Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text Full Text (PDF, 138K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JGP Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Kuzhikandathil, E. V. Articles by Oxford, G. S. Search for Related Content PubMed PubMed Citation Articles by Kuzhikandathil, E. V. Articles by Oxford, G. S. Social Bookmarking                            What's this?

Original Article

^a Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
Department of Cell & Molecular Physiology, CB # 7545, 452 MSRB, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.919-966-6927

gsox{at}med.unc.edu

The human D3 dopamine receptor can activate G-protein–coupled inward rectifier potassium channels (GIRKs), inhibit P/Q-type calcium channels, and inhibit spontaneous secretory activity in AtT-20 neuroendocrine cells (Kuzhikandathil, E.V., W. Yu, and G.S. Oxford. 1998. Mol. Cell. Neurosci. 12:390–402; Kuzhikandathil, E.V., and G.S. Oxford. 1999. J. Neurosci. 19:1698–1707). In this study, we evaluate the role of GIRKs in the D3 receptor-mediated inhibition of secretory activity in AtT-20 cells. The absence of selective blockers for GIRKs has precluded a direct test of the hypothesis that they play an important role in inhibiting secretory activity. However, the tetrameric structure of these channels provides a means of disrupting endogenous GIRK function using a dominant negative approach. To develop a dominant-negative GIRK mutant, the K⁺ selectivity amino acid sequence -GYG- in the putative pore domain of the human GIRK2 channels was mutated to -AAA-, -GLG-, or -GFG-. While the mutation of -GYG- to -GFG- did not affect channel function, both the -AAA- and -GLG- GIRK2 mutants were nonfunctional. This suggests that the aromatic ring of the tyrosine residue rather than its hydroxyl group is involved in maintaining the pore architecture of human GIRK2 channels. When expressed in AtT-20 cells, the nonfunctional AAA-GIRK2 and GLG-GIRK2 acted as effective dominant-negative mutants and significantly attenuated endogenous GIRK currents. Furthermore, these dominant-negative mutants interfered with the D3 receptor-mediated inhibition of secretion in AtT-20 cells, suggesting they are centrally involved in the signaling pathway of this secretory response. These results indicate that dominant-negative GIRK mutants are effective molecular tools to examine the role of GIRK channels in vivo.

Key Words: potassium channel structure • calcium channels • selectivity filter • autoreceptor • FM1-43

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				C. Zeng, I. Armando, Y. Luo, G. M. Eisner, R. A. Felder, and P. A. Jose Dysregulation of dopamine-dependent mechanisms as a determinant of hypertension: studies in dopamine receptor knockout mice Am J Physiol Heart Circ Physiol, February 1, 2008; 294(2): H551 - H569. [Abstract] [Full Text] [PDF]

				E. J. Coulson, L. M. May, S. L. Osborne, K. Reid, C. K. Underwood, F. A. Meunier, P. F. Bartlett, and P. Sah p75 Neurotrophin Receptor Mediates Neuronal Cell Death by Activating GIRK Channels through Phosphatidylinositol 4,5-Bisphosphate J. Neurosci., January 2, 2008; 28(1): 315 - 324. [Abstract] [Full Text] [PDF]

				E. T. Barfod, A. L. Moore, M. W. Roe, and S. D. Lidofsky Ca2+-activated IK1 Channels Associate with Lipid Rafts upon Cell Swelling and Mediate Volume Recovery J. Biol. Chem., March 23, 2007; 282(12): 8984 - 8993. [Abstract] [Full Text] [PDF]

				R. Wang, J. Su, X. Wang, H. Piao, X. Zhang, C. Y. Adams, N. Cui, and C. Jiang Subunit Stoichiometry of the Kir1.1 Channel in Proton-dependent Gating J. Biol. Chem., April 8, 2005; 280(14): 13433 - 13441. [Abstract] [Full Text] [PDF]

				E. A. Gay, J. D. Urban, D. E. Nichols, G. S. Oxford, and R. B. Mailman Functional Selectivity of D2 Receptor Ligands in a Chinese Hamster Ovary hD2L Cell Line: Evidence for Induction of Ligand-Specific Receptor States Mol. Pharmacol., July 1, 2004; 66(1): 97 - 105. [Abstract] [Full Text] [PDF]

				C. Zeng, D. Wang, Z. Yang, Z. Wang, L. D. Asico, C. S. Wilcox, G. M. Eisner, W. J. Welch, R. A. Felder, and P. A. Jose Dopamine D1 Receptor Augmentation of D3 Receptor Action in Rat Aortic or Mesenteric Vascular Smooth Muscles Hypertension, March 1, 2004; 43(3): 673 - 679. [Abstract] [Full Text] [PDF]

				A. Zou, Z. Lin, M. Humble, C. D. Creech, P. K. Wagoner, D. Krafte, T. J. Jegla, and A. D. Wickenden Distribution and functional properties of human KCNH8 (Elk1) potassium channels Am J Physiol Cell Physiol, December 1, 2003; 285(6): C1356 - C1366. [Abstract] [Full Text] [PDF]

				V. Davila, Z. Yan, L. C. Craciun, D. Logothetis, and D. Sulzer D3 Dopamine Autoreceptors Do Not Activate G-Protein-Gated Inwardly Rectifying Potassium Channel Currents in Substantia Nigra Dopamine Neurons J. Neurosci., July 2, 2003; 23(13): 5693 - 5697. [Abstract] [Full Text] [PDF]

				E. V. Kuzhikandathil and G. S. Oxford Classic D1 Dopamine Receptor Antagonist R-(+)-7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390) Directly Inhibits G Protein-Coupled Inwardly Rectifying Potassium Channels Mol. Pharmacol., July 1, 2002; 62(1): 119 - 126. [Abstract] [Full Text] [PDF]

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents