RESUMO
We have determined the molecular basis for Usher syndrome type 1F (USH1F) in two families segregating for this type of syndromic deafness. By fluorescence in situ hybridization, we placed the human homolog of the mouse protocadherin Pcdh15 in the linkage interval defined by the USH1F locus. We determined the genomic structure of this novel protocadherin, and found a single-base deletion in exon 10 in one USH1F family and a nonsense mutation in exon 2 in the second. Consistent with the phenotypes observed in these families, we demonstrated expression of PCDH15 in the retina and cochlea by RT-PCR and immunohistochemistry. This report shows that protocadherins are essential for maintenance of normal retinal and cochlear function.
Assuntos
Caderinas/genética , Surdez/genética , Mutação , Precursores de Proteínas/genética , Adulto , Sequência de Aminoácidos , Animais , Northern Blotting , Western Blotting , Proteínas Relacionadas a Caderinas , Caderinas/análise , Cóclea/química , Análise Mutacional de DNA , Feminino , Feto , Perfilação da Expressão Gênica , Ligação Genética , Humanos , Hibridização in Situ Fluorescente , Masculino , Camundongos , Dados de Sequência Molecular , Linhagem , Polimorfismo Conformacional de Fita Simples , Precursores de Proteínas/análise , Retina/química , Retina/embriologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , SíndromeRESUMO
We previously determined that Protocadherin 15 (Pcdh15) is associated with the Ames waltzer mutation in the mouse. Here we describe where the Pcdh15 gene is expressed at specific times during mouse development using RNA in situ hybridization. The expression of Pcdh15 is found in the sensory epithelium in the developing inner ear, in Rathke's pouch, and broadly throughout the brain with the highest level of expression being detected at embryonic day 16 (E16). Pcdh15 transcripts are also found in the developing eye, dorsal root ganglion, and the dorsal aspect of the neural tube, floor plate and ependymal cells adjacent to the neural canal. Additionally, expression is also detected in the developing glomeruli of the kidney, surface of the tongue, vibrissae, bronchi of the lung, and in the epithelium of the olfactory apparatus, gut and lung.
Assuntos
Caderinas/biossíntese , Orelha/embriologia , Epitélio/embriologia , Mutação , Sistema Nervoso/embriologia , Precursores de Proteínas/biossíntese , Animais , Proteínas Relacionadas a Caderinas , Sistema Nervoso Central/metabolismo , Hibridização In Situ , Rim/embriologia , RNA Mensageiro/metabolismo , Fatores de Tempo , Peixe-ZebraRESUMO
The neuroepithelia of the inner ear contain hair cells that function as mechanoreceptors to transduce sound and motion signals. Mutations affecting these neuroepithelia cause deafness and vestibular dysfuction in humans. Ames waltzer (av) is a recessive mutation found in mice that causes deafness and a balance disorder associated with the degeneration of inner ear neuroepithelia. Here we report that the gene that harbours the av mutation encodes a novel protocadherin. Cochlear hair cells in the av mutants show abnormal stereocilia by 10 days after birth (P10). This is the first evidence for the requirement of a protocadherin for normal function of the mammalian inner ear.
