Mechanism of the Switch from NO to H2O2 in Endothelium-Dependent Vasodilation in Diabetes

Juguilon, C.; Wang, Z.; Wang, Y.; Jamaiyar, A.; Enrick, M.; Gadd, J.; Chen, C.-L. W.; Pu, A.; Kolz, C.; Ohanyan, V.; Chen, Y.-R.; Zhang, Y.; Chilian, W. W.; Yin, L.

doi:10.1101/2021.05.18.444667

bioRxiv · 10.1101/2021.05.18.444667

Mechanism of the Switch from NO to H2O2 in Endothelium-Dependent Vasodilation in Diabetes

Juguilon, C.·Wang, Z.·Wang, Y.·Jamaiyar, A.·Enrick, M.·Gadd, J.·Chen, C.-L. W.·Pu, A.·Kolz, C.·Ohanyan, V.·Chen, Y.-R.·Zhang, Y.·Chilian, W. W.·Yin, L.

View original source ↗Export metadata ↓

Abstract

Coronary microvascular dysfunction is prevalent among diabetics and is correlated with cardiac mortality. Compromised endothelial-dependent dilation (EDD) is an early event in the progression of diabetes, but the mechanisms remain incompletely understood. Nitric oxide (NO) is the major endothelium-dependent vasodilatory metabolite in the healthy coronary circulation, but switches to hydrogen peroxide (H2O2) in coronary artery disease (CAD) patients. Because diabetes is a major risk factor for CAD we hypothesized that a similar switch from NO-to-H2O2 occurs in diabetes. Methods: Vasodilation was measured ex vivo in isolated coronary arteries from wild type (WT) and microRNA-21 (miR-21) null mice fed chow or high fat and sugar diet, and LepR null (db/db) mice using myography. Myocardial blood flow (MBF), blood pressure, and heart rate were measured in vivo using contrast echocardiography and a solid-state pressure sensor catheter. RNA from coronary arteries, endothelial cells and hearts were analyzed via qPCR for gene expression and protein expression was assessed via Western-Blot analyses. Superoxide was detected via electron paramagnetic resonance (EPR). Results: 1) Ex vivo coronary EDD and in vivo MBF was impaired in diabetes. 2) L-NAME (NO-synthase inhibitor) inhibited ex vivo coronary EDD and in vivo MBF in WT, while PEG-catalase (H2O2 scavenger) inhibited diabetic EDD ex vivo and MBF in vivo. 5) miR-21 deficiency blocked the NO-to-H2O2 switch and prevented diabetic vasodilation impairments. 6) Diabetic mice displayed increased serum NO and H2O2, upregulated mRNA expression of Sod1, Sod2, iNos, and Cav-1, and downregulated Pgc-1. Deficiency of miR-21 reversed these changes. 7) miR-21 deficiency increased PGC1, PPAR and eNOS protein and reduced detection of endothelial superoxide. Conclusions: Diabetics exhibit an NO-to-H2O2 switch in the mediator of EDD coronary dilation, which contributed to microvascular dysfunction and is mediated by miR-21. This study represents the first mouse model recapitulating the NO-to-H2O2 switch seen in CAD patients.

Source connections

Published article ↗

Explore related subjects

physiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Juguilon, C., Wang, Z., Wang, Y., Jamaiyar, A., Enrick, M., Gadd, J., Chen, C.-L. W., Pu, A., Kolz, C., Ohanyan, V., Chen, Y.-R., Zhang, Y., Chilian, W. W., Yin, L.. 2021-05-18. Mechanism of the Switch from NO to H2O2 in Endothelium-Dependent Vasodilation in Diabetes. https://doi.org/10.1101/2021.05.18.444667

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

28S-rsRNA facilitates PASMC proliferation through PKM2 β-hydroxybutyrylation

Ribosomal RNA-derived small RNAs (rsRNAs) are nucleic acid fragments originating from rRNA, the functions and roles of which in diseases remain incompletely understood. We identified 28S rsRNA-CTC_L20, an rsRNA whose expression is upregulated in hypoxic pulmonary artery smooth muscle cells (PASMCs) and in lung tissues of pulmonary hypertension (PH) models. In hypoxic cells, 28S rsRNA-CTC_L20 promotes PASMC proliferation, and its knockdown mitigates SuHx-induced pulmonary hypertension and vascular remodeling. Mechanistically, 28S rsRNA-CTC_L20 modulates {beta}-hydroxybutyrate (BHB) production by maintaining the stability of ketogenic enzyme mRNAs through its "CTGNNGG" motif. Elevated levels of BHB enhance the {beta}-hydroxybutyrylation modification at K166 of pyruvate kinase M2 (PKM2), increasing its activity and driving glycolysis to sustain proliferation. These results link ketone body metabolism to glycolysis in hypoxic cells and define an rsRNA-BHB-PKM2 {beta}-hydroxybutyrylation axis in PH. They also point to 28S rsRNA-CTC_L20 as a potential target for treating vascular remodeling.

physiology↗

bioRxiv2026

Selective activation of estrogen receptors modulates electrical activity and insulin secretion in human EndoC-βH1 cells

Estrogen receptors (ERs), ER and ER{beta} have important roles in the physiology of the endocrine pancreas in animal models, but the effects of ER activation on insulin-secreting human cells are still poorly understood. Here, we investigated the role of ER and ER{beta} as modulators of electrical activity and insulin secretion in the insulin-secreting human cell line EndoC-{beta}H1. Immunocytochemical analysis revealed a widespread cellular distribution of ER, while ER{beta} was predominantly localized outside the nucleus. We observed that both estradiol (E2) and the ER{beta} agonist diarylpropionitrile (DPN) led to a decrease in insulin secretion in the absence of stimulatory glucose concentrations, without affecting insulin content. Patch-clamp experiments revealed that a 48-hour treatment with either the ER agonist PPT or DPN resulted in depolarization of the resting membrane potential, increased action potential firing frequency, and altered the action potential waveform in EndoC-{beta}H1 cells. PPT increased voltage-dependent Ca2+ channel currents, while DPN reduced K+ and Na+ currents. These results suggest that activation of ER and ER{beta} modulates beta-cell electrical activity through distinct pathways involving ion channels. The effects of E2, PPT, and DPN were not caused by altered expression levels of ion channel genes after 48 hours of treatment. This suggests that these receptors act extranuclearly without affecting gene expression. Together, our findings demonstrate that selective activation of ER and ER{beta} modulates beta-cell excitability through distinct electrophysiological mechanisms and that E2 and DPN reduce basal insulin secretion in human EndoC-{beta}H1 cells. These results support ER and ER{beta} as potential targets for modulating human pancreatic beta-cell function.

physiology↗

bioRxiv2026

Body weight modifies the efficacy of lifespan-extending interventions in ad libitum-fed mice

Geroprotective interventions are often assessed by extension of lifespan in ad libitum-fed mice. Increased lifespan could therefore reflect rescue of adverse phenotypes of unhealthy controls. We analysed body weight and survival for 33,780 mice in the Interventions Testing Program (ITP) to test whether treatment effects varied with body weight. In males, each added standard deviation of attained adult weight made treatment 6% more favourable (HR 0.94), more apparent for interventions that lowered body weight (HR 0.90). Median lifespan increase rose from 6.2% in mice in the lightest quartile to 20.2% in the heaviest pre-dosing weight quartile among those experiments, mainly because control survival declined more steeply with weight than that of the intervention group. The effect of body weight was consistent across 13 of 14 compounds and reflected weight attained during adulthood rather than in early life. Weight-dependence of intervention effects was weak in ITP females, possibly because median survival of controls exceeded that of every sampled non-ITP female control group. Amelioration of weight-associated risk is therefore implicated as a major contributor to lifespan increases relative to heavy, short-lived controls. The geroprotective effects of these interventions may thus be less apparent in metabolically healthier mice or humans.

physiology↗