Diabetes-associated metabolic stress on the regulation of endothelial nitric oxide synthase content and mitochondrial function

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Mohanan Nair, Manoj Mohan
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Nitric oxide (NO), a vasoprotective and ubiquitous signaling molecule generated from the endothelial cells (EC) by the enzyme endothelial nitric oxide synthase (eNOS) have a vital role in regulation of vascular function and integrity. However, a significant attenuation of eNOS and NO leads to endothelial dysfunction (ED) and increased risk of cardiovascular disease (CVD) in diabetes. Lipoproteins particularly LDL, undergo glycation in diabetic patients and turns it into pro-atherogenic glycated LDL (glyLDL). However, the impact of glyLDL on eNOS, the transmembrane signalling events, involvement of mitochondrial and endoplasmic reticulum (ER) stress in EC remains unclear. Also, literatures reveal impaired platelet mitochondrial function in diabetes patients; however, the impact of family history of diabetes on platelet mitochondrial bioenergetics still remains unknown. In the present study, we had provided the evidence for diabetes-associated metabolic stress involving glyLDL can attenuate eNOS protein, gene and activity in EC, as well as glyLDL and high glucose attenuates eNOS content in EC. Receptor of advanced glycation end products (RAGE) and H-Ras pathway are implicated in the upstream signalling events in the downregulation of eNOS in EC. In addition, ER stress, impaired mitochondrial function due to significant reduction of complex-specific oxygen consumption and bioenergetics were identified in glyLDL-treated EC. Further, we have also detected significant impairment in platelet mitochondrial bioenergetics in healthy individuals with familial history of diabetes. Identifying the mechanisms involved in diabetes associated metabolic stress induced signaling in EC and early detection of mitochondrial impairment in healthy individuals will help to find new targets for the prevention and treatment of diabetic cardiovascular complications and improve quality of life in diabetic patients.
Endothelial cells, glycated LDL, endothelial nitric oxidase synthase, diabetes, mitochondria, oxidative stress