title: Phenotypically silent Cre recombination within the postnatal ventricular conduction system.
abstract: The cardiac conduction system (CCS) is composed of specialized cardiomyocytes that initiate and maintain cardiac rhythm. Any perturbation to the normal sequence of electrical events within the heart can result in cardiac arrhythmias. To understand how cardiac rhythm is established at the molecular level, several genetically modified mouse lines expressing Cre recombinase within specific CCS compartments have been created. In general, Cre driver lines have been generated either by homologous recombination of Cre into an endogenous locus or Cre expression driven by a randomly inserted transgene. However, haploinsufficiency of the endogenous gene compromises the former approach, while position effects negatively impact the latter. To address these limitations, we generated a Cre driver line for the ventricular conduction system (VCS) that preserves endogenous gene expression by targeting the Contactin2 (Cntn2) 3' untranslated region (3'UTR). Here we show that Cntn23'UTR-IRES-Cre-EGFP/+ mice recombine floxed alleles within the VCS and that Cre expression faithfully recapitulates the spatial distribution of Cntn2 within the heart. We further demonstrate that Cre expression initiates after birth with preservation of native Cntn2 protein. Finally, we show that Cntn23'UTR-IRES-Cre-EGFP/+ mice maintain normal cardiac mechanical and electrical function. Taken together, our results establish a novel VCS-specific Cre driver line without the adverse consequences of haploinsufficiency or position effects. We expect that our new mouse line will add to the accumulating toolkit of CCS-specific mouse reagents and aid characterization of the cell-autonomous molecular circuitry that drives VCS maintenance and function.
authors.affiliation: Department of Internal Medicine (Cardiology Division), UT Southwestern Medical Center, Dallas, TX, United States of America.
authors.forename: Samadrita
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: Department of Internal Medicine (Cardiology Division), UT Southwestern Medical Center, Dallas, TX, United States of America.
authors.forename: Minoti
authors.initials: M
authors.lastname: Bhakta
authors.affiliation: Department of Internal Medicine (Cardiology Division), UT Southwestern Medical Center, Dallas, TX, United States of America.|Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX, United States of America.|McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, TX, United States of America.|Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX, United States of America.
authors.forename: Nikhil Vilas
authors.identifier: http://orcid.org/0000-0002-8397-100X
authors.initials: NV
authors.lastname: Munshi
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics* / Q000503:physiopathology; D053840:Brugada Syndrome / Q000235:genetics* / Q000503:physiopathology; D000075224:Cardiac Conduction System Disease; D058969:Contactin 2 / Q000096:biosynthesis / Q000235:genetics*; D004195:Disease Models, Animal; D018390:Gene Targeting; D057895:Haploinsufficiency / Q000235:genetics; D006329:Heart Conduction System; D006352:Heart Ventricles / Q000378:metabolism / Q000503:physiopathology; D059765:Homologous Recombination / Q000235:genetics; D006801:Humans; D019426:Integrases / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000378:metabolism; D010641:Phenotype
chemical_list: D020413:3' Untranslated Regions; C548675:Cntn2 protein, mouse; D058969:Contactin 2; C045073:Cre recombinase; D019426:Integrases