title: Galpha12- and Galpha13-protein subunit linkage of D5 dopamine receptors in the nephron.
abstract: The roles of the G-protein alpha-subunits, Gs, Gi, and Gq/11, in the signal transduction of the D1-like dopamine receptors, D1 and D5, have been deciphered. Galpha12 and Galpha13, members of the 4th family of G protein subunits, are not linked with D1 receptors, and their linkage to D5 receptors is not known. Therefore, we studied the expression of Galpha12 and Galpha13 and interaction with D5 dopamine receptors in the kidney from normotensive Wistar-Kyoto (WKY) rats and D5 receptor-transfected HEK293 cells. Galpha12 and Galpha13 were found in the proximal tubule, distal convoluted tubule, and artery and vein in the WKY rat kidney. Whereas Galpha12 was expressed in the ascending limb of Henle, Galpha13 was expressed in the collecting duct and juxtaglomerular cells. In renal proximal tubules, Galpha12 and Galpha13, as with D5 receptors, were expressed in brush border membranes. Laser confocal microscopy revealed the colocalization of D5 receptors with Galpha12 and Galpha13 in rat renal brush border membranes, immortalized rat renal proximal tubule cells, and D5 receptor-transfected HEK293 cells. In these cells, a D1-like agonist, fenoldopam, increased the association of Galpha12 and Galpha13 with D5 receptors, results that were corroborated by immunoprecipitation experiments. We conclude that although both D1 and D5 receptors are linked to Galphas, they are differentially linked to Galpha12 and Galpha13. The consequences of the differential G-protein subunit linkage on D1- and D5-mediated sodium transport remains to be determined.
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, 3800 Reservoir Road, NW, Washington, DC 20007, USA.
authors.forename: Shaopeng
authors.initials: S
authors.lastname: Zheng
authors.forename: Peiying
authors.initials: P
authors.lastname: Yu
authors.forename: Chunyu
authors.initials: C
authors.lastname: Zeng
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Yang
authors.forename: Peter M
authors.initials: PM
authors.lastname: Andrews
authors.forename: Robin A
authors.initials: RA
authors.lastname: Felder
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Jose
mesh_terms: D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007668:Kidney / Q000737:chemistry; D007687:Kidney Tubules, Proximal / Q000737:chemistry / Q000378:metabolism; D018613:Microscopy, Confocal; D009399:Nephrons / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D021122:Protein Subunits; D051381:Rats; D011921:Rats, Inbred WKY; D017447:Receptors, Dopamine D1 / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D050641:Receptors, Dopamine D5
chemical_list: D004268:DNA-Binding Proteins; C493605:DRD5 protein, human; C493607:Drd5 protein, rat; D021122:Protein Subunits; D017447:Receptors, Dopamine D1; D050641:Receptors, Dopamine D5; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins