title: New BRAF knockin mice provide a pathogenetic mechanism of developmental defects and a therapeutic approach in cardio-facio-cutaneous syndrome.
abstract: Cardio-facio-cutaneous (CFC) syndrome is one of the 'RASopathies', a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. Germline mutations in BRAF cause CFC syndrome, which is characterized by heart defects, distinctive facial features and ectodermal abnormalities. To define the pathogenesis and to develop a potential therapeutic approach in CFC syndrome, we here generated new knockin mice (here Braf(Q241R/+)) expressing the Braf Q241R mutation, which corresponds to the most frequent mutation in CFC syndrome, Q257R. Braf(Q241R/+) mice manifested embryonic/neonatal lethality, showing liver necrosis, edema and craniofacial abnormalities. Histological analysis revealed multiple heart defects, including cardiomegaly, enlarged cardiac valves, ventricular noncompaction and ventricular septal defects. Braf(Q241R/+) embryos also showed massively distended jugular lymphatic sacs and subcutaneous lymphatic vessels, demonstrating lymphatic defects in RASopathy knockin mice for the first time. Prenatal treatment with a MEK inhibitor, PD0325901, rescued the embryonic lethality with amelioration of craniofacial abnormalities and edema in Braf(Q241R/+) embryos. Unexpectedly, one surviving pup was obtained after treatment with a histone 3 demethylase inhibitor, GSK-J4, or NCDM-32b. Combination treatment with PD0325901 and GSK-J4 further increased the rescue from embryonic lethality, ameliorating enlarged cardiac valves. These results suggest that our new Braf knockin mice recapitulate major features of RASopathies and that epigenetic modulation as well as the inhibition of the ERK pathway will be a potential therapeutic strategy for the treatment of CFC syndrome.
authors.affiliation: Department of Medical Genetics.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Inoue
authors.affiliation: Department of Medical Genetics.
authors.forename: Mitsuji
authors.initials: M
authors.lastname: Moriya
authors.affiliation: Department of Developmental Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Pediatric Cardiology, Division of Cardiovascular Development and Differentiation, Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan and.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Miyagawa-Tomita
authors.affiliation: Department of Medical Genetics.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Niihori
authors.affiliation: Department of Medical Genetics.
authors.forename: Daiju
authors.initials: D
authors.lastname: Oba
authors.affiliation: Department of Pathology.
authors.forename: Masao
authors.initials: M
authors.lastname: Ono
authors.affiliation: Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kure
authors.affiliation: Department of Developmental Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Department of Medical Genetics, National Research Institute for Child Health and Development, Tokyo, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsubara
authors.affiliation: Department of Medical Genetics, aokiy@med.tohoku.ac.jp.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Aoki
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology*; D004159:Diphenylamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004195:Disease Models, Animal; D004357:Drug Synergism; D004476:Ectodermal Dysplasia / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004622:Embryo, Mammalian; D019066:Facies; D005183:Failure to Thrive / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D055879:Gene Knock-In Techniques; D005804:Genes, Lethal; D006330:Heart Defects, Congenital / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D056466:Histone Demethylases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000002:abnormalities / Q000187:drug effects; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009206:Myocardium / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D015398:Signal Transduction; D012886:Skull / Q000002:abnormalities / Q000187:drug effects
chemical_list: D001549:Benzamides; D001552:Benzazepines; C000593030:GSK-J4; D056572:Histone Deacetylase Inhibitors; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; C506614:mirdametinib; D004159:Diphenylamine; D056466:Histone Demethylases; C482120:Braf protein, mouse; D048493:Proto-Oncogene Proteins B-raf; D020930:MAP Kinase Kinase Kinases