Cardiac mitochondrial dysfunction during hyperglycemia--the role of oxidative stress and p66Shc signaling

Methylseleninic acid inhibits human glioma growth in vitro and in vivo by triggering ROS-dependent oxidative damage and apoptosis

Selenium-containing agents showed novel anticancer activity by triggering pro-oxidative mechanism. Studies confirmed that methylseleninic acid (MeSe) displayed broad-spectrum anti-tumor activity against kinds of human cancers. However, the anticancer effects and mechanism of MeSe against human glioma growth have not been explored yet. Herein, the present study showed that MeSeA dose-dependently inhibited U251 and U87 human glioma cells growth in vitro. Flow cytometry analysis indicated that MeSe induced significant U251 cells apoptosis with a dose-dependent manner, followed by the activation of caspase-7, caspase-9 and caspase-3. Immunofluorescence staining revealed that MeSe time-dependently caused reactive oxide species (ROS) accumulation and subsequently resulted in oxidative damage, as convinced by the increased phosphorylation level of Ser428-ATR, Ser1981-ATM, Ser15-p53 and Ser139-histone. ROS inhibition by glutathione (GSH) effectively attenuated MeSe-induced ROS generation, oxidative damage, caspase-3 activation and cytotoxicity, indicating that ROS was an upstream factor involved in MeSe-mediated anticancer mechanism in glioma. Importantly, MeSe administration in nude mice significantly inhibited glioma growth in vivo by inducing apoptosis through triggering oxidative damage. Taken together, our findings validated the possibility that MeSe as a selenium-containing can act as potential tumor chemotherapy agent for therapy of human glioma.

Biofactors regulating mitochondrial function and dynamics in podocytes and podocytopathies

Podocytes are terminally differentiated kidney cells acting as the main gatekeepers of the glomerular filtration barrier; hence, inhibiting proteinuria. Podocytopathies are classified as kidney diseases caused by podocyte damage. Different genetic and environmental risk factors can cause podocyte damage and death. Recent evidence shows that mitochondrial dysfunction also contributes to podocyte damage. Understanding alterations in mitochondrial metabolism and function in podocytopathies and whether altered mitochondrial homeostasis/dynamics is a cause or effect of podocyte damage are issues that need in-depth studies. This review highlights the roles of mitochondria and their bioenergetics in podocytes. Then, factors/signalings that regulate mitochondria in podocytes are discussed. After that, the role of mitochondrial dysfunction is reviewed in podocyte injury and the development of different podocytopathies. Finally, the mitochondrial therapeutic targets are considered.

Hyperglycemia Negatively Affects IPSC-Derived Myoblast Proliferation and Skeletal Muscle Regeneration and Function

Diabetic myopathy is a co-morbidity diagnosed in most diabetes mellitus patients, yet its pathogenesis is still understudied, which hinders the development of effective therapies. This project aimed to investigate the effect of hyperglycemia on human myoblast physiology, devoid of other complicating factors, by utilizing human myoblasts derived from induced pluripotent stem cells (iPSCs), in a defined in vitro system. IPSC-derived myoblasts were expanded under three glucose conditions: low (5 mM), medium (17.5 mM) or high (25 mM). While hyperglycemic myoblasts demonstrated upregulation of Glut4 relative to the euglycemic control, myoblast proliferation demonstrated a glucose dose-dependent impedance. Further cellular analysis revealed a retarded cell cycle progression trapped at the S phase and G2/M phase and an impaired mitochondrial function in hyperglycemic myoblasts. Terminal differentiation of these hyperglycemic myoblasts resulted in significantly hypertrophic and highly branched myotubes with disturbed myosin heavy chain arrangement. Lastly, functional assessment of these myofibers derived from hyperglycemic myoblasts demonstrated comparatively increased fatigability. Collectively, the hyperglycemic myoblasts demonstrated deficient muscle regeneration capability and functionality, which falls in line with the sarcopenia symptoms observed in diabetic myopathy patients. This human-based iPSC-derived skeletal muscle hyperglycemic model provides a valuable platform for mechanistic investigation of diabetic myopathy and therapeutic development.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Paradoxical effect of fat diet in matrix metalloproteinases induced mitochondrial dysfunction in diabetic cardiomyopathy

AIMS

Diabetic cardiomyopathy represents the main cause of death among diabetic people. Despite this evidence, the molecular mechanisms triggered by impaired glucose and lipid metabolism inducing heart damage remain unclear. The aim of our study was to investigate the effect of altered metabolism on the early stages of cardiac injury in experimental diabetes.

METHODS

For this purpose, rats were fed a normocaloric diet (NPD) or a high fat diet (HFD) for up to 12 weeks. After the fourth week, streptozocin (35 mg/kg) was administered in a subgroup of both NPD and HFD rats to induce diabetes. Cardiac function was analysed by echocardiography. Matrix metalloproteinases (MMPs) activity and intracellular localization were assessed through zymography and immunofluorescence, whereas apoptotic and oxidative markers by immunohistochemistry and western blot.

RESULTS

Hyperglycaemia or hyperlipidaemia reduced ejection fraction and fractional shortening as compared with control. Unexpectedly, cardiac dysfunction was less marked in diabetic rats fed a hyperlipidaemic diet, suggesting an adaptive response of the myocardium to hyperglycaemia-induced injury. This response was characterized by the inhibition of N-terminal truncated-MMP-2 translocation from endoplasmic reticulum into mitochondria and by superoxide anion overproduction observed in cardiomyocytes under hyperglycaemia.

CONCLUSION

Overall, these findings suggest novel therapeutic targets aimed to counteract mitochondrial dysfunction in the onset of diabetic cardiomyopathy.

Structure-functional implications of longevity protein p66Shc in health and disease

ShcA (Src homologous- collagen homologue), family of adapter proteins, consists of three isoforms which integrate and transduce external stimuli to different signaling networks. ShcA family consists of p46Shc, p52Shc and p66Shc isoforms, characterized by having multiple protein-lipid and protein-protein interaction domains implying their functional diversity. Among the three isoforms p66Shc is structurally different containing an additional CH2 domain which attributes to its dual functionality in cell growth, mediating both cell proliferation and apoptosis. Besides, p66Shc is also involved in different biological processes including reactive oxygen species (ROS) production, cell migration, ageing, cytoskeletal reorganization and cell adhesion. Moreover, the interplay between p66Shc and ROS is implicated in the pathology of various dreadful diseases. Accordingly, here we discuss the recent structural aspects of all ShcA adaptor proteins but are highlighting the case of p66Shc as model isoform. Furthermore, this review insights the role of p66Shc in progression of chronic age-related diseases like neuro diseases, metabolic disorders (non-alcoholic fatty liver, obesity, diabetes, cardiovascular diseases, vascular endothelial dysfunction) and cancer in relation to ROS. We finally conclude that p66Shc might act as a valuable biomarker for the prognosis of these diseases and could be used as a potential therapeutic target.

The mystery of mitochondria-ER contact sites in physiology and pathology: A cancer perspective

Mitochondria-associated membranes (MAM), physical platforms that enable communication between mitochondria and the endoplasmic reticulum (ER), are enriched with many proteins and enzymes involved in several crucial cellular processes, such as calcium (Ca²⁺) homeostasis, lipid synthesis and trafficking, autophagy and reactive oxygen species (ROS) production. Accumulating studies indicate that tumor suppressors and oncogenes are present at these intimate contacts between mitochondria and the ER, where they influence Ca²⁺ flux between mitochondria and the ER or affect lipid homeostasis at MAM, consequently impacting cell metabolism and cell fate. Understanding these fundamental roles of mitochondria-ER contact sites as important domains for tumor suppressors and oncogenes can support the search for new and more precise anticancer therapies. In the present review, we summarize the current understanding of basic MAM biology, composition and function and discuss the possible role of MAM-resident oncogenes and tumor suppressors.

Propofol attenuates high glucose-induced P66shc expression in human umbilical vein endothelial cells through Sirt1

Perioperative hyperglycemia is a common metabolic disorder in clinic settings. Hyperglycemia leads to endothelial inflammation, endothelial cell apoptosis, and dysfunction, thus resulting in endothelial injury. Propofol (2,6-diisopropylphenol) is a widely used intravenous anesthetic in clinic settings. Our previous study indicated that propofol inhibits mitochondrial reactive oxygen species (ROS) production via down-regulation of phosphatase A2 (PP2A) expression, inhibition of Ser36-p66shc dephosphorylation and mitochondrial translocation, thus improving high glucose-induced endothelial injury. The expression of p66shc was inhibited by propofol in hyperglycemic human umbilical vein endothelial cells (HUVECs). However, the mechanism by which propofol inhibits p66shc expression in hyperglycemic HUVECs is still obscure. In the present study, we mainly examined how propofol inhibited high glucose-induced p66shc expression in HUVECs. Compared with 5 mM glucose treatment, high glucose increased p66shc expression and decreased sirt1 expression, which was inhibited by propofol treatment. Moreover, EX527 (a sirt1 inhibitor) reversed the effect of propofol against high glucose-induced p66shc expression. However, EX527 did not reverse the effects of propofol against high glucose-induced ROS accumulation, endothelial inflammation, and apoptosis. Furthermore, when cells were incubated with propofol, EX527, and FTY720 (a PP2A activator) simultaneously, the effects of propofol against high glucose-induced ROS accumulation, inflammation, and apoptosis were reversed. Our results suggested that propofol inhibited high glucose-induced p66shc expression via upregulation of sirt1 expression in hyperglycemic HUVECs. Moreover, propofol protects against high glucose-mediated ROS accumulation and endothelial injury via both inhibition of p66shc expression and dephosphorylation of Ser36-p66shc.

Spinochrome D Attenuates Doxorubicin-Induced Cardiomyocyte Death via Improving Glutathione Metabolism and Attenuating Oxidative Stress

Doxorubicin, an anthracycline from Streptomyces peucetius, exhibits antitumor activity against various cancers. However, doxorubicin is cardiotoxic at cumulative doses, causing increases in intracellular reactive oxygen species in the heart. Spinochrome D (SpD) has a structure of 2,3,5,6,8-pentahydroxy-1,4-naphthoquinone and is a structural analogue of well-known sea urchin pigment echinochrome A. We previously reported that echinochrome A is cardioprotective against doxorubicin toxicity. In the present study, we assessed the cardioprotective effects of SpD against doxorubicin and determined the underlying mechanism. ¹H-NMR-based metabolomics and mass spectrometry-based proteomics were utilized to characterize the metabolites and proteins induced by SpD in a human cardiomyocyte cell line (AC16) and human breast cancer cell line (MCF-7). Multivariate analyses identified 12 discriminating metabolites (variable importance in projection > 1.0) and 1814 proteins from SpD-treated AC16 cells. Proteomics and metabolomics analyses showed that glutathione metabolism was significantly influenced by SpD treatment in AC16 cells. SpD treatment increased ATP production and the oxygen consumption rate in D-galactose-treated AC16 cells. SpD protected AC16 cells from doxorubicin cytotoxicity, but it did not affect the anticancer properties. With SpD treatment, the mitochondrial membrane potential and mitochondrial calcium localization were significantly different between cardiomyocytes and cancer cell lines. Our findings suggest that SpD could be cardioprotective against the cytotoxicity of doxorubicin.

Restorative Effect of Semecarpus Anacardium on Altered Energy Metabolism in Type-2 Diabetes Mellitus-Induced Cardiac Dysfunction in Rats

Semecarpus anacardium is an important herbal drug that has been used against various ailments. To evaluate the cardioprotective effect of the drug against altered cardiac energy metabolism in type-2 diabetes rats, type-2 diabetes was induced in rats by feeding them with a high-fat diet for 2 weeks followed by intraperitoneal injection of streptozotocin (STZ) 35 mg/kg body weight twice 24 h apart and left for 12 weeks to develop cardiovascular complication. The effects of the nut milk extract on the glucose metabolizing enzymes and mitochondrial complex enzymes were studied using biochemical assays. The drug effectively ameliorated the alteration in cardiac energy metabolism in diabetic rats. The cardioprotective effect may be mediated through the ability of the drug to enhance glucose utilization and control the oxidative stress under diabetic conditions.

Uncoupling proteins as a therapeutic target to protect the diabetic heart

Myocardial remodeling and dysfunction caused by accelerated oxidative damage is a widely reported phenomenon within a diabetic state. Altered myocardial substrate preference appears to be the major cause of enhanced oxidative stress-mediated cell injury within a diabetic heart. During this process, exacerbated free fatty acid flux causes an abnormal increase in mitochondrial membrane potential leading to the overproduction of free radical species and subsequent cell damage. Uncoupling proteins (UCPs) are expressed within the myocardium and can protect against free radical damage by modulating mitochondrial respiration, leading to reduced production of reactive oxygen species. Moreover, transgenic animals lacking UCPs have been shown to be more susceptible to oxidative damage and display reduced cardiac function when compared to wild type animals. This suggests that tight regulation of UCPs is necessary for normal cardiac function and in the prevention of diabetes-induced oxidative damage. This review aims to enhance our understanding of the pathophysiological mechanisms relating to the role of UCPs in a diabetic heart, and further discuss known pharmacological compounds and hormones that can protect a diabetic heart through the modulation of UCPs.

Recent advances of adapter proteins in the regulation of heart diseases

Heart diseases are major causes of mortality. Cardiac hypertrophy, myocardial infarction (MI), viral cardiomyopathy, ischemic and reperfusion (I/R) heart injury finally lead to heart failure and death. Insulin and IGF1 signal pathways play key roles in normal cardiomyocyte growth and physiological cardiac hypertrophy while inflammatory signal pathway is associated with pathological cardiac hypertrophy, MI, viral cardiomyopathy, I/R heart injury, and heart failure. Adapter proteins are the major family proteins, which transduce signals from insulin, IGF1, or cytokine receptors to the downstream pathways and have been shown to regulate variety of heart diseases. Here, we summarized the recent advances in understanding the physiological and pathological roles of adapter proteins in heart failure.

L-Carnitine: An Antioxidant Remedy for the Survival of Cardiomyocytes under Hyperglycemic Condition

BACKGROUND

Metabolic alterations as hyperglycemia and inflammation induce myocardial molecular events enhancing oxidative stress and mitochondrial dysfunction. Those alterations are responsible for a progressive loss of cardiomyocytes, cardiac stem cells, and consequent cardiovascular complications. Currently, there are no effective pharmacological measures to protect the heart from these metabolic modifications, and the development of new therapeutic approaches, focused on improvement of the oxidative stress condition, is pivotal. The protective effects of levocarnitine (LC) in patients with ischemic heart disease are related to the attenuation of oxidative stress, but LC mechanisms have yet to be fully understood.

OBJECTIVE

The aim of this work was to investigate LC's role in oxidative stress condition, on ROS production and mitochondrial detoxifying function in H9c2 rat cardiomyocytes during hyperglycemia.

METHODS

H9c2 cells in the hyperglycemic state (25 mmol/L glucose) were exposed to 0.5 or 5 mM LC for 48 and 72 h: LC effects on signaling pathways involved in oxidative stress condition were studied by Western blot and immunofluorescence analysis. To evaluate ROS production, H9c2 cells were exposed to H₂O₂ after LC pretreatment.

RESULTS

Our in vitro study indicates how LC supplementation might protect cardiomyocytes from oxidative stress-related damage, preventing ROS formation and activating antioxidant signaling pathways in hyperglycemic conditions. In particular, LC promotes STAT3 activation and significantly increases the expression of antioxidant protein SOD2. Hyperglycemic cardiac cells are characterized by impairment in mitochondrial dysfunction and the CaMKII signal: LC promotes CaMKII expression and activation and enhancement of AMPK protein synthesis. Our results suggest that LC might ameliorate metabolic aspects of hyperglycemic cardiac cells. Finally, LC doses herein used did not modify H9c2 growth rate and viability.

CONCLUSIONS

Our novel study demonstrates that LC improves the microenvironment damaged by oxidative stress (induced by hyperglycemia), thus proposing this nutraceutical compound as an adjuvant in diabetic cardiac regenerative medicine.

Oxidative Stress and Cardiovascular Risk: Obesity, Diabetes, Smoking, and Pollution: Part 3 of a 3-Part Series

Oxidative stress occurs whenever the release of reactive oxygen species (ROS) exceeds endogenous antioxidant capacity. In this paper, we review the specific role of several cardiovascular risk factors in promoting oxidative stress: diabetes, obesity, smoking, and excessive pollution. Specifically, the risk of developing heart failure is higher in patients with diabetes or obesity, even with optimal medical treatment, and the increased release of ROS from cardiac mitochondria and other sources likely contributes to the development of cardiac dysfunction in this setting. Here, we explore the role of different ROS sources arising in obesity and diabetes, and the effect of excessive ROS production on the development of cardiac lipotoxicity. In parallel, contaminants in the air that we breathe pose a significant threat to human health. This paper provides an overview of cigarette smoke and urban air pollution, considering how their composition and biological effects have detrimental effects on cardiovascular health.

Resveratrol Pretreatment Attenuates Concanavalin A-induced Hepatitis through Reverse of Aberration in the Immune Response and Regenerative Capacity in Aged Mice

Loss of regenerative capacity plays a critical role in age-related autoimmune hepatitis. Evidence implicates SIRT1 and p66^shc in cell senescence, apoptosis, oxidative stress, and proliferation. This study investigated the effect of resveratrol on concanavalin A (Con A)-induced hepatitis in aged mice and the roles of SIRT1 and p66^shc. Aged mice were administrated resveratrol (30 mg/kg orally) seven times at an interval of 12 h before a single intravenous injection of Con A (20 mg/kg). Results showed that the cytokines, TNF-α, IL-6, IFN-γ, and MCP-1, as well as infiltration of macrophages, neutrophils, and T lymphocytes in liver were dramatically enhanced in the mice given only Con A. The aged mouse livers showed markedly raised oxidative stress and cell apoptosis. This oxidative stress further aggravated regenerative dysfunction as indicated by the decreased levels of Ki67, PCNA, Cyclin D1, and Cdk2. Conversely, these phenomena were attenuated by pretreatment with resveratrol. Moreover, resveratrol suppressed the elevation of p66^shc in the liver by reversing Con-A-mediated downregulation of SIRT1. The findings suggest that resveratrol protected against Con A-induced hepatitis in aged mice by attenuating an aberration of immune response and liver regeneration, partially via the mechanism of SIRT1-mediated repression of p66^shc expression.

New aspects of p66Shc in ischaemia reperfusion injury and other cardiovascular diseases

Although reactive oxygen species (ROS) act as crucial factors in the onset and progression of a wide array of diseases, they are also involved in numerous signalling pathways related to cell metabolism, growth and survival. ROS are produced at various cellular sites, and it is generally agreed that mitochondria generate the largest amount, especially those in cardiomyocytes. However, the identification of the most relevant sites within mitochondria, the interaction among the various sources, and the events responsible for the increase in ROS formation under pathological conditions are still highly debated, and far from being clarified. Here, we review the information linking the adaptor protein p66Shc with cardiac injury induced by ischaemia and reperfusion (I/R), including the contribution of risk factors, such as metabolic syndrome and ageing. In response to several stimuli, p66Shc migrates into mitochondria where it catalyses electron transfer from cytochrome c to oxygen resulting in hydrogen peroxide formation. Deletion of p66Shc has been shown to reduce I/R injury as well as vascular abnormalities associated with diabetes and ageing. However, p66Shc-induced ROS formation is also involved in insulin signalling and might contribute to self-endogenous defenses against mild I/R injury. In addition to its role in physiological and pathological conditions, we discuss compounds and conditions that can modulate the expression and activity of p66Shc.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Inhibition of p66Shc-mediated mitochondrial apoptosis via targeting prolyl-isomerase Pin1 attenuates intestinal ischemia/reperfusion injury in rats

Intestinal epithelial oxidative stress and apoptosis constitute key pathogenic mechanisms underlying intestinal ischemia/reperfusion (I/R) injury. We previously reported that the adaptor 66 kDa isoform of the adaptor molecule ShcA (p66Shc)-mediated pro-apoptotic pathway was activated after intestinal I/R. However, the upstream regulators of the p66Shc pathway involved in intestinal I/R remain to be fully identified. Here, we focused on the role of a prolyl-isomerase, peptidyl–prolyl cis–trans isomerase (Pin1), in the regulation of p66Shc activity during intestinal I/R. Intestinal I/R was induced in rats by superior mesenteric artery (SMA) occlusion. Juglone (Pin1 inhibitor) or vehicle was injected intraperitoneally before I/R challenge. Caco-2 cells were exposed to hypoxia/reoxygenation (H/R) in vitro to simulate an in vivo I/R model. We found that p66Shc was significantly up-regulated in the I/R intestine and that this up-regulation resulted in the accumulation of intestinal mitochondrial reactive oxygen species (ROS) and massive epithelial apoptosis. Moreover, intestinal I/R resulted in elevated protein expression and enzyme activity of Pin1 as well as increased interaction between Pin1 and p66Shc. This Pin1 activation was responsible for the translocation of p66Shc to the mitochondria during intestinal I/R, as Pin1 suppression by juglone or siRNA markedly blunted p66Shc mitochondrial translocation and the subsequent ROS generation and cellular apoptosis. Additionally, Pin1 inhibition alleviated gut damage and secondary lung injury, leading to improvement of survival after I/R. Collectively, our findings demonstrate for the first time that Pin1 inhibition protects against intestinal I/R injury, which could be partially attributed to the p66Shc-mediated mitochondrial apoptosis pathway. This may represent a novel prophylactic target for intestinal I/R injury.

Propofol inhibits high glucose-induced PP2A expression in human umbilical vein endothelial cells

Perioperative hyperglycemia is a common clinical metabolic disorder. Hyperglycemia could induce endothelial apoptosis, dysfunction and inflammation, resulting in endothelial injury. Propofol is a widely used anesthetic drug in clinical settings. Our previous studies indicated that propofol, via inhibiting high glucose-induced phosphatase A2 (PP2A) expression, attenuated high glucose-induced reactive oxygen species (ROS) accumulation, thus improving endothelial apoptosis, dysfunction and inflammation. However, the mechanisms by which propofol attenuated high glucose-induced PP2A expression is still obscure. In the present study, we examined how propofol attenuates high glucose-induced endothelial PP2A expression. Compared with 5mM glucose treatment, 15mM glucose up-regulated expression and activity of PP2A, increased cAMP response element binding protein (CREB), Ca²⁺-calmodulin dependent kinase II (CaMK II) phosphorylation and Ca²⁺ accumulation. More importantly, propofol decreased PP2A expression and activity, attenuated CREB, CaMK II phosphorylation and Ca²⁺ accumulation in a concentration-dependent manner. Moreover, we demonstrated that the effect of propofol was similar to that of MK801, an inhibitor of NMDA receptor. In contrast, rapastinel, an activator of NMDA receptor, antagonized the effect of propofol. Also, the effect of KN93, an inhibitor of CaMK II, was similar to that of propofol, except KN93 had no effect on 15mM glucose-mediated Ca²⁺ accumulation. Our data indicated that propofol, via inhibiting NMDA receptor, attenuated 15mM glucose-induced Ca²⁺ accumulation, CaMK II and CREB phosphorylation, thus inhibiting PP2A expression and improving 15mM glucose-induced endothelial dysfunction and inflammation.

Expression Profiling of Genes Related to Endothelial Cells Biology in Patients with Type 2 Diabetes and Patients with Prediabetes

Endothelial dysfunction appears to be an early sign indicating vascular damage and predicts the progression of atherosclerosis and cardiovascular disorders. Extensive clinical and experimental evidence suggests that endothelial dysfunction occurs in Type 2 Diabetes Mellitus (T2DM) and prediabetes patients. This study was carried out with an aim to appraise the expression levels in the peripheral blood of 84 genes related to endothelial cells biology in patients with diagnosed T2DM or prediabetes, trying to identify new genes whose expression might be changed under these pathological conditions. The study covered a total of 45 participants. The participants were divided into three groups: group 1, patients with T2DM; group 2, patients with prediabetes; group 3, control group. The gene expression analysis was performed using the Endothelial Cell Biology RT² Profiler PCR Array. In the case of T2DM, 59 genes were found to be upregulated, and four genes were observed to be downregulated. In prediabetes patients, increased expression was observed for 49 genes, with two downregulated genes observed. Our results indicate that diabetic and prediabetic conditions change the expression levels of genes related to endothelial cells biology and, consequently, may increase the risk for occurrence of endothelial dysfunction.

Phlorofucofuroeckol Improves Glutamate-Induced Neurotoxicity through Modulation of Oxidative Stress-Mediated Mitochondrial Dysfunction in PC12 Cells

Stroke is a complex neurodegenerative disorder with a clinically high prevalence and mortality. Despite many efforts to protect against ischemic stroke, its incidence and related permanent disabilities continue to increase. In this study, we found that pretreatment with phlorofucofuroeckol (PFF), isolated from brown algae species, significantly increased cell viability in glutamate-stimulated PC12 cells. Additionally, glutamate-stimulated cells showed irregular morphology, but PFF pretreatment resulted in improved cell morphology, which resembled that in cells cultured under normal conditions. We further showed that PFF pretreatment effectively inhibited glutamate-induced apoptotic cell death in a caspase-dependent manner. Reactive oxygen species (ROS) induced by oxidative stress are closely associated with ischemia-induced neurological diseases. Exposure of PC12 cells to glutamate induced abundant production of intracellular ROS and mitochondrial dysfunction, which was attenuated by PFF in a dose-dependent manner. In vivo studies revealed that PFF-mediated prevention was achieved predominantly through inhibition of apoptosis and mitochondrial ROS generation. Taken together, these results suggest the possibility of PFF as a neuroprotective agent in ischemic stroke.

Propofol ameliorates endothelial inflammation induced by hypoxia/reoxygenation in human umbilical vein endothelial cells: Role of phosphatase A2

Hypoxia/reoxygenation (H/R) induces endothelial inflammation with augmentation of endothelial adhesion molecules over-expression. Propofol was reported to attenuate endothelial adhesion molecule expression in some situations. Here, we examined the molecular mechanism for how propofol restored H/R-mediated up-regulation of endothelial adhesion molecules in human umbilical vein endothelial cells (HUVECs). Compared with the control group, H/R up-regulated expression of Pin-1 and PP2A, increased p66(Shc)-Ser(36) phosphorylation, induced p66(Shc) mitochondrial translocation, O2(-) accumulation and NF-κB activation, and decreased eNOS-Ser(1177) phosphorylation and nitric oxide (NO) production, thus up-regulating expression of endothelial adhesion molecules and increasing mononuclear-endothelial interaction. More importantly, except that propofol had no effect on H/R-induced p66(Shc)-Ser(36) phosphorylation, most of H/R-mediated changes were alleviated by propofol, resulting in the reduction of endothelial adhesion molecules expression and mononuclear-endothelial adhesion. Moreover, we demonstrated the protective effect of propofol on H/R-induced endothelial inflammation was similar to that of calyculin A, an inhibitor of PP2A. In contrast, FTY720, an activator of PP2A, antagonized the effect of propofol. Our data indicated that propofol down-regulated PP2A expression, leading to reduced dephosphorylation of p66(Shc)-Ser(36) and eNOS-Ser(1177), which is associated with ROS accumulation and NO reduction, resulting in inhibition of endothelial adhesion molecule expression and mononuclear-endothelial interaction.

Hyperglycemic and hyperlipidemic conditions alter cardiac cell biomechanical properties

Currently, many diabetic cardiomyopathy (DC) studies focus on either in vitro molecular pathways or in vivo whole-heart properties such as ejection fraction. However, as DC is primarily a disease caused by changes in structural and functional properties, such studies may not precisely identify the influence of hyperglycemia or hyperlipidemia in producing specific cellular changes, such as increased myocardial stiffness or diastolic dysfunction. To address this need, we developed an in vitro approach to examine how structural and functional properties may change as a result of a diabetic environment. Particle-tracking microrheology was used to characterize the biomechanical properties of cardiac myocytes and fibroblasts under hyperglycemia or hyperlipidemic conditions. We showed that myocytes, but not fibroblasts, exhibited increased stiffness under diabetic conditions. Hyperlipidemia, but not hyperglycemia, led to increased cFos expression. Although direct application of reactive oxygen species had only limited effects that altered myocyte properties, the antioxidant N-acetylcysteine had broader effects in limiting glucose or fatty-acid alterations. Changes consistent with clinical DC alterations occur in cells cultured in elevated glucose or fatty acids. However, the individual roles of glucose, reactive oxygen species, and fatty acids are varied, suggesting multiple pathway involvement.

ShcC proteins: brain aging and beyond

To date, most studies of Shc family of signaling adaptor proteins have been focused on the near-ubiquitously expressed ShcA, indicating its relevance to age-related diseases and longevity. Although the role of the neuronal ShcC protein is much less investigated, accumulated evidence suggests its importance for neuroprotection against such aging-associated conditions as brain ischemia and oxidative stress. Here, we summarize more than decade of studies on the ShcC expression and function in normal brain, age-related brain pathologies and immune disorders with a focus on the interactions of ShcC with signaling proteins/pathways, and the possible implications of these interactions for changes associated with aging.

Propofol protects against angiotensin II-induced mouse hippocampal HT22 cells apoptosis via inhibition of p66Shc mitochondrial translocation

Hippocampal neuronal oxidative stress and apoptosis have been reported to be involved in cognitive impairment, and angiotensin II could induce hippocampal oxidative stress and apoptosis. Propofol is a widely used intravenous anesthetic agent in clinical practice, and it demonstrates significant neuroprotective activities. In this study, we investigated the mechanism how propofol protected mouse hippocampal HT22 cells against angiotensin II-induced oxidative stress and apoptosis. Cell viability was evaluated with CCK8 kit. Protein expressions of active caspase 3, cytochrome c, p66(Shc), p-p66(shc)-Ser(36), protein kinase C βII (PKCβII), Pin-1 and phosphatase A2 (PP2A) were measured by Western blot. Superoxide anion (O2(.-)) accumulation was measured with the reduction of ferricytochrome c. Compared with the control group, angiotensin II up-regulated expression of PKCβII, Pin-1 and PP2A, induced p66(Shc)-Ser(36) phosphorylation, and facilitated p66(Shc) mitochondrial translocation, resulting in O2(.-) accumulation, mitochondrial cytochrome c release, caspase 3 activation, and the inhibition of cell viability. Importantly, we found propofol inhibited angiotensin II-induced PKCβII and PP2A expression and improved p66(Shc) mitochondrial translocation, O2(.-) accumulation, mitochondrial cytochrome c release, caspase 3 activation, inhibition of cell viability. On the other hand, propofol had no effects on angiotensin II-induced Pin-1 expression and p66(Shc)-Ser(36) phosphorylation. Moreover, the protective effects of propofol on angiotensin II-induced HT22 apoptosis were similar with calyculin A, an inhibitor of PP2A and CGP53353, an inhibitor of PKCβII. However, the protective effect of propofol could be reversed by FTY720, an activator of PP2A, rather than PMA, an activator of PKCβII. Our data indicated that propofol down-regulated PP2A expression, inhibiting dephosphorylation of p66(Shc)-Ser(36) and p66(Shc) mitochondrial translocation, decreasing O2(.-) accumulation, reducing mitochondrial cytochrome c release, inhibiting caspase 3 activation. By these mechanisms, it protects mouse hippocampal HT22 cells against angiotensin II-induced apoptosis.