Endothelial Cellular Senescence Research Articles

Endothelial cellular senescence and tau accumulation: An interplay full of opportunities?

Recent research has shown that tau protein can be passed to neighboring cells, leading to cellular senescence in the endothelial cells present in the central nervous system (CNS). This discovery could potentially open new doors for testing novel therapeutic compounds that specifically target senescent cells (senolytics) or for identifying new biomarkers that can enable early detection of tauopathies and dementia.

Environmental aluminum oxide inducing neurodegeneration in human neurovascular unit with immunity

Aluminum oxide nanoparticle (AlNP), a ubiquitous neurotoxin highly enriched in air pollution, is often produced as an inevitable byproduct in the manufacturing of industrial products such as cosmetics and metal materials. Meanwhile, ALNP has emerged as a significant public health concern due to its potential association with neurological diseases. However, the studies about the neurotoxic effects of AlNP are limited, partially due to the lack of physiologically relevant human neurovascular unit with innate immunity (hNVUI). Here, we employed our AlNP-treated hNVUI model to investigate the underlying mechanism of AlNP-driven neurodegeneration. First, we validated the penetration of AlNP across a blood–brain barrier (BBB) compartment and found AlNP-derived endothelial cellular senescence through the p16 and p53/p21 pathways. Our study showed that BBB-penetrating AlNP promoted reactive astrocytes, which produced a significant level of reactive oxygen species (ROS). The astrocytic neurotoxic factors caused neuronal damage, including the synaptic impairment, the accumulation of phosphoric-tau proteins, and even neuronal death. Our study suggests that AlNP could be a potential environmental risk factor of neurological disorders mediated by neuroinflammation.

Abstract 14459: Endothelial Cell Specific Expression of HIV-Nef Induces Endothelial Senescence and Reduced Cardiac Output

Introduction: People living with HIV experience increased cardiovascular comorbidities despite immediate prescription of combined antiviral therapy (ART) upon HIV diagnosis. Previously, we reported that the virally encoded HIV-Nef protein persists in extracellular vesicles (EV) of aviremic HIV patients on ART and endothelial-specific transgenic expression of HIV-Nef in murine models causes increased endothelial surface expression of the pro-apoptotic protein EMAPII. Co-culture with HIV-Nef expressing T cells induced endothelial senescence which could be completely abrogated by using EMAPII-neutralizing antibodies. Hypothesis: Here we hypothesize that endothelial Nef expression in transgenic mice induces EMAPII-associated endothelial senescence after intermittent exposure to hypoxia. Methods: Female (n=5) transgenic mice with endothelium-specific Nef expression using VE-Cadherin promoter were challenged with 4 weeks of mild hypoxia (10% O 2 ) followed by 8 weeks of normoxia and then evaluated for cardiac function using non-invasive echocardiography with INVEVO2100. Results: We observed decreased cardiac output (Nef= 15.10 ul/min vs WT= 21.46 ul/min, p<0.05). Subsequently, we observed a 3.5-fold increased frequency of senescent endothelial cells using the senescence-associated marker p16INK4α (Nef= 0.54% vs WT= 0.15%, p<0.05) from the heart using flow cytometry. Furthermore, we also observed a 3.5-fold increase in the frequency of EMAPII+/P16INK4α+ cells (Nef= 0.50% vs WT= 0.14%, p<0.05). Conclusions: Transgenic endothelial HIV-Nef expression leads to upregulation of endothelial cellular senescence and EMAPII expression. EMAPII-neutralizing antibodies and senolytic agents are likely tools to reduce HIV-Nef-induced senescence. Endothelial cell senescence could affect cardiac circulation to impair heart function. Future studies will evaluate sex differences in HIV-Nef induces cardiac output at various ages.

A novel role for YPEL2 in mediating endothelial cellular senescence via the p53/p21 pathway

Yippee-like 2 (YPEL2) is expressed in tissues and organs enriched in vascular networks, such as heart, kidney, and lung. However, the roles of YPEL2 in endothelial cell senescence and the expression of YPEL2 in atherosclerotic plaques have not yet been investigated. Here, we report the essential role of YPEL2 in promoting senescence in human umbilical vein endothelial cells (HUVECs) and the upregulation of YPEL2 in human atherosclerotic plaques. YPEL2 was significantly upregulated in both H2O2-induced senescent HUVECs and the arteries of aged mice. Endothelial YPEL2 deficiency significantly decreased H2O2-increased senescence-associated beta-galactosidase (SA-β-gal) activity and reversed H2O2-inhibited cell viability. Additionally, endothelial YPEL2 knockdown reduced H2O2-promoted THP-1 cell adhesion to HUVECs and downregulated ICAM1 and VCAM1 expression. Mechanistic studies divulged that the p53/p21 pathway was involved in YPEL2-induced cellular senescence. We conclude that YPEL2 promotes cellular senescence via the p53/p21 pathway and that YPEL2 expression is elevated in atherosclerosis. These findings reveal YPEL2 as a potential therapeutic target in aging-associated diseases.

Nitrosative stress induced by homocysteine thiolactone drives vascular cognitive impairments via GTP cyclohydrolase 1 S-nitrosylation in vivo

Backgrounds: Hyperhomocysteinemia (HHcy) is one of risk factors for vascular cognitive impairment (VCI). GTP cyclohydrolase 1 (GCH1) deficiency is critical to oxidative stress in vascular dysfunction. The aim of this study was designed to examine whether HHcy induces VCI through GCH1 S-nitrosylation, a redox-related post-translational modification of cysteine. MethodsThe VCI model was induced by feeding mice homocysteine thiolactone (HTL) for 16 consecutive weeks. The cognitive functions were evaluated by step-down avoidance test, passive avoidance step-through task test, and Morris water maze (MWM) test. Protein S-nitrosylation was assayed using a biotin-switch method. ResultsIn cell-free system, nitric oxide (NO) donor induced GCH1 protein S-nitrosylation and decreased GCH1 activity. In endothelial cells, HTL increased GCH1 S-nitrosylation, reduced tetrahydrobiopterin, and induced oxidative stress, which were attenuated by N-acetyl-cysteine, L-N6-1-Iminoethyl-lysine, mutant of GCH1 cysteine 141 to alanine (MT-GCH1) or gene deletion of inducible NO synthase (iNOS). Further, HTL incubation or iNOS overexpression promoted endothelial cellular senescence, but abolished by exogenous expression of MT-GCH1 or pharmacological approaches including N-acetyl-cysteine, L-sepiapterin, and tempol. In wildtype mice, long-term administration of HTL induced GCH1 S-nitrosylation and vascular stiffness, decreased cerebral blood flow, and damaged the cognitive functions. However, these abnormalities induced by HTL administration were rescued by enforced expression of MT-GCH1 or gene knockout of iNOS. In human subjects, GCH1 S-nitrosylation was increased and cognitive functions were impaired in patients with HHcy. ConclusionThe iNOS-mediated nitrosative stress induced by HTL drives GCH1 S-nitrosylation to induce cerebral vascular stiffness and cognitive impairments.

Alteration of E2F2 Expression in Governing Endothelial Cell Senescence.

Endothelial cell senescence has a vital implication for vascular dysfunction, leading to age-related cardiovascular disease, especially hypertension and atherosclerosis. E2F transcription factor 2 (E2F2) plays a critical role in cell proliferation, differentiation, and DNA damage response. Up to date, no study has ever connected E2F2 to vascular endothelial cell senescence. Here, we demonstrate that E2F2 is involved in endothelial cellular senescence. We found that E2F2 expression is decreased during the replicative senescence of human umbilical vein endothelial cells (HUVECs) and the aortas of aged mice. The knockdown of E2F2 in young HUVECs induces premature senescence characterized by an increase in senescence-associated β-galactosidase (SA-β-gal) activity, a reduction in phosphorylated endothelial nitric oxide synthase (p-eNOS) and sirtuin 1 (SIRT1), and the upregulation of senescence-associated secretory phenotype (SASP) IL-6 and IL-8. The lack of E2F2 promoted cell cycle arrest, DNA damage, and cell proliferation inhibition. Conversely, E2F2 overexpression reversed the senescence phenotype and enhanced the cellular function in the senescent cells. Furthermore, E2F2 deficiency downregulated downstream target genes including CNNA2, CDK1, and FOXM1, and overexpression restored the expression of these genes. Our findings demonstrate that E2F2 plays an indispensable role in endothelial cell senescence.

Elimination of Senescent Cells by Senolytics Facilitates Bony Endplate Microvessel Formation and Mitigates Disc Degeneration in Aged Mice

Senolytics are a class of drugs that selectively eliminate senescent cells and ameliorate senescence-associated disease. Studies have demonstrated the accumulation of senescent disc cells and the production of senescence-associated secretory phenotype decrease the number of functional cells in degenerative tissue. It has been determined that clearance of senescent cell by senolytics rejuvenates various cell types in several human organs, including the largest avascular structure, intervertebral disc (IVD). The microvasculature in the marrow space of bony endplate (BEP) are the structural foundation of nutrient exchange in the IVD, but to date, the anti-senescence effects of senolytics on senescent vascular endothelial cells in the endplate subchondral vasculature remains unclear. In this study, the relationships between endothelial cellular senescence in the marrow space of the BEP and IVD degeneration were investigated using the aged mice model. Immunofluorescence staining was used to evaluate the protein expression of P16, P21, and EMCN in vascular endothelial cells. Senescence-associated β-galactosidase staining was used to investigate the senescence of vascular endothelial cells. Meanwhile, the effects of senolytics on cellular senescence of human umbilical vein endothelial cells were investigated using a cell culture model. Preliminary results showed that senolytics alleviate endothelial cellular senescence in the marrow space of BEP as evidenced by reduced senescence-associated secretory phenotype. In the aged mice model, we found decreased height of IVD accompanied by vertebral bone mass loss and obvious changes to the endplate subchondral vasculature, which may lead to the decrease in nutrition transport into IVD. These findings may provide evidence that senolytics can eliminate the senescent cells and facilitate microvascular formation in the marrow space of the BEP. Targeting senescent cellular clearance mechanism to increase nutrient supply to the avascular disc suggests a potential treatment value of senolytics for IVD degenerative diseases.

Palmitic Acid, A Critical Metabolite, Aggravates Cellular Senescence Through Reactive Oxygen Species Generation in Kawasaki Disease.

Coronary artery lesions (CALs) are severe complications of Kawasaki disease (KD), resulting in stenosis and thrombogenesis. Metabolomic profiling of patients’ plasma could assist in elucidating the pathogenesis of CALs and identifying diagnostic biomarkers, which are imperative for clinical treatment. The metabolic profiles between KD patients with CALs and without CALs (non-coronary artery lesion, or NCAL, group) indicated the most significantly differentially expressed metabolite, palmitic acid (PA), showed the most massive fold change at 9.879. Furthermore, PA was proven to aggravate endothelial cellular senescence by increasing the generation of reactive oxygen species (ROS) in KD, and those two phenotypes were confirmed to be enriched among the differentially expressed genes between KD and normal samples from GEO datasets. Collectively, our findings indicate that cellular senescence may be one of the mechanisms of vascular endothelial damage in KD. PA may be a biomarker and potential therapeutic target for predicting the occurrence of CALs in KD patients. All things considered, our findings confirm that plasma metabolomics was able to identify promising biomarkers and potential pathogenesis mechanisms in KD. To conclude, Palmitic acid could be a novel target in future studies of CALs in patients with KD.

TGF-\u03b21 is involved in senescence-related pathways in glomerular endothelial cells via p16 translocation and p21 induction

p16 inhibits cyclin-dependent kinases and regulates senescence-mediated arrest as well as p21. Nuclear p16 promotes G1 cell cycle arrest and cellular senescence. In various glomerular diseases, nuclear p16 expression is associated with disease progression. Therefore, the location of p16 is important. However, the mechanism of p16 trafficking between the nucleus and cytoplasm is yet to be fully investigated. TGF-β1, a major cytokine involved in the development of kidney diseases, can upregulate p21 expression. However, the relationship between TGF-β1 and p16 is poorly understood. Here, we report the role of podocyte TGF-β1 in regulating the p16 behavior in glomerular endothelial cells. We analyzed podocyte-specific TGF-β1 overexpression mice. Although p16 was found in the nuclei of glomerular endothelial cells and led to endothelial cellular senescence, the expression of p16 did not increase in glomeruli. In cultured endothelial cells, TGF-β1 induced nuclear translocation of p16 without increasing its expression. Among human glomerular diseases, p16 was detected in the nuclei of glomerular endothelial cells. In summary, we demonstrated the novel role of podocyte TGF-β1 in managing p16 behavior and cellular senescence in glomeruli, which has clinical relevance for the progression of human glomerular diseases.

Vascular Endothelial Senescence: Pathobiological Insights, Emerging Long Noncoding RNA Targets, Challenges and Therapeutic Opportunities.

Cellular senescence is a stable form of cell cycle arrest in response to various stressors. While it serves as an endogenous pro-resolving mechanism, detrimental effects ensue when it is dysregulated. In this review, we introduce recent advances for cellular senescence and inflammaging, the underlying mechanisms for the reduction of nicotinamide adenine dinucleotide in tissues during aging, new knowledge learned from p16 reporter mice, and the development of machine learning algorithms in cellular senescence. We focus on pathobiological insights underlying cellular senescence of the vascular endothelium, a critical interface between blood and all tissues. Common causes and hallmarks of endothelial senescence are highlighted as well as recent advances in endothelial senescence. The regulation of cellular senescence involves multiple mechanistic layers involving chromatin, DNA, RNA, and protein levels. New targets are discussed including the roles of long noncoding RNAs in regulating endothelial cellular senescence. Emerging small molecules are highlighted that have anti-aging or anti-senescence effects in age-related diseases and impact homeostatic control of the vascular endothelium. Lastly, challenges and future directions are discussed including heterogeneity of endothelial cells and endothelial senescence, senescent markers and detection of senescent endothelial cells, evolutionary differences for immune surveillance in mice and humans, and long noncoding RNAs as therapeutic targets in attenuating cellular senescence. Accumulating studies indicate that cellular senescence is reversible. A better understanding of endothelial cellular senescence through lifestyle and pharmacological interventions holds promise to foster a new frontier in the management of cardiovascular disease risk.

Quercetin Attenuates Atherosclerosis via Modulating Oxidized LDL-Induced Endothelial Cellular Senescence.

Background and AimsEndothelial senescence is an important risk factor leading to atherosclerosis. The mechanism of quercetin against endothelial senescence is worth exploring.MethodsQuercetin (20 mg/kg/d) was administered to ApoE-/- mice intragastrically to evaluate the effectiveness of quercetin on atherosclerotic lesion in vivo. In vitro, human aortic endothelial cells (HAECs) were used to assess the effect of quercetin on cellular senescence induced by oxidized low-density lipoprotein (ox-LDL). Transcriptome microarray and quantitative RT-PCR was conducted to study the pharmacological targets of quercetin.ResultsApoE-/- mice demonstrated obvious lipid deposition in arterial lumina, high level of serum sIcam-1 and IL-6, and high density of Vcam-1 and lower density of Sirt1 in aorta. Quercetin administration decreased lipid deposition in arterial lumina, serum sIcam-1, and IL-6 and Vcam-1 in aorta, while increased the density of Sirt1 in aorta of ApoE-/- mice. In vitro, quercetin (0.3, 1, or 3 μmol/L) decreased the expression of senescence-associated β-galactosidase and improved cell morphology of HAECs. And quercetin decreased the cellular apoptosis and increased mitochondrial membrane potential (ΔΨm) in dose-dependent manner, and decreased ROS generation simultaneously. Transcriptome microarray suggested 254 differentially expressed (DE) mRNAs (110 mRNAs were upregulated and 144 mRNAs were downregulated) in HAECs after quercetin treatment (fold change > 1.5, P < 0 .05, Que vs Ox-LDL). GO and KEGG analysis indicated nitrogen metabolism, ECM-receptor interaction, complement, and coagulation cascades, p53 and mTOR signaling pathway were involved in the pharmacological mechanisms of quercetin against ox-LDL.ConclusionsQuercetin alleviated atherosclerotic lesion both in vivo and in vitro.

Salicin prevents TNF-α-induced cellular senescence in human umbilical vein endothelial cells (HUVECs)

Cellular senescence is strongly tied to vascular disease. The current study aims to examine ways that endothelial cellular senescence can be prevented and the mechanisms by which prevention of senescence occurs. Human umbilical vein endothelial cells were exposed to TNF-α to induce senescence; then salicin was administered in two doses – 50 and 100 µM – to establish a dose-dependent effect of salicin on SA-β-Gal, G1 cell cycle arrest, expression of p21 and PAI-1, p53 acetylation at K382, NRF2 and oxidative stress. NRF2 was examined as a mediating mechanism of salicin’s impact on cellular senescence and was found to account for salicin’s impact on SA-β-Gal, p21, PAI-1 and p53. Together, these results provide a compelling case that salicin has a substantial impact on numerous factors tied to cellular senescence in human endothelial cells. Thus, treatment with salicin may hold promise as a means of preventing aging-related vascular disease. Furthermore, salicin appears to operate via a functional pathway that is different from that affected by anti-inflammatory drugs (e.g. aspirin).

Appropriate dose of ethanol exerts anti-senescence and anti-atherosclerosis protective effects by activating ALDH2

Moderate alcohol consumption has been shown to reduce atherosclerosis-associated diseases. As shown in our earlier works, ethanol has a dose-dependent protective effects against endothelial cellular senescence by activating aldehyde dehydrogenase 2 (ALDH2) in vitro. However, whether ethanol administration possesses anti-atherosclerosis properties and whether ALDH2 is involved in the underlying mechanisms are unknown. In the present study, we revealed that the appropriate dose of ethanol reduced atherosclerotic plaque formation, and upregulated ALDH2 expression and activity in ApoE-/- mice. ALDH2 deficiency blocked the protection of ethanol against atherosclerotic plaque formation by inhibiting endothelium senescence. In contrast, Alda-1, which is a specific enzymatic agonist of ALDH2, enhanced the anti-senescence and anti-atherosclerosis effects of the appropriate dose of ethanol. Furthermore, following ALDH2 knockdown, resveratrol (an anti-aging compound) recovered the beneficial effects of ethanol against endothelial senescence in vitro. Thus, these results suggest that the appropriate dose of ethanol has protective effects against endothelial senescence and atherosclerosis by activating ALDH2.

Ku86 alleviates human umbilical vein endothelial cellular apoptosis and senescence induced by a low dose of ionizing radiation.

ObjectiveThe aim of this study was to observe the effect of Ku86 on cellular senescence and apoptosis induced by various doses of ionizing radiation in human umbilical vein endothelial cells (HUVECs).MethodsSenescence-associated β-galactosidase activity was detected to evaluate cell senescence. Apoptosis was determined by flow cytometry and a caspase enzyme determination kit. p16Ink4a, Sirt1, superoxide dismutase 2 (SOD2), xanthine oxidase (XOD), and Bcl-2 protein expression levels were measured by western blotting.ResultsLow doses of ionizing radiation induced cellular senescence and apoptosis in a dose-dependent manner. The Ku86 protein was negatively correlated with ionization intensity. After transfection of Ku86 with a vector (pcDNA 3.1), or interference with siRNA (si-Ku86), apoptosis/senescence and related protein expression were observed. Western blot results revealed that this induction of senescence was associated with activated Sirt1 and SOD2, and downregulation of p16Ink4a and XOD in 0.2 Gy ionizing radiation. The expression levels of apoptosis-associated proteins, such as Bcl-2, cleaved caspase-3, caspase-8, and caspase-9, were significantly altered in both the presence and absence of Ku86 with ionizing radiation (0.2 Gy).ConclusionsOur study revealed that Ku86 overexpression inhibits HUVEC apoptosis and senescence induced by low doses of ionizing radiation.

Salidroside attenuates endothelial cellular senescence via decreasing the expression of inflammatory cytokines and increasing the expression of SIRT3

ObjectiveEndothelial cellular senescence is an important contributor to the endothelial dysfunction and atherosclerosis. Our previous studies suggested that salidroside (SAL) can alleviate atherosclerosis and protect endothelial cells against oxidative stress induced damage. However, the effect and mechanism of SAL on endothelial cellular senescence is still unclear. Here, we investigated the underlying mechanisms of SAL on preventing endothelial cellular premature senescence. Methods and resultsWe established a hyperhomocysteinemia (HHcy)mouse model via high methionine diet (HMD) to explore the protective effect of SAL. According to our results, the HMD elevated the concentration of serum homocysteine. HHcy induced the collagen deposition and the up-regulation of senescence markers, i.e. p16INK4A and p21CIP1, in intima-medial of aorta. In addition, SAL also inhibited the expression of CD68 and intercellular adhesion molecule 1 (ICAM1) in aorta. In senescent human umbilical vein endothelial cells (HUVECs) induced by H2O2, SAL treatment alleviated the expression of p16INK4A and p21CIP1 and reduced the activity of senescence-associated (SA)-β-gal. Conclusionour data suggested that SAL decreased the expression of inflammatory cytokines and up-regulated the expression of SIRT3, which might be the underlying mechanism of SAL on preventing endothelial cells from premature senescence.

Intermittent high glucose implements stress-induced senescence in human vascular endothelial cells: role of superoxide production by NADPH oxidase.

Impaired glucose tolerance characterized by postprandial hyperglycemia, which occurs frequently in elderly persons and represents an important preliminary step in diabetes mellitus, poses an independent risk factor for the development of atherosclerosis. Endothelial cellular senescence is reported to precede atherosclerosis. We reported that continuous high glucose stimulus causes endothelial senescence more markedly than hypertension or dyslipidemia stimulus. In the present study, we evaluated the effect of fluctuating glucose levels on human endothelial senescence. Constant high glucose increased senescence-associated-β-galactosidase(SA-β-gal) activity, a widely used marker for cellular senescence. Interestingly, in intermittent high glucose, this effect was more pronounced as well as increase of p21 and p16INK4a , senescence related proteins with DNA damage. However, telomerase was not activated and telomere length was not shortened, thus stress-induced senescence was shown. However, constant high glucose activated telomerase and shortened telomere length, which suggested replicative senescence. Intermittent but not constant high glucose strikingly up-regulated the expression of p22phox, an NADPH oxidase component, increasing superoxide. The small interfering RNA of p22phox undermined the increase in SA-β-gal activity induced by intermittent high glucose. Conclusively, intermittent high glucose can promote vascular endothelial senescence more than constant high glucose, which is in partially dependent on superoxide overproduction.

Endothelial cellular senescence is inhibited by liver X receptor activation with an additional mechanism for its atheroprotection in diabetes

Senescence of vascular endothelial cells leads to endothelial dysfunction and contributes to the progression of atherosclerosis. Liver X receptors (LXRs) are nuclear receptors whose activation protects against atherosclerosis by transcriptional regulation of genes important in promoting cholesterol efflux and inhibiting inflammation. Here we found that LXR activation with specific ligands reduced the increase in senescence-associated (SA) β-gal activity, a senescence marker, and reversed the decrease in telomerase activity, a replicative senescence marker, in human endothelial cells under high glucose. This effect of LXR activation was associated with reduced reactive oxygen species and increased endothelial NO synthase activity. A series of experiments that used siRNAs indicated that LXRβ mediates the prevention of endothelial cellular senescence, and that sterol regulatory element binding protein-1, which was up-regulated as a direct LXRβ target gene, may act as a brake of endothelial cellular senescence. Although oral administration of the LXR ligand led to severe fatty liver in diabetic rats, concomitant therapy with metformin avoided the development of hepatic steatosis. However, the preventive effect of the LXR ligand on SA β-gal-stained cells in diabetic aortic endothelium was preserved even if metformin was coadministered. Taken together, our studies demonstrate that an additional mechanism, such as the regulation of endothelial cellular senescence, is related to the antiatherogenic properties of LXRs, and concomitant treatment with metformin may provide a clinically useful therapeutic strategy to alleviate an LXR activation-mediated adverse effects on liver triglyceride metabolism.

Icariin delays homocysteine-induced endothelial cellular senescence involving activation of the PI3K/AKT-eNOS signaling pathway

Context: Homocysteine-induced endothelial cellular senescence may contribute to some cardiovascular disorders. Icariin (ICA), a flavonoid derived from Epimedium sagittatum Maxim. (Berberidaceae), has been reported to increase production of nitric oxide (NO) and reduce reactive oxygen species (ROS) levels in human umbilical vein endothelial cells (HUVECs).Objective: To observe the effects of ICA on homocysteine-induced senescence and the underlying mechanisms in HUVECs.Materials and methods: ICA at concentrations of 0.1, 1, and 5 μM was added into homocysteine pretreated HUVECs. Cellular senescence was assayed by senescence-associated β-galactosidase (SA-β-gal) staining and cumulative population doublings (CPDs). ICA (5 μM) was given orally to homocysteine-treated rats, luminal surface of aortic artery of rats was subjected to SA-β-gal staining. Protein expression was measured by western blot.Results: Homocysteine significantly increased cellular senescence both in vitro and in vivo. After treatment by ICA, the percentage of SA-β-gal-positive cells, and the ROS level significantly decreased. The CPDs were partially restored. ICA also significantly reduced the mean density of SA-β-gal staining in vivo. We found that NO production and phosphorylation of AKT, ERK, and endothelial NO synthase (eNOS) were elevated by ICA in HUVECs. Furthermore, the increased level of NO production was fully abolished by the phosphatidylinositol-3-kinase (PI3K) inhibitor wortmannin. The mitogen-activated protein kinase (MEK) inhibitor PD98059, which can inhibit phosphorylation of ERK, did not show this ability.Discussion and conclusion: Our results indicate that ICA delays homocyteine-induced endothelial senescence in vitro and in vivo. Activation of PI3K/Akt-eNOS-dependent signaling pathway may be responsible for this efficacy of ICA.

E0473 Rapid re-endothelialization and anti-intimal hyperplasia coronary stent system with a novel biomacromolecular prohealing coating

BackgroundRapid healing of endothelium on the coronary stent is a crucial method to prevent late stent thrombosis, a rare but life-threatening complication of drug eluting stents (DES). Here we developed...

Ataxia Telangiectasia Mutated (ATM)-mediated DNA Damage Response in Oxidative Stress-induced Vascular Endothelial Cell Senescence

Oxidative stress regulates dysfunction and senescence of vascular endothelial cells. The DNA damage response and its main signaling pathway involving ataxia telangiectasia mutated (ATM) have been implicated in playing a central role in mediating the actions of oxidative stress; however, the role of the ATM signaling pathway in vascular pathogenesis has largely remained unclear. Here, we identify ATM to regulate oxidative stress-induced endothelial cell dysfunction and premature senescence. Oxidative stress induced senescence in endothelial cells through activation/phosphorylation of ATM by way of an Akt/p53/p21-mediated pathway. These actions were abrogated in cells in which ATM was knocked down by RNA interference or inhibited by specific inhibitory compounds. Furthermore, the in vivo significance of this regulatory pathway was confirmed using ATM knock-out mice in which induction of senescent endothelial cells in the aorta in a diabetic mouse model of endothelial dysfunction and senescence was attenuated in contrast to pathological changes seen in wild-type mice. Collectively, our results show that ATM through an ATM/Akt/p53/p21-dependent signaling pathway mediates an instructive role in oxidative stress-induced endothelial dysfunction and premature senescence.