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PGE2 upregulates renin through E-prostanoid receptor 1 via PKC/cAMP/CREB pathway in M-1 Cells

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Renal Physiology

Published online on

Abstract

During the early phase of angiotensin (ANG) II-dependent hypertension tubular prostaglandin E2 (PGE2) is increased. Renin synthesis and secretion in the collecting duct (CD) is upregulated by ANGII contributing to further intratubular ANGII formation. However, what happens first and whether the triggering mechanism is independent of tubular ANGII, remain unknown. PGE2 stimulates renin synthesis in juxtaglomerular (JG) cells via E-prostanoid (EP) receptors through cAMP/CREB pathway. EP receptors are also expressed in the CD. Here, we tested the hypothesis that renin is upregulated by PGE2 in CD cells. M-1 CD cell line expressed EP1, EP3 and EP4 but not EP2. Dose response experiments in the presence of AT1 receptor blockade with candesartan demonstrated that 10-6 M PGE2 maximally increases renin mRNA (~4 fold) and prorenin/renin protein levels (~2 fold). This response was prevented by micromolar doses of SC-19220 (EP1 antagonist), attenuated by the EP4 antagonist, L-161,982, and exacerbated by the highly selective EP3 antagonist, L-798106 (~10 fold increase). To further evaluate the signaling pathway involved we used the PKC inhibitor calphostin C and transfections with PKCα dominant negative (DN). Both strategies blunted the PGE2-induced increases in cAMP levels, CREB phosphorylation and augmentation of renin. Knockdown of EP1 receptor and CREB also prevented renin upregulation. These results indicate that PGE2 increases CD renin expression through EP1 receptor via PKC/cAMP/CREB pathway. Therefore, we conclude that during early stages of ANGII-dependent hypertension, there is augmentation of PGE2 that stimulates renin in the CD, resulting in increased tubular ANGII formation and further stimulation of renin.