High uric acid induces vascular endothelial cell injury via XBP1-PKM2 mediated glycolytic inhibition

Abstract Background/Introduction Although not fully understood, hyperuricemia induced endothelial dysfunction exhibits at the early onset of the pathology of atherosclerosis. Since aerobic glycolysis is the predominant energy source of endothelial cells, exploring the key glycolytic regulators that are responsible for maintaining the integrity of endothelial barrier may confer vascular homeostasis and prevent atherosclerosis. Purpose We aimed to investigate the role of high uric acid in the glycolysis of human umbilical vein endothelial cells (HUVECs), and reveal its potential molecular mechanism underlying endothelial cell injury early in their quiescence. Methods Glycolytic metabolism was determined by real-time extracellular flux analysis and seahorse test on the HUVECs exposed to high uric acid (600 and 800μmol/L). We examined the expression of pyruvate kinase muscle isoforms 2 (PKM2), a key enzyme of glycolysis, and transcription factor X-box binding protein 1 (XBP1), which was identified by RNA sequencing and chromatin immunoprecipitation combined with luciferase assay. Then, the effect of glycolytic regulation on the HUVECs functions under hypeuricemic condition was evaluated by molecular manipulating of XBP1-PKM2 signaling pathway. Results We observed that hyperuricemia inhibited glycolysis and led to reduced ATP production of HUVECs in vitro by inhibiting the expression of PKM2. In addition, both unsliced and sliced XBP1-(u/s) were also downregulated under the stimulation of high uric acid. Overexpression of XBP1-s increased the transcriptional level of PKM2 via binding the PKM2 promoter, and effectively recovered the glycolitic activity and ATP synthesis. Moreover, upregulating the XBP1-PKM2 pathway mitigated the HUVECs injury induced by hyperuricemia, including the abnormal release of endothelin-1, von Willebrand Factor, reactive oxygen species and nitric oxide, and poor cell proliferation, migration as well as tube formation. Conclusions Our data reveal that high uric acid induces HUVECs injury by downregulating glycolysis through the XBP1-PKM2 signaling axis.