Involvement of EP1 and EP2 receptors in the regulation of the Na,K-ATPase by prostaglandins in MDCK cells

Abstract

Prostaglandins are key regulators of ion transport in the kidney. In MDCK cells, which model distal tubule cells, the transcription of the Na,K-ATPase β1 subunit is regulated by PGE 1 and PGE 2 . To identify the EP receptors that mediate transcriptional regulation, transient transfection studies are conducted using the human β1 promoter/luciferase construct, pHβ1-1141 Luc. The involvement of EP1 and EP2 receptors is indicated by studies with the EP1 selective agonist 17-phenyl trinor PGE 2 , and the EP2 selective agonist butaprost (which stimulate), as well as by studies with the antagonists SC-51089 (EP1 specific) and AH 6809 (EP1 and EP2 specific). Consistent with the involvement of Gs coupled EP2 receptors, is that the PGE 1 stimulation is inhibited by the PKAI expression vector (encoding the protein kinase A (PKA) inhibitory protein), as well as by the myristolated PKA inhibitory peptide PKI. In addition to this evidence (for the involvement of EP2 receptors), evidence for the involvement of EP1 receptors in the PGE 1 mediated stimulation of Na,KATPase β subunit gene transcription includes the stimulatory effect of 17-phenyl trinor PGE 2 , as well as the inhibitory effects of SC-51089. Also consistent with the involvement of Gq coupled EP1 receptors, the PGE 1 stimulation is inhibited by the PKCI vector (encoding the PKC inhibitory domain), the PKC inhibitor Go 6976, thapsigargin, as well as the calmodulin antagonists W7 and W13.

PGE2 potentiates tonicity-induced COX-2 expression in renal medullary cells in a positive feedback loop involving EP2-cAMP-PKA signaling

“…1-3). Both types of G ␣s -coupled EP receptors, i.e., EP2 and EP4, have been detected in MDCK cells (26,38). Although the precise cellular localization of EP2 receptors in the kidney is not well defined, EP2 mRNA has been detected in the inner and outer medulla of the rat kidney but not in the cortex (19,20).…”

International Union of Basic and Clinical Pharmacology. LXXXIII: Classification of Prostanoid Receptors, Updating 15 Years of Progress

“…In the kidney, PGE 2 activates EP 1 receptors to inhibit Na ϩ absorption by the renal collecting duct (Guan et al, 1998). EP 1 receptors up-regulate transcription of the Na,K-ATPase ␤ subunit in Madin-Darby canine kidney cells (Matlhagela and Taub, 2006) and attenuate up-regulation of epithelial sodium channel mRNA in inner medullary collecting duct cells by aldosterone (Gonzá lez et al, 2009). EP 1 antagonists have been claimed as useful in the prevention of diabetic nephropathy (Makino et al, 2002) and hypertension-induced renal injury (Suganami et al, 2003).…”

Evidence for post-transcriptional regulation of Na,K-ATPase by prostaglandin E1

“…Previously, we presented evidence indicating that PGE 1 stimulates β1 subunit gene transcription through its interaction with 2 different classes of prostaglandin receptors, including Gq coupled EP1 receptors, which activate Phospholipase C, and Gs coupled EP2 receptors which activate adenylate cyclase [25,26]. The PGE 2 analog 16,16-dimethyl-PGE 2 has a 10 fold higher affinity for EP1 than EP2 receptors [27], and thus may only activate EP2 receptors in normal MDCK cells at high prostaglandin concentrations.…”