RESUMO
Hearing loss is the most common sensory deficit in humans. Because the auditory systems of mice and humans are conserved, studies on mouse models have predicted several human deafness genes and identified new genes involved in hearing. The deafwaddler (dfw) mouse mutant is deaf and displays vestibular/motor imbalance. Here we report that the gene encoding a plasma membrane Ca2+-ATPase type 2 pump (Atp2b2, also known as Pmca2) is mutated in dfw. An A-->G nucleotide transition in dfw DNA causes a glycine-to-serine substitution at a highly conserved amino-acid position, whereas in a second allele, dfw2J, a 2-base-pair deletion causes a frameshift that predicts a truncated protein. In the cochlea, the protein Atp2b2 is localized to stereocilia and the basolateral wall of hair cells in wild-type mice, but is not detected in dfw2J mice. This indicates that mutation of Atp2b2 may cause deafness and imbalance by affecting sensory transduction in stereocilia as well as neurotransmitter release from the basolateral membrane. These mutations affecting Atp2b2 in dfw and dfw2J are the first to be found in a mammalian plasma membrane calcium pump and define a new class of deafness genes that directly affect hair-cell physiology.
Assuntos
ATPases Transportadoras de Cálcio/genética , Surdez/genética , Mutação da Fase de Leitura/genética , Mutação Puntual/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Encéfalo/enzimologia , ATPases Transportadoras de Cálcio/análise , Membrana Celular/enzimologia , Mapeamento Cromossômico , Análise Mutacional de DNA , Modelos Animais de Doenças , Regulação Enzimológica da Expressão Gênica , Genes/genética , Camundongos , Camundongos Mutantes Neurológicos , Dados de Sequência Molecular , Órgão Espiral/enzimologia , RNA Mensageiro/análise , Vestíbulo do Labirinto/enzimologiaRESUMO
The autosomal recessive mouse mutation quivering (qv), which arose spontaneously in 1953, produces progressive ataxia with hind limb paralysis, deafness and tremor. Six additional spontaneous alleles, qvJ, qv2J, qv3J, qv4J, qvlnd and qvlnd2J, have been identified. Ear twitch responses (Preyer's reflex) to sound are absent in homozygous qv/qv mice, although cochlear morphology seems normal and cochlear potentials recorded at the round window are no different from those of control mice. However, responses from brainstem auditory nuclei show abnormal transmission of auditory information, indicating that, in contrast to the many known mutations causing deafness originating in the cochlea, deafness in qv is central in origin. Here we report that quivering mice carry loss-of-function mutations in the mouse beta-spectrin 4 gene (Spnb4) that cause alterations in ion channel localization in myelinated nerves; this provides a rationale for the auditory and motor neuropathies of these mice.
Assuntos
Surdez/genética , Mutação , Espectrina/genética , Tremor/genética , Animais , Córtex Auditivo/fisiopatologia , Genes Recessivos , Camundongos , Camundongos Endogâmicos CBA , Camundongos Mutantes , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Mouse chromosome 10 harbors several loci associated with hearing loss, including waltzer (v), modifier-of deaf waddler (mdfw) and Age-related hearing loss (Ahl). The human region that is orthologous to the mouse 'waltzer' region is located at 10q21-q22 and contains the human deafness loci DFNB12 and USH1D). Numerous mutations at the waltzer locus have been documented causing erratic circling and hearing loss. Here we report the identification of a new gene mutated in v. The 10.5-kb Cdh23 cDNA encodes a very large, single-pass transmembrane protein, that we have called otocadherin. It has an extracellular domain that contains 27 repeats; these show significant homology to the cadherin ectodomain. In v(6J), a GT transversion creates a premature stop codon. In v(Alb), a CT exchange generates an ectopic donor splice site, effecting deletion of 119 nucleotides of exonic sequence. In v(2J), a GA transition abolishes the donor splice site, leading to aberrant splice forms. All three alleles are predicted to cause loss of function. We demonstrate Cdh23 expression in the neurosensory epithelium and show that during early hair-cell differentiation, stereocilia organization is disrupted in v(2J) homozygotes. Our data indicate that otocadherin is a critical component of hair bundle formation. Mutations in human CDH23 cause Usher syndrome type 1D and thus, establish waltzer as the mouse model for USH1D.
Assuntos
Caderinas/genética , Células Ciliadas Auditivas Internas/patologia , Perda Auditiva Neurossensorial/genética , Mutação/genética , Sequência de Aminoácidos , Animais , Percepção Auditiva/fisiologia , Sequência de Bases , Caderinas/química , Caderinas/metabolismo , Clonagem Molecular , Cóclea/metabolismo , Análise Mutacional de DNA , Modelos Animais de Doenças , Células Ciliadas Auditivas Internas/metabolismo , Células Ciliadas Auditivas Internas/fisiopatologia , Células Ciliadas Auditivas Internas/ultraestrutura , Audição/fisiologia , Perda Auditiva Neurossensorial/patologia , Testes Auditivos , Hibridização In Situ , Camundongos , Camundongos Endogâmicos , Camundongos Mutantes , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , RNA Mensageiro/análise , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SíndromeRESUMO
DFNB3, a locus for nonsyndromic sensorineural recessive deafness, maps to a 3-centimorgan interval on human chromosome 17p11.2, a region that shows conserved synteny with mouse shaker-2. A human unconventional myosin gene, MYO15, was identified by combining functional and positional cloning approaches in searching for shaker-2 and DFNB3. MYO15 has at least 50 exons spanning 36 kilobases. Sequence analyses of these exons in affected individuals from three unrelated DFNB3 families revealed two missense mutations and one nonsense mutation that cosegregated with congenital recessive deafness.
Assuntos
Surdez/genética , Miosinas/genética , Sequência de Aminoácidos , Animais , Encéfalo/embriologia , Encéfalo/metabolismo , Mapeamento Cromossômico , Cromossomos Humanos Par 17 , Cóclea/embriologia , Cóclea/metabolismo , Cosmídeos , Surdez/congênito , Éxons , Feminino , Expressão Gênica , Genes Recessivos , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Mutação , Miosinas/química , Miosinas/fisiologia , Linhagem , Mutação Puntual , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
The shaker-2 mouse mutation, the homolog of human DFNB3, causes deafness and circling behavior. A bacterial artificial chromosome (BAC) transgene from the shaker-2 critical region corrected the vestibular defects, deafness, and inner ear morphology of shaker-2 mice. An unconventional myosin gene, Myo15, was discovered by DNA sequencing of this BAC. Shaker-2 mice were found to have an amino acid substitution at a highly conserved position within the motor domain of this myosin. Auditory hair cells of shaker-2 mice have very short stereocilia and a long actin-containing protrusion extending from their basal end. This histopathology suggests that Myo15 is necessary for actin organization in the hair cells of the cochlea.
Assuntos
Surdez/genética , Miosinas/genética , Sequência de Aminoácidos , Animais , Sítios de Ligação , Encéfalo/metabolismo , Cromossomos Bacterianos , Surdez/patologia , Surdez/terapia , Orelha Interna/metabolismo , Feminino , Teste de Complementação Genética , Células Ciliadas Auditivas/ultraestrutura , Humanos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Camundongos Transgênicos , Miosinas/química , Miosinas/metabolismo , Fenótipo , Mutação Puntual , TransgenesRESUMO
Phenotypic variation between individuals with the same disease alleles may be attributable to the genotype at another locus, which is referred to as a modifier gene. Recent functional studies of modifier genes of hearing-loss loci have begun to refine our understanding of hearing processes and will guide the rational design of medical therapies for hearing loss.
Assuntos
Alelos , Surdez/genética , Testes Genéticos/métodos , Células Ciliadas Auditivas/fisiologia , Mutação/genética , Animais , Mapeamento Cromossômico , Genótipo , Células Ciliadas Auditivas/ultraestrutura , Humanos , FenótipoRESUMO
Three members of the myb gene family, designated as A-myb, B-myb, and c-myb, have been described in many vertebrates. A large body of evidence indicates that the c-myb gene is essential for the development of most hematopoietic lineages. By contrast, the functions of A-myb and B-myb are less well understood. To further explore the relationship between the different myb family members we have compared the expression of A-myb and c-myb during mouse embryogenesis by Northern blotting and by in situ hybridization. In accordance with the important role of c-myb in the hematopoietic system, we detect high levels of c-myb expression in hematopoietic organs such as the fetal liver and the thymus. Surprisingly, we find that high levels of c-myb expression are not restricted to hematopoietic cells. We show that c-myb is strongly expressed in the neural retina and in epithelia of the respiratory tract. The side-by side analysis of c-myb and A-myb expression clearly shows that both genes are expressed in different, but overlapping sets of tissues. Our results suggest that the function of c-myb may not be restricted to hematopoietic cells.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Oncogenes , Animais , Sequência de Bases , Primers do DNA , Camundongos , Dados de Sequência Molecular , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-mybRESUMO
The myb gene family consists of three members, the c-myb proto-oncogene and two myb-related genes (A-myb and B-myb), all of which encode nuclear DNA-binding proteins. Unlike c-myb, which plays a critical role in hematopoietic cells, B-myb is expressed in a large spectrum of hematopoietic as well as non-hematopoietic cells and has been implicated in the control of cell proliferation. The isolation of B-myb cDNA clones from several species has shown that B-myb shares limited homology to the so-called exon 9A of the c-myb gene. This exon is involved in differential splicing as only a subfraction of c-myb mRNA contains exon 9A sequences. The presence in the B-myb cDNA of a sequence related to the exon 9A of c-myb has prompted us to investigate whether B-myb mRNA is also spliced differentially. We here show that B-myb mRNAs containing or lacking exon 9A related sequences are present in many cell types. In contrast to c-myb, where RNA containing the exon 9A constitutes only a minor mRNA fraction, B-myb RNA containing the exon 9A related sequences is the major mRNA form. The proteins encoded by the two B-myb mRNA species are unable to activate promoters to which they bind. Curiously, both B-myb proteins differ in their ability to activate the HSP70 promoter by a myb binding-site independent mechanism; B-myb protein containing exon 9A related aminoacid sequences activates the HSP70 promoter much more potently than the B-myb protein which lacks these sequences. Our results suggest that differential splicing may be a general feature of the members of the myb family and provide first evidence for functional differences of the splice variants.
Assuntos
Oncogenes , Splicing de RNA , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Proteínas de Choque Térmico HSP70/genética , Camundongos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , RNA Mensageiro/análiseRESUMO
B-myb is a member of the myb family of nuclear sequence-specific DNA-binding proteins which has been highly conserved among vertebrates. B-myb has been implicated in the control of cell proliferation, particularly at the G1/S transition of the cell cycle. So far, most of the work on B-myb has been performed in immortalized cell lines. Since these cells might show aberrant behavior of genes involved in proliferation control we have begun to investigate the role of B-myb in normal cells. As a first step, we have studied the expression of B-myb during mouse development. Here, we show the B-myb is expressed at similar levels during all stages of embryogenesis. In situ hybridization reveals a tight linkage between B-myb expression and proliferative activity (as assessed by the expression of the S-phase specific histone H4 gene) in most tissues and throughout embryonic development. However, B-myb and histone H4 expression are uncoupled during spermatogenesis in the adult mouse. Histone H4 is expressed at high levels in the early spermatogenic progenitor cells but not in successive stages of sperm cell development. By contrast, the highest levels of B-myb expression are found during the intermediate stages of spermatogenesis. Furthermore, we have found that B-myb mRNA isolated from the testis differs in size from that of other tissues. The data presented here strongly support the notion that B-myb plays a general role during proliferation of most cells. Furthermore, our results raise the possibility that the function of B-myb in cells undergoing meiosis may be different from its role in cells dividing mitotically.
Assuntos
Proteínas de Ciclo Celular , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica no Desenvolvimento , Transativadores , Fatores de Transcrição/genética , Animais , Sequência de Bases , Northern Blotting , Divisão Celular/genética , Masculino , Camundongos , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Espermatogênese/genéticaRESUMO
Here we describe the nucleotide sequence and expression pattern of a novel gene termed Coiled-coil-like protein 1 (Cclp1). A 2646bp open reading frame encodes a 882 amino acid protein with a predicted coiled-coil domain at the amino terminus. Cclp1 is expressed in a variety of adult tissues and during different stages of embryogenesis. The broad expression pattern suggests a general cellular function of CCLP1.
Assuntos
Proteínas de Ligação a DNA , Proteínas/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Camundongos , Dados de Sequência Molecular , Biossíntese de Proteínas , Proteínas/química , Alinhamento de SequênciaRESUMO
Cadherins are components of adherens junctions and play critical roles during embryogenesis and organogenesis. They interact through the formation of anti-parallel dimers to mediate cell adhesion, migration and compaction. We recently showed that cadherins also play important roles in the inner ear; mutations in cadherin 23 (Cdh23) disrupt stereocilia organization on hair cells leading to deafness and vestibular dysfunction in waltzer mice. Here we extend our initial study on the structure and function of Cdh23. The mouse Cdh23 locus is comprised of two 5'-untranslated exons and 69 coding exons; together they cover a genomic distance of at least 350 kb. Amino acid sequence alignments and secondary structure prediction suggest that Cdh23 ectodomains adopt a conformation similar to the classic cadherins. Nucleotide sequence analysis of six alleles of waltzer reveals a strong correlation between loss of function mutations and the deafness/waltzing phenotype. A Cdh23 transcript with a spliced exon 68 is the predominantly expressed isoform in the organ of Corti. Age-related hearing loss (Ahl) is a non-syndromic trait in common inbred strains of mice associated with the Ahl locus on chromosome 10. Sequence comparison of Cdh23 between C57BL/6J and CAST/Ei identified ten amino acid polymorphisms. In the 5'- and 3'-untranslated regions we detected 11 single nucleotide polymorphisms. None of these sequence changes correlate with the Ahl phenotype. Our results provide the necessary framework for further characterization of Cdh23-related hearing loss in mice.
Assuntos
Alelos , Processamento Alternativo , Caderinas/genética , Regiões 3' não Traduzidas , Regiões 5' não Traduzidas , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Éxons , Genes/genética , Íntrons , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Endogâmicos DBA , Camundongos Endogâmicos NOD , Camundongos Endogâmicos , Dados de Sequência Molecular , Mutação , Isoformas de Proteínas , Homologia de Sequência de AminoácidosRESUMO
The human ortholog of the gene responsible for audiogenic seizure susceptibility in Frings and BUB/BnJ mice (mouse gene symbol Mass1) recently was shown to underlie Usher syndrome type IIC (USH2C). Here we report that the Mass1frings mutation is responsible for the early onset hearing impairment of BUB/BnJ mice. We found highly significant linkage of Mass1 with ABR threshold variation among mice from two backcrosses involving BUB/BnJ mice with mice of strains CAST/EiJ and MOLD/RkJ. We also show an additive effect of the Cdh23 locus in modulating the progression of hearing loss in backcross mice. Together, these two loci account for more than 70% of the total ABR threshold variation among the backcross mice at all ages. The modifying effect of the strain-specific Cdh23ahl variant may account for the hearing and audiogenic seizure differences observed between Frings and BUB/BnJ mice, which share the Mass1frings mutation. During postnatal cochlear development in BUB/BnJ mice, stereocilia bundles develop abnormally and remain immature and splayed into adulthood, corresponding with the early onset hearing impairment associated with Mass1frings. Progressive base-apex hair cell degeneration occurs at older ages, corresponding with the age-related hearing loss associated with Cdh23ahl. The molecular basis and pathophysiology of hearing loss suggest BUB/BnJ and Frings mice as models to study cellular and molecular mechanisms underlying USH2C auditory pathology.
Assuntos
Cóclea/ultraestrutura , Modelos Animais de Doenças , Perda Auditiva/genética , Perda Auditiva/patologia , Mutação/genética , Receptores Acoplados a Proteínas G/genética , Animais , Cruzamentos Genéticos , Primers do DNA , Eletroforese em Gel de Ágar , Potenciais Evocados Auditivos do Tronco Encefálico , Camundongos , Camundongos Mutantes , Repetições de Microssatélites/genética , Microscopia Eletrônica de VarreduraRESUMO
A mutation in the tub gene causes maturity-onset obesity, insulin resistance, and sensory deficits. In contrast to the rapid juvenile-onset weight gain seen in diabetes (db) and obese (ob) mice, obesity in tubby mice develops gradually, and strongly resembles the late-onset obesity seen in the human population. Excessive deposition of adipose tissue eventually leads to a twofold increase of body weight. Tubby mice also suffer retinal degeneration and neurosensory hearing loss. The tripartite character of the tubby phenotype shows striking similarity to human obesity syndromes, such as Alström and Bardet-Biedl. Here we report the identification of a G --> T transversion in a candidate gene that abolishes a donor splice site in the 3' coding region and results in a larger transcript containing the unspliced intron. This alteration is predicted to replace the 44-carboxyterminal amino acids with a 20-amino-acid sequence not found in the wide-type protein. Additionally, a second, prematurely truncated transcript with the unspliced intron is observed in testis messenger RNA and a 2-3-fold increase in brain mRNA is observed in tubby mice compared to B6. The phenotype features of tubby mice may be the result of cellular apoptosis triggered by expression of the mutuated tub gene.
Assuntos
Obesidade/genética , Proteínas/genética , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Sequência de Bases , Encéfalo/metabolismo , Clonagem Molecular , DNA , Primers do DNA , Expressão Gênica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Dados de Sequência Molecular , Obesidade/complicações , Mutação Puntual , Splicing de RNA , Degeneração Retiniana/complicações , Degeneração Retiniana/genética , Homologia de Sequência de Aminoácidos , Testículo/metabolismoRESUMO
Tubby, an autosomal recessive mutation, mapping to mouse chromosome 7, was recently found to be the result of a splicing defect in a novel gene with unknown function. Database searches revealed that sequences corresponding to the C terminus of the tub protein were highly conserved across a number of species including humans, mice, Caenorhabditis elegans, Arabidopsis, rice, and maize, and that tub was a member of a gene family. We describe here, TUB, the human homolog of mouse tub, and two newly characterized family members, TULP1 for tubby like protein 1 and TULP2. These three family members, which differ in the N-terminal half of the protein, share 60-90% amino acid identity across their conserved C-terminal region and have distinct tissue expression patterns. Alternatively spliced transcripts with 5' variable sequences, three of which have been identified for the tubby gene, may mediate tissue specific expression. We also report that TUB, TULP1, and TULP2 map to human chromosomes 11p15.4, 6p21.3, and 19q13.1, respectively. TULP1 and TULP2 map within the minimal intervals identified for retinitis pigmentosa 14 on chromosome 6p21.3 and cone-rod dystrophy on chromosome 19q13.1. TULP1 and TULP2, which are expressed in the retina, make excellent candidates for these ocular diseases as a mutation within the tub gene is known to lead to early progressive retinal degeneration.
Assuntos
Oftalmopatias/genética , Proteínas do Olho/genética , Proteínas/genética , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Southern Blotting , Clonagem Molecular , DNA Complementar , Humanos , Camundongos , Dados de Sequência MolecularRESUMO
The deaf waddler (dfw) mutation is a model system to study the biology of neuroepithelial hearing defects in mice. Here we describe the identification and characterization of a new allele of deaf waddler (dfw2J) and present evidence for a hearing susceptibility locus (mdfw) that interacts with dfw. We found that CBy-dfw2J/dfw2J homozygotes exhibit no discernible auditory brainstem responses (ABR) to sound pressure level stimuli up to 100 dB, indicating a profound deafness. Interestingly, the ABR in CBy-dfw2J/+ heterozygotes is also abnormal, showing age-dependent elevated thresholds characteristic of a progressive hearing loss. When outcrossed onto the CAST/Ei strain, only 24% of the F2 CBy/CAST-dfw2J/ + heterozygotes displayed increased ABR thresholds, suggesting that a second locus, controlling hearing function in dfw2J/+ heterozygotes, was segregating in the CBy/CAST-dfw2J intercross. By linkage analysis, we localized this locus (mdfw) to Chromosome 10, between markers D10Mit127 and D10Mit185, within a 4.0 +/- 1.1 cM genetic interval. All CBy/CAST-dfw2J/+ heterozygotes that develop hearing loss are homozygous for the CBy-derived recessive allele (mdfwC). In contrast, CBy/ CAST-dfw2J/+ heterozygotes expressing even a single copy of the CAST/Ei-derived mdfw allele (Mdfw) retain their normal hearing function. Our results reveal an epistatic relationship between the mdfw and the dfw genes and provide a model system to study nonsyndromic hearing loss in mice.
Assuntos
Surdez/genética , Alelos , Animais , Mapeamento Cromossômico , Surdez/fisiopatologia , Suscetibilidade a Doenças , Potenciais Evocados Auditivos do Tronco Encefálico/genética , Triagem de Portadores Genéticos , Marcadores Genéticos , Homozigoto , Camundongos , Camundongos Endogâmicos A , Camundongos Endogâmicos AKR , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Mutantes Neurológicos , Repetições de Microssatélites , FenótipoRESUMO
Modifier-of-deafwaddler (mdfw) and waltzer (Cdh23v) are loci on mouse chromosome 10 encoding factors that are essential for the function of auditory hair cells. The BALB/cByJ-specific mdfw allele encodes a necessary and sufficient modifier that induces progressive early onset hearing loss in CBy-dfw2J heterozygotes. Recessive mutations in the waltzer locus result in circling behavior and congenital deafness. In this report we present a high-resolution integrated genetic and physical map of mdfw and Cdh23(v). Our genetic analyses localize mdfw between markers D10Mit60 and 148M13T7 within a 1.01-cM region. The Cdh23v critical interval is fully contained within the mdfw region and localizes between markers 146O23T7 and 148M13T7 within a 0.35-cM interval that is represented in an approximately 500-kb BAC contig. Our data suggest that mdfw and Cdh23v are allelic.
Assuntos
Mapeamento Cromossômico , Surdez/genética , Mutação/genética , Mapeamento Físico do Cromossomo , Alelos , Animais , Mapeamento de Sequências Contíguas , Feminino , Genes Recessivos/genética , Haplótipos , Audição/genética , Masculino , Camundongos , Camundongos Mutantes , Fenótipo , Polimorfismo Genético/genética , Mapeamento de Híbridos RadioativosRESUMO
Mybl2 encodes a transcription factor that is thought to play an important role in cell cycle progression. Here we report the chromosomal localization of Mybl2 in mouse and human. Using mouse Mybl2 cDNA clones as probes, we assigned Mybl2 in an interspecific backcross panel to distal Chromosome 2. Using human cDNA probes in combination with FISH analysis, we localized MYBL2 to chromosome 20q13.1, a region that is commonly deleted in myeloid disorders. Both chromosomal regions are highly homologous, and the map positions, therefore, confirm each other. However, our findings are in contrast to a previous report by Barletta et al. (Cancer Res. 51:3821-3824, 1991) that placed the MYBL2 gene on human chromosome Xq13.
Assuntos
Mapeamento Cromossômico , Cromossomos Humanos Par 12 , Proteínas Oncogênicas de Retroviridae/genética , Fatores de Transcrição/genética , Animais , Feminino , Humanos , Hibridização in Situ Fluorescente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Oncogênicas v-mybRESUMO
Following the positional cloning of PDS, the gene mutated in the deafness/goitre disorder Pendred syndrome (PS), numerous studies have focused on defining the role of PDS in deafness and PS as well as elucidating the function of the PDS-encoded protein (pendrin). To facilitate these efforts and to provide a system for more detailed study of the inner-ear defects that occur in the absence of pendrin, we have generated a Pds-knockout mouse. Pds(-/-) mice are completely deaf and also display signs of vestibular dysfunction. The inner ears of these mice appear to develop normally until embryonic day 15, after which time severe endolymphatic dilatation occurs, reminiscent of that seen radiologically in deaf individuals with PDS mutations. Additionally, in the second postnatal week, severe degeneration of sensory cells and malformation of otoconia and otoconial membranes occur, as revealed by scanning electron and fluorescence confocal microscopy. The ultrastructural defects seen in the Pds(-/-) mice provide important clues about the mechanisms responsible for the inner-ear pathology associated with PDS mutations.