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Mouse Model of Human Congenital Heart Disease Progressive Atrioventricular Block Induced by a Heterozygous Nkx2-5 Homeodomain Missense Mutation

Lookup NU author(s): Professor Bob Anderson

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Abstract

Background Heterozygous human NKX2-5 homeodomain (DNA-binding domain) missense mutations are highly penetrant for varied congenital heart defects, including progressive atrioventricular (AV) block requiring pacemaker implantation. We recently replicated this genetic defect in a murine knockin model, in which we demonstrated highly penetrant, pleiotropic cardiac anomalies. In this study, we examined postnatal AV conduction in the knockin mice.Methods and Results A murine knockin model (Arg52Gly, Nkx2-5(+/R52G)) in a 129/Sv background was analyzed by histopathology, surface, and telemetry ECG, and in vivo electrophysiology studies, comparing with control Nkx2-5(+/+) mice at diverse postnatal stages, ranging from postnatal day 1 (P1) to 17 months. PR prolongation (first degree AV block) was present at 4 weeks, 7 months, and 17 months of age, but not at P1 in the mutant mice. Advanced AV block was also occasionally demonstrated in the mutant mice. Electrophysiology studies showed that AV nodal function and right ventricular effective refractory period were impaired in the mutant mice, whereas sinus nodal function was not affected. AV nodal size was significantly smaller in the mutant mice than their controls at 4 weeks of age, corresponding to the presence of PR prolongation, but not P1, suggesting, at least in part, that the conduction abnormalities are the result of a morphologically atrophic AV node.Conclusions The highly penetrant and progressive AV block phenotype seen in human heterozygous missense mutations in NKX2-5 homeodomain was replicated in mice by knocking in a comparable missense mutation.

Publication metadata

Author(s): Chowdhury R, Ashraf H, Melanson M, Tanada Y, Nguyen M, Silberbach M, Wakimoto H, Benson DW, Anderson RH, Kasahara H

Publication type: Article

Publication status: Published

Journal: Circulation: Arrhythmia and Electrophysiology

Year: 2015

Volume: 8

Issue: 5

Pages: 1255-1264

Print publication date: 01/10/2015

Online publication date: 30/07/2015

Acceptance date: 09/07/2015

ISSN (print): 1941-3149

ISSN (electronic): 1941-3084

Publisher: Lippincott Williams & Wilkins, Ltd.

URL: http://dx.doi.org/10.1161/CIRCEP.115.002720

DOI: 10.1161/CIRCEP.115.002720

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