(Pro)renin Receptor-Dependent Induction of Profibrotic Factors Is Mediated by COX-2/EP4/NOX-4/Smad Pathway in Collecting Duct Cells.

Cristian Reyes-Martinez,Modar Kassan,Quynh My Nguyen,Alexis A Gonzalez

doi:10.3389/fphar.2019.00803

Abstract

The binding of prorenin to the (pro)renin receptor (PRR) triggers the activation of MAPK/ERK1/2 pathway, induction of cyclooxygenase-2 (COX-2), NOX-4-dependent production of reactive oxygen species (ROS), and the induction of transforming growth factor β (TGF-β) and profibrotic factors connecting tissue growth factor (CTGF) and plasminogen activator inhibitor (PAI-I) in collecting duct (CD) cells. However, the role of COX-2 and the intracellular pathways involved are not clear. We hypothesized that the PRR activation increases profibrotic factors through COX-2-mediated PGE2 activation of E prostanoid receptor 4 (EP4), upregulation of NOX-4/ROS production, and activation of Smad pathway in mouse CD cells. Recombinant prorenin increased ROS production and protein levels of CTGF, PAI-I, and TGF-β in M-1 CD cell line. Inhibition of MAPK, NOX-4, and COX-2 prevented this effect. Inhibition of MEK, COX-2, and EP4 also prevented the upregulation of NOX-4. Because TGF-β activates Smad pathway, we evaluate the phosphorylation of Smad2 and 3. COX-2 inhibition or EP4 antagonism significantly prevented phosphorylation of Smad 2/3. Mice that were infused with recombinant prorenin showed an induction in the expression of CTGF, PAI-I, TGF-β, fibronectin, and collagen I in isolated collecting ducts as well as the expression of alpha smooth muscle actin (α-SMA) in renal tissues. COX-2 inhibition prevented this induction. These results indicate that the induction of TGF-β, CTGF, PAI-I, and ROS occurs through PRR-dependent activation of MAPK and NOX-4; however, this mechanism depends on COX-2-derived PGE2 production and the activation of EP4 and Smad pathway.

Highlights

The binding of prorenin to therenin receptor (PRR) triggers the phosphorylation of mitogenactivated protein kinases/extracellular regulated kinases 1/2 (MAPK/ERK1/2) (Batenburg et al, 2007; Feldt et al, 2008; Muller et al, 2008; Ballarin-Gonzalez et al, 2013) and upregulates cyclooxygenase-2 (COX-2) in kidney tissues (Kaneshiro et al, 2006)
We recently showed that cultured collecting duct (CD) cells treated with nanomolar concentrations of recombinant prorenin undergo to epithelial–mesenchymal transition and have increased levels of intracellular reactive oxygen species (ROS), activation of MAPK pathway, and upregulation of profibrotic factors including connecting tissue growth factor (CTGF), plasminogen activator inhibitor-1 (PAI-I) and transforming growth factor β (TGF-β), fibronectin, and collagen I (Gonzalez et al, 2017)
We aimed to demonstrate that the activation of PRR increases profibrotic factors through COX2-mediated PGE2 activation of E prostanoid receptor 4 (EP4), the upregulation of NOX-4/ROS production, and activation of Smad pathway in mouse CD cells

Summary

Introduction

The binding of prorenin to the (pro)renin receptor (PRR) triggers the phosphorylation of mitogenactivated protein kinases/extracellular regulated kinases 1/2 (MAPK/ERK1/2) (Batenburg et al, 2007; Feldt et al, 2008; Muller et al, 2008; Ballarin-Gonzalez et al, 2013) and upregulates cyclooxygenase-2 (COX-2) in kidney tissues (Kaneshiro et al, 2006). PRR Increases Fibrotic Factors via COX-2/EP4/NOX-4/Smad activation by recombinant prorenin increases COX-2 expression independently of angiotensin (ANG) II in cultured renal collecting duct (CD) cells (Gonzalez et al, 2013). Both activation and upregulation of PRR have been associated with renal tissue damage (Kaneshiro et al, 2006; Kaneshiro et al, 2007; Ichihara et al, 2008). In human kidney embryonic (HEK) cells, augmentation of reactive oxygen species (ROS) is observed after PRR stimulation This effect is mediated by a NOX-4-dependent mechanism (Clavreul et al, 2011)

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