Trafficking of the Prorenin Receptor in Endothelial Cells

Abstract

Diabetic patients are at higher risk for hypertension and cardiovascular mortality than their normotensive, nondiabetic counterparts. Diabetic patients also have increased circulating prorenin which can bind to its receptor (PRR) to cause activation of the renin‐angiotensin system and fibrosis. We hypothesized that diabetes induces dysregulation of the endothelial PRR to exacerbate cardiovascular damage. Mouse pancreatic endothelial cells (MS1) were cultured and exposed to high glucose or low calcium (Ca2+) conditions for one hour. Cells were fixed for immunocytochemistry or fractionated and immunoblotted for PRR. Treatment with 25 mM glucose or 25 mM mannitol for one hour did not impact full length PRR expression or localization in the total membrane fraction. When Ca2+ was removed from the media, full length PRR increased in the cytosolic fraction by 3.6‐fold (P=0.022) compared to control. Restoration of physiological Ca2+ returned PRR expression to control levels in the cytosolic fraction, while neither sPRR nor full length PRR were altered in the total membrane fraction. Confocal imaging of fixed cells suggested that PRR in the total membrane fraction may be encapsulated in vesicles. These data indicate that Ca2+ may be an important regulator of endothelial PRR trafficking, possibly via a Ca2+‐dependent PRR cleavage pathway. Ongoing studies will establish the relationship between Ca2+ and sPRR/PRR and determine the impact of PRR trafficking on endothelial dysfunction. These studies will determine whether targeting of PRR can lower the risk of cardiovascular disease in patients with diabetes.Support or Funding InformationTulane Center for Engaged Learning and Technology, NIH HL133619, DK104375