GJC3 explained

Gap junction gamma-3, also known as connexin-29 (Cx29) or gap junction epsilon-1 (GJE1), is a protein that in humans is encoded by the GJC3 gene.^[1]

GJC3 is a conexin.

Function

This gene encodes a gap junction protein. The encoded protein is known as a connexin, most of which form gap junctions that provide direct connections between neighboring cells.^[1] However, Cx29, which is highly expressed in myelin-forming glial cells of the CNS and PNS, has not been documented to form gap junctions in any cell type. In both PNS and CNS myelinated axons, Cx29 is precisely colocalized with Kv1.2 voltage-gated K+ channels, where both proteins are concentrated in the juxtaparanode and along the inner mesaxon.^[2] By freeze-fracture immunogold labeling electron microscopy, Cx29 is identified in abundant "rosettes" of transmembrane protein particles in the innermost layer of myelin, directly apposed to equally abundant immunogold-labeled Kv1.1 potassium channels, both in the juxtaparanodal axolemma and along the inner mesaxon.^[3] A role in K⁺ handling during saltatory conduction is implied but not yet demonstrated.

Clinical significance

Mutations in this gene have been reported to be associated with nonsyndromic hearing loss.^[1]

References

Further reading

• Hong HM, Yang JJ, Su CC, Chang JY, Li TC, Li SY . A novel mutation in the connexin 29 gene may contribute to nonsyndromic hearing loss . Human Genetics . 127 . 2 . 191–9 . February 2010 . 19876648 . 10.1007/s00439-009-0758-y . 7892178 .
• Ramchander PV, Panda KC, Panda AK . Mutations in the connexin 29 gene are not a major cause of nonsyndromic hearing impairment in India . Genetic Testing and Molecular Biomarkers . 14 . 4 . 539–41 . August 2010 . 20632892 . 10.1089/gtmb.2010.0026 .
• Kleopa KA, Orthmann JL, Enriquez A, Paul DL, Scherer SS . Unique distributions of the gap junction proteins connexin29, connexin32, and connexin47 in oligodendrocytes . Glia . 47 . 4 . 346–57 . September 2004 . 15293232 . 10.1002/glia.20043 . 9498256 .
• Yang JJ, Wang WH, Lin YC, Weng HH, Yang JT, Hwang CF, Wu CM, Li SY . Prospective variants screening of connexin genes in children with hearing impairment: genotype/phenotype correlation . Human Genetics . 128 . 3 . 303–13 . September 2010 . 20593197 . 10.1007/s00439-010-0856-x . 1423816 .
• Söhl G, Nielsen PA, Eiberger J, Willecke K . Expression profiles of the novel human connexin genes hCx30.2, hCx40.1, and hCx62 differ from their putative mouse orthologues . Cell Communication & Adhesion . 10 . 1 . 27–36 . 2003 . 12881038 . 10.1080/15419060302063 . 225894 .
• Wang WH, Yang JJ, Lin YC, Yang JT, Chan CH, Li SY . Identification of novel variants in the Cx29 gene of nonsyndromic hearing loss patients using buccal cells and restriction fragment length polymorphism method . Audiology and Neuro-Otology . 15 . 2 . 81–7 . 2010 . 19657183 . 10.1159/000231633 . 24962158 .
• Altevogt BM, Kleopa KA, Postma FR, Scherer SS, Paul DL . Connexin29 is uniquely distributed within myelinating glial cells of the central and peripheral nervous systems . The Journal of Neuroscience . 22 . 15 . 6458–70 . August 2002 . 12151525 . 10.1523/JNEUROSCI.22-15-06458.2002. 6758161 . free .
• Sargiannidou I, Ahn M, Enriquez AD, Peinado A, Reynolds R, Abrams C, Scherer SS, Kleopa KA . Human oligodendrocytes express Cx31.3: function and interactions with Cx32 mutants . Neurobiology of Disease . 30 . 2 . 221–33 . May 2008 . 18353664 . 2704064 . 10.1016/j.nbd.2008.01.009 .

Notes and References

1. Web site: Entrez Gene: gap junction protein.
2. Altevogt BM, Kleopa KA, Postma FR, Scherer SS, Paul DL . Connexin29 is uniquely distributed within myelinating glial cells of the central and peripheral nervous systems . The Journal of Neuroscience . 22 . 15 . 6458–70 . August 2002 . 12151525 . 10.1523/JNEUROSCI.22-15-06458.2002. 6758161 . free .
3. Rash JE, Vanderpool KG, Yasumura T, Hickman J, Beatty JT, Nagy JI . KV1 channels identified in rodent myelinated axons, linked to Cx29 in innermost myelin: support for electrically active myelin in mammalian saltatory conduction . Journal of Neurophysiology . 115 . 4 . 1836–59 . April 2016 . 26763782 . 4869480 . 10.1152/jn.01077.2015 .