Heme Oxygenase (HO)-1 Induction Prevents Endoplasmic Reticulum Stress-Mediated Endothelial Cell Death and Dysfunction

Diabetes is intimately associated with cardiovascular complications. Much evidence highlighted the complex interplay between Endoplasmic Reticulum (ER) stress and oxidative stress in the pathogenesis of diabetes. Hemeoxygenase-1 (HO-1) induction was shown to protect against oxidative stress in diabetes; however the underlying molecular mechanisms have not yet been fully elucidated. We aim in this project to test the hypothesis that HO-1 induction will protect against high glucose-mediated ER stress and oxidative stress in endothelial cells and will enhance cell survival. Endothelial cells were cultured in physiological or high concentrations of glucose in the presence of cobalt protoporphyrin 1X (CoPP, HO-1 inducer), 4-phenylbutyrate (PBA, chemical chaperone to inhibit ER stress) or vehicle. Then, ER stress response was assessed (PCR, western blot). The productions of ROS (flow cytometer) and NO (Griess assay) were analysed. Also, apoptosis and caspase 3/7 activity were assessed. High glucose treatment in cells increased protein and mRNA expression of several ER stress response markers (BIP, CHOP, ATF4) and enhanced ROS production in addition to reducing NO release. Interestingly, the pre-treatment of cells with PBA or CoPP significantly reduced high glucose-mediated ER stress and oxidative stress in cells. Also, cells incubated with high glucose had enhanced apoptosis, increased protein expression of cleaved PARP and caspase-7 in addition to enhanced caspases 3/7 activity while cells pre-treated with either PBA or CoPP were totally protected. The mRNA expression of inflammatory cytokine IL-6 was enhanced in cells incubated with high glucose while those pre-treated with PBA or CoPP were prevented. These results highlight the importance of oxidative stress both in initiating or maintaining ER stress response and in mediating ER stress-induced damage and cell death in endothelial cells. This work also underscores the therapeutic potential of HO-1 induction against hyperglycaemia-mediated endothelial dysfunction.qscienc

Heme oxygenase (HO)-1 induction prevents Endoplasmic Reticulum stress-mediated endothelial cell death and impaired angiogenic capacity

Most of diabetic cardiovascular complications are attributed to endothelial dysfunction and impaired angiogenesis. Endoplasmic Reticulum (ER) and oxidative stresses were shown to play a pivotal role in the development of endothelial dysfunction in diabetes. Hemeoxygenase-1 (HO-1) was shown to protect against oxidative stress in diabetes; however, its role in alleviating ER stress-induced endothelial dysfunction remains not fully elucidated. We aim here to test the protective role of HO-1 against high glucose-mediated ER stress and endothelial dysfunction and understand the underlying mechanisms with special emphasis on oxidative stress, inflammation and cell death.Human Umbilical Vein Endothelial Cells (HUVECs) were grown in either physiological or intermittent high concentrations of glucose for 5days in the presence or absence of Cobalt (III) Protoporphyrin IX chloride (CoPP, HO-1 inducer) or 4-Phenyl Butyric Acid (PBA, ER stress inhibitor). Using an integrated cellular and molecular approach, we then assessed ER stress and inflammatory responses, in addition to apoptosis and angiogenic capacity in these cells.Our results show that HO-1 induction prevented high glucose-mediated increase of mRNA and protein expression of key ER stress markers. Cells incubated with high glucose exhibited high levels of oxidative stress, activation of major inflammatory and apoptotic responses [nuclear factor (NF)-κB and c-Jun N-terminal kinase (JNK)] and increased rate of apoptosis; however, cells pre-treated with CoPP or PBA were fully protected. In addition, high glucose enhanced caspases 3 and 7 cleavage and activity and augmented cleaved poly ADP ribose polymerase (PARP) expression whereas HO-1 induction prevented these effects. Finally, HO-1 induction and ER stress inhibition prevented high glucose-induced reduction in NO release and impaired the angiogenic capacity of HUVECs, and enhanced vascular endothelial growth factor (VEGF)-A expression.Altogether, we show here the critical role of ER stress-mediated cell death in diabetes-induced endothelial dysfunction and impaired angiogenesis and underscore the role of HO-1 induction as a key therapeutic modulator for ER stress response in ischemic disorders and diabetes. Our results also highlight the complex interplay between ER stress response and oxidative stress.This work was supported with grants to Dr Abdelali Agouni from the Royal Society, the Physiological Society, and Qatar University (grant QUUG-CPH-CPH-15/16-6). Mr Maamoun and Ms. Zachariah are supported by doctoral scholarships from Egyptian cultural bureau and Government of Botswana, respectively

High Selenium Intake is Associated with Endothelial Dysfunction: Critical Role for Endoplasmic Reticulum Stress

Selenium is associated with insulin resistance and may therefore affect endothelial function, increasing type II diabetes risk and associated cardiovascular-disease risk. However the underpinning molecular mechanisms involved are not clear. High selenium doses cause apoptosis in some cancer cells through the induction of endoplasmic reticulum (ER) stress response, a mechanism also involved in the pathogenesis of insulin resistance and endothelial dysfunction (ED). Thus we hypothesised that high selenium intake could cause ED through ER stress. Endothelial cells were treated with selenite (0.5–20 μM) in the presence or absence of the ER chemical chaperone, 4-phenylbutryic acid (PBA). High selenium concentrations (5–10 μM of selenite) compared to physiological concentration (0.5 μM) enhanced mRNA expression of several pro-apoptotic ER stress markers; such as activating transcription factor-4 (ATF4) and CAAA/enhanced-binding homologous protein (CHOP). In addition, Griess assay showed that high selenite treatment (5–20 μM) reduced NO production. Moreover, flow cytometry assays showed that high selenium enhanced ROS production and apoptosis in cells. Finally, supra-nutritional concentrations of selenite increased caspases 3/7 activity in endothelial cells compared to the physiological concentration. Interestingly, the pre-incubation of cells with PBA completely reversed all the effects of high selenium indicating the involvement of ER stress response. Overall, we show here that high selenium treatment causes endothelial dysfunction and cell death through the activation of ER stress response. These results highlight the importance of a balanced selenium intake in order to achieve maximal health benefits. These findings also underscore the importance to monitor cardiovascular risk development in cancer patients supplemented with high amounts of selenium as part of their chemotherapeutic intervention.qscienc

Crosstalk Between Oxidative Stress and Endoplasmic Reticulum (ER) Stress in Endothelial Dysfunction and Aberrant Angiogenesis Associated With Diabetes: A Focus on the Protective Roles of Heme Oxygenase (HO)-1

Type-2 diabetes prevalence is continuing to rise worldwide due to physical inactivity and obesity epidemic. Diabetes and fluctuations of blood sugar are related to multiple micro- and macrovascular complications, that are attributed to oxidative stress, endoplasmic reticulum (ER) activation and inflammatory processes, which lead to endothelial dysfunction characterized, among other features, by reduced availability of nitric oxide (NO) and aberrant angiogenic capacity. Several enzymatic anti-oxidant and anti-inflammatory agents have been found to play protective roles against oxidative stress and its downstream signaling pathways. Of particular interest, heme oxygenase (HO) isoforms, specifically HO-1, have attracted much attention as major cytoprotective players in conditions associated with inflammation and oxidative stress. HO operates as a key rate-limiting enzyme in the process of degradation of the iron-containing molecule, heme, yielding the following byproducts: carbon monoxide (CO), iron, and biliverdin. Because HO-1 induction was linked to pro-oxidant states, it has been regarded as a marker of oxidative stress; however, accumulating evidence has established multiple cytoprotective roles of the enzyme in metabolic and cardiovascular disorders. The cytoprotective effects of HO-1 depend on several cellular mechanisms including the generation of bilirubin, an anti-oxidant molecule, from the degradation of heme; the induction of ferritin, a strong chelator of free iron; and the release of CO, that displays multiple anti-inflammatory and anti-apoptotic actions. The current review article describes the major molecular mechanisms contributing to endothelial dysfunction and altered angiogenesis in diabetes with a special focus on the interplay between oxidative stress and ER stress response. The review summarizes the key cytoprotective roles of HO-1 against hyperglycemia-induced endothelial dysfunction and aberrant angiogenesis and discusses the major underlying cellular mechanisms associated with its protective effects

Heme oxygenase (HO)-1 induction prevents endoplasmic reticulum stress-mediated endothelial cell death and impaired angiogenic capacity induced by high glucose.

Most diabetic cardiovascular complications are mediated by endothelial dysfunction and impaired angiogenesis. Endoplasmic Reticulum [ER] and oxidative stresses were shown to play a pivotal role in the development of endothelial dysfunction in diabetes. The cytoprotective effects of Hemeoxygenase-1 [HO-1] were extensively studied; however, its role in alleviating ER stress-induced endothelial dysfunction remains elusive. We aim here to test the role of HO-1 against high glucose-mediated ER stress response and endothelial dysfunction and understand the underlying mechanisms with special emphasis on oxidative stress, inflammation and cell death. Primary Human Umbilical Vein Endothelial cells [HUVECs] were harbored in culture medium containing high glucose (33 mM) for 5 days with 8 hrs intermittent recovery periods to mimic the diabetic milieu. Using a wide array of molecular biology techniques, we were able to show that this chronic and intermittent exposure of HUVECs to high glucose significantly increased mRNA and protein expression of key ER stress markers namely, binding immunoglobulin protein [BiP], activation transcription factor-4 [ATF-4], CCAAT-enhancer-binding protein homologous protein [CHOP], and phosphorylated eukaryotic initiation factor2α [p-eIF-2α]. In addition, there was a significant elevation in ROS associated with significant increased phosphorylation of p47phox regulatory subunit of NADPH oxidase [NOX]. Moreover, inflammatory and apoptotic responses were also elicited, featured mainly by significant increase in phosphorylation/activation of IκB kinase [IKK] and c-Jun, and upregulation of IL-6, whereas apoptosis was featured by showing significantly increased caspase3/7 activity and cell death. Vascular endothelial growth factor-A [VEGF-A] expression, Nitric Oxide [NO] production, and tube formation capacity were also significantly inhibited by high glucose. Pre-treatment by HO-1 inducer Cobalt protoporphyrin IX [CoPP] significantly abolished all the observed effects with high glucose. Altogether, to the best of our knowledge, we present for the first time the role of HO-1 induction as a potential antagonist to ER stress response against high glucose mediated endothelial dysfunction and impaired angiogenesis

Heme Oxygenase (HO)-1 Induction Prevents Endoplasmic Reticulum Stress-Mediated Endothelial Cell Death and Impaired Angiogenic Capacity

Most of diabetic cardiovascular complications are attributed to endothelial dysfunction and impaired angiogenesis. Endoplasmic Reticulum (ER) and oxidative stresses were shown to play a pivotal role in the development of endothelial dysfunction in diabetes. Hemeoxygenase-1 (HO-1) was shown to protect against oxidative stress in diabetes; however, its role in alleviating ER stress-induced endothelial dysfunction remains not fully elucidated. We aim here to test the protective role of HO-1 against high glucose-mediated ER stress and endothelial dysfunction and understand the underlying mechanisms with special emphasis on oxidative stress, inflammation and cell death. Human Umbilical Vein Endothelial Cells (HUVECs) were grown in either physiological or intermittent high concentrations of glucose for 5 days in the presence or absence of Cobalt (III) Protoporphyrin IX chloride (CoPP, HO-1 inducer) or 4-Phenyl Butyric Acid (PBA, ER stress inhibitor). Using an integrated cellular and molecular approach, we then assessed ER stress and inflammatory responses, in addition to apoptosis and angiogenic capacity in these cells. Our results show that HO-1 induction prevented high glucose-mediated increase of mRNA and protein expression of key ER stress markers. Cells incubated with high glucose exhibited high levels of oxidative stress, activation of major inflammatory and apoptotic responses [nuclear factor (NF)-κB and c-Jun N-terminal kinase (JNK)] and increased rate of apoptosis; however, cells pre-treated with CoPP or PBA were fully protected. In addition, high glucose enhanced caspases 3 and 7 cleavage and activity and augmented cleaved poly ADP ribose polymerase (PARP) expression whereas HO-1 induction prevented these effects. Finally, HO-1 induction and ER stress inhibition prevented high glucose-induced reduction in NO release and impaired the angiogenic capacity of HUVECs, and enhanced vascular endothelial growth factor (VEGF)-A expression. Altogether, we show here the critical role of ER stress-mediated cell death in diabetes-induced endothelial dysfunction and impaired angiogenesis and underscore the role of HO-1 induction as a key therapeutic modulator for ER stress response in ischemic disorders and diabetes. Our results also highlight the complex interplay between ER stress response and oxidative stress

Endoplasmic Reticulum Stress: A Critical Molecular Driver of Endothelial Dysfunction and Cardiovascular Disturbances Associated with Diabetes

Physical inactivity and sedentary lifestyle contribute to the widespread epidemic of obesity among both adults and children leading to rising cases of diabetes. Cardiovascular disease complications associated with obesity and diabetes are closely linked to insulin resistance and its complex implications on vascular cells particularly endothelial cells. Endoplasmic reticulum (ER) stress is activated following disruption in post-translational protein folding and maturation within the ER in metabolic conditions characterized by heavy demand on protein synthesis, such as obesity and diabetes. ER stress has gained much interest as a key bridging and converging molecular link between insulin resistance, oxidative stress, and endothelial cell dysfunction and, hence, represents an interesting drug target for diabetes and its cardiovascular complications. We reviewed here the role of ER stress in endothelial cell dysfunction, the primary step in the onset of atherosclerosis and cardiovascular disease. We specifically focused on the contribution of oxidative stress, insulin resistance, endothelial cell death, and cellular inflammation caused by ER stress in endothelial cell dysfunction and the process of atherogenesis

Cinacalcet versus Parathyroidectomy in the Treatment of Secondary Hyperparathyroidism Post Renal Transplantation

Background. Persistent hyperparathyroidism (HPT) with hypercalcemia is prevalent after transplant and is considered a risk factor for progressive bone loss and fractures and vascular calcification, as well as the development of tubulointerstitial calcifications of renal allografts and graft dysfunction. The subtotal parathyroidectomy is the standard treatment, although currently it has been replaced by the calcimimetic cinacalcet

Endoplasmic reticulum stress and oxidative stress drive endothelial dysfunction induced by high selenium

Selenium is an essential trace element important for human health. A balanced intake is, however, crucial to maximize the health benefits of selenium. At physiological concentrations, selenium mediates antioxidant, anti-inflammatory, and pro-survival actions. However, supra-nutritional selenium intake was associated with increased diabetes risk leading potentially to endothelial dysfunction, the initiating step in atherosclerosis. High selenium causes apoptosis in cancer cells via endoplasmic reticulum (ER) stress, a mechanism also implicated in endothelial dysfunction. Nonetheless, whether ER stress drives selenium-induced endothelial dysfunction, remains unknown. Here, we investigated the effects of increasing concentrations of selenium on endothelial cells. High selenite reduced nitric oxide bioavailability and impaired angiogenesis. High selenite also induced ER stress, increased reactive oxygen species (ROS) production, and apoptosis. Pretreatment with the chemical chaperone, 4-phenylbutyrate, prevented the toxic effects of selenium. Our findings support a model where high selenite leads to endothelial dysfunction through activation of ER stress and increased ROS production. These results highlight the importance of tailoring selenium supplementation to achieve maximal health benefits and suggest that prophylactic use of selenium supplements as antioxidants may entail risk