title: Disruption of prostaglandin E2 receptor EP4 impairs urinary concentration via decreasing aquaporin 2 in renal collecting ducts.
abstract: The antidiuretic hormone arginine vasopressin is a systemic effector in urinary concentration. However, increasing evidence suggests that other locally produced factors may also play an important role in the regulation of water reabsorption in renal collecting ducts. Recently, prostaglandin E2 (PGE2) receptor EP4 has emerged as a potential therapeutic target for the treatment of nephrogenic diabetes insipidus, but the underlying mechanism is unknown. To evaluate the role of EP4 in regulating water homeostasis, mice with renal tubule-specific knockout of EP4 (Ksp-EP4(-/-)) and collecting duct-specific knockout of EP4 (AQP2-EP4(-/-)) were generated using the Cre-loxP recombination system. Urine concentrating defect was observed in both Ksp-EP4(-/-) and AQP2-EP4(-/-) mice. Decreased aquaporin 2 (AQP2) abundance and apical membrane targeting in renal collecting ducts were evident in Ksp-EP4(-/-) mice. In vitro studies demonstrated that AQP2 mRNA and protein levels were significantly up-regulated in mouse primary inner medullary collecting duct (IMCD) cells after pharmacological activation or adenovirus-mediated overexpression of EP4 in a cAMP/cAMP-response element binding protein-dependent manner. In addition, EP4 activation or overexpression also increased AQP2 membrane accumulation in a mouse IMCD cell line (IMCD3) stably transfected with the AQP2 gene, mainly through the cAMP/protein kinase A and extracellular signal-regulated kinase pathways. In summary, the EP4 receptor in renal collecting ducts plays an important role in regulating urinary concentration under physiological conditions. The ability of EP4 to promote AQP2 membrane targeting and increase AQP2 abundance makes it a potential therapeutic target for the treatment of clinical disorders including acquired and congenital diabetes insipidus.
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Rong
authors.initials: R
authors.lastname: Cao
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Shengnan
authors.initials: S
authors.lastname: Du
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Xiao
authors.initials: X
authors.lastname: Jia
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Senfeng
authors.initials: S
authors.lastname: Zheng
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Shizheng
authors.initials: S
authors.lastname: Huang
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China;
authors.forename: Qifei
authors.initials: Q
authors.lastname: Han
authors.affiliation: Department of Physiology, AstraZeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Health Science Center, Shenzhen, 518060, China;
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physiology, AstraZeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Health Science Center, Shenzhen, 518060, China;
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX 77204;
authors.forename: Yifei
authors.initials: Y
authors.lastname: Miao
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; jgustafsson@uh.edu kangjihong@bjmu.edu.cn youfeiguan@szu.edu.cn.
authors.forename: Jihong
authors.initials: J
authors.lastname: Kang
authors.affiliation: Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX 77204; jgustafsson@uh.edu kangjihong@bjmu.edu.cn youfeiguan@szu.edu.cn.
authors.forename: Jan-Åke
authors.initials: JÅ
authors.lastname: Gustafsson
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; Department of Physiology, AstraZeneca-Shenzhen University Joint Institute of Nephrology, Shenzhen University Health Science Center, Shenzhen, 518060, China; Department of Physiology, Dalian Medical University, Dalian, Liaoning 116044, China jgustafsson@uh.edu kangjihong@bjmu.edu.cn youfeiguan@szu.edu.cn.
authors.forename: Youfei
authors.initials: Y
authors.lastname: Guan
mesh_terms: D000818:Animals; D051399:Aquaporin 2 / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D015232:Dinoprostone / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000494:pharmacology; D007671:Kidney Concentrating Ability / Q000235:genetics*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D061251:Primary Cell Culture; D011760:Pyrrolidinones / Q000494:pharmacology; D034622:RNA Interference; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000819:agonists / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014867:Water / Q000378:metabolism
chemical_list: D051399:Aquaporin 2; C561931:CAY 10580; D017362:Cyclic AMP Response Element-Binding Protein; C545651:Ptger4 protein, mouse; D011760:Pyrrolidinones; D058309:Receptors, Prostaglandin E, EP4 Subtype; D014867:Water; D000242:Cyclic AMP; D015232:Dinoprostone
keywords: antidiuretic hormone; arachidonic acid; cyclooxygenase; gene targeting; water homeostasis