ERM Complex, a Therapeutic Target for Vascular Leakage Induced by Diabetes

Background: Ezrin, radixin, and moesin (the ERM complex) interact directly with membrane proteins regulating their attachment to actin filaments. ERM protein activation modifies cytoskeleton organization and alters the endothelial barrier function, thus favoring vascular leakage. However, little is known regarding the role of ERM proteins in diabetic retinopathy (DR). Objective: This study aimed to examine whether overexpression of the ERM complex exists in db/db mice and its main regulating factors. Methods: 9 male db/db mice and 9 male db/+ aged 14 weeks were analyzed. ERM proteins were assessed by western blot and by immunohistochemistry. Vascular leakage was determined by the Evans blue method. To assess ERM regulation, HRECs were cultured in a medium containing 5.5 mM D-glucose (mimicking physiological conditions) and 25 mM D-glucose (mimicking hyperglycemia that occurs in diabetic patients). Moreover, treatment with TNF-α, IL-1β, or VEGF was added to a high glucose condition. The expression of ERM proteins was quantified by RT-PCR. Cell permeability was evaluated by measuring movements of FITC-dextran. Results: A significant increase of ERM in diabetic mice in comparison with non-diabetic mice was observed. A high glucose condition alone did not have any effect on ERM expression. However, TNF-α and IL-1β induced a significant increase in ERM proteins. Conclusion: The increase of ERM proteins induced by diabetes could be one of the mechanisms involved in vascular leakage and could be considered as a therapeutic target. Moreover, the upregulation of the ERM complex by diabetes is induced by inflammatory mediators rather than by high glucose itself.

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PPARβ/δ accelerates bone regeneration in diabetic mellitus by enhancing AMPK/mTOR pathway-mediated autophagy

Stem Cell Research & Therapy ◽

10.1186/s13287-021-02628-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Miao Chen ◽

Dian Jing ◽

Rui Ye ◽

Jianru Yi ◽

Zhihe Zhao

Keyword(s):

Bone Regeneration ◽

Osteogenic Differentiation ◽

Bone Healing ◽

High Glucose ◽

Diabetic Rats ◽

Diabetic Patients ◽

Regulatory Effect ◽

Compound C ◽

High Glucose Condition ◽

Glucose Condition

Abstract Background Diabetic patients are more vulnerable to skeletal complications. Peroxisome proliferators-activated receptor (PPAR) β/δ has a positive regulatory effect on bone turnover under physiologic glucose concentration; however, the regulatory effect in diabetes mellitus has not been investigated yet. Herein, we explored the effects of PPARβ/δ agonist on the regeneration of diabetic bone defects and the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) under a pathological high-glucose condition. Methods We detected the effect of PPARβ/δ agonist on osteogenic differentiation of rBMSCs in vitro and investigated the bone healing process in diabetic rats after PPARβ/δ agonist treatment in vivo. RNA sequencing was performed to detect the differentially expressed genes and enriched pathways. Western blot was performed to detect the autophagy-related protein level. Laser confocal microscope (LSCM) and transmission electron microscope (TEM) were used to observe the formation of autophagosomes. Results Our results demonstrated that the activation of PPARβ/δ can improve the osteogenic differentiation of rBMSCs in high-glucose condition and promote the bone regeneration of calvarial defects in diabetic rats, while the inhibition of PPARβ/δ alleviated the osteogenic differentiation of rBMSCs. Mechanistically, the activation of PPARβ/δ up-regulates AMPK phosphorylation, yielding mTOR suppression and resulting in enhanced autophagy activity, which further promotes the osteogenic differentiation of rBMSCs in high-glucose condition. The addition of AMPK inhibitor Compound C or autophagy inhibitor 3-MA inhibited the osteogenesis of rBMSCs in high-glucose condition, suggesting that PPARβ/δ agonist promotes osteogenic differentiation of rBMSCs through AMPK/mTOR-regulated autophagy. Conclusion In conclusion, our study demonstrates the potential role of PPARβ/δ as a molecular target for the treatment of impaired bone quality and delayed bone healing in diabetic patients for the first time.

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Combination of ferric ammonium citrate with cytokines involved in apoptosis and insulin secretion of human pancreatic beta cells related to diabetes in thalassemia

PeerJ ◽

10.7717/peerj.9298 ◽

2020 ◽

Vol 8 ◽

pp. e9298

Author(s):

Patchara Rattanaporn ◽

Sissades Tongsima ◽

Thomas Mandrup-Poulsen ◽

Saovaros Svasti ◽

Dalina Tanyong

Keyword(s):

Insulin Secretion ◽

Cell Viability ◽

High Glucose ◽

Ammonium Citrate ◽

Ferric Ammonium Citrate ◽

High Glucose Condition ◽

Genes Expression ◽

Tnf Α ◽

Ferric Ammonium ◽

Glucose Condition

Background Diabetes mellitus (DM) is a common complication found in β-thalassemia patients. The mechanism of DM in β-thalassemia patients is still unclear, but it could be from an iron overload and increase of some cytokines, such as interleukin1-β (IL-1β) and tumor necrosis factor-α (TNF-α). The objective of this study was to study the effect of interaction between ferric ammonium citrate (FAC) and cytokines, IL-1β and TNF-α, on 1.1B4 human pancreatic β-cell line. Methods The effect of the combination of FAC and cytokines on cell viability was studied by MTT assay. Insulin secretion was assessed by the enzyme-linked immunosorbent assay (ELISA). The reactive oxygen species (ROS) and cell apoptosis in normal and high glucose condition were determined by flow cytometer. In addition, gene expression of apoptosis, antioxidant; glutathione peroxidase 1 (GPX1) and superoxide dismutase 2 (SOD2), and insulin secretory function were studied by real-time polymerase chain reaction (Real-time PCR). Results The findings revealed that FAC exposure resulted in the decrease of cell viability and insulin-release, and the induction of ROS and apoptosis in pancreatic cells. Interestingly, a combination of FAC and cytokines had an additive effect on SOD2 antioxidants’ genes expression and endoplasmic reticulum (ER) stress. In addition, it reduced the insulin secretion genes expression; insulin (INS), glucose kinase (GCK), protein convertase 1 (PSCK1), and protein convertase 2 (PSCK2). Moreover, the highest ROS and the lowest insulin secretion were found in FAC combined with IL-1β and TNF-α in the high-glucose condition of human pancreatic beta cell, which could be involved in the mechanism of DM development in β-thalassemia patients.

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Proteasome subunit-α type-6 protein is post-transcriptionally repressed by the microRNA-4490 in diabetic nephropathy

Bioscience Reports ◽

10.1042/bsr20180815 ◽

2018 ◽

Vol 38 (5) ◽

Cited By ~ 1

Author(s):

Ying Feng ◽

Ming-yue Jin ◽

Dong-wei Liu ◽

Li Wei

Keyword(s):

Diabetic Nephropathy ◽

Protein Expression ◽

Mrna Expression ◽

High Glucose ◽

Renal Cortex ◽

Luciferase Assay ◽

Diabetic Patients ◽

Proteasome Subunit ◽

High Glucose Condition ◽

Glucose Condition

A common complication of both type I and type II diabetes is nephropathy, characterized by accumulation of extracellular matrix in the glomerular mesangium. This indicates a central role of mesangial cells in the pathophysiology of diabetic nephropathy. Using the proteomic approach, it was earlier elucidated in a rat model that the proteasome subunit-α type-6 protein (PSMA6) is suppressed in the renal cortex in nephropathic kidney. However, the underlying mechanism effecting suppression of PSMA6 protein in the renal cortex is not yet known. Twenty diabetic patients were enrolled and the expression level of PSMA6 in them was detected by immunohistochemistry. The protein and mRNA expression levels of PSMA6 in NRK-52E cells under high glucose condition were determined by Western blot and quantitative real-time PCR, respectively. Dual luciferase assay was used to detect the relationship of PSMA6 and miR-4490. Our results show that PSMA6 protein is down-regulated in patients with diabetic nephropathy compared with healthy control. Using the NRK-52E cell line cultured under high glucose condition as an in vitro model of diabetic nephropathy, we show that loss of PSMA6 protein expression occured independent of changes the in PSMA6 mRNA expression. We next elucidate that PSMA6 mRNA is post-transcriptionally regulated by the microRNA (miRNA)-4490, whose expression is inversely correlated to PSMA6 protein expression. Using reporter assays we show that PSMA6 is a direct target of the miR-4490. Exogenous manipulation of miR-4490 levels modulated expression of PSMA6, indicating that miR-4490 can be tested as a biomarker for nephropathy in diabetic patients.

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The ERM Complex: A New Player Involved in Diabetes-induced Vascular Leakage

Current Medicinal Chemistry ◽

10.2174/0929867325666181016162327 ◽

2020 ◽

Vol 27 (18) ◽

pp. 3012-3022 ◽

Cited By ~ 1

Author(s):

Olga Simó-Servat ◽

Cristina Hernández ◽

Rafael Simó

Keyword(s):

Vascular Dysfunction ◽

Microvascular Complications ◽

Focal Adhesions ◽

Vascular Leakage ◽

Diabetic Patients ◽

Erm Proteins ◽

Cytoskeleton Reorganization ◽

Tnf Α ◽

Diabetic Microvascular Complications

Background: Microvascular complications remain an important cause of morbidity in diabetic patients, and they are associated with a significant economic burden for healthcare systems. Vascular leakage is one of the earlier hallmarks in diabetic microvascular complications. Ezrin, Radixin and Moesin (ERM) proteins have recently been involved in vascular dysfunction under the effect of molecular mediators of diabetes complications. In this review, we will present the available evidence regarding the role of these proteins in vascular leakage and their putative implication in diabetic microvascular complications. Methods and Results: A comprehensive literature search of the electronic MEDLINE database was performed between November 2017 and January 2018. As a result, 36 articles have been reviewed and discussed. Discussion: ERM proteins are cytoskeleton-membrane linkers, and when activated in endothelial cells are able to induce cytoskeleton reorganization in stress fibers leading to the disassembly of focal adhesions and the formation of paracellular gaps which result in an increase of vascular permeability. The activation of these proteins is induced by mediators involved in diabetic complications such as PKC activation, TNF-α, AGEs and oxidative stress. In conclusion, ERMs play an essential role in endothelium homeostasis and can be envisaged as a new therapeutic molecular target for preventing or arresting diabetes-induced vascular leakage.

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High Glucose Attenuates Cardioprotective Effects of Glucagon-Like Peptide-1 Through Induction of Mitochondria Dysfunction via Inhibition of β-Arrestin-Signaling

Frontiers in Physiology ◽

10.3389/fphys.2021.648399 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xietian Pan ◽

Chengxiang Li ◽

Haokao Gao

Keyword(s):

Signaling Pathway ◽

High Glucose ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Diabetic Patients ◽

High Glucose Condition ◽

Normal Glucose ◽

Cardioprotective Effects ◽

Glucagon Like Peptide 1 ◽

Glucose Condition

An increased vulnerability has been detected after ischemia/reperfusion injury in cardiomyocytes in diabetic patients. Glucagon-like peptide-1 (GLP-1) has been proven to have a notable cardioprotective effect in cardiomyocytes. However, in diabetic patients, the cardioprotective effects of GLP-1 are compromised, which is called GLP-1 resistance. β-arrestin is one of the two main downstream effectors of GLP-1 and β-arrestin signaling pathway exerts cardioprotective effects upon activation of GLP-1R. Our hypothesis is that the increased vulnerability of cardiomyocytes in diabetic patients is partly due to disruption of the β-arrestin signaling pathway. To test this, we analyzed cardiomyocyte viability and survival in high glucose and normal glucose condition after hypoxia/reoxygenation injury in vitro, additional GLP-1 was used to determine whether β-arrestin signaling pathway was involved. We also investigated the role of mitochondrial dysfunction in GLP-1 resistance. Our results showed that cardioprotective effects of GLP-1 were reduced in high glucose cultured H9C2 cells compared to normal glucose cultured H9C2, verifying the existence of GLP-1 resistance in high glucose cultured H9C2 cells. Further study suggested that β-arrestin plays a key role in GLP-1 resistance: β-arrestin expression is notably downregulated in high glucose condition and cardioprotective effects of GLP-1 can be diminished by downregulation of β-arrestin in normal glucose condition while upregulation of β-arrestin can restore cardioprotective effects of GLP-1 in high glucose condition. Then we explore how β-arrestin affects the cardioprotective effects of GLP-1 and found that β-arrestin exerts cardioprotective effects by improving mitochondria quality control via the PI3K/Akt signaling pathway. Thus, our study found out a new mechanism of GLP-1 resistance of cardiomyocytes in high glucose conditions that impaired β-arrestin expression, caused mitochondria dysfunction and eventually cell death. Our study provided a new perspective in treating myocardial ischemia/reperfusion injury in diabetic patients.

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HADC regulates the diabetic vascular endothelial dysfunction by targetting MnSOD

Bioscience Reports ◽

10.1042/bsr20181042 ◽

2018 ◽

Vol 38 (5) ◽

Cited By ~ 2

Author(s):

Qian Hou ◽

Ke Hu ◽

Xiaofeng Liu ◽

Jiao Quan ◽

Zehao Liu

Keyword(s):

Oxidative Stress ◽

Endothelial Dysfunction ◽

High Glucose ◽

Vascular Dysfunction ◽

Diabetic Patients ◽

Vascular Endothelial ◽

Mechanism Study ◽

Histone Deacetylase 2 ◽

High Glucose Condition ◽

Glucose Condition

Vascular dysfunction is a common result of diabetes in humans. However, the mechanism underlying diabetic vascular dysfunction is not fully understood. Here in the present study, we showed that the histone deacetylase 2 (HDAC2) promoted the endothelial dysfunction induced by diabetes. The expression and activity of HDAC2 were up-regulated in vascular endothelial cells (ECs) from diabetic patients and mice. The expression of HDAC2 was also increased by high glucose stress in isolated human ECs. HDAC2 knockdown repressed the proliferation rate and promoted high glucose-induced apoptosis of ECs, which was associated with the activation of apoptotic pathways (Bcl-2, Caspase 3, and Bax). By contrast, HDAC2 overexpression led to opposing results. Significantly, we observed that HDAC2 regulated the accumulation of reactive oxygen species (ROS) induced by high glucose in ECs, which accounted for the effects of HDAC2 on proliferation and apoptosis because antioxidants, N-acetyl-l-cysteine (NAC) or MnTBAP treatment blocked the effects of HDAC2 on apoptosis of ECs under high glucose condition. Mechanism study revealed that HDAC2 bound to the promoter of MnSOD and repressed the expression of MnSOD by regulating the level of acetylated H3K9 and H3K27, which led to the promotion of oxidative stress and contributed to the function of HDAC2 in ECs under high glucose condition. Altogether, our evidence demonstrated that HDAC2-MnSOD signaling was critical in oxidative stress and proliferation as well as the survival of ECs under high glucose condition.

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