scholarly journals Knockout of vascular smooth muscle EGF receptor in a mouse model prevents obesity-induced vascular dysfunction and renal damage in vivo

Diabetologia ◽  
2020 ◽  
Vol 63 (10) ◽  
pp. 2218-2234
Author(s):  
Christian Stern ◽  
Barbara Schreier ◽  
Alexander Nolze ◽  
Sindy Rabe ◽  
Sigrid Mildenberger ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Smooth Muscle ◽  
Mitochondrial Dysfunction ◽  
Renal Damage ◽  
Egf Receptor ◽  
Vascular Dysfunction ◽  
Cellular Level

Abstract Aims/hypothesis Obesity causes type 2 diabetes leading to vascular dysfunction and finally renal end-organ damage. Vascular smooth muscle (VSM) EGF receptor (EGFR) modulates vascular wall homeostasis in part via serum response factor (SRF), a major regulator of VSM differentiation and a sensor for glucose. We investigated the role of VSM-EGFR during obesity-induced renovascular dysfunction, as well as EGFR–hyperglycaemia crosstalk. Methods The role of VSM-EGFR during high-fat diet (HFD)-induced type 2 diabetes was investigated in a mouse model with inducible, VSM-specific EGFR-knockout (KO). Various structural and functional variables as well as transcriptome changes, in vivo and ex vivo, were assessed. The impact of hyperglycaemia on EGFR-induced signalling and SRF transcriptional activity and the underlying mechanisms were investigated at the cellular level. Results We show that VSM-EGFR mediates obesity/type 2 diabetes-induced vascular dysfunction, remodelling and transcriptome dysregulation preceding renal damage and identify an EGFR–glucose synergism in terms of SRF activation, matrix dysregulation and mitochondrial function. EGFR deletion protects the animals from HFD-induced endothelial dysfunction, creatininaemia and albuminuria. Furthermore, we show that HFD leads to marked changes of the aortic transcriptome in wild-type but not in KO animals, indicative of EGFR-dependent SRF activation, matrix dysregulation and mitochondrial dysfunction, the latter confirmed at the cellular level. Studies at the cellular level revealed that high glucose potentiated EGFR/EGF receptor 2 (ErbB2)-induced stimulation of SRF activity, enhancing the graded signalling responses to EGF, via the EGFR/ErbB2–ROCK–actin–MRTF pathway and promoted mitochondrial dysfunction. Conclusions/interpretation VSM-EGFR contributes to HFD-induced vascular and subsequent renal alterations. We propose that a potentiated EGFR/ErbB2–ROCK–MRTF–SRF signalling axis and mitochondrial dysfunction underlie the role of EGFR. This advanced working hypothesis will be investigated in mechanistic depth in future studies. VSM-EGFR may be a therapeutic target in cases of type 2 diabetes-induced renovascular disease. Data availability The datasets generated during and/or analysed during the current study are available in: (1) share_it, the data repository of the academic libraries of Saxony-Anhalt (10.25673/32049.2); and (2) in the gene expression omnibus database with the study identity GSE144838 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE144838).

scholarly journals Early or advanced stage type 2 diabetes is not accompanied by in vivo skeletal muscle mitochondrial dysfunction

2008 ◽  
Vol 158 (5) ◽  
pp. 643-653 ◽  
Author(s):  
H M De Feyter ◽  
N M A van den Broek ◽  
S F E Praet ◽  
K Nicolay ◽  
L J C van Loon ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Resonance Spectroscopy ◽  
Diabetes Patients

ObjectiveSeveral lines of evidence support a potential role of skeletal muscle mitochondrial dysfunction in the pathogenesis of insulin resistance and/or type 2 diabetes. However, it remains to be established whether mitochondrial dysfunction represents either cause or consequence of the disease. We examined in vivo skeletal muscle mitochondrial function in early and advanced stages of type 2 diabetes, with the aim to gain insight in the proposed role of mitochondrial dysfunction in the aetiology of insulin resistance and/or type 2 diabetes.MethodsTen long-standing, insulin-treated type 2 diabetes patients, 11 subjects with impaired fasting glucose, impaired glucose tolerance and/or recently diagnosed type 2 diabetes, and 12 healthy, normoglycaemic controls, matched for age and body composition and with low habitual physical activity levels were studied. In vivo mitochondrial function of the vastus lateralis muscle was evaluated from post-exercise phosphocreatine (PCr) recovery kinetics using 31P magnetic resonance spectroscopy (MRS). Intramyocellular lipid (IMCL) content was assessed in the same muscle using single-voxel 1H MRS.ResultsIMCL content tended to be higher in the type 2 diabetes patients when compared with normoglycaemic controls (P=0.06). The31P MRS parameters for mitochondrial function, i.e. PCr and ADP recovery time constants and maximum aerobic capacity, did not differ between groups.ConclusionsThe finding that in vivo skeletal muscle oxidative capacity does not differ between long-standing, insulin-treated type 2 diabetes patients, subjects with early stage type 2 diabetes and sedentary, normoglycaemic controls suggests that mitochondrial dysfunction does not necessarily represent either cause or consequence of insulin resistance and/or type 2 diabetes.

scholarly journals Vascular Disease in Diabetic Women: Why Do They Miss the Female Protection?

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Ana Paula Villela Dantas ◽  
Zuleica Bruno Fortes ◽  
Maria Helena Catelli de Carvalho
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Cardiovascular Disease ◽  
Type 2 Diabetes Mellitus ◽  
Vascular Disease ◽  
Vascular Dysfunction ◽  
Protective Effects ◽  
Vascular Protection

Gender plays a pivotal role in the onset as well as in the progression of the cardiovascular disease with a higher morbidity and mortality being detected in men with respect to women. Type 2 Diabetes Mellitus (T2DM) may reduce gender-related differences in the prevalence of cardiovascular disease by fading the vascular protective effects afforded by estrogen in females. This article will discuss the role of sex and sex hormones on the incidence and mechanisms involved in vascular dysfunction associated to T2DM, which might explain why women with T2DM lack the vascular protection.

scholarly journals Mesenchymal Stem Cells Ameliorate Mitochondrial Dysfunction in α - cells and Hyperglucagonemia in type 2 Diabetes via SIRT1/FoxO3a Signaling

2021 ◽  
Author(s):  
Jia Song ◽  
Lingshu Wang ◽  
Xinghong Guo ◽  
Qin He ◽  
Chen Cui ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Glucagon Secretion ◽  
Sirtuin 1 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Umbilical Cord ◽  
Therapeutic Effects

Abstract Background: Dysregulation of α-cells results in hyperglycemia and hyperglucagonemia in type 2 diabetes mellitus (T2DM). Mesenchymal stem cell (MSC)-based therapy increases oxygen consumption of islets and enhances insulin secretion. However, the underlying mechanism for the protective role of MSCs in α- cell mitochondrial dysfunction remains unclear. Here, we evaluated the efficacy and molecular mechanisms of human umbilical cord MSCs (hucMSCs) on α-cell mitochondrial function and glucagon secretion in T2DM.Methods: hucMSCs were used to treat two kinds of T2DM mice and αTC1-6 cells to explore the role of hucMSCs in improving α-cell mitochondrial dysfunction and hyperglucagonemia. Plasma and supernatant glucagon were detected by enzyme-linked immunosorbent assay (ELISA). Mitochondrial function of α-cells was assessed by the Seahorse Analyzer. To investigate the underlying mechanisms, Sirtuin 1 (SIRT1), Forkhead box O3a (FoxO3a), glucose transporter type1 (GLUT1), and glucokinase (GCK) were assessed by western blotting analysis.Results: In vivo, hucMSC infusion improved glucose and insulin tolerance, as well as hyperglycemia and hyperglucagonemia in T2DM mice. Meanwhile, hucMSC intervention rescued islet structure and decreased α- to β-cell ratio. Consistently, glucagon secretion from αTC1-6 cells was inhibited by hucMSCs in vitro. Meanwhile, hucMSC treatment activated intracellular SIRT1/FoxO3a signaling, promoted glucose uptake and activation, alleviated mitochondrial dysfunction, and enhanced ATP production. However, transfection of SIRT1 small interfering RNA (siRNA) or the application of SIRT1 inhibitor EX-527 weakened the therapeutic effects of hucMSCs on mitochondrial function and glucagon secretion.Conclusions: Our observations indicate that hucMSCs mitigate mitochondrial dysfunction and glucagon hypersecretion of α-cells in T2DM via SIRT1/FoxO3a signaling, which provides novel evidence demonstrating the potential for hucMSCs in treating T2DM.

scholarly journals Endothelial Dysfunction: Is There a Hyperglycemia-Induced Imbalance of NOX and NOS?

2019 ◽  
Vol 20 (15) ◽  
pp. 3775 ◽  
Author(s):  
Cesar A. Meza ◽  
Justin D. La Favor ◽  
Do-Houn Kim ◽  
Robert C. Hickner
Keyword(s):  
Type 2 Diabetes ◽  
Cardiovascular Disease ◽  
Blood Flow ◽  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Vascular Dysfunction ◽  
Vascular Complications ◽  
Enzymatic Production

NADPH oxidases (NOX) are enzyme complexes that have received much attention as key molecules in the development of vascular dysfunction. NOX have the primary function of generating reactive oxygen species (ROS), and are considered the main source of ROS production in endothelial cells. The endothelium is a thin monolayer that lines the inner surface of blood vessels, acting as a secretory organ to maintain homeostasis of blood flow. The enzymatic production of nitric oxide (NO) by endothelial NO synthase (eNOS) is critical in mediating endothelial function, and oxidative stress can cause dysregulation of eNOS and endothelial dysfunction. Insulin is a stimulus for increases in blood flow and endothelium-dependent vasodilation. However, cardiovascular disease and type 2 diabetes are characterized by poor control of the endothelial cell redox environment, with a shift toward overproduction of ROS by NOX. Studies in models of type 2 diabetes demonstrate that aberrant NOX activation contributes to uncoupling of eNOS and endothelial dysfunction. It is well-established that endothelial dysfunction precedes the onset of cardiovascular disease, therefore NOX are important molecular links between type 2 diabetes and vascular complications. The aim of the current review is to describe the normal, healthy physiological mechanisms involved in endothelial function, and highlight the central role of NOX in mediating endothelial dysfunction when glucose homeostasis is impaired.

scholarly journals Role of zinc in insulin regulation and diabetes

2017 ◽  
Vol 05 (02) ◽  
pp. 83-87
Author(s):  
Resham Poudel ◽  
Yuvaraj Bhusal ◽  
Biswaraj Tharu ◽  
Nisha Kafle
Keyword(s):  
Oxidative Stress ◽  
Type 2 Diabetes ◽  
Renal Damage ◽  
Hemoglobin A1c ◽  
Zn Deficiency ◽  
Improve Insulin Sensitivity ◽  
Potential Implication ◽  
Insulin Regulation

AbstractZinc (Zn) affects glucose metabolism through insulin regulation and has potential implication in diabetes. Zn deficiency has not been proven in diabetes; however, observations of hyperzincuria, hypozincemia, and Zn malabsorption in diabetes indicate additional requirements for Zn. Mutation in Zn transporter 8 – a key protein in insulin secretion – has been associated with Type 2 diabetes. Zn supplementation in prediabetics and diabetics has been supported to improve plasma glucose, hemoglobin A1c (HbA1c), and lipids and potentially improve insulin sensitivity, reduce oxidative stress, and protect from renal damage.

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