Type 1 Diabetes impairs vascular relaxation via increases in endothelial glycolysis and activation of the HIF1a-PFKFB3-Nox1 pathway in mice.
Authors: Atawia Reem , Bruder do Nascimento Thiago , Batori Robert , Kennard Simone , Antonova Galina , Jordan Coleton , Mehta Vinay , Ushio-Fukai Masuko , Fukai Tohru , Huo Yuqing , Patel Vijay , Fulton David , Belin de Chantemèle Eric 
Published: May 2023

Type 1 diabetes (T1D), which prevalence is currently on the rise, is a major risk factor for cardiovascular disease (CVD). Although T1D induces endothelial dysfunction, a precursor and contributor to CVD, its etiology remains ill-defined. Aberrant increases in endothelial cell (EC) glycolysis mainly via increased expression/ activity of its regulatory enzyme, 6-phosphofructo-2- kinase/fructose-2, 6-bisphosphatase 3 (PFKFB3) contribute to several vascular disorders. Nevertheless, whether alterations in EC glycolysis impairs endothelium dependent relaxation (EDR) is unknown. Using Akita mice, a genetic model of T1D, and a newly developed assay to measure EC glycolytic capacity in aortic explants via Seahorse analyzer, we tested the hypothesis that T1D impairs endothelial function via increasing EC glycolysis. Aortic explants from Akita mice exhibited a 1.7-fold increase in glycolysis to WT (P<0.05). EC-denudation abolished these increases which identify EC as the source of increased vascular glycolysis. These metabolic changes were accompanied by a 2-fold increase in EC PFKFB3 expression in aortas of Akita mice and inhibition of PFKFB3 using 3PO restored EDR in Akita mice. Interestingly, increases in EC glycolysis in situ via transduction of adenoviral vectors to overexpress either PFKFB3 (Ad-PFKFB3) or a constitutively active form of PFK2 to drive glycolysis independent of PFKFB3 (Ad-GlycoHi) reproduced the endothelial dysfunction associated with T1D. Also, EC transduced in vitro with Ad-PFKFB3 depicted increased expression of the ROS–producing enzyme, NADPH oxidase homolog, Nox1, and its co-activator, NoxA1(p<0.05). Similarly, aorta EC from Akita mice revealed increased Nox1 and NoxA1 expression. Inhibition of Nox1 fully restored EDR in Akita and Ad-PFKFB3-transduced WT aortas. Consistently, aortas from Nox1 KO mice were protected from Ad-PFKFB3-induced endothelial dysfunction. T1D markedly increased the aortic expression of the Advanced Glycation End products (AGE) precursor methylglyoxal (MG) (p<0.05), thus, we tested the contribution of AGE to T1D-induced EC glycolysis. Aortic rings exposed to MG showed increased EC PFKFB3 and Nox1 expression and impaired EDR. The latter was restored in rings incubated with 3PO or in rings from EC-specific PFKFB3 deficient mice (p<0.05). Also, T1D and exposure to MG upregulated hypoxia-inducible factor 1α(HIF1α) expression in EC. HIF1α inhibition blunted MG-mediated PFKFB3 upregulation in aorta EC (p<0.05). In Conclusion, this study identified for the first time a role for endothelial PFKFB3-mediated glycolysis in T1D-induced endothelial dysfunction. The underlying mechanism involves AGE and HIF1α as upstream regulators and NOX1 as a downstream target for PFKFB3. Thus, PFKFB3 and Nox1 inhibitors are potential therapeutic targets for diabetes-induced vascular complications. R01s (1R01HL147639-01A1 and 1R01HL155265-01) and 19EIA34760167 to E.J. Belin de Chantemèle. APS APHYS00010 and 2020AHA000POST000204982 to R.T.Atawia This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.