title: Jak2 and Ca2+/calmodulin are key intermediates for bradykinin B2 receptor-mediated activation of Na+/H+ exchange in KNRK and CHO cells.
abstract: Na(+)/H(+) exchangers are ubiquitous in mammalian cells, carrying out key functions, such as cell volume defense, acid-base homeostasis, and regulation of the cytoskeleton. We used two screening technologies (FLIPR and microphysiometry) to characterize the signal transduction pathway used by the bradykinin B(2) receptor to activate Na(+)/H(+) exchange in two cell lines, KNRK and CHO. In both cell types, B(2) receptor activation resulted in rapid increases in the rate of proton extrusion that were sodium-dependent and could be blocked by the Na(+)/H(+) exchange inhibitors EIPA and MIA or by replacing extracellular sodium with TMA. Activation of Na(+)/H(+) exchange by bradykinin was concentration-dependent and could be blocked by the selective B(2) receptor antagonist HOE140, but not by the B(1) receptor antagonist des-Arg10-HOE140. Inhibitors of Jak2 tyrosine kinase (genistein and AG490) and of CAM (W-7 and calmidazolium) attenuated bradykinin-induced activation of Na(+)/H(+) exchange. Bradykinin induced formation of a complex between CAM and Jak2, supporting a regulatory role for Jak2 and CAM in the activation of Na(+)/H(+) exchange in KNRK and CHO cells. We propose that this pathway (B(2) receptor --> Jak2 --> CAM --> Na(+)/H(+) exchanger) is a fundamental regulator of Na(+)/H(+) exchange activity.
authors.affiliation: Department of Medicine (Nephrology Division) of the Medical University of South Carolina, Charleston, South Carolina, USA.
authors.forename: David
authors.initials: D
authors.lastname: Lefler
authors.forename: Yurii V
authors.initials: YV
authors.lastname: Mukhin
authors.forename: Tobiah
authors.initials: T
authors.lastname: Pettus
authors.forename: L M Fredrik
authors.initials: LM
authors.lastname: Leeb-Lundberg
authors.forename: Maria N
authors.initials: MN
authors.lastname: Garnovskaya
authors.forename: John R
authors.initials: JR
authors.lastname: Raymond
mesh_terms: D000818:Animals; D016466:CHO Cells; D020013:Calcium Signaling; D002147:Calmodulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D006224:Cricetinae; D053614:Janus Kinase 2; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D043782:Receptor, Bradykinin B2 / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D011518:Proto-Oncogene Proteins; D043782:Receptor, Bradykinin B2; D017923:Sodium-Hydrogen Exchangers; D011505:Protein-Tyrosine Kinases; D053614:Janus Kinase 2