Abstract
Endothelial cells (ECs) play a central role in ischemia. ATP-Synthase is now recognized to be ectopically expressed in the cell surface of many cell types, with putative roles described in angiogenesis, proliferation, and intracellular pH regulation. DJ-1 is a multifunctional protein, involved in cell protection against ischemia, ischemia-reperfusion (I/R), and oxidative stress, that regulates mitochondrial ATP-synthase. Here we focused on the characterization of the endothelial dynamics of DJ-1, and its implication in the regulation of the ectopic ATP-synthase (ecATP-S) activity, during acute ischemia and I/R in ECs. We found that DJ-1 is secreted from ECs, by a mechanism enhanced in ischemia and I/R. A cleaved form of DJ-1 (DJ-1∆C) was found only in the secretome of ischemic cells. The ecATP-S activity increased following acute ischemia in ECs, coinciding with DJ-1 and DJ-1∆C secretion. The inhibition of DJ-1 expression inhibited the ecATP-S response to ischemia by ∼ 50%, and its exogenous administration maximized the effect, together with an enhanced Akt phosphorylation and angiotube-formation potential at reperfusion. Immunoprecipitation studies showed direct interaction between DJ-1 and the ecATP-S. Altogether suggesting that DJ-1 is actively cleaved and released from ischemic ECs and plays an important role in the regulation of the ecATP-S activity during acute ischemia and reperfusion.