Go to JCI Insight
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Alerts
  • Advertising/recruitment
  • Subscribe
  • Contact
  • Current Issue
  • Past Issues
  • By specialty
    • COVID-19
    • Cardiology
    • Gastroenterology
    • Immunology
    • Metabolism
    • Nephrology
    • Neuroscience
    • Oncology
    • Pulmonology
    • Vascular biology
    • All ...
  • Videos
    • Conversations with Giants in Medicine
    • Author's Takes
  • Reviews
    • View all reviews ...
    • 100th Anniversary of Insulin's Discovery (Jan 2021)
    • Hypoxia-inducible factors in disease pathophysiology and therapeutics (Oct 2020)
    • Latency in Infectious Disease (Jul 2020)
    • Immunotherapy in Hematological Cancers (Apr 2020)
    • Big Data's Future in Medicine (Feb 2020)
    • Mechanisms Underlying the Metabolic Syndrome (Oct 2019)
    • Reparative Immunology (Jul 2019)
    • View all review series ...
  • Viewpoint
  • Collections
    • Recently published
    • In-Press Preview
    • Commentaries
    • Concise Communication
    • Editorials
    • Viewpoint
    • Top read articles
  • Clinical Medicine
  • JCI This Month
    • Current issue
    • Past issues

  • Current issue
  • Past issues
  • Specialties
  • Reviews
  • Review series
  • Conversations with Giants in Medicine
  • Author's Takes
  • Recently published
  • In-Press Preview
  • Commentaries
  • Concise Communication
  • Editorials
  • Viewpoint
  • Top read articles
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Alerts
  • Advertising/recruitment
  • Subscribe
  • Contact
Progressive atrioventricular conduction defects and heart failure in mice expressing a mutant Csx/Nkx2.5 homeoprotein
Hideko Kasahara, … , Charles I. Berul, Seigo Izumo
Hideko Kasahara, … , Charles I. Berul, Seigo Izumo
Published July 15, 2001
Citation Information: J Clin Invest. 2001;108(2):189-201. https://doi.org/10.1172/JCI12694.
View: Text | PDF
Article

Progressive atrioventricular conduction defects and heart failure in mice expressing a mutant Csx/Nkx2.5 homeoprotein

  • Text
  • PDF
Abstract

A DNA nonbinding mutant of the NK2 class homeoprotein Nkx2.5 dominantly inhibits cardiogenesis in Xenopus embryos, causing a small heart to develop or blocking heart formation entirely. Recently, ten heterozygous CSX/NKX2.5 homeoprotein mutations were identified in patients with congenital atrioventricular (AV) conduction defects. All four missense mutations identified in the human homeodomain led to markedly reduced DNA binding. To examine the effect of a DNA binding–impaired mutant of mouse Csx/Nkx2.5 in the embryonic heart, we generated transgenic mice expressing one such allele, I183P, under the β-myosin heavy chain promoter. Unexpectedly, transgenic mice were born apparently normal, but the accumulation of Csx/Nkx2.5(I183P) mutant protein in the embryo, neonate, and adult myocardium resulted in progressive and profound cardiac conduction defects and heart failure. P-R prolongation observed at 2 weeks of age rapidly progressed into complete AV block as early as 4 weeks of age. Expression of connexins 40 and 43 was dramatically decreased in the transgenic heart, which may contribute to the conduction defects in the transgenic mice. This transgenic mouse model may be useful in the study of the pathogenesis of cardiac dysfunction associated with CSX/NKX2.5 mutations in humans.

Authors

Hideko Kasahara, Hiroko Wakimoto, Margaret Liu, Colin T. Maguire, Kimber L. Converso, Tetsuo Shioi, Weei-Yuarn Huang, Warren J. Manning, David Paul, Joel Lawitts, Charles I. Berul, Seigo Izumo

×

Figure 7

Options: View larger image (or click on image) Download as PowerPoint
Expression of Csx/Nkx2.5(I183P) and endogenous Csx/Nkx2.5 in TG mice. (a...
Expression of Csx/Nkx2.5(I183P) and endogenous Csx/Nkx2.5 in TG mice. (a) Immunohistochemistry showed Csx/Nkx2.5(I183P) mutant protein expression in atria and ventricle in embryonic, neonatal, and adult atria (#25-A) and ventricles (#25-V). Bars = 50 mm. (b–g) Adult heart from NTG (b, d, f) and TG (c, e, g) mice were coimmunostained with anti-Csx/Nkx2.5 Ab (d, e, FITC) and anti-FLAG Ab (f, g, rhodamine). Nuclear staining was shown in Blue (b, c). Most of the FITC and rhodamine stainings in e and g were colocalized. Bars = 50 mm. (h) Mutant protein expression at 14 (lane 2) and 17 dpc (lane 4) by Western blotting using anti-FLAG pAb (upper panels) and anti-Csx/Nkx2.5 mAb (lower panels). In lane 2 and 4, both endogenous and mutant proteins were recognized with anti-Csx/Nkx2.5 Ab and showed approximately twofold higher Csx/Nkx2.5 protein expression than NTG (lane 1 vs. lane 2, lane 3 vs. lane 4). (i) Western blot analysis of heart lysate from neonate, 3 and 6 weeks of NTG and TG mice with anti-Csx/Nkx2.5 mAb detected endogenous protein in NTG hearts (lanes 1, 3, 5) as well as the endogenous plus the mutant protein in TG heart (lanes 2, 4, 6). (j) Northern blot analysis of Csx/Nkx2.5 and SV40 poly A. At neonatal stage, Csx/Nkx2.5 mRNA was detected as a major single band in NTG heart (Csx/Nkx2.5, lane 1), and two bands in TG heart (lane 2). The slower migrating ban hybridized with SV40 poly A probe indicating the transcript of I183P mutant (SV40 pA, lane 2). In NTG hearts, Csx/Nkx2.5 mRNA level was downregulated after birth (compare lane 1 vs. lanes 3, 5, 7). However, the downregulation of the endogenous Csx/Nkx2.5 was not observed in TG hearts (lanes 2, 4, 6, 8), indicating the upregulation of endogenous Csx/Nkx2.5 in TG hearts.
Follow JCI:
Copyright © 2021 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)

Sign up for email alerts