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Gene Review

Gjc1  -  gap junction protein, gamma 1

Mus musculus

Synonyms: C130009G16Rik, Cnx45, Connexin-45, Cx45, Cxn-45, ...
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Disease relevance of Gja7


High impact information on Gja7

  • Heterozygous Cx45(+/)(-) mice showed strong expression of the reporter gene in vascular and visceral smooth muscle cells [3].
  • Cx36 and Cx45 immunoreactive signals were found in the inner and outer plexiform layer, both of which are known to show interneuronal gap junctions [4].
  • Thus, the expression of Cx45 and Cx43 is upregulated during skeletal muscle regeneration and Cx43 is required for normal myogenesis in vitro and adult muscle regeneration in vivo [5].
  • A comparison of the kinetics of fluorescent dye transfer showed Cx32, Cx26 and Cx45 to have progressively decreasing permeabilities to LY, but increasing permeabilities to DAPI [6].
  • Mice with targeted replacement of the Cx45 coding region by lacZ showed a vascular expression similar to Cx43 [7].

Biological context of Gja7

  • In fetal ovary, the mRNA transcripts for 3 more connexins (Cx31, Cx37 and Cx45) were expressed in all the genotypes [8].
  • The connexin genes Cx31 and Cx45 coding for proteins of gap junctional subunits have been assigned to mouse chromosomes 4 and 11 by Southern blot hybridization of specific gene probes to DNA from mouse x Chinese hamster somatic cell hybrids [9].
  • We found that Cx40/Cx45 double deficiency (Cx40(-/-)/Cx45(+/-)) causes a variety of cardiac defects leading to high mortality during embryonic development and at birth [10].
  • Cx45 might be one of the genetic modifiers that can cause variations in the phenotype of connexin40-deficient animals [10].
  • Connexin40 (Cx40) and connexin45 (Cx45) are involved in both cardiac morphogenesis and propagation of electrical activity [10].

Anatomical context of Gja7

  • The data show that native insulin-producing cells express a connexin isoform (Cx36) which differs from those (Cx43 and Cx45) expressed by vascular islet cells [7].
  • To investigate whether these connexins form heterotypic gap junctions between ON cone bipolar and AII amacrine cells, we used newly developed Cx45 antibodies and studied the cellular and subcellular distribution of this protein in the mouse retina [11].
  • In the mature inner ear, Cx45 was expressed in the entire vasculature [12].
  • From birth onwards, Cx45 expression could be detected in some inner ear capillaries [12].
  • In the AV node, cell-cell coupling is mediated by abundantly expressed Cx30.2 and Cx45 and Cx40, which is expressed to a lesser extent [13].

Associations of Gja7 with chemical compounds

  • In rodents, gene knock out in mice have vastly improved our understanding of the role of Cx genes in mouse placental development: Cx26 in transplacental uptake of glucose, Cx31 in the proliferative process of trophoblastic cells and Cx45 in placental vascularisation [14].
  • Antibodies to the gap junction protein connexin45 (Cx45) were obtained by immunizing rabbits with fusion protein consisting of glutathione S-transferase and 138 carboxy-terminal amino acids of mouse Cx45 [15].
  • Treatment with dibutyryl cyclic adenosine- or guanosine monophosphate (cAMP, cGMP) did not alter the level of Cx45 phosphorylation, in either Cx45 transfectants or in 293 or BHK21 cells [15].
  • The connexin45 (Cx45) gene was cloned from a mouse genomic Bacterial Artificial Chromosome library [16].
  • Alterations of the electrophysiological properties of the Cx45(-/-) cardiac myocytes were indicated both by extracellular recording on planar multielectrode array probes and by intracellular Ca(2+) recording of the fluorescent Ca(2+) indicator fura-2 [17].

Co-localisations of Gja7

  • We quantified the distributions of these two connexins in the ON sublamina, and detected 30% of the Cx45 signals to be co-localized with or in close apposition to Cx36 signals [11].

Other interactions of Gja7

  • Transcripts of three connexin isoforms (Cx36, Cx43 and Cx45) have been reported in rodent pancreatic islets, but the precise distribution of the cognate proteins is still unknown [7].
  • Cx40 and Cx45 mRNAs were detectable in ventricular homogenates even at 17.5 dpc, probably accounting for the residual conduction function [18].
  • Several genes involved in vasculogenesis and cardiogenesis were validated by real time quantitative PCR (RTQPCR), including Connexin 45, a gene required for normal vascular development, and Dnajb9 a gene implicated in microvascular differentiation [19].
  • Of great surprise is the function of Cx45 in the endothelium, where it is essential for synchronized activation of the transcription factor Nfatc1 [20].
  • The residual 5% coupling contributed by the additional connexins (Cx40, Cx45, and Cx46) expressed in KO astrocytes still suffices to provide a more substantial portion of Ca2+ wave propagation than does signaling through extracellular purinergic pathways [21].

Analytical, diagnostic and therapeutic context of Gja7

  • RESULTS: Total Cx45 protein abundance measured by immunoblotting was not different in Cx43-deficient or null hearts compared to wild-type control hearts [22].
  • The present study was undertaken to determine the distribution pattern of Cx36, Cx43, and Cx45 by immunofluorescence, as well as their gene expression levels by quantitative PCR during postnatal development of the mouse retina [23].
  • Specificity of the Cx45 antibodies was determined, among others, by Western blot and immunostaining of mouse heart, where Cx45 is abundantly expressed [11].
  • As reported previously (Maxeiner et al., 2005), Cx45 was found in some ON bipolar cells, but RT-PCR showed Cx36 and not Cx45 to be expressed by the type 357 bipolar cells [24].
  • As shown by immunoblotting and immunofluorescence, the affinity-purified antibodies recognized Cx45 protein in transfected human HeLa cells as well as in the kidney-derived human and hamster cell lines 293 and BHK21, respectively [15].


  1. Expression patterns of connexin genes in mouse retina. Güldenagel, M., Söhl, G., Plum, A., Traub, O., Teubner, B., Weiler, R., Willecke, K. J. Comp. Neurol. (2000) [Pubmed]
  2. Fine-structural analysis and connexin expression in the retina of a transgenic model of Huntington's disease. Petrasch-Parwez, E., Habbes, H.W., Weickert, S., Löbbecke-Schumacher, M., Striedinger, K., Wieczorek, S., Dermietzel, R., Epplen, J.T. J. Comp. Neurol. (2004) [Pubmed]
  3. Defective vascular development in connexin 45-deficient mice. Krüger, O., Plum, A., Kim, J.S., Winterhager, E., Maxeiner, S., Hallas, G., Kirchhoff, S., Traub, O., Lamers, W.H., Willecke, K. Development (2000) [Pubmed]
  4. Connexin expression in the retina. Söhl, G., Güldenagel, M., Traub, O., Willecke, K. Brain Res. Brain Res. Rev. (2000) [Pubmed]
  5. Expression of connexins during differentiation and regeneration of skeletal muscle: functional relevance of connexin43. Araya, R., Eckardt, D., Maxeiner, S., Krüger, O., Theis, M., Willecke, K., Sáez, J.C. J. Cell. Sci. (2005) [Pubmed]
  6. A quantitative analysis of connexin-specific permeability differences of gap junctions expressed in HeLa transfectants and Xenopus oocytes. Cao, F., Eckert, R., Elfgang, C., Nitsche, J.M., Snyder, S.A., H-ulser, D.F., Willecke, K., Nicholson, B.J. J. Cell. Sci. (1998) [Pubmed]
  7. Replacement by a lacZ reporter gene assigns mouse connexin36, 45 and 43 to distinct cell types in pancreatic islets. Theis, M., Mas, C., Döring, B., Degen, J., Brink, C., Caille, D., Charollais, A., Krüger, O., Plum, A., Nepote, V., Herrera, P., Meda, P., Willecke, K. Exp. Cell Res. (2004) [Pubmed]
  8. mRNA expression pattern of multiple members of connexin gene family in normal and abnormal fetal gonads in mouse. Juneja, S.C. Indian J. Physiol. Pharmacol. (2003) [Pubmed]
  9. Chromosomal assignments of mouse connexin genes, coding for gap junctional proteins, by somatic cell hybridization. Schwarz, H.J., Chang, Y.S., Hennemann, H., Dahl, E., Lalley, P.A., Willecke, K. Somat. Cell Mol. Genet. (1992) [Pubmed]
  10. Cardiac morphogenetic defects and conduction abnormalities in mice homozygously deficient for connexin40 and heterozygously deficient for connexin45. Kr??ger, O., Maxeiner, S., Kim, J.S., van Rijen, H.V., de Bakker, J.M., Eckardt, D., Tiemann, K., Lewalter, T., Ghanem, A., L??deritz, B., Willecke, K. J. Mol. Cell. Cardiol. (2006) [Pubmed]
  11. Localization of heterotypic gap junctions composed of connexin45 and connexin36 in the rod pathway of the mouse retina. Dedek, K., Schultz, K., Pieper, M., Dirks, P., Maxeiner, S., Willecke, K., Weiler, R., Janssen-Bienhold, U. Eur. J. Neurosci. (2006) [Pubmed]
  12. Expression of the connexin43- and connexin45-encoding genes in the developing and mature mouse inner ear. Cohen-Salmon, M., Maxeiner, S., Krüger, O., Theis, M., Willecke, K., Petit, C. Cell Tissue Res. (2004) [Pubmed]
  13. Connexin-mediated cardiac impulse propagation: connexin 30.2 slows atrioventricular conduction in mouse heart. Kreuzberg, M.M., Willecke, K., Bukauskas, F.F. Trends Cardiovasc. Med. (2006) [Pubmed]
  14. Involvement of gap junctions in placental functions and development. Malassiné, A., Cronier, L. Biochim. Biophys. Acta (2005) [Pubmed]
  15. Immunochemical characterization of the gap junction protein connexin45 in mouse kidney and transfected human HeLa cells. Butterweck, A., Gergs, U., Elfgang, C., Willecke, K., Traub, O. J. Membr. Biol. (1994) [Pubmed]
  16. Sequence and structure of the mouse connexin45 gene. Baldridge, D., Lecanda, F., Shin, C.S., Stains, J., Civitelli, R. Biosci. Rep. (2001) [Pubmed]
  17. Conduction abnormality in gap junction protein connexin45-deficient embryonic stem cell-derived cardiac myocytes. Egashira, K., Nishii, K., Nakamura, K., Kumai, M., Morimoto, S., Shibata, Y. The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology. (2004) [Pubmed]
  18. Null mutation of connexin43 causes slow propagation of ventricular activation in the late stages of mouse embryonic development. Vaidya, D., Tamaddon, H.S., Lo, C.W., Taffet, S.M., Delmar, M., Morley, G.E., Jalife, J. Circ. Res. (2001) [Pubmed]
  19. Microarray analysis of the Df1 mouse model of the 22q11 deletion syndrome. Prescott, K., Ivins, S., Hubank, M., Lindsay, E., Baldini, A., Scambler, P. Hum. Genet. (2005) [Pubmed]
  20. Regulation of the epithelial-mesenchymal transformation through gap junction channels in heart development. Nishii, K., Kumai, M., Shibata, Y. Trends Cardiovasc. Med. (2001) [Pubmed]
  21. Calcium waves between astrocytes from Cx43 knockout mice. Scemes, E., Dermietzel, R., Spray, D.C. Glia (1998) [Pubmed]
  22. Redistribution of connexin45 in gap junctions of connexin43-deficient hearts. Johnson, C.M., Kanter, E.M., Green, K.G., Laing, J.G., Betsuyaku, T., Beyer, E.C., Steinberg, T.H., Saffitz, J.E., Yamada, K.A. Cardiovasc. Res. (2002) [Pubmed]
  23. Expression of connexins 36, 43, and 45 during postnatal development of the mouse retina. Kihara, A.H., Mantovani de Castro, L., Belmonte, M.A., Yan, C.Y., Moriscot, A.S., Hamassaki, D.E. J. Neurobiol. (2006) [Pubmed]
  24. Different functional types of bipolar cells use different gap-junctional proteins. Lin, B., Jakobs, T.C., Masland, R.H. J. Neurosci. (2005) [Pubmed]
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