Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Oct;50(10):717-27.
doi: 10.1002/dvg.22034. Epub 2012 May 14.

Analysis of a Jup hypomorphic allele reveals a critical threshold for postnatal viability

David Swope  1 , Jifen Li, Eliane J Muller, Glenn L Radice
Affiliations

Analysis of a Jup hypomorphic allele reveals a critical threshold for postnatal viability

David Swope et al. Genesis. 2012 Oct.

Abstract

Mutations in the human Jup gene cause arrhythmogenic right ventricular cardiomyopathy (ARVC), a heart muscle disease that often leads to sudden cardiac death. Inactivation of the murine Jup gene (also known as plakoglobin) results in embryonic lethality due to cardiac rupture. In an effort to generate a conditional knockout allele, a neomycin cassette was introduced into the murine plakoglobin (PG) gene. This allele (PG F(N)) functions as a hypomorph when combined with a null allele (PG Δ). About half of the PG F(N)/Δ animals were smaller than their littermates and died before weaning age, whereas the remaining PG F(N)/Δ animals survived. Despite the reduced levels of PG in the heart, there were no signs of cardiomyopathy or cardiac dysfunction as determined by echocardiography. Importantly, the PG homolog, β-catenin (CTNNB1), was increased in the PG F(N)/Δ hearts. In addition to its structural role as part of the N-cadherin/catenin adhesion complex, β-catenin is a downstream effector of Wnt signaling. However, no change in β-catenin/TCF reporter activity was observed in PG F(N)/Δ embryos suggesting that excess β-catenin was not likely causing increased transcription of Wnt/β-catenin target genes. These data suggest novel function(s) for PG beyond the heart and define a critical threshold of PG expression that is necessary for postnatal survival.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Generation of PG hypomorph mouse model
(A) Schematic representation of the expected gene replacement at the PG locus. loxP sites are represented by triangles. The rectangles represent FRT sites. The combination of PG floxed allele (FN) containing a neomycin cassette (neo) with the germline null allele (Δ) resulted in a PG hypomorph (PG FN/Δ). (B) Quantification of PG mRNA expression in PG +/+, PG Δ/+, and PG FN/Δ hearts (n=4 for each genotype) at 3 months of age. (C) Representative Western blot of heart lysates from 1 month old PG +/+, PG FN/+ and PG FN/Δ mice (n=6 for each genotype) were immunoblotted for PG and GAPDH. *, p<0.05; ***, p<0.001.
Figure 2
Figure 2. Histological analysis of PG hypomorph heart
(A) Representative image of PG hypomorph mouse (PG FN/Δ) at postnatal day 10 compared to control littermate (PG FN/+). (B) Representative image of PG hypomorph heart (PG FN/Δ) at postnatal day 10 compared to control littermates (PG FN/+). (C-H) Heart sections from PG FN/+ and PG FN/Δ mice 14 days old were stained with H&E (C,D,F,G) or Masson’s trichrome (E,H).
Figure 3
Figure 3. Growth retardation in surviving PG hypomorph mice
Body weight measurements of PG hypomorph (PG FN/Δ) and control littermates (PG FN/+) taken between 4 – 32 weeks of age. **, p<0.01; ***, p<0.001.
Figure 4
Figure 4. ICD expression of junctional proteins in PG hypomorph heart
Heart sections from PG FN/+ (A,B,C,D) and PG FN/Δ (E,F,G,H) mice at 5 months were immunostained for plakoglobin (PG) (A,E), β-catenin (β-cat) (B,F), N-cadherin (Ncad) (C,G) and Cx43 (D,H). Insets show higher magnification of ICD staining. Note the decreased expression of PG and modest upregulation of β-cat at the ICD of PG hypomorph hearts compared with controls. No significant change was seen in either N-cadherin or Cx43 expression at the ICD.
Figure 5
Figure 5. ICD expression of desmosomal proteins in PG hypomorph heart
Heart sections from PG FN/+ (A,B) and PG FN/Δ (C,D) mice at 5 months were immunostained for plakophilin-2 (PKP2) (A,C) and desmoplakin (DP) (B,D). Insets show higher magnification of ICD staining. No significant change was seen in either PKP2 or DP expression at the ICD.
Figure 6
Figure 6. Cardiac histology and functional analysis in PG hypomorph mice
Heart sections from PG FN/+ and PG FN/Δ mice at 5 months were H&E (A,B,D,E) or Masson’s trichrome (C,F) stained. (G-I) M-mode two-dimensional echocardiography measurements of ejection fraction (EF) and fractional shortening (FS), left ventricular end-systolic and -diastolic internal dimension (LVID), and left ventricular posterior and anterior wall thickness during systole and diastole (LVPW, LVAW; respectively) for PG hypomorph (n=9) and control (n=6) mice at 12 months of age. No signs of cardiac pathology, fibrosis, hypertrophy or reduced cardiac function were seen in PG hypomorph mice.
Figure 7
Figure 7. β-catenin expression in PG hypomorph mice
(A) Representative Western blot of heart lysates from 1 month old PG +/+, PG FN/+ and PG FN/Δ mice (n=6 for each genotype) probed for β-catenin (β-cat), activated β-catenin (ABC) and GAPDH. Note the significant increase in total β-catenin and ABC protein levels in PG hypomorph hearts. (B) Quantification of β-catenin mRNA expression in PG +/+ (n=4) and PG FN/Δ (n=4) hearts at 3 months of age. (C) Representative images of PG FN/+; BAT-gal and PG FN/Δ; BAT-gal embryos at E10.5 stained with X-gal. (D) Quantification of β-galactosidase activity in PG +/+; BAT-gal (n= 30) and PG FN/Δ; BAT-gal (n= 23) embryos at E10.5. **, p<0.01. ***, p<0.001.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Asimaki A, Syrris P, Wichter T, Matthias P, Saffitz JE, McKenna WJ. A novel dominant mutation in plakoglobin causes arrhythmogenic right ventricular cardiomyopathy. Am J Hum Genet. 2007;81:964–973. - PMC - PubMed
    1. Asimaki A, Tandri H, Huang H, Halushka MK, Gautam S, Basso C, Thiene G, Tsatsopoulou A, Protonotarios N, McKenna WJ, Calkins H, Saffitz JE. A new diagnostic test for arrhythmogenic right ventricular cardiomyopathy. N Engl J Med. 2009;360:1075–1084. - PubMed
    1. Basso C, Corrado D, Marcus FI, Nava A, Thiene G. Arrhythmogenic right ventricular cardiomyopathy. Lancet. 2009;373:1289–1300. - PubMed
    1. Bauce B, Nava A, Beffagna G, Basso C, Lorenzon A, Smaniotto G, De Bortoli M, Rigato I, Mazzotti E, Steriotis A, Marra MP, Towbin JA, Thiene G, Danieli GA, Rampazzo A. Multiple mutations in desmosomal proteins encoding genes in arrhythmogenic right ventricular cardiomyopathy/dysplasia. Heart Rhythm. 2010;7:22–29. - PubMed
    1. Bierkamp C, McLaughlin KJ, Schwarz H, Huber O, Kemler R. Embryonic heart and skin defects in mice lacking plakoglobin. Dev Biol. 1996;180:780–785. - PubMed

Publication types

MeSH terms