Catweasel mice: a novel role for Six1 in sensory patch development and a model for branchio-oto-renal syndrome.
Large-scale mouse mutagenesis initiatives have provided new mouse mutants that are useful models of human deafness and vestibular dysfunction. Catweasel is a novel N-ethyl-N-nitrosourea (ENU)-induced mutation. Heterozygous catweasel mutant mice exhibit mild headtossing associated with a posterior crista defect. We mapped the catweasel mutation to a critical region of 13 Mb on chromosome 12 containing the Six1, -4 and -6 genes. We identified a basepair substitution in exon 1 of the Six1 gene that changes a conserved glutamic acid (E) at position 121 to a glycine (G) in the Six1 homeodomain. Cwe/Cwe animals lack Preyer and righting reflexes, display severe headshaking and have severely truncated cochlea and semicircular canals. Cwe/Cwe animals had very few hair cells in the utricle, but their ampullae and cochlea were devoid of any hair cells. Bmp4, Jag1 and Sox2 expression were largely absent at early stages of sensory development and NeuroD expression was reduced in the developing vestibulo-acoustic ganglion. Lastly we show that Six1 genetically interacts with Jag1. We propose that the catweasel phenotype is due to a hypomorphic mutation in Six1 and that catweasel mice are a suitable model for branchio-oto-renal syndrome. In addition Six1 has a pivotal role in early sensory patch development and may act in the same genetic pathway as Jag1.
Bosman
Erika A
EA
The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK.
Quint
Elizabeth
E
Fuchs
Helmut
H
Hrabé de Angelis
Martin
M
Steel
Karen P
KP
D000595:Amino Acid Sequence; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism; D019280:Branchio-Oto-Renal Syndrome / Q000196:embryology / Q000235:genetics* / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D007758:Ear, Inner / Q000002:abnormalities / Q000196:embryology / Q000254:growth & development; D004622:Embryo, Mammalian / Q000002:abnormalities / Q000502:physiology; D005038:Ethylnitrosourea; D006198:Hair Cells, Auditory / Q000473:pathology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D000072100:Jagged-1 Protein; D007668:Kidney / Q000002:abnormalities / Q000196:embryology / Q000254:growth & development; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009153:Mutagens; D017354:Point Mutation; D055748:SOXB1 Transcription Factors / Q000378:metabolism; D000072099:Serrate-Jagged Proteins
C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D002135:Calcium-Binding Proteins; D018398:Homeodomain Proteins; D036341:Intercellular Signaling Peptides and Proteins; C000606273:JAG1 protein, human; C000606274:Jag1 protein, mouse; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D009153:Mutagens; D055748:SOXB1 Transcription Factors; D000072099:Serrate-Jagged Proteins; C490947:Six1 protein, mouse; C527783:Sox2 protein, mouse; D005038:Ethylnitrosourea