Inhibition of Cardiac Delayed Rectifier K⁺ Current by Overexpression of the Long-QT Syndrome HERG G628S Mutation in Transgenic Mice

From the Divisions of Molecular Genetics (P.B., G.R.A., B.N., J.K., L.J.D.G.) and Cardiovascular and Metabolic Diseases (C.-M.S., T.R.B., B.J., T.M.A., W.S., T.J.C.), Wyeth-Ayerst Research, Princeton, NJ.

Correspondence to Dr Thomas J. Colatsky, Wyeth-Ayerst Research, PO Box 42528, Philadelphia, PA 19101-2528. E-mail colatst{at}war.wyeth.com

Abstract—Mutations in the HERG gene are linked to the LQT2 form of the inherited long-QT syndrome. Transgenic mice were generated expressing high myocardial levels of a particularly severe form of LQT2-associated HERG mutation (G628S). Hearts from G628S mice appeared normal except for a modest enlargement seen only in females. Ventricular myocytes isolated from adult wild-type hearts consistently exhibited an inwardly rectifying E-4031–sensitive K⁺ current resembling the rapidly activating cardiac delayed rectifier K⁺ current (I_kr) in its time and voltage dependence; this current was not found in cells isolated from G628S mice. Action potential duration was significantly prolonged in single myocytes from G628S ventricle (cycle length=1 second, 26°C) but not in recordings from intact ventricular strips studied at more physiological rates and temperature (200 to 400 bpm, 37°C). ECG intervals, including QT duration, were unchanged, although minor aberrancies were noted in 20% (16/80) of the G628S mice studied, primarily involving the QRS complex and, more rarely, T-wave morphology. The aberrations were more commonly observed in females than males but could not be correlated with sex-based differences in action potential duration. These results establish the presence of I_Kr in the adult mouse ventricle and demonstrate the ability of the G628S mutation to exert a dominant negative effect on endogenous I_Kr in vivo, leading to the expected LQT2 phenotype of prolonged repolarization at the single cell level but not QT prolongation in the intact animal. The model may be useful in dissecting repolarization currents in the mouse heart and as a means of examining the mechanism(s) by which the G628S mutation exerts its dominant negative effect on native cardiac cells in vivo.

Key Words: long-QT syndrome • mice, transgenic • HERG • potassium channels • electrocardiography

This article has been cited by other articles:

				T. K. Roepke, A. Kontogeorgis, C. Ovanez, X. Xu, J. B. Young, K. Purtell, P. A. Goldstein, D. J. Christini, N. S. Peters, F. G. Akar, et al. Targeted deletion of kcne2 impairs ventricular repolarization via disruption of IK,slow1 and Ito,f FASEB J, October 1, 2008; 22(10): 3648 - 3660. [Abstract] [Full Text] [PDF]

				R. Arnaout, T. Ferrer, J. Huisken, K. Spitzer, D. Y. R. Stainier, M. Tristani-Firouzi, and N. C. Chi Zebrafish model for human long QT syndrome PNAS, July 3, 2007; 104(27): 11316 - 11321. [Abstract] [Full Text] [PDF]

				G. Salama and B. London Mouse models of long QT syndrome J. Physiol., January 1, 2007; 578(1): 43 - 53. [Abstract] [Full Text] [PDF]

				G. Thomas, M. J. Killeen, I. S. Gurung, P. Hakim, R. Balasubramaniam, C. A. Goddard, A. A. Grace, and C. L.-H. Huang Mechanisms of ventricular arrhythmogenesis in mice following targeted disruption of KCNE1 modelling long QT syndrome 5 J. Physiol., January 1, 2007; 578(1): 99 - 114. [Abstract] [Full Text] [PDF]

				D. J. Milan and C. A. MacRae Animal models for arrhythmias Cardiovasc Res, August 15, 2005; 67(3): 426 - 437. [Abstract] [Full Text] [PDF]

				J. V. Tranquillo, J. Hlavacek, and C. S. Henriquez An integrative model of mouse cardiac electrophysiology from cell to torso Europace, January 1, 2005; 7(s2): S56 - S70. [Abstract] [Full Text] [PDF]

				J. Brouillette, R. B. Clark, W. R. Giles, and C. Fiset Functional properties of K+ currents in adult mouse ventricular myocytes J. Physiol., September 15, 2004; 559(3): 777 - 798. [Abstract] [Full Text] [PDF]

				R. B. Clark, M. E. Mangoni, A. Lueger, B. Couette, J. Nargeot, and W. R. Giles A rapidly activating delayed rectifier K+ current regulates pacemaker activity in adult mouse sinoatrial node cells Am J Physiol Heart Circ Physiol, May 1, 2004; 286(5): H1757 - H1766. [Abstract] [Full Text] [PDF]

				G. X. Liu, J. Zhou, S. Nattel, and G. Koren Single-channel recordings of a rapid delayed rectifier current in adult mouse ventricular myocytes: basic properties and effects of divalent cations J. Physiol., April 15, 2004; 556(2): 401 - 413. [Abstract] [Full Text] [PDF]

				S. A. Kodirov, M. Brunner, J. M. Nerbonne, P. Buckett, G. F. Mitchell, and G. Koren Attenuation of IK,slow1 and IK,slow2 in Kv1/Kv2DN mice prolongs APD and QT intervals but does not suppress spontaneous or inducible arrhythmias Am J Physiol Heart Circ Physiol, January 1, 2004; 286(1): H368 - H374. [Abstract] [Full Text] [PDF]

				H.-S. Cho, M. Takano, and A. Noma The electrophysiological properties of spontaneously beating pacemaker cells isolated from mouse sinoatrial node J. Physiol., July 1, 2003; 550(1): 169 - 180. [Abstract] [Full Text] [PDF]

				J. P. Lees-Miller, J. Guo, J. R. Somers, D. E. Roach, R. S. Sheldon, D. E. Rancourt, and H. J. Duff Selective Knockout of Mouse ERG1 B Potassium Channel Eliminates IKr in Adult Ventricular Myocytes and Elicits Episodes of Abrupt Sinus Bradycardia Mol. Cell. Biol., March 15, 2003; 23(6): 1856 - 1862. [Abstract] [Full Text] [PDF]

				J. Zhou, S. Kodirov, M. Murata, P. D. Buckett, J. M. Nerbonne, and G. Koren Regional upregulation of Kv2.1-encoded current, IK,slow2, in Kv1DN mice is abolished by crossbreeding with Kv2DN mice Am J Physiol Heart Circ Physiol, February 1, 2003; 284(2): H491 - H500. [Abstract] [Full Text] [PDF]

				S. Danik, C. Cabo, C. Chiello, S. Kang, A. L. Wit, and J. Coromilas Correlation of repolarization of ventricular monophasic action potential with ECG in the murine heart Am J Physiol Heart Circ Physiol, July 1, 2002; 283(1): H372 - H381. [Abstract] [Full Text] [PDF]

				J. M. Nerbonne, C. G. Nichols, T. L. Schwarz, and D. Escande Genetic Manipulation of Cardiac K+ Channel Function in Mice: What Have We Learned, and Where Do We Go From Here? Circ. Res., November 23, 2001; 89(11): 944 - 956. [Abstract] [Full Text] [PDF]

				S. Demolombe, G. Lande, F. Charpentier, M. A van Roon, M. J.B van den Hoff, G. Toumaniantz, I. Baro, G. Guihard, N. Le Berre, A. Corbier, et al. Transgenic mice overexpressing human KvLQT1 dominant-negative isoform Part I: Phenotypic characterisation Cardiovasc Res, May 1, 2001; 50(2): 314 - 327. [Abstract] [Full Text] [PDF]

				G. Lande, S. Demolombe, A. Bammert, A. Moorman, F. Charpentier, and D. Escande Transgenic mice overexpressing human KvLQT1 dominant-negative isoform Part II: Pharmacological profile Cardiovasc Res, May 1, 2001; 50(2): 328 - 334. [Abstract] [Full Text] [PDF]

				U. C. Hoppe, E. Marban, and D. C. Johns Distinct gene-specific mechanisms of arrhythmia revealed by cardiac gene transfer of two long QT disease genes, HERG and KCNE1 PNAS, April 24, 2001; 98(9): 5335 - 5340. [Abstract] [Full Text] [PDF]

				C.-C. Shieh, M. Coghlan, J. P. Sullivan, and M. Gopalakrishnan Potassium Channels: Molecular Defects, Diseases, and Therapeutic Opportunities Pharmacol. Rev., December 1, 2000; 52(4): 557 - 594. [Abstract] [Full Text] [PDF]

				S. P. Thomas, L. Bircher-Lehmann, S. A. Thomas, J. Zhuang, J. E. Saffitz, and A. G. Kleber Synthetic Strands of Neonatal Mouse Cardiac Myocytes : Structural and Electrophysiological Properties Circ. Res., September 15, 2000; 87(6): 467 - 473. [Abstract] [Full Text] [PDF]

				A. Jeron, G. F. Mitchell, J. Zhou, M. Murata, B. London, P. Buckett, S. D. Wiviott, and G. Koren Inducible polymorphic ventricular tachyarrhythmias in a transgenic mouse model with a long Q-T phenotype Am J Physiol Heart Circ Physiol, June 1, 2000; 278(6): H1891 - H1898. [Abstract] [Full Text] [PDF]

				V. S. Chauhan, S. Tuvia, M. Buhusi, V. Bennett, and A. O. Grant Abnormal Cardiac Na+ Channel Properties and QT Heart Rate Adaptation in Neonatal AnkyrinB Knockout Mice Circ. Res., March 3, 2000; 86(4): 441 - 447. [Abstract] [Full Text] [PDF]

				M. Zaniboni, A. E. Pollard, L. Yang, and K. W. Spitzer Beat-to-beat repolarization variability in ventricular myocytes and its suppression by electrical coupling Am J Physiol Heart Circ Physiol, March 1, 2000; 278(3): H677 - H687. [Abstract] [Full Text] [PDF]

				L. Wang, S. Swirp, and H. Duff Age-dependent response of the electrocardiogram to K+ channel blockers in mice Am J Physiol Cell Physiol, January 1, 2000; 278(1): C73 - C80. [Abstract] [Full Text] [PDF]

				X. H.T. Wehrens, S. Kirchhoff, and P. A. Doevendans Mouse electrocardiography: An interval of thirty years Cardiovasc Res, January 1, 2000; 45(1): 231 - 237. [Abstract] [Full Text] [PDF]

				H. I. Akbarali, H. Thatte, X. D. He, W. R. Giles, and R. K. Goyal Role of HERG-like K+ currents in opossum esophageal circular smooth muscle Am J Physiol Cell Physiol, December 1, 1999; 277(6): C1284 - C1290. [Abstract] [Full Text] [PDF]

				A. D. Wickenden, P. Lee, R. Sah, Q. Huang, G. I. Fishman, and P. H. Backx Targeted Expression of a Dominant-Negative Kv4.2 K+ Channel Subunit in the Mouse Heart Circ. Res., November 26, 1999; 85(11): 1067 - 1076. [Abstract] [Full Text] [PDF]

				A. A. Selyanko, P. Delmas, J. K. Hadley, L. Tatulian, I. C. Wood, M. Mistry, B. London, and D. A. Brown Dominant-Negative Subunits Reveal Potassium Channel Families That Contribute to M-Like Potassium Currents J. Neurosci., March 1, 2002; 22(5): RC212 - RC212. [Abstract] [Full Text] [PDF]

				B. London, W. Guo, X.-h. Pan, J. S. Lee, V. Shusterman, C. J. Rocco, D. A. Logothetis, J. M. Nerbonne, and J. A. Hill Targeted Replacement of Kv1.5 in the Mouse Leads to Loss of the 4-Aminopyridine-Sensitive Component of IK,slow and Resistance to Drug-Induced QT Prolongation Circ. Res., May 11, 2001; 88(9): 940 - 946. [Abstract] [Full Text] [PDF]