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Gene Review

GJA8  -  gap junction protein, alpha 8, 50kDa

Homo sapiens

Synonyms: CAE, CAE1, CTRCT1, CX50, CZP1, ...
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Disease relevance of GJA8

  • Cx50 expression was diminished in malignant pheochromocytomas [1].
  • Mutations in GJA8 cause 3.3% of congenital cataracts in the population of India [2].
  • These vectors employ the cis-acting element (CAE I) that directs the transcription of one of the most strongly expressed genes of cowpox virus [3].
  • Two insertion vectors have been constructed; each is designed to allow cloned genes to be placed immediately downstream of a modified version of CAE I within a poxvirus genome [3].
  • Sixty-eight patients with non-small cell lung cancer were treated in a prospectively randomized study with cyclophosphamide, doxorubicin (Adriamycin), and etoposide (VP16-213) with cisplatinum (CAE +/- P) [4].

Psychiatry related information on GJA8


High impact information on GJA8

  • Loci for autosomal dominant "zonular pulverulent" cataract have been mapped to chromosomes 1q (CZP1) and 13q (CZP3) [7].
  • A missense mutation in the human connexin50 gene (GJA8) underlies autosomal dominant "zonular pulverulent" cataract, on chromosome 1q [8].
  • Sequence analysis of the entire protein-coding region of the GJA8 gene from the pedigree detected a C-->T transition in codon 88, which introduced a novel MnlI restriction-enzyme site that also cosegregated with the cataract [8].
  • CZP1, a locus for autosomal dominant "zonular pulverulent" cataract, previously had been linked with the Duffy blood-group-antigen locus on chromosome 1q [8].
  • To map the CZP1 locus we performed linkage analysis using microsatellite markers on two distantly related branches of the original Ev. pedigree, which now spans eight generations [8].

Chemical compound and disease context of GJA8


Biological context of GJA8

  • RESULTS: Several single nucleotide polymorphisms in CRYG, CRYBB2, and GJA8 genes were observed [11].
  • CONCLUSIONS: This study confirms the previous provisional assignment of MP70 to human chromosome 1 and regionally localizes the gene to 1q21 [12].
  • These results suggest that the C-terminus of human Cx50 is involved in pHi sensitivity, but has little influence over single-channel conductance, voltage dependence, or gating kinetics [13].
  • The DNA probe contained the entire MP70 coding region within a clone isolated from a human genomic DNA library [12].
  • We used the dual whole-cell patch-clamp technique to investigate the macroscopic and single-channel properties of gap junctional channels formed by wild-type human Cx50 and a truncation mutant (Cx50A294stop) after transfection of N2A cells [13].

Anatomical context of GJA8

  • Immunohistochemistry showed that Cx50 expression seemed to be the predominant form of Cx expressed in human chromaffin cells, whereas Cx43 immunoreactivity was the most prominent form found in the adrenal cortex [1].
  • The blocking action of 2-APB did not substantially alter transjunctional voltage-dependent gating of Cx50 gap junction channels, and recordings from poorly coupled pairs of Cx50-transfected N2A cells indicated that 2-APB reduced gap junction channel open probability without changing the main state single-channel conductance [14].
  • We have examined the effect of three lens fiber cell membrane proteins, MP20, MP26 and MP70, on the permeability properties of unilamellar phospholipid liposomes [15].
  • There was no Cx50 expression observed and Cx40 was localized in the endothelial cells of blood vessels, with the Huntington's diseased brains having more numerous and smaller blood vessels than normal tissue [16].
  • HeLa cell nuclear extract contained a protein that specifically binds to CAE1 and CAE2 and recognized by anti-ZNF143 antibody [17].

Associations of GJA8 with chemical compounds


Other interactions of GJA8

  • Gap junction channels formed by connexin 50 (Cx50) are critical for maintenance of lens transparency [13].
  • We show now that MP70 can be solubilized separately from MIP in mild detergent solutions, and that this treatment results in the dissociation of the fibre gap junctions [23].

Analytical, diagnostic and therapeutic context of GJA8


  1. Expression of connexins in chromaffin cells of normal human adrenals and in benign and malignant pheochromocytomas. Willenberg, H.S., Schott, M., Saeger, W., Tries, A., Scherbaum, W.A., Bornstein, S.R. Ann. N. Y. Acad. Sci. (2006) [Pubmed]
  2. Novel mutations in GJA8 associated with autosomal dominant congenital cataract and microcornea. Devi, R.R., Vijayalakshmi, P. Mol. Vis. (2006) [Pubmed]
  3. A poxvirus-derived vector that directs high levels of expression of cloned genes in mammalian cells. Patel, D.D., Ray, C.A., Drucker, R.P., Pickup, D.J. Proc. Natl. Acad. Sci. U.S.A. (1988) [Pubmed]
  4. Randomized study of cyclophosphamide, doxorubicin, and etoposide (VP16-213) with or without cisplatinum in non-small cell lung cancer. Fuks, J.Z., Aisner, J., Van Echo, D.A., Schipper, H., Levitt, M., Ostrow, S., Wiernik, P.H. J. Clin. Oncol. (1983) [Pubmed]
  5. The human lens intrinsic membrane protein MP70 (Cx50) gene: clonal analysis and chromosome mapping. Church, R.L., Wang, J.H., Steele, E. Curr. Eye Res. (1995) [Pubmed]
  6. Evolution of childhood absence epilepsy, juvenile myoclonic epilepsy and epilepsy with grand mal on awakening. Shian, W.J., Chi, C.S. Zhonghua Minguo xiao er ke yi xue hui za zhi [Journal]. Zhonghua Minguo xiao er ke yi xue hui (1994) [Pubmed]
  7. Connexin46 mutations in autosomal dominant congenital cataract. Mackay, D., Ionides, A., Kibar, Z., Rouleau, G., Berry, V., Moore, A., Shiels, A., Bhattacharya, S. Am. J. Hum. Genet. (1999) [Pubmed]
  8. A missense mutation in the human connexin50 gene (GJA8) underlies autosomal dominant "zonular pulverulent" cataract, on chromosome 1q. Shiels, A., Mackay, D., Ionides, A., Berry, V., Moore, A., Bhattacharya, S. Am. J. Hum. Genet. (1998) [Pubmed]
  9. N-alpha-Cocoyl-L-arginine ethyl ester, DL-pyroglutamic acid salt, as an inactivator of hepatitis B surface antigen. Sugimoto, Y., Toyoshima, S. Antimicrob. Agents Chemother. (1979) [Pubmed]
  10. Phase I study of gemcitabine and liposomal doxorubicin in relapsed ovarian cancer. D'Agostino, G., Ferrandina, G., Garganese, G., Salerno, M.G., Lorusso, D., Farnetano, M.G., Mancuso, S., Scambia, G. Oncology (2002) [Pubmed]
  11. Mutation analysis of congenital cataracts in Indian families: identification of SNPS and a new causative allele in CRYBB2 gene. Santhiya, S.T., Manisastry, S.M., Rawlley, D., Malathi, R., Anishetty, S., Gopinath, P.M., Vijayalakshmi, P., Namperumalsamy, P., Adamski, J., Graw, J. Invest. Ophthalmol. Vis. Sci. (2004) [Pubmed]
  12. Regional mapping of the human MP70 (Cx50; connexin 50) gene by fluorescence in situ hybridization to 1q21.1. Geyer, D.D., Church, R.L., Steele, E.C., Heinzmann, C., Kojis, T.L., Klisak, I., Sparkes, R.S., Bateman, J.B. Mol. Vis. (1997) [Pubmed]
  13. Functional role of the carboxyl terminal domain of human connexin 50 in gap junctional channels. Xu, X., Berthoud, V.M., Beyer, E.C., Ebihara, L. J. Membr. Biol. (2002) [Pubmed]
  14. Block of Specific Gap Junction Channel Subtypes by 2-Aminoethoxydiphenyl Borate (2-APB). Bai, D., Del Corsso, C., Srinivas, M., Spray, D.C. J. Pharmacol. Exp. Ther. (2006) [Pubmed]
  15. The permeability of reconstituted liposomes containing the purified lens fiber cell integral membrane proteins MP20, MP26 and MP70. Jarvis, L.J., Louis, C.F. J. Membr. Biol. (1992) [Pubmed]
  16. Connexin expression in Huntington's diseased human brain. Vis, J.C., Nicholson, L.F., Faull, R.L., Evans, W.H., Severs, N.J., Green, C.R. Cell Biol. Int. (1998) [Pubmed]
  17. Transcriptional regulation of the mouse cytosolic chaperonin subunit gene Ccta/t-complex polypeptide 1 by selenocysteine tRNA gene transcription activating factor family zinc finger proteins. Kubota, H., Yokota, S., Yanagi, H., Yura, T. J. Biol. Chem. (2000) [Pubmed]
  18. Mefloquine effects on the lens suggest cooperative gating of gap junction channels. Martinez-Wittinghan, F.J., Srinivas, M., Sellitto, C., White, T.W., Mathias, R.T. J. Membr. Biol. (2006) [Pubmed]
  19. Dose-intensity meta-analysis of chemotherapy regimens in small-cell carcinoma of the lung. Klasa, R.J., Murray, N., Coldman, A.J. J. Clin. Oncol. (1991) [Pubmed]
  20. Characterization of neutral proteinases from Alzheimer-affected and control brain specimens: identification of calcium-dependent metalloproteinases from the hippocampus. Backstrom, J.R., Miller, C.A., Tökés, Z.A. J. Neurochem. (1992) [Pubmed]
  21. Current standards of care in small-cell and non-small-cell lung cancer. Schiller, J.H. Oncology (2001) [Pubmed]
  22. Myasthenia gravis. Antibodies to skeletal muscle cell surface antigens. Gilhus, N.E., Aarli, J.A., Matre, R. J. Neuroimmunol. (1983) [Pubmed]
  23. Dissociation of lens fibre gap junctions releases MP70. Kistler, J., Bullivant, S. J. Cell. Sci. (1988) [Pubmed]
  24. Gap junction structures and distribution patterns of immunoreactive connexins 46 and 50 in lens regrowths of Rhesus monkeys. Lo, W.K., Shaw, A.P., Takemoto, L.J., Grossniklaus, H.E., Tigges, M. Exp. Eye Res. (1996) [Pubmed]
  25. The impact of Filgrastim schedule variation on hematopoietic recovery post-chemotherapy. Crawford, J., Kreisman, H., Garewal, H., Jones, S.E., Shoemaker, D., Pupa, M.R., Armstrong, S., Tomita, D., Dziem, G. Ann. Oncol. (1997) [Pubmed]
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