Timing of Myocardial Trpm7 Deletion During Cardiogenesis Variably Disrupts Adult Ventricular Function, Conduction, and Repolarization
Year: 2013
Type: article
Abstract: BACKGROUND: Transient receptor potential (TRP) channels are a superfamily of broadly expressed ion channels with diverse physiological roles. TRPC1, TRPC3, and TRPC6 are believed to contribute to cardiac hypertrophy in mouse models. Human mutations in TRPM4 have been linked to progressive familial heart block. TRPM7 is a divalent-permeant channel and kinase of unknown function, recently implicated in the pathogenesis of atrial fibrillation; however, its function in ventricular myocardium remains unexplored. METHODS AND RESULTS: We generated multiple cardiac-targeted knockout mice to test the hypothesis that TRPM7 is required for normal ventricular function. Early cardiac Trpm7 deletion (before embryonic day 9; TnT/Isl1-Cre) results in congestive heart failure and death by embryonic day 11.5 as a result of hypoproliferation of the compact myocardium. Remarkably, Trpm7 deletion late in cardiogenesis (about embryonic day 13; αMHC-Cre) produces viable mice with normal adult ventricular size, function, and myocardial transcriptional profile. Trpm7 deletion at an intermediate time point results in 50% of mice developing cardiomyopathy associated with heart block, impaired repolarization, and ventricular arrhythmias. Microarray analysis reveals elevations in transcripts of hypertrophy/remodeling genes and reductions in genes important for suppressing hypertrophy (Hdac9) and for ventricular repolarization (Kcnd2) and conduction (Hcn4). These transcriptional changes are accompanied by action potential prolongation and reductions in transient outward current (Ito; Kcnd2). Similarly, the pacemaker current (If; Hcn4) is suppressed in atrioventricular nodal cells, accounting for the observed heart block. CONCLUSIONS: Trpm7 is dispensable in adult ventricular myocardium under basal conditions but is critical for myocardial proliferation during early cardiogenesis. Loss of Trpm7 at an intermediate developmental time point alters the myocardial transcriptional profile in adulthood, impairing ventricular function, conduction, and repolarization.
Source: Circulation
Institutions: Brigham and Women's Hospital, Boston Children's Hospital, Howard Hughes Medical Institute, Harvard University, Inserm, Harvard–MIT Division of Health Sciences and Technology, Institut de Génomique Fonctionnelle, Manton Center for Orphan Disease Research, Massachusetts Institute of Technology
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Funders: Howard Hughes Medical Institute, Agence Nationale de la Recherche, National Institutes of Health, National Heart, Lung, and Blood Institute, National Institute of General Medical Sciences, National Institute of Neurological Disorders and Stroke, Eunice Kennedy Shriver National Institute of Child Health and Human Development
Awards: Arythmies dépendantes du calcium intracellulaire : mécanismes de la tachycardie polymorphe ventriculaire lié au stress., TRP Channel Mediated Pain Circuitry, Medical Scientist Training Program, Identification of a Stretch-Activated Channel with a Role in Cardiac Development, Pathogenesis and Treatment of Muscular Dystrophy, Intellectual and Developmental Disablities Research Center, G943165902
OpenAlex ID: W1981187805