt1-mediated mitochondrial improvement in stroke

Brain repair, especially axonal sprouting, is critical to restore motor function in disabled stroke patients. Liraglutide (LG) is a new kind of long-acting analogue of glucagon-like peptide-1 (GLP-1) and has potential protective effects in stroke. The mitochondria participate in brain repair after cerebral injury. However, the mechanism of the effect of LG on brain repair and its potential influence on mitochondria in stroke remains obscure. Here, in focal cerebral cortical ischemic mice model, LG improved the motor functional recovery and promoted axonal sprouting by restoring the activities of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Moreover, LG remarkably increased the cell survival rate and revived the NeuN and GAP-43 levels in cortical neurons under hydrogen peroxide (H₂ O₂ ) exposure. It was also observed that LG reduced the generation of reactive oxygen species, stabilized the mitochondrial membrane potential, enhanced the levels of adenosine triphosphate, enhanced activities of mitochondrial complex-I, and decreased protein expression levels of fission-1 in H₂ O₂ -injured cortical neurons. Additionally, LG suppressed the expressions of sirtuin 1 (Sirt1) in cortical neurons exposed to H₂ O₂ . Furthermore, knockdown of Sirt1 by short interfering RNA facilitated the LG-mediated mitochondrial protection in cortical neurons under H₂ O₂ . Collectively, this data from the present study illustrated that LG exerted a promoting influence on brain repair, after cerebral ischemic injury, through Sirt1-mediated mitochondrial improvement.

MicroRNA-34a (miR-34a) Mediates Retinal Endothelial Cell Premature Senescence through Mitochondrial Dysfunction and Loss of Antioxidant Activities

Stress-associated premature senescence (SAPS) is involved in retinal microvascular injury and diabetic retinopathy. We have investigated the role and mode of action of miR-34a in retinal endothelial cells senescence in response to glucidic stress. Human retinal microvascular endothelial cells (HuREC) were exposed to glucidic stress (high glucose (HG) = 25 mM d-glucose) and compared to cells exposed to normal glucose (NG = 5 mM) or the osmotic control l-glucose (LG = 25 mM). HG stimulation of HuREC increased the expression of miR-34a and induced cellular senescence. HG also increased the expression of p16ink4a and p21waf1, while decreasing the histone deacetylase SIRT1. These effects were associated with diminished mitochondrial function and loss of mitochondrial biogenesis factors (i.e., PGC-1α, NRF1, and TFAM). Transfection of the cells with miR-34a inhibitor (IB) halted HG-induced mitochondrial dysfunction and up-regulation of senescence-associated markers, whereas miR-34a mimic promoted cellular senescence and mitochondrial dysfunction. Moreover, HG lowered levels of the mitochondrial antioxidants TrxR2 and SOD2, an effect blunted by miR-34a IB, and promoted by miR-34a mimic. 3’-UTR (3’-untranslated region) reporter assay of both genes validated TrxR2 as a direct target of miR-34a, but not SOD2. Our results show that miR-34a is a key player of HG-induced SAPS in retinal endothelial cells via multiple pathways involved in mitochondrial function and biogenesis.

New Insights into Chronological Mobility of Retrotransposons In Vivo

Tissue aging is the gradual decline of physiological homeostasis accompanied with accumulation of senescent cells, decreased clearance of unwanted biological compounds, and depletion of stem cells. Senescent cells were cell cycle arrested in response to various stimuli and identified using distinct phenotypes and changes in gene expression. Senescent cells that accumulate with aging can compromise normal tissue function and inhibit or stop repair and regeneration. Selective removal of senescent cells can slow the aging process and inhibits age-associated diseases leading to extended lifespans in mice and thus provides a possibility for developing antiaging therapy. To monitor the appearance of senescent cells in vivo and target them, a clearer understanding of senescent cell expression markers is needed. We investigated the age-associated expression of three molecular hallmarks of aging: SA-β-gal, P16INK4a, and retrotransposable elements (RTEs), in different mouse tissues during chronological aging. Our data showed that the expression of these markers is variable with aging in the different tissues. P16INK4a showed consistent increases with age in most tissues, while expression of RTEs was variable among different tissues examined. These data suggest that biological changes occurring with physiological aging may be useful in choosing the appropriate timing of therapeutic interventions to slow the aging process or keep more susceptible organs healthier in the aging process.

Endothelial senescence is induced by phosphorylation and nuclear export of telomeric repeat binding factor 2-interacting protein

The interplay among signaling events for endothelial cell (EC) senescence, apoptosis, and activation and how these pathological conditions promote atherosclerosis in the area exposed to disturbed flow (d-flow) in concert remain unclear. The aim of this study was to determine whether telomeric repeat-binding factor 2-interacting protein (TERF2IP), a member of the shelterin complex at the telomere, can regulate EC senescence, apoptosis, and activation simultaneously, and if so, by what molecular mechanisms. We found that d-flow induced p90RSK and TERF2IP interaction in a p90RSK kinase activity-dependent manner. An in vitro kinase assay revealed that p90RSK directly phosphorylated TERF2IP at the serine 205 (S205) residue, and d-flow increased TERF2IP S205 phosphorylation as well as EC senescence, apoptosis, and activation by activating p90RSK. TERF2IP phosphorylation was crucial for nuclear export of the TERF2IP-TRF2 complex, which led to EC activation by cytosolic TERF2IP-mediated NF-κB activation and also to senescence and apoptosis of ECs by depleting TRF2 from the nucleus. Lastly, using EC-specific TERF2IP-knockout (TERF2IP-KO) mice, we found that the depletion of TERF2IP inhibited d-flow-induced EC senescence, apoptosis, and activation, as well as atherosclerotic plaque formation. These findings demonstrate that TERF2IP is an important molecular switch that simultaneously accelerates EC senescence, apoptosis, and activation by S205 phosphorylation.

Role of sirtuin-1 in diabetic nephropathy

Diabetic nephropathy (DN) is a research priority for scientists around the world because of its high prevalence and poor prognosis. Although several mechanisms have been shown to be involved in its pathogenesis and many useful drugs have been developed, the management of DN remains challenging. Increasing amounts of evidence show that silent information regulator 2 homolog 1 (sirtuin-1), a nicotinamide adenine dinucleotide (NAD+)–dependent protein deacetylase, plays a crucial role in the pathogenesis and development of DN. Clinical data show that gene polymorphisms of sirtuin-1 affect patient vulnerability to DN. In addition, upregulation of sirtuin-1 attenuates DN in various experimental models of diabetes and in renal cells, including podocytes, mesangial cells, and renal proximal tubular cells, incubated with high concentrations of glucose or advanced glycation end products. Mechanistically, sirtuin-1 has its renoprotective effects by modulating metabolic homeostasis and autophagy, resisting apoptosis and oxidative stress, and inhibiting inflammation through deacetylation of histones and the transcription factors p53, forkhead box group O, nuclear factor-κB, hypoxia-inducible factor-1α, and others. Furthermore, some microRNAs have been implicated in the progression of DN because they target sirtuin-1 mRNA. Several synthetic drugs and natural compounds have been identified that upregulate the expression and activity of sirtuin-1, which protects against DN. The present review will summarize advances in knowledge regarding the role of sirtuin-1 in the pathogenesis of DN. The available evidence implies that sirtuin-1 has great potential as a clinical target for the prevention and treatment of diabetes.

Hyperglycemia modulates redox, inflammatory and vasoactive markers through specific signaling pathways in cerebral endothelial cells: Insights on insulin protective action

Type 2 diabetes is associated with major vascular dysfunctions, leading to clinical complications such as stroke. It is also known that hyperglycemia dysregulates blood-brain barrier homeostasis by altering cerebral endothelial cell function. Oxidative stress may play a critical role. The aim of this study was to evaluate the effect of hyperglycemia and insulin on the production of redox, inflammatory and vasoactive markers by cerebral endothelial cells. Murine bEnd.3 cerebral endothelial cells were exposed to hyperglycemia in the presence or not of insulin. Results show that hyperglycemia altered the expression of genes encoding the ROS-producing enzyme Nox4, antioxidant enzymes Cu/ZnSOD, catalase and HO-1 as well as Cu/ZnSOD, MnSOD and catalase enzymatic activities, leading to a time-dependent modulation of ROS levels. Cell preconditioning with inhibitors targeting PI3K, JNK, ERK, p38 MAPK or NFĸB signaling molecules partly blocked hyperglycemia-induced oxidative stress. Conversely, AMPK inhibitor exacerbated ROS production, suggesting a protective role of AMPK on the antioxidant defense system. Hyperglycemia also modulated both gene expression and nuclear translocation of the redox-sensitive transcription factor Nrf2. Moreover, hyperglycemia caused a pro-inflammatory response by activating NFĸB-AP-1 pathway and IL-6 secretion. Hyperglycemia reduced eNOS gene expression and NO levels, while increasing ET-1 gene expression. Importantly, insulin counteracted all the deleterious effects of hyperglycemia. Collectively, these results demonstrate that hyperglycemia dysregulated redox, inflammatory and vasoactive markers in cerebral endothelial cells. Insulin exerted a protective action against hyperglycemia effects. Thus, it will be of high interest to evaluate the benefits of antioxidant and anti-inflammatory strategies against hyperglycemia-mediated vascular complications in type 2 diabetes.

TXNIP regulates AKT-mediated cellular senescence by direct interaction under glucose-mediated metabolic stress

Aging is associated with an inevitable and universal loss of cell homeostasis and restricts an organism's lifespan by an increased susceptibility to diseases and tissue degeneration. The glucose uptake associated with producing energy for cell survival is one of the major causes of ROS production under physiological conditions. However, the overall mechanisms by which glucose uptake results in cellular senescence remain mysterious. In this study, we found that TXNIP deficiency accelerated the senescent phenotypes of MEF cells under high glucose condition. TXNIP^‐/‐ MEF cells showed greater induced glucose uptake and ROS levels than wild‐type cells, and N‐acetylcysteine (NAC) treatment rescued the cellular senescence of TXNIP^‐/‐ MEF cells. Interestingly, TXNIP^‐/‐ MEF cells showed continuous activation of AKT during long‐term subculture, and AKT signaling inhibition completely blocked the cellular senescence of TXNIP^‐/‐ MEF cells. In addition, we found that TXNIP interacted with AKT via the PH domain of AKT, and their interaction was increased by high glucose or H₂O₂ treatment. The inhibition of AKT activity by TXNIP was confirmed using western blotting and an in vitro kinase assay. TXNIP deficiency in type 1 diabetes mice (Akita) efficiently decreased the blood glucose levels and finally increased mouse survival. However, in normal mice, TXNIP deficiency induced metabolic aging of mice and cellular senescence of kidney cells by inducing AKT activity and aging‐associated gene expression. Altogether, these results suggest that TXNIP regulates cellular senescence by inhibiting AKT pathways via a direct interaction under conditions of glucose‐derived metabolic stress.

Epigenetic Contribution to the Development and Progression of Vascular Diabetic Complications

SIGNIFICANCE

The number of people suffering from diabetes worldwide is steadily rising. Complications from diabetes, including cardiovascular and renal disease, contribute to the high morbidity and mortality associated with this disease. Recent Advances: Hyperglycemia promotes tissue damage through diverse mechanisms involving increased production of reactive oxygen species. Increased oxidative stress drives changes in chromatin structure that mediate gene expression changes leading to the upregulation of proinflammatory and profibrotic mediators. The epigenetic contribution to diabetes-induced changes in gene expression is increasingly recognized as a key factor in the development and progression of vascular diabetic complications.

CRITICAL ISSUES

The mechanisms through which stimuli from the diabetic milieu promote epigenetic changes remain poorly understood. In addition, glycemic control constitutes an important factor influencing epigenetic states in diabetes, and the phenomenon of hyperglycemic memory warrants further research.

FUTURE DIRECTIONS

Knowledge of the molecular mechanisms underlying epigenetic changes in diabetes may allow the design of novel therapeutic strategies to reduce the burden of diabetic complications. Furthermore, certain epigenetic markers are detected early during the onset of diabetes and its complications and may prove useful as biomarkers for disease risk prediction.

MicroRNAs Regulating Reactive Oxygen Species in Cardiovascular Diseases

SIGNIFICANCE

Oxidative stress caused by overproduction of reactive oxygen species (ROS) in cells is one of the most important contributors to the pathogenesis of cardiovascular and metabolic diseases such as hypertension and atherosclerosis. Excessive accumulation of ROS impairs, while limiting oxidative stress protects cardiovascular and metabolic function through various cellular mechanisms. Recent Advances: MicroRNAs (miRNAs) are novel regulators of oxidative stress in cardiovascular cells that modulate the expression of redox-related genes. This article summarizes recent advances in our understanding of how miRNAs target major ROS generators, antioxidant signaling pathways, and effectors in cells of the cardiovascular system.

CRITICAL ISSUES

The role of miRNAs in regulating ROS in cardiovascular cells is complicated because miRNAs can target multiple redox-related genes, act on redox regulatory pathways indirectly, and display context-dependent pro- or antioxidant effects. The complex regulatory network of ROS and the plethora of targets make it difficult to pin point the role of miRNAs and develop them as therapeutics. Therefore, these properties should be considered when designing strategies for therapeutic or diagnostic development.

FUTURE DIRECTIONS

Future studies can gain a better understanding of redox-related miRNAs by investigating their own regulatory mechanisms and the dual role of ROS in the cardiovascular systems. The combination of improved study design and technical advancements will reveal newer pathophysiological importance of redox-related miRNAs.

High glucose concentration suppresses a SIRT2 regulated pathway that enhances neurite outgrowth in cultured adult sensory neurons

In peripheral nerve under hyperglycemic conditions high flux of d-glucose through the polyol pathway drives an aberrant redox state contributing to neurodegeneration in diabetic sensorimotor polyneuropathy (DSPN). Sirtuins, including SIRT2, detect the redox state via the NAD⁺/NADH ratio to regulate mitochondrial function via, in part, AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α). In adult dorsal root ganglia (DRG) sensory neurons mitochondrial dysfunction has been proposed as an etiological factor in dying-back neuropathy in diabetes. We tested the hypothesis that a high concentration of d-glucose depleted SIRT2 expression via enhancement of polyol pathway activity. We posited that this would lead to impaired mitochondrial function and suppression of neurite outgrowth in cultured sensory neurons. The use of dominant negative mutants or neurons from SIRT2 knockout (KO) mice to block SIRT2 signaling revealed that neurons derived from control or type 1 diabetic rodents required SIRT2 for optimal neurite outgrowth. Over-expression of WT-SIRT2 elevated neurite outgrowth in normal and diabetic cultures. SIRT2 protein isoforms 2.1 and 2.2 were reduced by 20-30% in DRG of type 1 diabetic mice (p < .05). After 72 h exposure to high d-glucose (25 mM vs 5 mM) cultured sensory neurons showed a significant 2-fold (p < .05) decrease in SIRT2 expression, P-AMPK, levels of respiratory Complexes II/III and respiratory capacity. DRG neurons expressed aldose reductase and the aforementioned deficits were prevented by treatment with aldose reductase inhibitors (lidorestat or sorbinil) or sorbitol dehydrogenase inhibitor (SDI-158). In cultures derived from type 1 diabetic rats treatment with SDI-158 elevated expression of SIRT2, P-AMPK/PGC-1α and neurite outgrowth (p < .05). SIRT2 KO neurons exhibited deficits in the LKB-1/AMPK/PGC-1α pathway and mitochondrial function. In cultured neurons the SIRT2 pathway enhances axonal outgrowth and this signaling axis encompassing activation of AMPK/PGC-1α is impaired in DSPN, in part, due to enhanced polyol pathway activity caused by hyperglycemia.

Designing in vitro Blood-Brain Barrier Models Reproducing Alterations in Brain Aging

Blood-brain barrier (BBB) modeling in vitro is a huge area of research covering study of intercellular communications and development of BBB, establishment of specific properties that provide controlled permeability of the barrier. Current approaches in designing new BBB models include development of new (bio) scaffolds supporting barriergenesis/angiogenesis and BBB integrity; use of methods enabling modulation of BBB permeability; application of modern analytical techniques for screening the transfer of metabolites, bio-macromolecules, selected drug candidates and drug delivery systems; establishment of 3D models; application of microfluidic technologies; reconstruction of microphysiological systems with the barrier constituents. Acceptance of idea that BBB in vitro models should resemble real functional activity of the barrier in different periods of ontogenesis and in different (patho) physiological conditions leads to proposal that establishment of BBB in vitro model with alterations specific for aging brain is one of current challenges in neurosciences and bioengineering. Vascular dysfunction in the aging brain often associates with leaky BBB, alterations in perivascular microenvironment, neuroinflammation, perturbed neuronal and astroglial activity within the neurovascular unit, impairments in neurogenic niches where microvascular scaffold plays a key regulatory role. The review article is focused on aging-related alterations in BBB and current approaches to development of “aging” BBB models in vitro.

Epigenetic control of gene regulation during development and disease: A view from the retina

Complex biological processes, such as organogenesis and homeostasis, are stringently regulated by genetic programs that are fine-tuned by epigenetic factors to establish cell fates and/or to respond to the microenvironment. Gene regulatory networks that guide cell differentiation and function are modulated and stabilized by modifications to DNA, RNA and proteins. In this review, we focus on two key epigenetic changes - DNA methylation and histone modifications - and discuss their contribution to retinal development, aging and disease, especially in the context of age-related macular degeneration (AMD) and diabetic retinopathy. We highlight less-studied roles of DNA methylation and provide the RNA expression profiles of epigenetic enzymes in human and mouse retina in comparison to other tissues. We also review computational tools and emergent technologies to profile, analyze and integrate epigenetic information. We suggest implementation of editing tools and single-cell technologies to trace and perturb the epigenome for delineating its role in transcriptional regulation. Finally, we present our thoughts on exciting avenues for exploring epigenome in retinal metabolism, disease modeling, and regeneration.

Pleurotus albidus Modulates Mitochondrial Metabolism Disrupted by Hyperglycaemia in EA.hy926 Endothelial Cells

Hyperglycaemia exacerbates the production of reactive oxygen species (ROS), contributing to the multiple complications associated with diabetes. Mitochondrial dysfunction is also known to be associated with diabetes. Therefore, the aim of this work was to study the effect of Pleurotus albidus extract on the mitochondrial dysfunction induced by hyperglycaemia in EA.hy926 endothelial cells. The results showed that P. albidus treatment prevented the increase in the activity of complex I of the electron transport chain and minimized the ROS production induced by hyperglycaemia. In addition, the extract minimized oxidative damage to lipids and proteins, caused an imbalance in the antioxidant enzyme activities of superoxide dismutase and catalase, and decreased the nitric oxide levels induced by hyperglycaemia. These data contribute to our understanding of the mitochondrial disorder induced by hyperglycaemia as well as establishing the conditions required to minimize these alterations.

Aging-Induced Biological Changes and Cardiovascular Diseases

Aging is characterized by functional decline in homeostatic regulation and vital cellular events. This process can be linked with the development of cardiovascular diseases (CVDs). In this review, we discussed aging-induced biological alterations that are associated with CVDs through the following aspects: (i) structural, biochemical, and functional modifications; (ii) autonomic nervous system (ANS) dysregulation; (iii) epigenetic alterations; and (iv) atherosclerosis and stroke development. Aging-mediated structural and biochemical modifications coupled with gradual loss of ANS regulation, vascular stiffening, and deposition of collagen and calcium often disrupt cardiovascular system homeostasis. The structural and biochemical adjustments have been consistently implicated in the progressive increase in mechanical burden and functional breakdown of the heart and vessels. In addition, cardiomyocyte loss in this process often reduces adaptive capacity and cardiovascular function. The accumulation of epigenetic changes also plays important roles in the development of CVDs. In summary, the understanding of the aging-mediated changes remains promising towards effective diagnosis, discovery of new drug targets, and development of new therapies for the treatment of CVDs.

Role of Sirtuin 1 in the pathogenesis of ocular disease (Review)

Sirtuin (SIRT)1, a member of the SIRT family, is a highly conserved NAD+‑dependent histone deacetylase, which has a regulatory role in numerous physiological and pathological processes by removing acetyl groups from various proteins. SIRT1 controls the activity of numerous transcription factors and cofactors, which impacts the downstream gene expression, and eventually alleviates oxidative stress and associated damage. Numerous studies have revealed that dysfunction of SIRT1 is linked with ocular diseases, including cataract, age‑associated macular degeneration, diabetic retinopathy and glaucoma, while ectopic upregulation of SIRT1 protects against various ocular diseases. In the present review, the significant role of SIRT1 and the potential therapeutic value of modulating SIRT1 expression in ocular development and eye diseases is summarized.

Sirtuins and Accelerated Aging in Scleroderma

PURPOSE OF REVIEW

Premature activation of aging-associated molecular mechanisms is emerging as an important contributor to many diseases, including scleroderma. Among central regulators of the aging process are a group of histone deacetylases called sirtuins (SIRTs). Recent findings implicate these molecules as pathophysiological players in scleroderma skin and lung fibrosis. The goal of this article is to review recent studies on the involvement of SIRTs in scleroderma from the perspective of aging-related molecular mechanisms.

RECENT FINDINGS

Despite a degree of controversy in this rapidly developing field, the majority of data suggest that SIRT levels are decreased in tissues from patients with scleroderma compared to healthy controls as well as in animal models of scleroderma. Molecular studies reveal several mechanisms through which declining SIRT levels contribute to fibrosis, with the most attention given to modulation of the TGF-β signaling pathway. Activation of SIRTs in cell culture and in animal models elicits antifibrotic effects. Declining SIRT levels and activity are emerging as pathophysiological contributors to scleroderma. Restoration of SIRTs may be therapeutic in patients with scleroderma.

The Role of Sirtuins in Antioxidant and Redox Signaling

SIGNIFICANCE

Antioxidant and redox signaling (ARS) events are regulated by critical molecules that modulate antioxidants, reactive oxygen species (ROS) or reactive nitrogen species (RNS), and/or oxidative stress within the cell. Imbalances in these molecules can disturb cellular functions to become pathogenic. Sirtuins serve as important regulators of ARS in cells. Recent Advances: Sirtuins (SIRTs 1-7) are a family of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases with the ability to deacetylate histone and nonhistone targets. Recent studies show that sirtuins modulate the regulation of a variety of cellular processes associated with ARS. SIRT1, SIRT3, and SIRT5 protect the cell from ROS, and SIRT2, SIRT6, and SIRT7 modulate key oxidative stress genes and mechanisms. Interestingly, SIRT4 has been shown to induce ROS production and has antioxidative roles as well.

CRITICAL ISSUES

A complete understanding of the roles of sirtuins in redox homeostasis of the cell is very important to understand the normal functioning as well as pathological manifestations. In this review, we have provided a critical discussion on the role of sirtuins in the regulation of ARS. We have also discussed mechanistic interactions among different sirtuins. Indeed, a complete understanding of sirtuin biology could be critical at multiple fronts.

FUTURE DIRECTIONS

Sirtuins are emerging to be important in normal mammalian physiology and in a variety of oxidative stress-mediated pathological situations. Studies are needed to dissect the mechanisms of sirtuins in maintaining redox homeostasis. Efforts are also required to assess the targetability of sirtuins in the management of redox-regulated diseases. Antioxid. Redox Signal. 28, 643-661.

Functional genetic variants within the SIRT2 gene promoter in type 2 diabetes mellitus

AIMS

Type 2 diabetes mellitus (T2D) is a common and complex metabolic diseases caused by interactions between environmental and genetic factors. Genome-wide association studies have identified more than 80 common genetic variants for T2D, which account for only ∼10% of the heritability of T2D cases. SIRT2, a member of NAD(+)-dependent class III deacetylases, is involved in genomic stability, metabolism, inflammation, oxidative stress and autophagy. In maintaining metabolic homeostasis, SIRT2 regulates adipocyte differentiation, fatty acid oxidation, gluconeogenesis, and insulin sensitivity. Thus, we hypothesized that DNA sequence variants (DSVs) in SIRT2 gene promoter may change SIRT2 levels, contributing to T2D.

METHODS

SIRT2 gene promoter was genetically and functionally analyzed in large cohorts of T2D patients (n = 365) and ethnic-matched controls (n = 358).

RESULTS

A total of 18 DSVs, including 5 SNPs, were identified in this study. Four novel heterozygous DSVs (g.38900912G > T, g.38900561C > T, g.38900359C > T and g.38900237G > A) were identified in four T2D patients, three of which (g.38900912G > T, g.38900359C > T and g.38900237G > A) significantly increased the transcriptional activity of the SIRT2 gene promoter in cultured pancreatic beta cells (P < .01). Seven novel heterozygous DSVs were only found in controls, and one heterozygous deletion DSV and five SNPs were found in both T2D patients and controls, which did not significantly affect SIRT2 gene promoter activity (P > .05).

CONCLUSIONS

Our findings suggested that the DSVs may increase SIRT2 gene promoter activity and SIRT2 levels, contributing to T2D development as a risk factor.

Gene Expression, Oxidative Stress, and Senescence of Primary Coronary Endothelial Cells Exposed to Postprandial Serum of Healthy Adult and Elderly Volunteers after Oven-Cooked Meat Meals

Epidemiological studies have linked high consumption of meat with major age-related diseases including cardiovascular diseases. Abnormal postprandial increases in plasma lipids after a meat meal have been hypothesized among the pathogenetic mechanisms. However, it is still unknown if the postprandial serum derived after a normal meat meal is able to affect endothelial function, and if the type of meat and the age of the donors are critical factors. Here, we show the effects of postprandial sera derived from healthy adults and elderly volunteers who consumed meat meals on human coronary artery endothelial cell (HCAEC) oxidative stress, gene expression, DNA damage, and cellular senescence. We observed that a single exposure to postprandial serum induces a slight increase in ROS that is associated with modulation of gene expression pathways related to oxidative stress response and metabolism. The postprandial-induced increase in ROS is not associated with a measurable DNA oxidative damage. However, repeated exposure to postprandial serum induces an acceleration of cellular senescence. Taking into account the deleterious role of cellular senescence in age-related vascular diseases, the results suggest a new mechanism by which excessive meat consumption and time spent in postprandial state may affect health status during aging.

Advances in Cellular Characterization of the Sirtuin Isoform, SIRT7

SIRT7 is one of seven mammalian sirtuins that functions as an NAD⁺-dependent histone/protein deacetylase. SIRT7 is the least well-known member of the sirtuin family, but recent efforts have identified its involvement in various cellular processes, such as ribosome biogenesis, gene expression, cellular metabolism and cancer. Here we provide an update on the functions and mechanisms of SIRT7 in cellular regulation and disease.

SIRT6 protects against endothelial dysfunction and atherosclerosis in mice

SIRT6 is an important member of sirtuin family that represses inflammation, aging and DNA damage, three of which are causing factors for endothelial dysfunction. SIRT6 expression is decreased in atherosclerotic lesions from ApoE^−/− mice and human patients. However, the role of SIRT6 in regulating vascular endothelial function and atherosclerosis is not well understood. Here we show that SIRT6 protects against endothelial dysfunction and atherosclerosis. Global and endothelium-specific SIRT6 knockout mice exhibited impaired endothelium-dependent vasorelaxation. Moreover, SIRT6^+/− haploinsufficient mice fed a high-fat diet (HFD) also displayed impaired endothelium-dependent vasorelaxation. Importantly, SIRT6^+/−;ApoE^−/− mice after HFD feeding exhibited exacerbated atherosclerotic lesion development, concurrent with increased expression of the proinflammatory cytokine VCAM-1. Loss- and gain-of-SIRT6 function studies in cultured human endothelial cells (ECs) showed that SIRT6 attenuated monocyte adhesion to ECs. RNA-sequencing profiling revealed that SIRT6 overexpression decreased the expression of multiple atherosclerosis-related genes, including proatherogenic gene TNFSF4 (tumor necrosis factor superfamily member 4). Chromatin immunoprecipitation assays showed that SIRT6 decreased TNFSF4 gene expression by binding to and deacetylating H3K9 at TNFSF4 gene promoter. Collectively, these findings demonstrate that SIRT6 play a pivotal role in maintaining endothelial function and increased SIRT6 activity could be a new therapeutic strategy to combat atherosclerotic disease.

Emerging Evidence of Epigenetic Modifications in Vascular Complication of Diabetes

Genes, dietary, and lifestyle factors have been shown to be important in the pathophysiology of diabetes and associated microvascular complications. Epigenetic modifications, such as DNA methylation, histone acetylation, and post-transcriptional RNA regulation, are being increasingly recognized as important mediators of the complex interplay between genes and the environment. Recent studies suggest that diabetes-induced dysregulation of epigenetic mechanisms resulting in altered gene expression in target cells can lead to diabetes-associated complications, such as diabetic cardiomyopathy, diabetic nephropathy, retinopathy, and so on, which are the major contributors to diabetes-associated morbidity and mortality. Thus, knowledge of dysregulated epigenetic pathways involved in diabetes can provide much needed new drug targets for these diseases. In this review, we constructed our search strategy to highlight the role of DNA methylation, modifications of histones and role of non-coding RNAs (microRNAs and long non-coding RNAs) in vascular complications of diabetes, including cardiomyopathy, nephropathy, and retinopathy.

The spectrum of T cell metabolism in health and disease

In healthy individuals, metabolically quiescent T cells survey lymph nodes and peripheral tissues in search of cognate antigens. During infection, T cells that encounter cognate antigens are activated and - in a context-specific manner - proliferate and/or differentiate to become effector T cells. This process is accompanied by important changes in cellular metabolism (known as metabolic reprogramming). The magnitude and spectrum of metabolic reprogramming as it occurs in T cells in the context of acute infection ensure host survival. By contrast, altered T cell metabolism, and hence function, is also observed in various disease states, in which T cells actively contribute to pathology. In this Review, we introduce the idea that the spectrum of immune cell metabolic states can provide a basis for categorizing human diseases. Specifically, we first summarize the metabolic and interlinked signalling requirements of T cells responding to acute infection. We then discuss how metabolic reprogramming of T cells is linked to disease.

5-methoxytryptophan protects MSCs from stress induced premature senescence by upregulating FoxO3a and mTOR

5-methoxytryptophan (5-MTP) is a newly discovered tryptophan metabolite which controls stress-induced inflammatory signals. To determine whether 5-MTP protects against stress-induced mesenchymal stem cell (MSC) senescence, we incubated bone marrow-derived MSC (BM-MSC) in high-glucose medium or regular medium for 2 weeks followed by addiction of 5-MTP (10 μM) or vehicle for 48 h. 5-MTP reduced p16 and p21 expression, senescence-associated β-Gal (SA-β-Gal) and IL-6 secretion and increased BrdU incorporation. 5-MTP exerted a similar effect on BM-MSC senescence induced by a sublethal concentration of H2O2. 5-MTP enhanced FoxO3a expression and increased superoxide dismutase and catalase activities in HG BM-MSCs. Silencing of FoxO3a with siRNA abrogated 5-MTP-mediated reduction of SA-β-Gal and IL-6 secretion but not p21 or p16. Since mechanistic target of rapamycin (mTOR) is involved in cellular senescence, we determined whether 5-MTP influences mTOR expression. Our data reveal that mTOR protein level was depressed in HG-MSC which was rescued by 5-MTP. Rapamycin abrogated 5-MTP-mediated suppression of p16, p21, SA-β-Gal and IL-6 and rise of BrdU incorporation. Our findings suggest that 5-MTP protects MSCs against stress-induced senescence via FoxO3a and mTOR upregulation and has potential to improve cell expansion for cell therapy.

Short-term High Dose of Quercetin and Resveratrol Alters Aging Markers in Human Kidney Cells

Background:

Hyperglycemia-mediated oxidative stress implicates in etiology of kidney cell aging and diabetic nephropathy. We evaluated the effects of different doses of resveratrol and quercetin and their combination therapy on aging marker in human kidney cell culture under hyperglycemia condition.

Methods:

Human embryonic kidney cell (HEK-293) was cultured in Dulbecco's Modified Eagle Medium (DMEM) containing 100 mM (18 mg/L) for 24 h. The cells were treated with resveratrol (2.5, 5, 10 μm), quercetin (3, 6, 12 μm), and combination of these (R 2.5 μm, Q 3 μm) and (R 5 μm, Q 6 μm) and (R 10 μm, Q 12 μm) for 48 h, and then, cells were lysed to access RNA and lysate.

Results:

The analysis of data showed that beta-galactosidase enzyme gene expression as an aging marker in all treatment groups has reduced in a dose-dependent manner. Gene expression of Sirtuin1 and thioredoxin (Trx) in all treated groups in comparison to control group increased in a dose-dependent fashion. Trx interacting protein (TXNIP) gene expression decreased in a dose-dependent manner in all treated groups, especially in resveratrol and combination therapy.

Conclusions:

According to the results of this research, quercetin, resveratrol, and especially combination treatments with increased expression levels of antioxidants, can reduce aging markers in HEK cell line in hyperglycemia conditions. These results lead us to use flavonoids such as resveratrol for anti-aging potential.

Shared metabolic and immune-inflammatory, oxidative and nitrosative stress pathways in the metabolic syndrome and mood disorders

This review examines the shared immune-inflammatory, oxidative and nitrosative stress (IO&NS) and metabolic pathways underpinning metabolic syndrome (MetS), bipolar disorder (BD) and major depressive disorder (MDD). Shared pathways in both MetS and mood disorders are low grade inflammation, including increased levels of pro-inflammatory cytokines and acute phase proteins, increased lipid peroxidation with formation of malondialdehyde and oxidized low density lipoprotein cholesterol (LDL-c), hypernitrosylation, lowered levels of antioxidants, most importantly zinc and paraoxonase (PON1), increased bacterial translocation (leaky gut), increased atherogenic index of plasma and Castelli risk indices; and reduced levels of high-density lipoprotein (HDL-c) cholesterol. Insulin resistance is probably not a major factor associated with mood disorders. Given the high levels of IO&NS and metabolic dysregulation in BD and MDD and the high comorbidity with the atherogenic components of the MetS, mood disorders should be viewed as systemic neuro-IO&NS-metabolic disorders. The IO&NS-metabolic biomarkers may have prognostic value and may contribute to the development of novel treatments targeting neuro-immune, neuro-oxidative and neuro-nitrosative pathways.

PLK2 Plays an Essential Role in High D-Glucose-Induced Apoptosis, ROS Generation and Inflammation in Podocytes

Diabetic kidney disease (DKD) is a serious complication of hyperglycemia. Currently, there is no effective therapeutic intervention for DKD. In this study, we sought to provide a set of gene profile in diabetic kidneys. We identified 338 genes altered in diabetes-induced DKD glomeruli, and PLK2 exhibited the most dramatic change. Gene set enrichment analysis (GSEA) indicated multiple signaling pathways are involved DKD pathogenesis. Here, we investigated whether PLK2 contributes to podocyte dysfunction, a characteristic change in the development of DKD. High D-glucose (HDG) significantly increased PLK2 expression in mouse podocytes. Suppressing PLK2 attenuated HDG-induced apoptosis and inflammatory responses both in vitro and in vivo. NAC, an antioxidant reagent, rescued HDG and PLK2 overexpression-induced kidney injuries. In summary, we demonstrated that silencing PLK2 attenuates HDG-induced podocyte apoptosis and inflammation, which may serve as a future therapeutic target in DKD.

Sirt1 Inhibits Oxidative Stress in Vascular Endothelial Cells

The vascular endothelium is a layer of cells lining the inner surface of vessels, serving as a barrier that mediates microenvironment homeostasis. Deterioration of either the structure or function of endothelial cells (ECs) results in a variety of cardiovascular diseases. Previous studies have shown that reactive oxygen species (ROS) is a key factor that contributes to the impairment of ECs and the subsequent endothelial dysfunction. The longevity regulator Sirt1 is a NAD⁺-dependent deacetylase that has a potential antioxidative stress activity in vascular ECs. The mechanisms underlying the protective effects involve Sirt1/FOXOs, Sirt1/NF-κB, Sirt1/NOX, Sirt1/SOD, and Sirt1/eNOs pathways. In this review, we summarize the most recent reports in this field to recapitulate the potent mechanisms involving the protective role of Sirt1 in oxidative stress and to highlight the beneficial effects of Sirt1 on cardiovascular functions.

The role of dietary carbohydrates in organismal aging

Carbohydrates are essential nutrients that are used as a primary source of energy. Carbohydrate utilization should be properly controlled, as abnormal regulation of carbohydrate metabolism is associated with diseases, such as diabetes, cardiovascular diseases, and stroke. These metabolic syndromes have become a serious problem in developed countries, and there is an increased need for research examining the influence of carbohydrates on animal physiology. Diets enriched in glucose, a major carbohydrate, are also associated with accelerated aging in several model organisms, including yeast and Caenorhabditis elegans (C. elegans). Genetic factors that mediate the effects of high glucose diets on aging have been identified during the last decade, mostly through the use of C. elegans. In this review, we describe studies that determine the effects of carbohydrate-enriched diets on aging by focusing on the mechanisms through which evolutionarily conserved pathways mediate the lifespan-altering effects of glucose in C. elegans. These include the insulin/insulin-like growth factor-1, sterol-regulatory element-binding protein, and AMP-activated protein kinase signaling pathways. We also discuss the effects of various carbohydrates and carbohydrate-derived metabolites on aging in model organisms and cultured mammalian cells. Finally, we discuss how dietary carbohydrates influence health and aging in humans.

Functional genetic variants within the SIRT2 gene promoter in acute myocardial infarction

Coronary artery disease (CAD), including acute myocardial infarction (AMI) is the complication of atherosclerosis. Recently, genome-wide association studies have identified a large number of CAD-related genetic variants. However, only 10% of CAD cases could be explained. Low frequent and rare genetic variants have been recently proposed to be main causes for CAD. SIRT2 is a member of sirtuin family, NAD(+)-dependent class III deacetylases. SIRT2 is involved in genomic stability, metabolism, inflammation, oxidative stress and autophagy, as well as in platelet function. Thus, we hypothesized that genetic variants in SIRT2 gene may contribute to AMI. In this study, SIRT2 gene promoter was analyzed in large cohorts of AMI patients (n = 375) and ethnic-matched controls (n = 377). Three novel heterozygous DSVs (g.38900888_91delTAAA, g.38900270A>G and g.38899853C>T) were identified in three AMI patients, but in none of controls. These DSVs significantly altered the transcriptional activity of the SIRT2 gene promoter (P<0.05) in both HEK-293 and H9c2 cells. Five novel heterozygous DSVS (g.38900562C>T, g.38900413A>C, g.38900030G>A, g.38899925A>C and g.38899852C>T) were only found in controls, which did not significantly affected SIRT2 gene promoter activity (P>0.05). In addition, four novel heterozygous DSVs and five SNPs were found in both AMI patients and control with similar frequencies (P>0.05), two SNPs of which were examined and did not affect SIRT2 gene promoter activity (P>0.05). Taken together, the DSVs identified in AMI patients may change SIRT2 level by affecting the transcriptional activity of SIRT2 gene promoter, contributing to the AMI development as a rare risk factor.