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2.
Neuron ; 109(16): 2604-2615.e9, 2021 08 18.
Artículo en Inglés | MEDLINE | ID: mdl-34242565

RESUMEN

Nicotine stimulates dopamine (DA) neurons of the ventral tegmental area (VTA) to establish and maintain reinforcement. Nicotine also induces anxiety through an as yet unknown circuitry. We found that nicotine injection drives opposite functional responses of two distinct populations of VTA DA neurons with anatomically segregated projections: it activates neurons that project to the nucleus accumbens (NAc), whereas it inhibits neurons that project to the amygdala nuclei (Amg). We further show that nicotine mediates anxiety-like behavior by acting on ß2-subunit-containing nicotinic acetylcholine receptors of the VTA. Finally, using optogenetics, we bidirectionally manipulate the VTA-NAc and VTA-Amg pathways to dissociate their contributions to anxiety-like behavior. We show that inhibition of VTA-Amg DA neurons mediates anxiety-like behavior, while their activation prevents the anxiogenic effects of nicotine. These distinct subpopulations of VTA DA neurons with opposite responses to nicotine may differentially drive the anxiogenic and the reinforcing effects of nicotine.


Asunto(s)
Ansiedad/tratamiento farmacológico , Vías Nerviosas/efectos de los fármacos , Nicotina/farmacología , Agonistas Nicotínicos/farmacología , Área Tegmental Ventral/efectos de los fármacos , Amígdala del Cerebelo/efectos de los fármacos , Amígdala del Cerebelo/metabolismo , Animales , Ansiedad/inducido químicamente , Ansiedad/fisiopatología , Dopamina/metabolismo , Neuronas Dopaminérgicas/efectos de los fármacos , Neuronas Dopaminérgicas/fisiología , Masculino , Ratones , Vías Nerviosas/fisiología , Nicotina/metabolismo , Núcleo Accumbens/efectos de los fármacos , Núcleo Accumbens/fisiología , Receptores Nicotínicos/efectos de los fármacos , Receptores Nicotínicos/metabolismo , Refuerzo en Psicología , Área Tegmental Ventral/fisiología
3.
Sci Rep ; 10(1): 16430, 2020 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-33009420

RESUMEN

The hair bundle of cochlear hair cells is the site of auditory mechanoelectrical transduction. It is formed by three rows of stiff microvilli-like protrusions of graduated heights, the short, middle-sized, and tall stereocilia. In developing and mature sensory hair cells, stereocilia are connected to each other by various types of fibrous links. Two unconventional cadherins, protocadherin-15 (PCDH15) and cadherin-23 (CDH23), form the tip-links, whose tension gates the hair cell mechanoelectrical transduction channels. These proteins also form transient lateral links connecting neighboring stereocilia during hair bundle morphogenesis. The proteins involved in anchoring these diverse links to the stereocilia dense actin cytoskeleton remain largely unknown. We show that the long isoform of whirlin (L-whirlin), a PDZ domain-containing submembrane scaffold protein, is present at the tips of the tall stereocilia in mature hair cells, together with PCDH15 isoforms CD1 and CD2; L-whirlin localization to the ankle-link region in developing hair bundles moreover depends on the presence of PCDH15-CD1 also localizing there. We further demonstrate that L-whirlin binds to PCDH15 and CDH23 with moderate-to-high affinities in vitro. From these results, we suggest that L-whirlin is part of the molecular complexes bridging PCDH15-, and possibly CDH23-containing lateral links to the cytoskeleton in immature and mature stereocilia.


Asunto(s)
Cadherinas/metabolismo , Cóclea/metabolismo , Células Ciliadas Auditivas/metabolismo , Proteínas de la Membrana/metabolismo , Precursores de Proteínas/metabolismo , Animales , Proteínas Relacionadas con las Cadherinas , Diferenciación Celular/fisiología , Femenino , Masculino , Mecanotransducción Celular/fisiología , Ratones , Ratones Endogámicos C57BL , Microscopía Electrónica de Rastreo/métodos , Isoformas de Proteínas/metabolismo , Estereocilios/metabolismo
4.
Proc Natl Acad Sci U S A ; 116(51): 25948-25957, 2019 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-31776257

RESUMEN

The function of outer hair cells (OHCs), the mechanical actuators of the cochlea, involves the anchoring of their tallest stereocilia in the tectorial membrane (TM), an acellular structure overlying the sensory epithelium. Otogelin and otogelin-like are TM proteins related to secreted epithelial mucins. Defects in either cause the DFNB18B and DFNB84B genetic forms of deafness, respectively, both characterized by congenital mild-to-moderate hearing impairment. We show here that mutant mice lacking otogelin or otogelin-like have a marked OHC dysfunction, with almost no acoustic distortion products despite the persistence of some mechanoelectrical transduction. In both mutants, these cells lack the horizontal top connectors, which are fibrous links joining adjacent stereocilia, and the TM-attachment crowns coupling the tallest stereocilia to the TM. These defects are consistent with the previously unrecognized presence of otogelin and otogelin-like in the OHC hair bundle. The defective hair bundle cohesiveness and the absence of stereociliary imprints in the TM observed in these mice have also been observed in mutant mice lacking stereocilin, a model of the DFNB16 genetic form of deafness, also characterized by congenital mild-to-moderate hearing impairment. We show that the localizations of stereocilin, otogelin, and otogelin-like in the hair bundle are interdependent, indicating that these proteins interact to form the horizontal top connectors and the TM-attachment crowns. We therefore suggest that these 2 OHC-specific structures have shared mechanical properties mediating reaction forces to sound-induced shearing motion and contributing to the coordinated displacement of stereocilia.


Asunto(s)
Células Ciliadas Auditivas Externas/metabolismo , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Estereocilios/metabolismo , Membrana Tectoria/metabolismo , Animales , Cóclea/citología , Sordera/congénito , Sordera/genética , Sordera/metabolismo , Predisposición Genética a la Enfermedad , Células Ciliadas Auditivas Externas/citología , Células Ciliadas Vestibulares/metabolismo , Pérdida Auditiva Sensorineural/congénito , Pérdida Auditiva Sensorineural/genética , Ratones , Ratones Noqueados , Membrana Tectoria/citología
5.
Proc Natl Acad Sci U S A ; 116(10): 4496-4501, 2019 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-30782832

RESUMEN

Autosomal recessive genetic forms (DFNB) account for most cases of profound congenital deafness. Adeno-associated virus (AAV)-based gene therapy is a promising therapeutic option, but is limited by a potentially short therapeutic window and the constrained packaging capacity of the vector. We focus here on the otoferlin gene underlying DFNB9, one of the most frequent genetic forms of congenital deafness. We adopted a dual AAV approach using two different recombinant vectors, one containing the 5' and the other the 3' portions of otoferlin cDNA, which exceed the packaging capacity of the AAV when combined. A single delivery of the vector pair into the mature cochlea of Otof-/- mutant mice reconstituted the otoferlin cDNA coding sequence through recombination of the 5' and 3' cDNAs, leading to the durable restoration of otoferlin expression in transduced cells and a reversal of the deafness phenotype, raising hopes for future gene therapy trials in DFNB9 patients.


Asunto(s)
Sordera/terapia , Dependovirus/genética , Terapia Genética , Proteínas de la Membrana/genética , Animales , Sordera/genética , Modelos Animales de Enfermedad , Vectores Genéticos , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos
7.
Int J Pediatr Otorhinolaryngol ; 112: 1-5, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30055715

RESUMEN

BACKGROUND: Consanguinity rate is high in Algeria, and the population is thus at high risk for genetic diseases transmitted on an autosomal recessive mode. Inherited congenital hearing impairment (HI) is a highly heterogeneous disorder, which affects approximately 1 in 800 Algerian newborns. Several hundreds of genes responsible for deafness have been reported among which more than one hundred are responsible for isolated deafness, of which 19 have already been reported to be involved in the Algerian population. This study focuses on patients from the Ghardaïa province, an ethnically and geographically isolated region of Southern Algeria that has the highest consanguinity rate in the country (56%). METHODS: Eleven families, with at least two related members experiencing moderate to profound congenital HI, were recruited and screened for mutations in known HI genes. RESULTS: A preliminary screening for common mutations in GJB2 and GJB6 identified the prevalent GJB2:c.35delG mutation in four families. Targeted exome sequencing further identified the causal mutations in the remaining seven families: CIB2:c.97C > T; p.(Arg33*), MYO7A:c.470+1G > A; p.(?), and SLC26A4:c.410C > T; p.(Ser137Leu) biallelic mutations in two families each, and a TECTA:c.2743 A > G; p.(Ile915Val) monoallelic mutation in the only family with autosomal dominant transmission of the HI. Of note, the missense mutations of SLC26A4 and TECTA had not been previously reported. CONCLUSION: These results further substantiate the genetic heterogeneity of HI, even in reportedly isolated populations. However, several families may harbor the same mutations as a result of a long history of marriages between relatives. This study has important implications for the HI molecular diagnosis strategy, and to develop genetic counseling for families originating from the Ghardaïa province of Algeria.


Asunto(s)
Heterogeneidad Genética , Pérdida Auditiva/genética , Argelia , Proteínas de Unión al Calcio/genética , Conexina 26 , Conexinas/genética , Consanguinidad , Proteínas de la Matriz Extracelular/genética , Femenino , Proteínas Ligadas a GPI/genética , Marcadores Genéticos , Humanos , Masculino , Proteínas de Transporte de Membrana/genética , Mutación , Miosina VIIa , Miosinas/genética , Transportadores de Sulfato
8.
Elife ; 62017 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-29111973

RESUMEN

Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca2+-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (OtofAla515,Ala517/Ala515,Ala517) with lower Ca2+-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca2+ currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced. Lower Ca2+ sensitivity and delay of the fast and sustained components of synaptic exocytosis were revealed by membrane capacitance measurement upon modulations of intracellular Ca2+ concentration, by varying Ca2+ influx through voltage-gated Ca2+-channels or Ca2+ uncaging. Otoferlin thus functions as a Ca2+ sensor, setting the rates of primed vesicle fusion with the presynaptic plasma membrane and synaptic vesicle pool replenishment in the IHC active zone.


Asunto(s)
Células Ciliadas Auditivas/fisiología , Fusión de Membrana , Proteínas de la Membrana/metabolismo , Receptores Sensibles al Calcio/metabolismo , Sinapsis/fisiología , Vesículas Sinápticas/metabolismo , Animales , Calcio/metabolismo , Técnicas de Sustitución del Gen , Proteínas de la Membrana/genética , Ratones , Unión Proteica , Receptores Sensibles al Calcio/genética
9.
Proc Natl Acad Sci U S A ; 114(36): 9695-9700, 2017 09 05.
Artículo en Inglés | MEDLINE | ID: mdl-28835534

RESUMEN

Our understanding of the mechanisms underlying inherited forms of inner ear deficits has considerably improved during the past 20 y, but we are still far from curative treatments. We investigated gene replacement as a strategy for restoring inner ear functions in a mouse model of Usher syndrome type 1G, characterized by congenital profound deafness and balance disorders. These mice lack the scaffold protein sans, which is involved both in the morphogenesis of the stereociliary bundle, the sensory antenna of inner ear hair cells, and in the mechanoelectrical transduction process. We show that a single delivery of the sans cDNA by the adenoassociated virus 8 to the inner ear of newborn mutant mice reestablishes the expression and targeting of the protein to the tips of stereocilia. The therapeutic gene restores the architecture and mechanosensitivity of stereociliary bundles, improves hearing thresholds, and durably rescues these mice from the balance defects. Our results open up new perspectives for efficient gene therapy of cochlear and vestibular disorders by showing that even severe dysmorphogenesis of stereociliary bundles can be corrected.


Asunto(s)
Síndromes de Usher/genética , Síndromes de Usher/terapia , Animales , Animales Recién Nacidos , ADN Complementario/administración & dosificación , ADN Complementario/genética , Dependovirus/genética , Modelos Animales de Enfermedad , Potenciales Evocados Auditivos del Tronco Encefálico , Terapia Genética/métodos , Vectores Genéticos , Células Ciliadas Auditivas/patología , Células Ciliadas Auditivas/fisiología , Humanos , Ratones , Ratones Noqueados , Microscopía Electrónica de Rastreo , Proteínas del Tejido Nervioso/deficiencia , Proteínas del Tejido Nervioso/genética , Síndromes de Usher/fisiopatología , Vestíbulo del Laberinto/patología , Vestíbulo del Laberinto/fisiopatología
10.
FEBS Lett ; 591(15): 2299-2310, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28653419

RESUMEN

Mutations in the gene encoding harmonin, a multi-PDZ domain-containing submembrane protein, cause Usher syndrome type 1 (congenital deafness and balance disorder, and early-onset sight loss). The structure of the protein and biological activities of its three different classes of splice isoforms (a, b, and c) remain poorly understood. Combining biochemical and biophysical analyses, we show that harmonin-a1 can switch between open and closed conformations through intramolecular binding of its C-terminal PDZ-binding motif to its N-terminal supramodule NTD-PDZ1 and through a flexible PDZ2-PDZ3 linker. This conformational switch presumably extends to most harmonin isoforms, and it is expected to have an impact on the interaction with some binding partners, as shown here for cadherin-related 23, another component of the hair cell mechanoelectrical transduction machinery.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/química , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Cadherinas/metabolismo , Proteínas de Ciclo Celular , Dicroismo Circular , Proteínas del Citoesqueleto , Células HEK293 , Humanos , Resonancia Magnética Nuclear Biomolecular , Conformación Proteica , Dominios Proteicos , Dispersión del Ángulo Pequeño , Transducción de Señal , Resonancia por Plasmón de Superficie , Difracción de Rayos X
11.
Hum Mol Genet ; 26(11): 2006-2017, 2017 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-28334861

RESUMEN

The olfacto-genital syndrome (Kallmann syndrome) associates congenital hypogonadism due to gonadotropin-releasing hormone (GnRH) deficiency and anosmia. This is a genetically heterogeneous developmental disease with various modes of transmission, including oligogenic inheritance. Previous reports have involved defective cell signaling by semaphorin-3A in the disease pathogenesis. Here, we report that the embryonic phenotype of Plxna1-/- mutant mice lacking plexin-A1 (a major receptor of class 3 semaphorins), though not fully penetrant, resembles that of Kallmann syndrome fetuses. Pathohistological analysis indeed showed a strongly abnormal development of the peripheral olfactory system and defective embryonic migration of the neuroendocrine GnRH cells to the hypothalamic brain region in some of the mutant mice, which resulted in reduced fertility in adult males. We thus screened 250 patients for the presence of mutations in PLXNA1, and identified different nonsynonymous mutations (p.V349L, p.V437L, p.R528W, p.H684Y, p.G720E, p.R740H, p.R813H, p.R840Q, p.A854T, p.R897H, p.L1464V, p.K1618T, p.C1744F), all at heterozygous state, in 15 patients. Most of these mutations are predicted to affect plexin-A1 stability or signaling activity based on predictive algorithms and a structural model of the protein. Moreover, in vitro experiments allowed us to show the existence of deleterious effects of eight mutations (including a transcript splicing defect), none of which are expected to result in a complete loss of protein synthesis, targeting, or signaling activity, though. Our findings indicate that signaling insufficiency through plexin-A1 can contribute to the pathogenesis of Kallmann syndrome, and further substantiate the oligogenic pattern of inheritance in this developmental disorder.


Asunto(s)
Síndrome de Kallmann/metabolismo , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Adulto , Animales , Movimiento Celular , Femenino , Hormona Liberadora de Gonadotropina/deficiencia , Heterocigoto , Humanos , Hipogonadismo/genética , Hipotálamo/metabolismo , Masculino , Ratones , Mutación , Proteínas del Tejido Nervioso/fisiología , Células Neuroendocrinas/metabolismo , Neuronas/metabolismo , Bulbo Olfatorio/fisiología , Receptores de Superficie Celular/fisiología , Reproducción , Semaforina-3A/genética , Semaforina-3A/metabolismo , Semaforinas/metabolismo , Transducción de Señal
12.
Proc Natl Acad Sci U S A ; 114(8): 2054-2059, 2017 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-28179572

RESUMEN

The remarkable hearing capacities of mammals arise from various evolutionary innovations. These include the cochlear outer hair cells and their singular feature, somatic electromotility, i.e., the ability of their cylindrical cell body to shorten and elongate upon cell depolarization and hyperpolarization, respectively. To shed light on the processes underlying the emergence of electromotility, we focused on the ßV giant spectrin, a major component of the outer hair cells' cortical cytoskeleton. We identified strong signatures of adaptive evolution at multiple sites along the spectrin-ßV amino acid sequence in the lineage leading to mammals, together with substantial differences in the subcellular location of this protein between the frog and the mouse inner ear hair cells. In frog hair cells, spectrin ßV was invariably detected near the apical junctional complex and above the cuticular plate, a dense F-actin meshwork located underneath the apical plasma membrane. In the mouse, the protein had a broad punctate cytoplasmic distribution in the vestibular hair cells, whereas it was detected in the entire lateral wall of cochlear outer hair cells and had an intermediary distribution (both cytoplasmic and cortical, but restricted to the cell apical region) in cochlear inner hair cells. Our results support a scenario where the singular organization of the outer hair cells' cortical cytoskeleton may have emerged from molecular networks initially involved in membrane trafficking, which were present near the apical junctional complex in the hair cells of mammalian ancestors and would have subsequently expanded to the entire lateral wall in outer hair cells.


Asunto(s)
Movimiento Celular/fisiología , Células Ciliadas Auditivas Internas/fisiología , Células Ciliadas Auditivas Externas/fisiología , Mamíferos/fisiología , Espectrina/genética , Actinas/metabolismo , Adaptación Biológica/genética , Animales , Aves/fisiología , Simulación por Computador , Fenómenos Electrofisiológicos , Células HeLa , Audición/fisiología , Humanos , Ratones , Mutación , Filogenia , Espectrina/metabolismo , Xenopus laevis/fisiología
13.
PLoS One ; 11(9): e0161893, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27583663

RESUMEN

Usher syndrome (USH) is an autosomal recessive disorder characterized by a dual sensory impairment affecting hearing and vision. USH is clinically and genetically heterogeneous. Ten different causal genes have been reported. We studied the molecular bases of the disease in 18 unrelated Algerian patients by targeted-exome sequencing, and identified the causal biallelic mutations in all of them: 16 patients carried the mutations at the homozygous state and 2 at the compound heterozygous state. Nine of the 17 different mutations detected in MYO7A (1 of 5 mutations), CDH23 (4 of 7 mutations), PCDH15 (1 mutation), USH1C (1 mutation), USH1G (1 mutation), and USH2A (1 of 2 mutations), had not been previously reported. The deleterious consequences of a missense mutation of CDH23 (p.Asp1501Asn) and the in-frame single codon deletion in USH1G (p.Ala397del) on the corresponding proteins were predicted from the solved 3D-structures of extracellular cadherin (EC) domains of cadherin-23 and the sterile alpha motif (SAM) domain of USH1G/sans, respectively. In addition, we were able to show that the USH1G mutation is likely to affect the binding interface between the SAM domain and USH1C/harmonin. This should spur the use of 3D-structures, not only of isolated protein domains, but also of protein-protein interaction interfaces, to predict the functional impact of mutations detected in the USH genes.


Asunto(s)
Predisposición Genética a la Enfermedad , Variación Genética , Síndromes de Usher/genética , Argelia , Humanos , Mutación Missense
14.
Eur J Hum Genet ; 24(12): 1730-1738, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27460420

RESUMEN

Usher syndrome (USH), the most prevalent cause of hereditary deafness-blindness, is an autosomal recessive and genetically heterogeneous disorder. Three clinical subtypes (USH1-3) are distinguishable based on the severity of the sensorineural hearing impairment, the presence or absence of vestibular dysfunction, and the age of onset of the retinitis pigmentosa. A total of 10 causal genes, 6 for USH1, 3 for USH2, and 1 for USH3, and an USH2 modifier gene, have been identified. A robust molecular diagnosis is required not only to improve genetic counseling, but also to advance gene therapy in USH patients. Here, we present an improved diagnostic strategy that is both cost- and time-effective. It relies on the sequential use of three different techniques to analyze selected genomic regions: targeted exome sequencing, comparative genome hybridization, and quantitative exon amplification. We screened a large cohort of 427 patients (139 USH1, 282 USH2, and six of undefined clinical subtype) from various European medical centers for mutations in all USH genes and the modifier gene. We identified a total of 421 different sequence variants predicted to be pathogenic, about half of which had not been previously reported. Remarkably, we detected large genomic rearrangements, most of which were novel and unique, in 9% of the patients. Thus, our strategy led to the identification of biallelic and monoallelic mutations in 92.7% and 5.8% of the USH patients, respectively. With an overall 98.5% mutation characterization rate, the diagnosis efficiency was substantially improved compared with previously reported methods.


Asunto(s)
Pruebas Genéticas/métodos , Mutación , Síndromes de Usher/genética , Alelos , Hibridación Genómica Comparativa/métodos , Europa (Continente) , Exoma , Proteínas de la Matriz Extracelular/genética , Genes Modificadores , Humanos , Sensibilidad y Especificidad , Análisis de Secuencia de ADN/métodos , Síndromes de Usher/diagnóstico
15.
Int J Pediatr Otorhinolaryngol ; 87: 28-33, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27368438

RESUMEN

Congenital deafness is certainly one of the most common monogenic diseases in humans, but it is also one of the most genetically heterogeneous, which makes molecular diagnosis challenging in most cases. Whole-exome sequencing in two out of three Algerian siblings affected by recessively-inherited, moderate to severe sensorineural deafness allowed us to identify a novel splice donor site mutation (c.5272+1G > A) in the gene encoding α-tectorin, a major component of the cochlear tectorial membrane. The mutation was present at the homozygous state in the three affected siblings, and at the heterozygous state in their unaffected, consanguineous parents. To our knowledge, this is the first reported TECTA mutation leading to the DFNB21 form of hearing impairment among Maghrebian individuals suffering from congenital hearing impairment, which further illustrates the diversity of the genes involved in congenital deafness in the Maghreb.


Asunto(s)
Proteínas de la Matriz Extracelular/genética , Pérdida Auditiva Sensorineural/genética , Argelia , Alelos , Niño , Consanguinidad , Femenino , Proteínas Ligadas a GPI/genética , Heterocigoto , Homocigoto , Humanos , Masculino , Mutación , Linaje , Sitios de Empalme de ARN
16.
Am J Hum Genet ; 98(6): 1266-1270, 2016 06 02.
Artículo en Inglés | MEDLINE | ID: mdl-27259055

RESUMEN

By genetic linkage analysis in a large consanguineous Iranian family with eleven individuals affected by severe to profound congenital deafness, we were able to define a 2.8 Mb critical interval (at chromosome 1p21.2-1p21.1) for an autosomal-recessive nonsyndromic deafness locus (DFNB). Whole-exome sequencing allowed us to identify a CDC14A biallelic nonsense mutation, c.1126C>T (p.Arg376(∗)), which was present in the eight clinically affected individuals still alive. Subsequent screening of 115 unrelated individuals affected by severe or profound congenital deafness of unknown genetic cause led us to identify another CDC14A biallelic nonsense mutation, c.1015C>T (p.Arg339(∗)), in an individual originating from Mauritania. CDC14A encodes a protein tyrosine phosphatase. Immunofluorescence analysis of the protein distribution in the mouse inner ear showed a strong labeling of the hair cells' kinocilia. By using a morpholino strategy to knockdown cdc14a in zebrafish larvae, we found that the length of the kinocilia was reduced in inner-ear hair cells. Therefore, deafness caused by loss-of-function mutations in CDC14A probably arises from a morphogenetic defect of the auditory sensory cells' hair bundles, whose differentiation critically depends on the proper growth of their kinocilium.


Asunto(s)
Cilios/patología , Células Ciliadas Auditivas/patología , Pérdida Auditiva Sensorineural/etiología , Mutación/genética , Monoéster Fosfórico Hidrolasas/genética , Índice de Severidad de la Enfermedad , Adulto , Anciano , Animales , Cilios/metabolismo , Femenino , Técnica del Anticuerpo Fluorescente , Células Ciliadas Auditivas/enzimología , Pérdida Auditiva Sensorineural/patología , Humanos , Larva/genética , Larva/crecimiento & desarrollo , Masculino , Ratones , Persona de Mediana Edad , Linaje , Proteínas Tirosina Fosfatasas , Adulto Joven , Pez Cebra/genética , Pez Cebra/crecimiento & desarrollo
17.
Cell ; 163(4): 894-906, 2015 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-26544938

RESUMEN

A deficiency in pejvakin, a protein of unknown function, causes a strikingly heterogeneous form of human deafness. Pejvakin-deficient (Pjvk(-/-)) mice also exhibit variable auditory phenotypes. Correlation between their hearing thresholds and the number of pups per cage suggest a possible harmful effect of pup vocalizations. Direct sound or electrical stimulation show that the cochlear sensory hair cells and auditory pathway neurons of Pjvk(-/-) mice and patients are exceptionally vulnerable to sound. Subcellular analysis revealed that pejvakin is associated with peroxisomes and required for their oxidative-stress-induced proliferation. Pjvk(-/-) cochleas display features of marked oxidative stress and impaired antioxidant defenses, and peroxisomes in Pjvk(-/-) hair cells show structural abnormalities after the onset of hearing. Noise exposure rapidly upregulates Pjvk cochlear transcription in wild-type mice and triggers peroxisome proliferation in hair cells and primary auditory neurons. Our results reveal that the antioxidant activity of peroxisomes protects the auditory system against noise-induced damage.


Asunto(s)
Pérdida Auditiva Provocada por Ruido/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Peroxisomas/metabolismo , Proteínas/metabolismo , Animales , Vías Auditivas , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/patología , Pérdida Auditiva Provocada por Ruido/patología , Humanos , Ratones , Ratones Noqueados , Proteínas del Tejido Nervioso/genética , Neuronas/metabolismo , Estrés Oxidativo , Proteínas/genética
18.
Orphanet J Rare Dis ; 10: 96, 2015 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-26282398

RESUMEN

BACKGROUND: More than 70 % of the cases of congenital deafness are of genetic origin, of which approximately 80 % are non-syndromic and show autosomal recessive transmission (DFNB forms). To date, 60 DFNB genes have been identified, most of which cause congenital, severe to profound deafness, whereas a few cause delayed progressive deafness in childhood. We report the study of two Algerian siblings born to consanguineous parents, and affected by progressive hearing loss. METHOD: After exclusion of GJB2 (the gene most frequently involved in non-syndromic deafness in Mediterranean countries), we performed whole-exome sequencing in one sibling. RESULTS: A frame-shift variant (c.1014delC; p.Ser339Alafs*15) was identified in EPS8L2, encoding Epidermal growth factor receptor Pathway Substrate 8 L2, a protein of hair cells' stereocilia previously implicated in progressive deafness in the mouse. This variant predicts a truncated, inactive protein, or no protein at all owing to nonsense-mediated mRNA decay. It was detected at the homozygous state in the two clinically affected siblings, and at the heterozygous state in the unaffected parents and one unaffected sibling, whereas it was never found in a control population of 150 Algerians with normal hearing or in the Exome Variant Server database. CONCLUSION: Whole-exome sequencing allowed us to identify a new gene responsible for childhood progressive hearing loss transmitted on the autosomal recessive mode.


Asunto(s)
Genes Recesivos , Pérdida Auditiva/genética , Proteínas de la Membrana/genética , Niño , Conexina 26 , Conexinas , Consanguinidad , Progresión de la Enfermedad , Femenino , Mutación del Sistema de Lectura , Humanos , Masculino , Proteínas de Microfilamentos , Linaje
19.
Nat Rev Endocrinol ; 11(9): 547-64, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26194704

RESUMEN

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder caused by the deficient production, secretion or action of gonadotropin-releasing hormone (GnRH), which is the master hormone regulating the reproductive axis. CHH is clinically and genetically heterogeneous, with >25 different causal genes identified to date. Clinically, the disorder is characterized by an absence of puberty and infertility. The association of CHH with a defective sense of smell (anosmia or hyposmia), which is found in ∼50% of patients with CHH is termed Kallmann syndrome and results from incomplete embryonic migration of GnRH-synthesizing neurons. CHH can be challenging to diagnose, particularly when attempting to differentiate it from constitutional delay of puberty. A timely diagnosis and treatment to induce puberty can be beneficial for sexual, bone and metabolic health, and might help minimize some of the psychological effects of CHH. In most cases, fertility can be induced using specialized treatment regimens and several predictors of outcome have been identified. Patients typically require lifelong treatment, yet ∼10-20% of patients exhibit a spontaneous recovery of reproductive function. This Consensus Statement summarizes approaches for the diagnosis and treatment of CHH and discusses important unanswered questions in the field.


Asunto(s)
Hipogonadismo/patología , Hipogonadismo/terapia , Consenso , Europa (Continente) , Femenino , Hormona Liberadora de Gonadotropina/genética , Hormona Liberadora de Gonadotropina/metabolismo , Humanos , Hipogonadismo/diagnóstico , Hipogonadismo/genética , Masculino , Maduración Sexual
20.
Mol Genet Genomic Med ; 3(3): 189-96, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-26029705

RESUMEN

The genetic heterogeneity of congenital hearing disorders makes molecular diagnosis expensive and time-consuming using conventional techniques such as Sanger sequencing of DNA. In order to design an appropriate strategy of molecular diagnosis in the Algerian population, we explored the diversity of the involved mutations by studying 65 families affected by autosomal recessive forms of nonsyndromic hearing impairment (DFNB forms), which are the most prevalent early onset forms. We first carried out a systematic screening for mutations in GJB2 and the recurrent p.(Arg34*) mutation in TMC1, which were found in 31 (47.7%) families and 1 (1.5%) family, respectively. We then performed whole exome sequencing in nine of the remaining families, and identified the causative mutations in all the patients analyzed, either in the homozygous state (eight families) or in the compound heterozygous state (one family): (c.709C>T: p.(Arg237*)) and (c.2122C>T: p.(Arg708*)) in OTOF, (c.1334T>G: p.(Leu445Trp)) in SLC26A4, (c.764T>A: p.(Met255Lys)) in GIPC3, (c.518T>A: p.(Cys173Ser)) in LHFPL5, (c.5336T>C: p.(Leu1779Pro)) in MYO15A, (c.1807G>T: p.(Val603Phe)) in OTOA, (c.6080dup: p.(Asn2027Lys*9)) in PTPRQ, and (c.6017del: p.(Gly2006Alafs*13); c.7188_7189ins14: p.(Val2397Leufs*2)) in GPR98. Notably, 7 of these 10 mutations affecting 8 different genes had not been reported previously. These results highlight for the first time the genetic heterogeneity of the early onset forms of nonsyndromic deafness in Algerian families.

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