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Riza AL, Alkhzouz C, Farcaș M, Pîrvu A, Miclea D, Mihuț G, Pleșea RM, Ștefan D, Drodar M, Lazăr C, Study OBOTHINT, Study OBOTFUSE, Ioana M, Popp R. Non-Syndromic Hearing Loss in a Romanian Population: Carrier Status and Frequent Variants in the GJB2 Gene. Genes (Basel) 2022; 14:69. [PMID: 36672810 PMCID: PMC9858611 DOI: 10.3390/genes14010069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022] Open
Abstract
The genetic causes of autosomal recessive nonsyndromic hearing loss (ARNSHL) are heterogeneous and highly ethnic-specific. We describe GJB2 (connexin 26) variants and carrier frequencies as part of our study and summarize previously reported ones for the Romanian population. In total, 284 unrelated children with bilateral congenital NSHL were enrolled between 2009 and 2018 in northwestern Romania. A tiered diagnostic approach was used: all subjects were tested for c.35delG, c.71G>A and deletions in GJB6 (connexin 30) using PCR-based methods. Furthermore, 124 cases undiagnosed at this stage were analyzed by multiplex-ligation-dependent probe amplifications (MLPA), probe mix P163, and sequencing of GJB2 exon 2. Targeted allele-specific PCR/restriction fragment length polymorphism (RFLP) established definite ethio-pathogenical diagnosis for 72/284 (25.35%) of the cohort. Out of the 124 further analyzed, in 12 cases (9.67%), we found compound heterozygous point mutations in GJB2. We identified one case of deletion of exon 1 of the WFS1 (wolframin) gene. Carrier status evaluation used Illumina Infinium Global Screening Array (GSA) genotyping: the HINT cohort-416 individuals in northwest Romania, and the FUSE cohort-472 individuals in southwest Romania. GSA variants yielded a cumulated risk allele presence of 0.0284. A tiered diagnostic approach may be efficient in diagnosing ARNSHL. The summarized contributions to Romanian descriptive epidemiology of ARNSHL shows that pathogenic variants in the GJB2 gene are frequent among NSHL cases and have high carrier rates, especially for c.35delG and c.71G>A. These findings may serve in health strategy development.
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Affiliation(s)
- Anca-Lelia Riza
- Regional Centre of Medical Genetics Dolj, Emergency County Hospital Craiova, 200642 Craiova, Romania
- Laboratory of Human Genomics, University of Medicine and Pharmacy of Craiova, 200638 Craiova, Romania
| | - Camelia Alkhzouz
- First Pediatric Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
- Clinical Emergency Hospital for Children, 400394 Cluj-Napoca, Romania
| | - Marius Farcaș
- Molecular Sciences Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
| | - Andrei Pîrvu
- Regional Centre of Medical Genetics Dolj, Emergency County Hospital Craiova, 200642 Craiova, Romania
- Laboratory of Human Genomics, University of Medicine and Pharmacy of Craiova, 200638 Craiova, Romania
| | - Diana Miclea
- First Pediatric Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
- Clinical Emergency Hospital for Children, 400394 Cluj-Napoca, Romania
| | - Gheorghe Mihuț
- ENT Department, Clinical Emergency Hospital for Children, 400394 Cluj-Napoca, Romania
| | - Răzvan-Mihail Pleșea
- Regional Centre of Medical Genetics Dolj, Emergency County Hospital Craiova, 200642 Craiova, Romania
- Laboratory of Human Genomics, University of Medicine and Pharmacy of Craiova, 200638 Craiova, Romania
| | - Delia Ștefan
- Molecular Sciences Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
| | - Mihaela Drodar
- Laboratory of Human Genomics, University of Medicine and Pharmacy of Craiova, 200638 Craiova, Romania
| | - Călin Lazăr
- First Pediatric Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
- Clinical Emergency Hospital for Children, 400394 Cluj-Napoca, Romania
| | | | | | - Mihai Ioana
- Regional Centre of Medical Genetics Dolj, Emergency County Hospital Craiova, 200642 Craiova, Romania
- Laboratory of Human Genomics, University of Medicine and Pharmacy of Craiova, 200638 Craiova, Romania
| | - Radu Popp
- Molecular Sciences Department, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
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Advances in the development of connexin hemichannel inhibitors selective toward Cx43. Future Med Chem 2021; 13:379-392. [PMID: 33399487 DOI: 10.4155/fmc-2020-0291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Gap-junction channels formed by two connexin hemichannels play diverse and pivotal roles in intercellular communication and regulation. Normally hemichannels at the plasma membrane participate in autocrine and paracrine signaling, but abnormal increase in their activity can lead or contribute to various diseases. Selective inhibitors toward connexin hemichannels are of great interest. Among more than 20 identified isoforms of connexins, connexin 43 (Cx43) attracts the most interest due to its prevalence and link to cell damage in many disorders or diseases. Traditional antibacterial kanamycin decorated with hydrophobic groups yields amphiphilic kanamycins that show low cytotoxicity and prominent inhibitory effect against Cx43. This review focuses on the development of amphiphilic kanamycins as connexin hemichannel inhibitors and their future perspective.
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Adadey SM, Esoh KK, Quaye O, Amedofu GK, Awandare GA, Wonkam A. GJB4 and GJC3 variants in non-syndromic hearing impairment in Ghana. Exp Biol Med (Maywood) 2020; 245:1355-1367. [PMID: 32524838 PMCID: PMC7441344 DOI: 10.1177/1535370220931035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/11/2020] [Indexed: 12/13/2022] Open
Abstract
IMPACT STATEMENT Although connexins are known to be the major genetic factors associated with HI, only a few studies have investigated GJB4 and GJC3 variants among hearing-impaired patients. This study is the first to report GJB4 and GJC3 variants from an African HI cohort. We have demonstrated that GJB4 and GJC3 genes may not contribute significantly to HI in Ghana, hence these genes should not be considered for routine clinical screening in Ghana. However, it is important to study a larger population to determine the association of GJB4 and GJC3 variants with HI.
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Affiliation(s)
- Samuel M Adadey
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra LG 54, Ghana
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
| | | | - Osbourne Quaye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra LG 54, Ghana
| | | | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra LG 54, Ghana
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
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Auditory and Olfactory Deficits in Essential Tremor - Review of the Current Evidence. Tremor Other Hyperkinet Mov (N Y) 2020; 10:3. [PMID: 32775017 PMCID: PMC7394198 DOI: 10.5334/tohm.57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Essential tremor (ET) is the most common adult movement disorder, characterized by several motor and increasingly well recognized non-motor symptoms. Sensory deficits, such as hearing impairment and olfactory dysfunction, are amongst them. This review analyzes the available evidence of these sensory deficits and their possible mechanistic basis in patients with ET. Method: A PubMed literature search on the topic was performed in the May 2019 database. Results: Nineteen articles on hearing impairment and olfactory dysfunction in ET patients were identified. The prevalence of hearing impairment is higher in ET patients than healthy controls or Parkinson disease. Cochlear pathologies are suggested as the underlying cause, but there is still a lack of information about retrocochlear pathologies and central auditory processing. Reports on olfactory dysfunction have conflicting results. The presence of mild olfactory dysfunction in ET was suggested. Conflicting results may be due to the lack of consideration of the disease’s heterogeneity, but according to recent data, most studies do not find prominent evidence of olfactory loss in ET. Conclusion: Although there is increasing interest in studies on non-motor symptoms in ET, there are few studies on sensory deficits, which are of particularly high prevalence. More studies are needed on to investigate the basis of non-motor symptoms, including sensory deficits.
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Avenarius MR, Jung JY, Askew C, Jones SM, Hunker KL, Azaiez H, Rehman AU, Schraders M, Najmabadi H, Kremer H, Smith RJH, Géléoc GSG, Dolan DF, Raphael Y, Kohrman DC. Grxcr2 is required for stereocilia morphogenesis in the cochlea. PLoS One 2018; 13:e0201713. [PMID: 30157177 PMCID: PMC6114524 DOI: 10.1371/journal.pone.0201713] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/22/2018] [Indexed: 11/18/2022] Open
Abstract
Hearing and balance depend upon the precise morphogenesis and mechanosensory function of stereocilia, the specialized structures on the apical surface of sensory hair cells in the inner ear. Previous studies of Grxcr1 mutant mice indicated a critical role for this gene in control of stereocilia dimensions during development. In this study, we analyzed expression of the paralog Grxcr2 in the mouse and evaluated auditory and vestibular function of strains carrying targeted mutations of the gene. Peak expression of Grxcr2 occurs during early postnatal development of the inner ear and GRXCR2 is localized to stereocilia in both the cochlea and in vestibular organs. Homozygous Grxcr2 deletion mutants exhibit significant hearing loss by 3 weeks of age that is associated with developmental defects in stereocilia bundle orientation and organization. Despite these bundle defects, the mechanotransduction apparatus assembles in relatively normal fashion as determined by whole cell electrophysiological evaluation and FM1-43 uptake. Although Grxcr2 mutants do not exhibit overt vestibular dysfunction, evaluation of vestibular evoked potentials revealed subtle defects of the mutants in response to linear accelerations. In addition, reduced Grxcr2 expression in a hypomorphic mutant strain is associated with progressive hearing loss and bundle defects. The stereocilia localization of GRXCR2, together with the bundle pathologies observed in the mutants, indicate that GRXCR2 plays an intrinsic role in bundle orientation, organization, and sensory function in the inner ear during development and at maturity.
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Affiliation(s)
- Matthew R. Avenarius
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Jae-Yun Jung
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Charles Askew
- Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia, United States of America
- Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sherri M. Jones
- Department of Communication Sciences and Disorders, East Carolina University, Greenville, North Carolina, United States of America
| | - Kristina L. Hunker
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Atteeq U. Rehman
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Margit Schraders
- Hearing & Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hannie Kremer
- Hearing & Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J. H. Smith
- Molecular Otolaryngology and Renal Research Laboratories, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Gwenaëlle S. G. Géléoc
- Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - David F. Dolan
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Yehoash Raphael
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - David C. Kohrman
- Department of Otolaryngology/Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
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Beyer EC, Berthoud VM. Gap junction gene and protein families: Connexins, innexins, and pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:5-8. [PMID: 28559187 DOI: 10.1016/j.bbamem.2017.05.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/18/2017] [Accepted: 05/25/2017] [Indexed: 02/08/2023]
Abstract
Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that form gap junction channels are not conserved. Vertebrate gap junctions are formed by connexins, while invertebrate gap junctions are formed by innexins. Interestingly, vertebrates and lower chordates contain innexin homologs, the pannexins, which also form channels, but rarely (if ever) make intercellular channels. While the connexin and the innexin/pannexin polypeptides do not share significant sequence similarity, all three of these protein families share a similar membrane topology and some similarities in quaternary structure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States.
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States
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Martínez-Saucedo M, Rivera-Vega M, Gonzalez-Huerta L, Urueta-Cuéllar H, Cuevas-Covarrubias S. Exome sequencing analysis reveals homozygous GJB2 gene mutation in a Mexican family with profound hearing loss. REVISTA MÉDICA DEL HOSPITAL GENERAL DE MÉXICO 2017. [DOI: 10.1016/j.hgmx.2016.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Two novel compound heterozygous families with a trimutation in the GJB2 gene causing sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2015; 79:2295-9. [PMID: 26553399 DOI: 10.1016/j.ijporl.2015.10.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/20/2015] [Accepted: 10/22/2015] [Indexed: 11/22/2022]
Abstract
BACKGROUND Sensorineural hearing loss (SNHL) is a genetically heterogeneous disease. GJB2 gene mutations seem to be the most frequent cause of hereditary hearing impairment in several populations. There is variability in the mutations in the GJB2 gene worldwide; this remarks the influence of ethnic background in SNHL. OBJECTIVE To describe the presence of two trimutations in the GJB2 gene in two Mexican families with hereditary SNHL. MATERIALS AND METHODS Two unrelated Mexican families with prelingual SNHL were included in the study. Analysis of the GJB2 gene through PCR and DNA direct sequencing analysis was performed in all members of the families and in 100 normal controls. RESULTS Affected member of the family 1 showed the trimutation p.S19R/p.R32S/p.E47*, whereas affected members of the family 2 showed the trimutation p.F31I/p.W44*/p.V84M. Parents of both families were heterozygous with normal audition. CONCLUSION We found a novel mutation in the GJB2 gene and two trimutations with SNHL not previously reported. This remarks the complexity in the pattern of mutations in the GJB2 gene in SNHL and enriches the spectrum of the type of molecular defects in the GJB2 gene.
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Loeza-Becerra F, Rivera-Vega MDR, Martínez-Saucedo M, Gonzalez-Huerta LM, Urueta-Cuellar H, Berrruecos-Villalobos P, Cuevas-Covarrubias S. Particular distribution of the GJB2/GJB6 gene mutations in Mexican population with hearing impairment. Int J Pediatr Otorhinolaryngol 2014; 78:1057-60. [PMID: 24774219 DOI: 10.1016/j.ijporl.2014.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/30/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Hereditary sensorineural hearing loss (SNHL) is a genetically heterogeneous disorder worldwide. Mutations in the GJB2 gene are a frequent cause of hereditary SNHL. There is a prevalence of certain mutations in various populations which suggests that specific mutations may be influenced by ethnic background. OBJECTIVE To analyze the prevalence of GJB2, GJB6 mutations in several geographic areas of Mexico in patients with hereditary SNHL. MATERIALS AND METHODS One hundred and forty Mexican unrelated propositi with prelingual SNHL were included in the study. All patients had three previous generations born in Mexico and belonged to no specific ethnic group. Analyses of the GJB2 and GJB6 genes and mt.1555A<G were performed in all subjects. RESULTS Twenty-three homozygous mutations, 57 heterozygous mutations, 1 double heterozygous (GJB2/GJB6) and 59 wild-type genotypes in the GJB2 gene were observed. Three patients had the homozygous c.del35 mutation whereas 26 patients were heterozygous for this gene defect. Only one patient with the GJB6 gene deletion was present (it includes the double heterozygous GJB2/GJB6). The mt.1555A>G mutation was not detected. CONCLUSION We found a great variety of mutations depending on the analyzed region in patients with SNHL; 57.86% of patients had affection in one or two alleles in GJB2 or GJB6 genes whereas 42.14% were wild-type. In some cases, allele distribution depended on region. Molecular studies of more genes involved in hereditary non-syndromic SNHL are required to completely confirm the molecular basis of hearing loss in Mexican population.
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Affiliation(s)
- Francisco Loeza-Becerra
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - María del Refugio Rivera-Vega
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Mirna Martínez-Saucedo
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Luz María Gonzalez-Huerta
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Héctor Urueta-Cuellar
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Pedro Berrruecos-Villalobos
- Servicio de Audiología, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico
| | - Sergio Cuevas-Covarrubias
- Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
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Fiori MC, Reuss L, Cuello LG, Altenberg GA. Functional analysis and regulation of purified connexin hemichannels. Front Physiol 2014; 5:71. [PMID: 24611052 PMCID: PMC3933781 DOI: 10.3389/fphys.2014.00071] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 02/06/2014] [Indexed: 01/08/2023] Open
Abstract
Gap-junction channels (GJCs) are aqueous channels that communicate adjacent cells. They are formed by head-to-head association of two hemichannels (HCs), one from each of the adjacent cells. Functional HCs are connexin hexamers composed of one or more connexin isoforms. Deafness is the most frequent sensineural disorder, and mutations of Cx26 are the most common cause of genetic deafness. Cx43 is the most ubiquitous connexin, expressed in many organs, tissues, and cell types, including heart, brain, and kidney. Alterations in its expression and function play important roles in the pathophysiology of very frequent medical problems such as those related to cardiac and brain ischemia. There is extensive information on the relationship between phosphorylation and Cx43 targeting, location, and function from experiments in cells and organs in normal and pathological conditions. However, the molecular mechanisms of Cx43 regulation by phosphorylation are hard to tackle in complex systems. Here, we present the use of purified HCs as a model for functional and structural studies. Cx26 and Cx43 are the only isoforms that have been purified, reconstituted, and subjected to functional and structural analysis. Purified Cx26 and Cx43 HCs have properties compatible with those demonstrated in cells, and present methodologies for the functional analysis of purified HCs reconstituted in liposomes. We show that phosphorylation of serine 368 by PKC produces a partial closure of the Cx43 HCs, changing solute selectivity. We also present evidence that the effect of phosphorylation is highly cooperative, requiring modification of several connexin subunits, and that phosphorylation of serine 368 elicits conformational changes in the purified HCs. The use of purified HCs is starting to provide critical data to understand the regulation of HCs at the molecular level.
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Affiliation(s)
- Mariana C Fiori
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center Lubbock, TX, USA
| | - Luis Reuss
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center Lubbock, TX, USA
| | - Luis G Cuello
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center Lubbock, TX, USA
| | - Guillermo A Altenberg
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center Lubbock, TX, USA
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de Zwart-Storm EA, Martin PE, van Steensel MAM. Gap junction diseases of the skin: novel insights from new mutations. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/edm.09.47] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Silva LSD, Netto RCM, Sanches SGG, Carvallo RMM. Auditory measurements in parents of individuals with autosomal recessive hearing loss. PRO-FONO : REVISTA DE ATUALIZACAO CIENTIFICA 2011; 22:403-8. [PMID: 21271090 DOI: 10.1590/s0104-56872010000400007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 11/30/2010] [Indexed: 11/21/2022]
Abstract
BACKGROUND Audiological evaluation of parents of individuals with autosomal recessive hearing loss. AIM To study the audiological profile of parents of individuals with autosomal recessive hearing loss, inferred by family history or by molecular tests that detected heterozygous mutations in the GJB2 gene. This gene codes Connexin 26. METHOD Participants were 36 subjects, ranging between 30 and 60 years, who were divided into two groups: a control group composed by individuals without auditory complaints and without family history of hearing loss, and a research group composed by heterozygous parents of individuals with autosomal recessive hearing loss or heterozygous for connexin 26 mutations. All subjects underwent pure tone audiometry (0.25 to 8 kHz), high frequencies audiometry (9 to 20 kHz) and distortion product otoacoustic emissions (DPOAE). RESULTS There were significant differences between the groups when considering the amplitude of DPOAE in the frequencies of 1001 and 1501 Hz. Amplitude was higher in the control group. There was no significant difference between the groups for pure tone thresholds from 0.25 to 20 KHz. CONCLUSION The DPOAE were more effective, in comparison to the pure tone audiometry, to detect auditory differences between the groups. More studies of this type are necessary to confirm the observed results.
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Majumder P, Crispino G, Rodriguez L, Ciubotaru CD, Anselmi F, Piazza V, Bortolozzi M, Mammano F. ATP-mediated cell-cell signaling in the organ of Corti: the role of connexin channels. Purinergic Signal 2010; 6:167-87. [PMID: 20806010 PMCID: PMC2912995 DOI: 10.1007/s11302-010-9192-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 05/31/2010] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Connexin 26 (Cx26) and connexin 30 (Cx30) form hemichannels that release ATP from the endolymphatic surface of cochlear supporting and epithelial cells and also form gap junction (GJ) channels that allow the concomitant intercellular diffusion of Ca(2+) mobilizing second messengers. Released ATP in turn activates G-protein coupled P2Y(2) and P2Y(4) receptors, PLC-dependent generation of IP(3), release of Ca(2+) from intracellular stores, instigating the regenerative propagation of intercellular Ca(2+) signals (ICS). The range of ICS propagation is sensitive to the concentration of extracellular divalent cations and activity of ectonucleotidases. Here, the expression patterns of Cx26 and Cx30 were characterized in postnatal cochlear tissues obtained from mice aged between P5 and P6. The expression gradient along the longitudinal axis of the cochlea, decreasing from the basal to the apical cochlear turn (CT), was more pronounced in outer sulcus (OS) cells than in inner sulcus (IS) cells. GJ-mediated dye coupling was maximal in OS cells of the basal CT, inhibited by the nonselective connexin channel blocker carbenoxolone (CBX) and absent in hair cells. Photostimulating OS cells with caged inositol (3,4,5) tri-phosphate (IP(3)) resulted in transfer of ICS in the lateral direction, from OS cells to IS cells across the hair cell region (HCR) of medial and basal CTs. ICS transfer in the opposite (medial) direction, from IS cells photostimulated with caged IP(3) to OS cells, occurred mostly in the basal CT. In addition, OS cells displayed impressive rhythmic activity with oscillations of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) coordinated by the propagation of Ca(2+) wavefronts sweeping repeatedly through the same tissue area along the coiling axis of the cochlea. Oscillations evoked by uncaging IP(3) or by applying ATP differed greatly, by as much as one order of magnitude, in frequency and waveform rise time. ICS evoked by direct application of ATP propagated along convoluted cellular paths in the OS, which often branched and changed dynamically over time. Potential implications of these findings are discussed in the context of developmental regulation and cochlear pathophysiology. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s11302-010-9192-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Paromita Majumder
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Giulia Crispino
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Laura Rodriguez
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Catalin Dacian Ciubotaru
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Fabio Anselmi
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Valeria Piazza
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Mario Bortolozzi
- Dipartimento di Fisica “G. Galilei”, Università di Padova, via Marzolo 8, 35129 Padova, Italy
- Istituto di Neuroscienze, CNR, Padova, Italy
| | - Fabio Mammano
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, via Marzolo 8, 35129 Padova, Italy
- Istituto di Neuroscienze, CNR, Padova, Italy
- Centro Interdipartimentale per lo Studio dei Segnali Cellulari, Università di Padova, via G. Orus 2, 35129 Padova, Italy
- VIMM, Via G. Orus 2, 35129 Padova, Italy
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Scemes E, Spray DC, Meda P. Connexins, pannexins, innexins: novel roles of "hemi-channels". Pflugers Arch 2008; 457:1207-26. [PMID: 18853183 DOI: 10.1007/s00424-008-0591-5] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 09/17/2008] [Indexed: 12/11/2022]
Affiliation(s)
- Eliana Scemes
- The Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, USA
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15
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16
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Förster C. Tight junctions and the modulation of barrier function in disease. Histochem Cell Biol 2008; 130:55-70. [PMID: 18415116 PMCID: PMC2413111 DOI: 10.1007/s00418-008-0424-9] [Citation(s) in RCA: 424] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2008] [Indexed: 12/22/2022]
Abstract
Tight junctions create a paracellular barrier in epithelial and endothelial cells protecting them from the external environment. Two different classes of integral membrane proteins constitute the tight junction strands in epithelial cells and endothelial cells, occludin and members of the claudin protein family. In addition, cytoplasmic scaffolding molecules associated with these junctions regulate diverse physiological processes like proliferation, cell polarity and regulated diffusion. In many diseases, disruption of this regulated barrier occurs. This review will briefly describe the molecular composition of the tight junctions and then present evidence of the link between tight junction dysfunction and disease.
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Affiliation(s)
- Carola Förster
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstrasse 6, 97070, Würzburg, Germany.
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17
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Quiet as a mouse: dissecting the molecular and genetic basis of hearing. Nat Rev Genet 2008; 9:277-90. [PMID: 18283275 DOI: 10.1038/nrg2309] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mouse genetics has made crucial contributions to the understanding of the molecular mechanisms of hearing. With the help of a plethora of mouse mutants, many of the key genes that are involved in the development and functioning of the auditory system have been elucidated. Mouse mutants continue to shed light on the genetic and physiological bases of human hearing impairment, including both early- and late-onset deafness. A combination of genetic and physiological studies of mouse mutant lines, allied to investigations into the protein networks of the stereocilia bundle in the inner ear, are identifying key complexes that are crucial for auditory function and for providing profound insights into the underlying causes of hearing loss.
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18
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Guan BC, Si JQ, Jiang ZG. Blockade of gap junction coupling by glycyrrhetinic acids in guinea pig cochlear artery: a whole-cell voltage- and current-clamp study. Br J Pharmacol 2007; 151:1049-60. [PMID: 17572704 PMCID: PMC2042944 DOI: 10.1038/sj.bjp.0707244] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 02/12/2007] [Accepted: 02/16/2007] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Glycyrrhetinic acids (GAs) are widely used as gap junction blockers, but their efficacy and side effects have not been well determined. EXPERIMENTAL APPROACH Whole-cell electrical recordings were made from vascular smooth muscle cells (VSMCs) embedded in or dissociated from, guinea pig cochlear artery segments. KEY RESULTS 18beta- & 18alpha-GA concentration-dependently increased membrane input resistance (R(in)) of in situ VSMCs, with a maximal input conductance (G(in)=1/R(in)) reduction of 92% & 77% and IC(50) of 2.0 & 4.4 microm, respectively. 18betaGA (30 microM) resulted in a R(in) of 2.2 GOmega and C(in) of 12 pF, comparable to those of freshly dissociated VSMCs (3.1 GOmega & 6.1 pF). The GAs (> or =30 microM) caused a depolarization in VSMCs in situ. In dispersed VSMCs, they both inhibited delayed rectifiers; 18betaGA also activated a non-selective cation conductance while 18alphaGA inactivated a voltage-independent K+-conductance. ACh induced an outward current in VSMCs in situ at -40 mV, with a positive slope I/V relation and a reversal potential near E(K). The ACh-induced current was attenuated by 18beta- & 18alphaGA with an IC(50) of 4.3 & 7.8 microM, respectively. CONCLUSIONS AND IMPLICATIONS 18betaGA blocked the vascular gap junctions, achieving a complete electrical isolation of the recorded VSMC at > or =30 microM while causing a mild depolarization by a complex conductance alteration. 18betaGA suppressed the ACh-induced current in VSMC by blocking the myoendothelial gap junction and by a non-junctional action. 18alphaGA at 30-100 microM failed to fully block the gap junctions while exerting side actions.
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Affiliation(s)
- B-C Guan
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health and Science University Portland, OR, USA
| | - J-Q Si
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health and Science University Portland, OR, USA
- Department of Physiology, Shihezi University Medical College Shihezi, Xinjiang, PR China
| | - Z-G Jiang
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health and Science University Portland, OR, USA
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19
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Xie H, Vucetic S, Iakoucheva LM, Oldfield CJ, Dunker AK, Obradovic Z, Uversky VN. Functional anthology of intrinsic disorder. 3. Ligands, post-translational modifications, and diseases associated with intrinsically disordered proteins. J Proteome Res 2007; 6:1917-32. [PMID: 17391016 PMCID: PMC2588348 DOI: 10.1021/pr060394e] [Citation(s) in RCA: 298] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Currently, the understanding of the relationships between function, amino acid sequence, and protein structure continues to represent one of the major challenges of the modern protein science. As many as 50% of eukaryotic proteins are likely to contain functionally important long disordered regions. Many proteins are wholly disordered but still possess numerous biologically important functions. However, the number of experimentally confirmed disordered proteins with known biological functions is substantially smaller than their actual number in nature. Therefore, there is a crucial need for novel bionformatics approaches that allow projection of the current knowledge from a few experimentally verified examples to much larger groups of known and potential proteins. The elaboration of a bioinformatics tool for the analysis of functional diversity of intrinsically disordered proteins and application of this data mining tool to >200 000 proteins from the Swiss-Prot database, each annotated with at least one of the 875 functional keywords, was described in the first paper of this series (Xie, H.; Vucetic, S.; Iakoucheva, L. M.; Oldfield, C. J.; Dunker, A. K.; Obradovic, Z.; Uversky, V.N. Functional anthology of intrinsic disorder. 1. Biological processes and functions of proteins with long disordered regions. J. Proteome Res. 2007, 5, 1882-1898). Using this tool, we have found that out of the 710 Swiss-Prot functional keywords associated with at least 20 proteins, 262 were strongly positively correlated with long intrinsically disordered regions, and 302 were strongly negatively correlated. Illustrative examples of functional disorder or order were found for the vast majority of keywords showing strongest positive or negative correlation with intrinsic disorder, respectively. Some 80 Swiss-Prot keywords associated with disorder- and order-driven biological processes and protein functions were described in the first paper (see above). The second paper of the series was devoted to the presentation of 87 Swiss-Prot keywords attributed to the cellular components, domains, technical terms, developmental processes, and coding sequence diversities possessing strong positive and negative correlation with long disordered regions (Vucetic, S.; Xie, H.; Iakoucheva, L. M.; Oldfield, C. J.; Dunker, A. K.; Obradovic, Z.; Uversky, V. N. Functional anthology of intrinsic disorder. 2. Cellular components, domains, technical terms, developmental processes, and coding sequence diversities correlated with long disordered regions. J. Proteome Res. 2007, 5, 1899-1916). Protein structure and functionality can be modulated by various post-translational modifications or/and as a result of binding of specific ligands. Numerous human diseases are associated with protein misfolding/misassembly/misfunctioning. This work concludes the series of papers dedicated to the functional anthology of intrinsic disorder and describes approximately 80 Swiss-Prot functional keywords that are related to ligands, post-translational modifications, and diseases possessing strong positive or negative correlation with the predicted long disordered regions in proteins.
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Affiliation(s)
- Hongbo Xie
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Slobodan Vucetic
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Lilia M. Iakoucheva
- Laboratory of Statistical Genetics, The Rockefeller University, New York, NY 10021
| | - Christopher J. Oldfield
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
| | - A. Keith Dunker
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
| | - Zoran Obradovic
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Vladimir N. Uversky
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
- Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
- Correspondence should be addressed to: Vladimir N. Uversky, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS#4021, Indianapolis, IN 46202, USA; Phone: 317-278-9194; Fax: 317-274-4686; E-mail:
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20
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Bicego M, Beltramello M, Melchionda S, Carella M, Piazza V, Zelante L, Bukauskas FF, Arslan E, Cama E, Pantano S, Bruzzone R, D’Andrea P, Mammano F. Pathogenetic role of the deafness-related M34T mutation of Cx26. Hum Mol Genet 2006; 15:2569-87. [PMID: 16849369 PMCID: PMC2829448 DOI: 10.1093/hmg/ddl184] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26), are the major cause of genetic non-syndromic hearing loss. The role of the allelic variant M34T in causing hereditary deafness remains controversial. By combining genetic, clinical, biochemical, electrophysiological and structural modeling studies, we have re-assessed the pathogenetic role of the M34T mutation. Genetic and audiological data indicate that the majority of heterozygous carriers and all five compound heterozygotes exhibited an impaired auditory function. Functional expression in transiently transfected HeLa cells showed that, although M34T was correctly synthesized and targeted to the plasma membrane, it inefficiently formed intercellular channels that displayed an abnormal electrical behavior and retained only 11% of the unitary conductance of the wild-type protein (HCx26wt). Moreover, M34T channels failed to support the intercellular diffusion of Lucifer Yellow and the spreading of mechanically induced intercellular Ca2+ waves. When co-expressed together with HCx26wt, M34T exerted dominant-negative effects on cell-cell coupling. Our findings are consistent with a structural model, predicting that the mutation leads to a constriction of the channel pore. These data support the view that M34T is a pathological variant of Cx26 associated with hearing impairment.
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Affiliation(s)
- Massimiliano Bicego
- Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, University of Trieste, 34127 Trieste, Italy
| | - Martina Beltramello
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Salvatore Melchionda
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Massimo Carella
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Valeria Piazza
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Leopoldo Zelante
- Servizio di Genetica Medica, IRCCS-Ospedale Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Feliksas F. Bukauskas
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Edoardo Arslan
- Servizio di Audiologia e Foniatria, University of Padova, 35128 Padova, Italy
| | - Elona Cama
- Servizio di Audiologia e Foniatria, University of Padova, 35128 Padova, Italy
| | - Sergio Pantano
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM)
| | - Roberto Bruzzone
- Département de Neuroscience, Institut Pasteur, 75015 Paris, France
- To whom correspondence should be addressed at: Département de Neuroscience, Institut Pasteur, 25, rue du Dr Roux, 75015 Paris, France. Tel: +33 140613436; Fax: +33 140613421;
| | - Paola D’Andrea
- Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, University of Trieste, 34127 Trieste, Italy
| | - Fabio Mammano
- Istituto Veneto di Medicina Molecolare (VIMM), Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
- Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM)
- Dipartimento di Fisica ‘G.Galilei’, Università di Padova, 35131 Padova, Italy
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Couloigner V, Sterkers O, Ferrary E. What's new in ion transports in the cochlea? Pflugers Arch 2006; 453:11-22. [PMID: 16773381 DOI: 10.1007/s00424-006-0103-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 05/02/2006] [Indexed: 11/26/2022]
Abstract
Recent advances in the field of the physiology of inner ear fluids permitted the characterization of the molecular mechanisms involved in critical processes such as the absorption of K(+) through cochlear sensory hair cells (mechanoelectrical transduction) or the secretion of K(+) by marginal cells of the stria vascularis. In addition, new pathways for ion circulations were evidenced. Mutations of transporters involved in some of these pathways, especially in K(+) recycling through gap junction systems, and in local pH regulation, are among the most frequent etiologies of genetic deafness in humans.
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Affiliation(s)
- Vincent Couloigner
- Inserm EMI U-0112, Faculté Xavier Bichat, 16, rue Henri Huchard, Paris 75018, France.
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