RESUMEN
TMPRSS3-related hearing loss presents challenges in correlating genotypic variants with clinical phenotypes due to the small sample sizes of previous studies. We conducted a cross-sectional genomics study coupled with retrospective clinical phenotype analysis on 127 individuals. These individuals were from 16 academic medical centers across 6 countries. Key findings revealed 47 unique TMPRSS3 variants with significant differences in hearing thresholds between those with missense variants versus those with loss-of-function genotypes. The hearing loss progression rate for the DFNB8 subtype was 0.3 dB/year. Post-cochlear implantation, an average word recognition score of 76% was observed. Of the 51 individuals with two missense variants, 10 had DFNB10 with profound hearing loss. These 10 all had at least one of 4 TMPRSS3 variants predicted by computational modeling to be damaging to TMPRSS3 structure and function. To our knowledge, this is the largest study of TMPRSS3 genotype-phenotype correlations. We find significant differences in hearing thresholds, hearing loss progression, and age of presentation, by TMPRSS3 genotype and protein domain affected. Most individuals with TMPRSS3 variants perform well on speech recognition tests after cochlear implant, however increased age at implant is associated with worse outcomes. These findings provide insight for genetic counseling and the on-going design of novel therapeutic approaches.
Asunto(s)
Estudios de Asociación Genética , Pérdida Auditiva , Proteínas de la Membrana , Serina Endopeptidasas , Humanos , Femenino , Masculino , Serina Endopeptidasas/genética , Adulto , Proteínas de la Membrana/genética , Pérdida Auditiva/genética , Niño , Persona de Mediana Edad , Adolescente , Preescolar , Genotipo , Estudios de Cohortes , Fenotipo , Mutación Missense , Estudios Transversales , Adulto Joven , Estudios Retrospectivos , Anciano , Proteínas de NeoplasiasRESUMEN
The inner ear is derived from the otic placode, one of the numerous cranial sensory placodes that emerges from the pre-placodal ectoderm (PPE) along its anterior-posterior axis. However, the molecular dynamics underlying how the PPE is regionalized are poorly resolved. We used stem cell-derived organoids to investigate the effects of Wnt signaling on early PPE differentiation and found that modulating Wnt signaling significantly increased inner ear organoid induction efficiency and reproducibility. Alongside single-cell RNA sequencing, our data reveal that the canonical Wnt signaling pathway leads to PPE regionalization and, more specifically, medium Wnt levels during the early stage induce (1) expansion of the caudal neural plate border (NPB), which serves as a precursor for the posterior PPE, and (2) a caudal microenvironment that is required for otic specification. Our data further demonstrate Wnt-mediated induction of rostral and caudal cells in organoids and more broadly suggest that Wnt signaling is critical for anterior-posterior patterning in the PPE.
Asunto(s)
Oído Interno , Vía de Señalización Wnt , Animales , Ratones , Reproducibilidad de los Resultados , Oído Interno/metabolismo , Diferenciación Celular , Ectodermo/metabolismo , Organoides , Células Madre , Regulación del Desarrollo de la Expresión GénicaRESUMEN
BACKGROUND: We analyzed the genetic causes of sensorineural hearing loss in racial and ethnic minorities of South Florida by reviewing demographic, phenotypic, and genetic data on 136 patients presenting to the Hereditary Hearing Loss Clinic at the University of Miami. In our retrospective chart review, of these patients, half self-identified as Hispanic, and the self-identified racial distribution was 115 (86%) White, 15 (11%) Black, and 6 (4%) Asian. Our analysis helps to reduce the gap in understanding the prevalence, impact, and genetic factors related to hearing loss among diverse populations. RESULTS: The causative gene variant or variants were identified in 54 (40%) patients, with no significant difference in the molecular diagnostic rate between Hispanics and Non-Hispanics. However, the total solve rate based on race was 40%, 47%, and 17% in Whites, Blacks, and Asians, respectively. In Non-Hispanic Whites, 16 different variants were identified in 13 genes, with GJB2 (32%), MYO7A (11%), and SLC26A4 (11%) being the most frequently implicated genes. In White Hispanics, 34 variants were identified in 20 genes, with GJB2 (22%), MYO7A (7%), and STRC-CATSPER2 (7%) being the most common. In the Non-Hispanic Black cohort, the gene distribution was evenly dispersed, with 11 variants occurring in 7 genes, and no variant was identified in 3 Hispanic Black probands. For the Asian cohort, only one gene variant was found out of 6 patients. CONCLUSION: This study demonstrates that the diagnostic rate of genetic studies in hearing loss varies according to race in South Florida, with more heterogeneity in racial and ethnic minorities. Further studies to delineate deafness gene variants in underrepresented populations, such as African Americans/Blacks from Hispanic groups, are much needed to reduce racial and ethnic disparities in genetic diagnoses.
Asunto(s)
Pérdida Auditiva Sensorineural , Humanos , Asiático/genética , Negro o Afroamericano/genética , ADN/genética , Florida/epidemiología , Pérdida Auditiva Sensorineural/epidemiología , Pérdida Auditiva Sensorineural/genética , Hispánicos o Latinos/genética , Péptidos y Proteínas de Señalización Intercelular , Estudios Retrospectivos , Blanco/genéticaRESUMEN
INTRODUCTION: Hearing loss is a common sensory disorder that impacts patients across the lifespan. Many genetic variants have been identified that contribute to non-syndromic hearing loss. Yet, genetic testing is not routinely administered when hearing loss is diagnosed, particularly in adults. In this study, genetic testing was completed in patients with known hearing loss. METHODS: 104 patients who were evaluated for hearing loss were enrolled and received genetic testing. RESULTS: Of those 104 patients, 39 had available genetic testing, 20 had one missing allele, and 45 yielded no genetic diagnosis. Of the 39 cases with genetic testing data, 24 were simplex cases and 15 were multiplex cases. A majority of patients presented with an autosomal recessive inheritance pattern (n=32), 26 of whom presented with congenital hearing loss. 38% of cases were positive for GJB2 mutation with c.35delG being the most common pathogenic variant. These findings are consistent with previous literature suggesting GJB2 mutations are the most common causes of non-syndromic hearing loss. CONCLUSION: Given the frequency of genetic variants in patients with hearing loss, genetic testing should be considered as a routine part of the hearing loss work-up, particularly as gene therapies are studied and become more widely available.
RESUMEN
OBJECTIVE: To determine whether subjects who have recovered from COVID-19 smell and taste disturbance perform similarly to their COVID-naïve baseline, on gold-standard smell and taste tests. STUDY DESIGN: Prospective cross-sectional study. SETTING: University of Miami Department of Otolaryngology in Miami, FL between September 2021, and August 2022. METHODS: Those previously COVID-19 positive composed the experimental group, those who reported being COVID-naïve composed the control group. Mean total score for the UPSIT Smell Test, and the Burghart Taste Strip test were the primary outcome measures. RESULTS: 70 adult subjects (35 former COVID-positive, 35 COVID-naïve) were enrolled, with 21 females and 14 males in each group. 87 % of all subjects were white and were almost distributed evenly between Hispanic and non-Hispanic. Mean UPSIT total score for the experimental group was 30.6 (95 % CI 28.9-32.3), mean UPSIT total score for the control group was 31.2 (95 % CI 29.7-32.8). Mean Burghart total score for the experimental group was 11.3 (95 % CI 10.6-12.0), mean Burghart total score for the control group was 10.7 (95 % CI 9.7-11.8). These showed a significant overlap of the 95 % CI of the mean total score between the control group and the experimental group, suggesting no significant difference between the two groups. CONCLUSION: These results suggest that COVID-19 patients who experience smell and taste disturbance and recover, regain sensory ability similar to their pre-COVID ability. Further study is needed to validate these findings, but the results are promising in the long-term recovery of COVID-19.
Asunto(s)
COVID-19 , Trastornos del Olfato , Adulto , Masculino , Femenino , Humanos , Estudios Transversales , Trastornos del Olfato/etiología , Estudios Prospectivos , Recuperación de la Función , Olfato , DisgeusiaRESUMEN
P2RX2 encodes the P2X2 receptor, which is an adenosine triphosphate (ATP) gated (purinoreceptor) ion channel. P2RX2 c. 178G > T (p.V60L) mutation was previously identified in two unrelated Chinese families, as the cause of human DFNA41, a form of dominant, early-onset and progressive sensorineural hearing loss. We generated and characterized a knock-in mouse model based on human p.V60L mutation that recapitulates the human phenotype. Heterozygous KI mice started to exhibit hearing loss at 21-day-old and progressed to deafness by 6-month-old. Vestibular dysfunction was also observed in mutant mice. Abnormal morphology of the inner hair cells and ribbon synapses was progressively observed in KI animals suggesting that P2rx2 plays a role in the membrane spatial location of the ribbon synapses. These results suggest that P2rx2 is essential for acoustic information transfer, which can be the molecular mechanism related to hearing loss.
Asunto(s)
Pérdida Auditiva Sensorineural/genética , Receptores Purinérgicos P2X2/genética , Adenosina Trifosfato/metabolismo , Animales , Modelos Animales de Enfermedad , Técnicas de Sustitución del Gen , Células Ciliadas Auditivas Internas/patología , Pérdida Auditiva Sensorineural/patología , Heterocigoto , Humanos , Ratones , Mutación/genética , Linaje , Fenotipo , Sinapsis/genética , Sinapsis/patología , Enfermedades Vestibulares/genética , Enfermedades Vestibulares/patologíaRESUMEN
Concurrent hearing and genetic screening of newborns is expected to play important roles not only in early detection and diagnosis of congenital deafness, which triggers intervention, but also in predicting late-onset and progressive hearing loss and identifying individuals who are at risk of drug-induced HL. Concurrent hearing and genetic screening in the whole newborn population in Beijing was launched in January 2012. This study included 180,469 infants born in Beijing between April 2013 and March 2014, with last follow-up on February 24, 2018. Hearing screening was performed using transiently evoked otoacoustic emission (TEOAE) and automated auditory brainstem response (AABR). For genetic testing, dried blood spots were collected and nine variants in four genes, GJB2, SLC26A4, mtDNA 12S rRNA, and GJB3, were screened using a DNA microarray platform. Of the 180,469 infants, 1,915 (1.061%) were referred bilaterally or unilaterally for hearing screening; 8,136 (4.508%) were positive for genetic screening (heterozygote, homozygote, or compound heterozygote and mtDNA homoplasmy or heteroplasmy), among whom 7,896 (4.375%) passed hearing screening. Forty (0.022%) infants carried two variants in GJB2 or SLC26A4 (homozygote or compound heterozygote) and 10 of those infants passed newborn hearing screening. In total, 409 (0.227%) infants carried the mtDNA 12S rRNA variant (m.1555A>G or m.1494C>T), and 405 of them passed newborn hearing screening. In this cohort study, 25% of infants with pathogenic combinations of GJB2 or SLC26A4 variants and 99% of infants with an m.1555A>G or m.1494C>T variant passed routine newborn hearing screening, indicating that concurrent screening provides a more comprehensive approach for management of congenital deafness and prevention of ototoxicity.
Asunto(s)
Pruebas Genéticas/métodos , Pérdida Auditiva/diagnóstico , Beijing , Pruebas con Sangre Seca , Femenino , Predisposición Genética a la Enfermedad , Humanos , Recién Nacido , MasculinoRESUMEN
Background: Waardenburg syndrome (WS) is one of the most common forms of syndromic deafness with heterogeneity of loci and alleles and variable expressivity of clinical features. Methods: The technology of single-nucleotide variants (SNV) and copy number variation (CNV) detection was developed to investigate the genotype spectrum of WS in a Chinese population. Results: Ninety WS patients and 24 additional family members were recruited for the study. Fourteen mutations had not been previously reported, including c.808C>G, c.117C>A, c.152T>G, c.803G>T, c.793-3T >G, and c.801delT on PAX3; c.642_650delAAG on MITF; c.122G>T and c.127C>T on SOX10; c.230C>G and c.365C>T on SNAI2; and c.481A>G, c.1018C>G, and c.1015C>T on EDNRB. Three CNVs were de novo and first reported in our study. Five EDNRB variants were associated with WS type 1 in the heterozygous state for the first time, with a detection rate of 22.2%. Freckles occur only in WS type 2. Yellow hair, amblyopia, congenital ptosis, narrow palpebral fissures, and pigmentation spots are rare and unique symptoms in WS patients from China. Conclusions: EDNRB should be considered as another prevalent pathogenic gene in WS type 1. Our study expanded the genotype and phenotype spectrum of WS, and diagnostic next-generation sequencing is promising for WS.
Asunto(s)
Genotipo , Fenotipo , Polimorfismo de Nucleótido Simple , Síndrome de Waardenburg/diagnóstico , Alelos , China , Variaciones en el Número de Copia de ADN , Exones , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Mutación , Linaje , Síndrome de Waardenburg/genéticaRESUMEN
Autosomal dominant nonsyndromic hearing loss (ADNSHL) is a highly genetically heterogeneous disorder. Up to date only approximately 37 ADNSHL-causing genes have been identified. The goal of this study was to determine the causative gene in a five-generation Chinese family with ADNSHL. A Chinese family was ascertained. Simultaneously, two affected individuals and one normal hearing control from the family were analyzed by whole exome capture sequencing. To assess the functional effect of the identified variant, in-vitro studies were performed. novel missense variant, c.512A>G (p.His171Arg) in exon 8 of the ELMO domain-containing 3 (ELMOD3) gene, was identified as a causative variant in this family affected by late-onset and progressive ADNSHL. The variant was validated by Sanger sequencing and found to co-segregate with the phenotype within the pedigree and was absent in 500 ethnically matched unrelated normal hearing control subjects. To our knowledge, this is the first report of a family with ADNSHL caused by ELMOD3 mutation. Western blots and immunofluorescence staining demonstrated that p.His171Arg resulted in abnormal expression levels of ELMOD3 and abnormal subcellular localization. Furthermore, the analysis of the stability of the wild-type (WT) and mutant ELMOD3 protein shows that the decay of p.His171Arg is faster than that of the WT, suggesting a shorter halflife of the c.512A > G variant. A novel variant in the ELMOD3 gene, encoding a member of the engulfment and cell motility (ELMO) family of GTPase-activating proteins, was identified for the first time as responsible for ADNSHL.
Asunto(s)
Proteínas Activadoras de GTPasa/genética , Pérdida Auditiva Sensorineural/genética , Adulto , Secuencia de Aminoácidos/genética , Movimiento Celular/genética , China/epidemiología , Exoma/genética , Femenino , Pérdida Auditiva Sensorineural/fisiopatología , Humanos , Masculino , Mutación , Linaje , FenotipoRESUMEN
Avian bone metabolism diseases affect the development and production of chickens, and many of these diseases can be prevented and controlled by balanced nutrition and hormone medicine. The steroid hormone 1α,25-dihydroxyvitamin D3 plays a key role in maintaining the balance of avian bone metabolism. Clinically, 1α,25-(OH)2D3 has been used to treat several bone diseases. Although several previous studies have investigated the effects of 1α,25-(OH)2D3 on osteoclastogenesis, the mechanisms underpinning osteoclast (OC) activity remain largely unknown. Herein, we used molecular and cell biology approaches to demonstrate that 1α,25-(OH)2D3 increases avian OC formation and activity, and upregulates bone resorption-related genes. Moreover, 1α,25-(OH)2D3 regulates the OC cytoskeleton by increasing the formation of zipper-like structure in OC precursor cells to potentiate OC activity via the Src/Rac1 signaling pathway. These findings provide new insight into the role of 1α,25-(OH)2D3 in OC activity.
Asunto(s)
Osteoclastos/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Vitamina D/análogos & derivados , Vitaminas/farmacología , Proteína de Unión al GTP rac1/metabolismo , Familia-src Quinasas/metabolismo , Animales , Células Cultivadas , Pollos , Citoesqueleto/efectos de los fármacos , Citoesqueleto/metabolismo , Citoesqueleto/ultraestructura , Osteoclastos/citología , Osteoclastos/metabolismo , Vitamina D/metabolismo , Vitamina D/farmacología , Vitaminas/metabolismoRESUMEN
Ear is a complex system where appropriate ionic composition is essential for maintaining the tissue homeostasis and hearing function. Ion transporters and channels present in the auditory system plays a crucial role in maintaining proper ionic composition in the ear. The extracellular fluid, called endolymph, found in the cochlea of the mammalian inner ear is particularly unique due to its electrochemical properties. At an endocochlear potential of about +80 mV, signaling initiated by acoustic stimuli at the level of the hair cells is dependent on the unusually high potassium (K+ ) concentration of endolymph. There are ion channels and transporters that exists in the ear to ensure that K+ is continually being cycled into the stria media endolymph. This review is focused on the discussion of the molecular and genetic basis of previously and newly recognized ion channels and transporters that support sensory hair cell excitation based on recent knock-in and knock-out studies of these channels. This article also addresses the molecular and genetic defects and the pathophysiology behind Meniere's disease as well as how the dysregulation of these ion transporters can result in severe defects in hearing or even deafness. Understanding the role of ion channels and transporters in the auditory system will facilitate in designing effective treatment modalities against ear disorders including Meniere's disease and hearing loss. J. Cell. Physiol. 232: 743-758, 2017. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Vías Auditivas/metabolismo , Canales Iónicos/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Animales , Humanos , Modelos Biológicos , Modelos Moleculares , Mutación/genéticaRESUMEN
Ear is a sensitive organ involved in hearing and balance function. The complex signaling network in the auditory system plays a crucial role in maintaining normal physiological function of the ear. The inner ear comprises a variety of host signaling pathways working in synergy to deliver clear sensory messages. Any disruption, as minor as it can be, has the potential to affect this finely tuned system with temporary or permanent sequelae including vestibular deficits and hearing loss. Mutations linked to auditory symptoms, whether inherited or acquired, are being actively researched for ways to reverse, silence, or suppress them. In this article, we discuss recent advancements in understanding the pathways involved in auditory system signaling, from hair cell development through transmission to cortical centers. Our review discusses Notch and Wnt signaling, cell to cell communication through connexin and pannexin channels, and the detrimental effects of reactive oxygen species on the auditory system. There has been an increased interest in the auditory community to explore the signaling system in the ear for hair cell regeneration. Understanding signaling pathways in the auditory system will pave the way for the novel avenues to regenerate sensory hair cells and restore hearing function. J. Cell. Physiol. 232: 2710-2721, 2017. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Diferenciación Celular , Proliferación Celular , Células Ciliadas Auditivas/metabolismo , Audición , Receptores Notch/metabolismo , Regeneración , Proteínas Wnt/metabolismo , Vía de Señalización Wnt , Animales , Vías Auditivas/metabolismo , Vías Auditivas/patología , Conexinas/metabolismo , Células Ciliadas Auditivas/patología , Humanos , Células Laberínticas de Soporte/metabolismo , Células Laberínticas de Soporte/patología , NADPH Oxidasas/metabolismo , FenotipoRESUMEN
Neurotransmitters, including catecholamines and serotonin, play a crucial role in maintaining homeostasis in the human body. Studies on these neurotransmitters mainly revolved around their role in the "fight or flight" response, transmitting signals across a chemical synapse and modulating blood flow throughout the body. However, recent research has demonstrated that neurotransmitters can play a significant role in the gastrointestinal (GI) physiology. Norepinephrine (NE), epinephrine (E), dopamine (DA), and serotonin have recently been a topic of interest because of their roles in the gut physiology and their potential roles in GI and central nervous system pathophysiology. These neurotransmitters are able to regulate and control not only blood flow, but also affect gut motility, nutrient absorption, GI innate immune system, and the microbiome. Furthermore, in pathological states, such as inflammatory bowel disease (IBD) and Parkinson's disease, the levels of these neurotransmitters are dysregulated, therefore causing a variety of GI symptoms. Research in this field has shown that exogenous manipulation of catecholamine serum concentrations can help in decreasing symptomology and/or disease progression. In this review article, we discuss the current state-of-the-art research and literature regarding the role of neurotransmitters in regulation of normal GI physiology, their impact on several disease processes, and novel work focused on the use of exogenous hormones and/or psychotropic medications to improve disease symptomology. J. Cell. Physiol. 232: 2359-2372, 2017. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Bacterias/metabolismo , Encéfalo/metabolismo , Catecolaminas/metabolismo , Sistema Nervioso Entérico/metabolismo , Microbioma Gastrointestinal , Tracto Gastrointestinal/inervación , Tracto Gastrointestinal/microbiología , Serotonina/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Encéfalo/fisiopatología , Enfermedades del Sistema Nervioso Central/metabolismo , Enfermedades del Sistema Nervioso Central/microbiología , Enfermedades del Sistema Nervioso Central/fisiopatología , Enfermedades Gastrointestinales/metabolismo , Enfermedades Gastrointestinales/microbiología , Enfermedades Gastrointestinales/fisiopatología , Interacciones Huésped-Patógeno , Humanos , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Hearing loss is the most common sensory deficit in humans. We show that a point mutation in DCDC2 (DCDC2a), a member of doublecortin domain-containing protein superfamily, causes non-syndromic recessive deafness DFNB66 in a Tunisian family. Using immunofluorescence on rat inner ear neuroepithelia, DCDC2a was found to localize to the kinocilia of sensory hair cells and the primary cilia of nonsensory supporting cells. DCDC2a fluorescence is distributed along the length of the kinocilium with increased density toward the tip. DCDC2a-GFP overexpression in non-polarized COS7 cells induces the formation of long microtubule-based cytosolic cables suggesting a role in microtubule formation and stabilization. Deafness mutant DCDC2a expression in hair cells and supporting cells causes cilium structural defects, such as cilium branching, and up to a 3-fold increase in length ratios. In zebrafish, the ortholog dcdc2b was found to be essential for hair cell development, survival and function. Our results reveal DCDC2a to be a deafness gene and a player in hair cell kinocilia and supporting cell primary cilia length regulation likely via its role in microtubule formation and stabilization.
Asunto(s)
Cilios/metabolismo , Genes Recesivos , Células Ciliadas Auditivas/metabolismo , Pérdida Auditiva Sensorineural/genética , Proteínas Asociadas a Microtúbulos/genética , Mutación Missense , Secuencia de Aminoácidos , Animales , Línea Celular , Mapeo Cromosómico , Análisis Mutacional de ADN , Modelos Animales de Enfermedad , Proteína Doblecortina , Femenino , Expresión Génica , Genes Reporteros , Homocigoto , Humanos , Masculino , Datos de Secuencia Molecular , Linaje , Alineación de Secuencia , Pez CebraRESUMEN
Hearing impairment, or deafness (in its most severe form), is one of the most common human sensory disorders. There have been several reports of autosomal dominant mutations in the POU4F3 gene, which is associated with non-syndromic hearing loss. In this study, we identified a novel heterozygous mutation (c.602delT, p.L201fs) in the gene POU4F3 by taking advantage of whole-exome sequencing, which was validated by Sanger sequencing and completely co-segregated within a large hearing impaired Chinese family. We have focused on this pedigree since 2002, and we have mapped a deafness locus named DFNA42 (which has been renamed DFNA52, OMIM entry 607683) via a genome-wide scan. Furthermore, we analyzed this mutational variant and found that it was located at the beginning of the first functional domain of POU4F3, which could theoretically impair the function of POU4F3. We have identified a novel frameshift mutation in the POU4F3 gene. Further functional studies of variants of this specific gene are needed to illustrate the pathogenic mechanism(s) that underlie hearing impairment.
Asunto(s)
Mutación del Sistema de Lectura/genética , Pérdida Auditiva Sensorineural/genética , Proteínas de Homeodominio/genética , Factor de Transcripción Brn-3C/genética , Pueblo Asiatico/genética , Secuencia de Bases , Exoma/genética , Pérdida Auditiva Sensorineural/patología , Humanos , Linaje , Análisis de Secuencia de ADNRESUMEN
Hearing loss (HL) is a common sensory impairment in humans, with significant economic and social impacts. With nearly 20% of the world's population, China has focused on economic development and health awareness to improve the care for its hearing-impaired population. Recently, the Chinese government has initiated national programs such as the China Disabled Persons Federation to fund prevention, treatment, and rehabilitation of hearing impairment. Newborn hearing screening and auditory rehabilitation programs in China have expanded exponentially with government support. While facing many challenges and overcoming obstacles, cochlear implantation (CI) programs in China have also experienced considerable growth. This review discusses the implementation of CI programs for HL in China and presents current HL data including epidemiology, newborn hearing screening, and determination of genetic etiologies. Sharing the experience in Chinese auditory rehabilitation and CI programs will shine a light on the developmental pathway of healthcare infrastructure to meet emerging needs of the hearing-impaired population in other developing countries.
Asunto(s)
Implantación Coclear , Corrección de Deficiencia Auditiva , Pérdida Auditiva/rehabilitación , China/epidemiología , Implantes Cocleares , Pérdida Auditiva/diagnóstico , Pérdida Auditiva/epidemiología , Pruebas Auditivas , Humanos , Recién Nacido , Tamizaje Neonatal , Desarrollo de ProgramaRESUMEN
Hereditary hearing loss (HL) is characterized by both allelic and locus genetic heterogeneity. Both recessive and dominant forms of HL may be caused by different mutations in the same deafness gene. In a family with post-lingual progressive non-syndromic deafness, whole-exome sequencing of genomic DNA from five hearing-impaired relatives revealed a single variant, p.Gly488Glu (rs145970949:G>A) in MYO3A, co-segregating with HL as an autosomal dominant trait. This amino acid change, predicted to be pathogenic, alters a highly conserved residue in the motor domain of MYO3A. The mutation severely alters the ATPase activity and motility of the protein in vitro, and the mutant protein fails to accumulate in the filopodia tips in COS7 cells. However, the mutant MYO3A was able to reach the tips of organotypic inner ear culture hair cell stereocilia, raising the possibility of a local effect on positioning of the mechanoelectrical transduction (MET) complex at the stereocilia tips. To address this hypothesis, we investigated the interaction of MYO3A with the cytosolic tail of the integral tip-link protein protocadherin 15 (PCDH15), a core component of MET complex. Interestingly, we uncovered a novel interaction between MYO3A and PCDH15 shedding new light on the function of myosin IIIA at stereocilia tips.
Asunto(s)
Cadherinas/metabolismo , Sordera/genética , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Miosina Tipo III/genética , Miosina Tipo III/metabolismo , Polimorfismo de Nucleótido Simple , Sustitución de Aminoácidos , Animales , Células COS , Proteínas Relacionadas con las Cadherinas , Células Cultivadas , Niño , Preescolar , Chlorocebus aethiops , Sordera/metabolismo , Femenino , Predisposición Genética a la Enfermedad , Células Ciliadas Auditivas Internas/citología , Células Ciliadas Auditivas Internas/metabolismo , Humanos , Masculino , Persona de Mediana Edad , LinajeRESUMEN
Matrix metalloproteinases (MMPs) are a diverse group of proteolytic enzymes and play an important role in the degradation and remodeling of the extracellular matrix (ECM). In normal physiological conditions, MMPs are usually minimally expressed. Despite their low expression, MMPs have been implicated in many cellular processes ranging from embryological development to apoptosis. The activity of MMPs is controlled at three different stages: (1) transcription; (2) zymogen activation; and (3) inhibition of active forms by tissue inhibitor metalloproteinases (TIMPs). They can collectively degrade any component of ECM and basement membrane, and their excessive activity has been linked to numerous pathologies mainly including, but not limited to, tumor invasion and metastasis. The lack of information about several MMPs and the steady stream of new discoveries suggest that there is much more to be studied in this field. In particular, there is a need for controlling their expression in disease states. Various studies over the past 30 years have found that each MMP has a specific mode of activation, action, and inhibition. Drugs specifically targeting individual MMPs could revolutionize the treatment of a great number of health conditions and tremendously reduce their burden. In this review article, we have summarized the recent advances in understanding the role of MMPs in physiological and pathological conditions. J. Cell. Physiol. 231: 2599-2621, 2016. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Enfermedad , Metaloproteinasas de la Matriz/metabolismo , Animales , Humanos , Inhibidores de la Metaloproteinasa de la Matriz/química , Inhibidores de la Metaloproteinasa de la Matriz/farmacología , Modelos MolecularesRESUMEN
The P2X purinergic receptors are cation-selective channels gated by extracellular adenosine 5'-triphosphate (ATP). These purinergic receptors are found in virtually all mammalian cell types and facilitate a number of important physiological processes. Within the past few years, the characterization of crystal structures of the zebrafish P2X4 receptor in its closed and open states has provided critical insights into the mechanisms of ligand binding and channel activation. Understanding of this gating mechanism has facilitated to design and interpret new modeling and structure-function experiments to better elucidate how different agonists and antagonists can affect the receptor with differing levels of potency. This review summarizes the current knowledge on the structure, activation, allosteric modulators, function, and location of the different P2X receptors. Moreover, an emphasis on the P2X2 receptors has been placed in respect to its role in the auditory system. In particular, the discovery of three missense mutations in P2X2 receptors could become important areas of study in the field of gene therapy to treat progressive and noise-induced hearing loss. J. Cell. Physiol. 231: 1656-1670, 2016. © 2015 Wiley Periodicals, Inc.
Asunto(s)
Adenosina Trifosfato/metabolismo , Vías Auditivas/metabolismo , Pérdida Auditiva Provocada por Ruido/metabolismo , Audición , Activación del Canal Iónico , Receptores Purinérgicos P2X/metabolismo , Transducción de Señal , Animales , Vías Auditivas/efectos de los fármacos , Vías Auditivas/fisiopatología , Predisposición Genética a la Enfermedad , Audición/efectos de los fármacos , Pérdida Auditiva Provocada por Ruido/genética , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pérdida Auditiva Provocada por Ruido/terapia , Humanos , Activación del Canal Iónico/efectos de los fármacos , Ligandos , Modelos Moleculares , Mutación Missense , Fenotipo , Conformación Proteica , Agonistas del Receptor Purinérgico P2X/farmacología , Antagonistas del Receptor Purinérgico P2X/farmacología , Receptores Purinérgicos P2X/química , Receptores Purinérgicos P2X/efectos de los fármacos , Receptores Purinérgicos P2X/genética , Transducción de Señal/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Identifying the genetic etiology in a person with hearing loss (HL) is challenging due to the extreme genetic heterogeneity in HL and the population-specific variability. In this study, after excluding GJB2 variants, targeted resequencing of 180 deafness-related genes revealed the causative variants in 11 of 19 (58%) Brazilian probands with autosomal recessive HL. Identified pathogenic variants were in MYO15A (10 families) and CLDN14 (one family). Remarkably, the MYO15A p.(Val1400Met) variant was identified in eight families from the city of Monte Santo in the northeast region of Brazil. Haplotype analysis of this variant was consistent with a single founder. No other cases with this variant were detected among 105 simplex cases from other cities of northeastern Brazil, suggesting that this variant is confined to a geographical region. This study suggests that it is feasible to develop population-specific screening for deafness variants once causative variants are identified in different geographical groups.