title: Homeobox protein Hop functions in the adult cardiac conduction system.
abstract: Hop is an unusual homeobox gene expressed in the embryonic and adult heart. Hop acts downstream of Nkx2-5 during development, and Nkx2-5 mutations are associated with cardiac conduction system (CCS) defects. Inactivation of Hop in the mouse is lethal in half of the expected null embryos. Here, we show that Hop is expressed strongly in the adult CCS. Hop-/- adult mice display conduction defects below the atrioventricular node (AVN) as determined by invasive electrophysiological testing. These defects are associated with decreased expression of connexin40. Our results suggest that Hop functions in the adult CCS and demonstrate conservation of molecular hierarchies between embryonic myocardium and the specialized conduction tissue of the mature heart.
authors.affiliation: Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pa, USA.
authors.forename: Fraz A
authors.initials: FA
authors.lastname: Ismat
authors.forename: Maozhen
authors.initials: M
authors.lastname: Zhang
authors.forename: Hyun
authors.initials: H
authors.lastname: Kook
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.forename: Rong
authors.initials: R
authors.lastname: Zhou
authors.forename: Victor A
authors.initials: VA
authors.lastname: Ferrari
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Epstein
authors.forename: Vickas V
authors.initials: VV
authors.lastname: Patel
mesh_terms: D000818:Animals; D017630:Connexins / Q000032:analysis; D004562:Electrocardiography; D006329:Heart Conduction System / Q000502:physiology*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D014157:Transcription Factors / Q000502:physiology; D000097003:Gap Junction alpha-5 Protein
chemical_list: D017630:Connexins; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D014157:Transcription Factors; D000097003:Gap Junction alpha-5 Protein; C466740:Hop protein, mouse; C484469:Nkx2-5 protein, mouse