title: The p.Cys169Tyr variant of connexin 26 is not a polymorphism.
abstract: Mutations in the GJB2 gene, which encodes the gap junction protein connexin 26 (Cx26), are the primary cause of hereditary prelingual hearing impairment. Here, the p.Cys169Tyr missense mutation of Cx26 (Cx26C169Y), previously classified as a polymorphism, has been identified as causative of severe hearing loss in two Qatari families. We have analyzed the effect of this mutation using a combination of confocal immunofluorescence microscopy and molecular dynamics simulations. At the cellular level, our results show that the mutant protein fails to form junctional channels in HeLa transfectants despite being correctly targeted to the plasma membrane. At the molecular level, this effect can be accounted for by disruption of the disulfide bridge that Cys169 forms with Cys64 in the wild-type structure (Cx26WT). The lack of the disulfide bridge in the Cx26C169Y protein causes a spatial rearrangement of two important residues, Asn176 and Thr177. In the Cx26WT protein, these residues play a crucial role in the intra-molecular interactions that permit the formation of an intercellular channel by the head-to-head docking of two opposing hemichannels resident in the plasma membrane of adjacent cells. Our results elucidate the molecular pathogenesis of hereditary hearing loss due to the connexin mutation and facilitate the understanding of its role in both healthy and affected individuals.
authors: Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy.
authors: Francesco
authors: F
authors: Zonta
authors: Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy.
authors: Giorgia
authors: G
authors: Girotto
authors: Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy.
authors: Damiano
authors: D
authors: Buratto
authors: Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy.
authors: Giulia
authors: G
authors: Crispino
authors: Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy.
authors: Anna
authors: A
authors: Morgan
authors: Audiology and Balance Unit, National Program for Early Detection of Hearing Loss, WH, Hamad Medical Corporation (HMC) Doha, Doha, Qatar.
authors: Khalid
authors: K
authors: Abdulhadi
authors: Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar.
authors: Moza
authors: M
authors: Alkowari
authors: Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar.
authors: Ramin
authors: R
authors: Badii
authors: Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy, Medical Genetics, Institute for Maternal and Child Health-IRCCS 'Burlo Garofolo', Trieste, Italy and.
authors: Paolo
authors: P
authors: Gasparini
authors: Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy, CNR Institute of Cell Biology and Neurobiology, 00015 Monterotondo, Rome, Italy fabio.mammano@cnr.it.
authors: Fabio
authors: F
authors: Mammano
mesh_terms: D000483:Alleles; D019943:Amino Acid Substitution; D002460:Cell Line; D000072259:Connexin 26; D017630:Connexins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000235:genetics; D015870:Gene Expression; D005838:Genotype; D034381:Hearing Loss / Q000175:diagnosis / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008958:Models, Molecular; D020125:Mutation, Missense; D010375:Pedigree; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D014162:Transfection
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26
references: J Med Genet. 2000 Jan;37(1):41-3
references: 10633133
references: J Biol Chem. 2003 Jan 17;278(3):1807-16
references: 12384501
references: J Comput Chem. 2003 Dec;24(16):1999-2012
references: 14531054
references: Proteins. 2007 Mar 1;66(4):930-40
references: 17154419
references: Biochem J. 2006 Jul 1;397(1):1-14
references: 16761954
references: Front Physiol. 2014 Mar 04;5:85
references: 24624091
references: Hum Genet. 2000 Apr;106(4):399-405
references: 10830906
references: Curr Protoc Hum Genet. 2013 Jan;Chapter 7:Unit7.20
references: 23315928
references: Am J Hum Genet. 2005 Dec;77(6):945-57
references: 16380907
references: Biochim Biophys Acta. 2004 Mar 23;1662(1-2):96-101
references: 15033581
references: Cell Commun Signal. 2013 Feb 27;11(1):15
references: 23445664
references: Hum Mol Genet. 2006 Sep 1;15(17):2569-87
references: 16849369
references: Nature. 1997 May 1;387(6628):80-3
references: 9139825
references: Curr Opin Otolaryngol Head Neck Surg. 2008 Oct;16(5):452-7
references: 18797288
references: Prog Biophys Mol Biol. 2007 May-Jun;94(1-2):120-43
references: 17470375
references: Nat Methods. 2010 Aug;7(8):575-6
references: 20676075
references: Eur J Biochem. 1991 Apr 10;197(1):141-4
references: 1707811
references: J Biomol Struct Dyn. 2012;29(5):985-98
references: 22292956
references: J Comp Neurol. 2003 Dec 8;467(2):207-31
references: 14595769
references: Cold Spring Harb Perspect Biol. 2009 Jul;1(1):a002576
references: 20066080
references: Biophys J. 1992 Apr;62(1):172-80; discussion 180-2
references: 1376165
references: EMBO J. 2002 Jul 15;21(14):3598-607
references: 12110573
references: Hum Mutat. 2004 Oct;24(4):305-11
references: 15365987
references: FEBS Lett. 2014 Apr 17;588(8):1304-14
references: 24607543
references: Biomed Res Int. 2014;2014:307976
references: 24551843
references: FEBS Lett. 2014 Apr 17;588(8):1205-11
references: 24631534
references: Front Biosci (Landmark Ed). 2011;16:3252-74
references: 21622233
references: Cell Commun Adhes. 2003 Jul-Dec;10(4-6):173-80
references: 14681012
references: Biochemistry. 1993 Jan 19;32(2):412-20
references: 8422350
references: J Med Genet. 2004 Mar;41(3):147-54
references: 14985372
references: FEBS Lett. 2014 Apr 17;588(8):1230-7
references: 24492007
references: PLoS One. 2008;3(7):e2614
references: 18648547
references: Electrophoresis. 1997 Dec;18(15):2714-23
references: 9504803
references: Arch Otolaryngol Head Neck Surg. 2001 Aug;127(8):927-33
references: 11493200
references: Hum Mutat. 2001;18(1):42-51
references: 11438992
references: Arch Otolaryngol Head Neck Surg. 2001 Sep;127(9):1037-42
references: 11556849
references: Eur J Clin Invest. 2011 Jan;41(1):103-16
references: 20840374
references: Nucleic Acids Res. 2003 Jul 1;31(13):3812-4
references: 12824425
references: Hum Genet. 2013 Oct;132(10):1077-130
references: 23820649
references: Cell Biochem Biophys. 2015 Apr;71(3):1623-42
references: 25388846
references: Nature. 2009 Apr 2;458(7238):597-602
references: 19340074
references: FASEB J. 2004 May;18(7):860-2
references: 15033936
references: Int J Audiol. 2012 Mar;51(3):181-5
references: 22103400
references: Eur J Hum Genet. 2004 Apr;12(4):279-84
references: 14694360
references: J Chem Theory Comput. 2008 Mar;4(3):435-47
references: 26620784