Journal Article

Glucose-sensing microRNA-21 disrupts ROS homeostasis and impairs antioxidant responses in cellular glucose variability

Micheloni, Stefano, Prattichizzo, Francesco, Ceriello, Antonio, La Sala, Lucia, Mrakic-Sposta, Simona

2018

Overview

Background Antioxidant enzymes play a fundamental role in counteracting oxidative stress induced by high glucose. Although mitochondrial superoxide dismutase (SOD2) is the principal defence against the toxicity of superoxide anions, the mechanism of its inactivation in diabetic subjects is still poorly understood. Recently, microRNA-21 has been associated with diabetes, although its function remains unclear. We sought to explore the mechanism underlying defective SOD2 antioxidant response in HUVECs during exposures to constant high glucose and oscillating glucose (as glucose variability model, GV) and the role of miR-21 in increasing the susceptibility to oxidative stress by disrupting reactive oxygen species (ROS) homeostasis. Methods HUVECs exposed for 1 week to constant high glucose and GV were subjected to quantitative electron paramagnetic resonance for ROS measurements. Superoxide anions, SOD2 protein levels and mitochondrial membrane potential (ΔΨm) were also evaluated. Endogenous miR-21 and its putative ROS-homeostatic target genes (KRIT1, FoxO1, NFE2L2 and SOD2) were tested using mimic-miR-21 and quantified by qPCR. Luciferase assays were performed to test miR-21/3′-UTR-SOD2 binding. Results We observed upregulation of microRNA-21, overproduction of superoxide anions and total ROS generation, depolarisation of the mitochondrial membrane potential (ΔΨm) and defective SOD2 antioxidant response in HUVECs subjected to constant high glucose and GV exposures. We also found that exogenous mimic-microRNA-21 targeted putative microRNA-21 ROS-homeostatic target genes, e.g., KRIT1, NRF2 and SOD2, which were significantly downregulated. All these effects were reverted by a microRNA-21 inhibitor, which improved SOD2 and KRIT1 expression, reduced the levels of ROS production and ameliorated ΔΨm. Conclusions Our data demonstrate the association of microRNA-21 with oscillating and high glucose and early mitochondrial dysfunction. We found that microRNA-21 may promote the suppression of homeostatic signalling that normally limits ROS damage. These data provide novel clues about the inhibition of microRNA-21 as a new therapeutic approach to protect against cellular oxidative injury in glucose variability and diabetes.

• Publisher: BioMed Central,Springer Nature B.V,BMC
• Subject: 3' Untranslated Regions / Angiology / Anions / Antioxidants / Antioxidants - metabolism / Apoptosis / Binding Sites / Cardiology / Cardiovascular disease / Cells, Cultured / Chemoreception / Diabetes / Diabetes mellitus / Diabetic retinopathy / Enzymes / Epigenetics / Forkhead Box Protein O1 - genetics / Forkhead Box Protein O1 - metabolism / FOXO1 protein / Gene expression / Gene Expression Regulation, Enzymologic / Glucose / Glucose - toxicity / Growth factors / Homeostasis / Human Umbilical Vein Endothelial Cells - drug effects / Human Umbilical Vein Endothelial Cells - enzymology / Humans / Hyperglycemia / KRIT1 / KRIT1 Protein - genetics / KRIT1 Protein - metabolism / Medicine / Medicine & Public Health / Membrane potential / Membrane Potential, Mitochondrial - drug effects / Membrane proteins / Metabolism / MicroRNAs / MicroRNAs - genetics / MicroRNAs - metabolism / miR-21 / miRNA / Mitochondria / Mitochondria - drug effects / Mitochondria - enzymology / Mitochondrial dysfunction / NF-E2-Related Factor 2 - genetics / NF-E2-Related Factor 2 - metabolism / Original Investigation / Oxidative stress / Oxidative Stress - drug effects / Reactive oxygen species / Reactive Oxygen Species - metabolism / Rodents / ROS homeostasis / Signal Transduction - drug effects / SOD2 / Superoxide / Superoxide anion / Superoxide anions / Superoxide dismutase / Superoxide Dismutase - genetics / Superoxide Dismutase - metabolism / Toxicity