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Hum Mol Genet. 2015 Dec 20;24(25):7349-60. doi: 10.1093/hmg/ddv435. Epub 2015 Oct 15.

Adult mice expressing a Braf Q241R mutation on an ICR/CD-1 background exhibit a cardio-facio-cutaneous syndrome phenotype.

Author information

1
Department of Medical Genetics and.
2
Department of Pediatric Cardiology and Division of Cardiovascular Development and Differentiation, Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan.
3
Department of Pediatrics, Seirei Hamamatsu General Hospital, Shizuoka, Japan.
4
Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Gunma, Japan and.
5
Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
6
Department of Medical Genetics and National Research Institute for Child Health and Development, Tokyo, Japan.
7
Department of Medical Genetics and aokiy@med.tohoku.ac.jp.

Abstract

Activation of the RAS pathway has been implicated in oncogenesis and developmental disorders called RASopathies. Germline mutations in BRAF have been identified in 50-75% of patients with cardio-facio-cutaneous (CFC) syndrome, which is characterized by congenital heart defects, distinctive facial features, short stature and ectodermal abnormalities. We recently demonstrated that mice expressing a Braf Q241R mutation, which corresponds to the most frequent BRAF mutation (Q257R) in CFC syndrome, on a C57BL/6J background are embryonic/neonatal lethal, with multiple congenital defects, preventing us from analyzing the phenotypic consequences after birth. Here, to further explore the pathogenesis of CFC syndrome, we backcrossed these mice onto a BALB/c or ICR/CD-1 genetic background. On a mixed (BALB/c and C57BL/6J) background, all heterozygous Braf(Q241R/+) mice died between birth and 24 weeks and exhibited growth retardation, sparse and ruffled fur, liver necrosis and atrial septal defects (ASDs). In contrast, 31% of the heterozygous Braf(Q241R/+) ICR mice survived over 74 weeks. The surviving Braf(Q241R/+) ICR mice exhibited growth retardation, sparse and ruffled fur, a hunched appearance, craniofacial dysmorphism, long and/or dystrophic nails, extra digits and ovarian cysts. The Braf(Q241R/+) ICR mice also showed learning deficits in the contextual fear-conditioning test. Echocardiography indicated the presence of pulmonary stenosis and ASDs in the Braf(Q241R/+) ICR mice, which were confirmed by histological analysis. These data suggest that the heterozygous Braf(Q241R/+) ICR mice show similar phenotypes as CFC syndrome after birth and will be useful for elucidating the pathogenesis and potential therapeutic strategies for RASopathies.

PMID:
26472072
DOI:
10.1093/hmg/ddv435
[Indexed for MEDLINE]

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