Gap junctions in Drosophila: developmental expression of the entire innexin gene family

Abstract

Invertebrate gap junctions are composed of proteins called innexins and eight innexin encoding loci have been identified in the now complete genome sequence of Drosophila melanogaster. The intercellular channels formed by these proteins are multimeric and previous studies have shown that, in a heterologous expression system, homo- and hetero-oligomeric channels can form, each combination possessing different gating characteristics. Here we demonstrate that the innexins exhibit complex overlapping expression patterns during oogenesis, embryogenesis, imaginal wing disc development and central nervous system development and show that only certain combinations of innexin oligomerization are possible in vivo. This work forms an essential basis for future studies of innexin interactions in Drosophila and outlines the potential extent of gap-junction involvement in development.

Immunocytochemical study of gap junction-related protein, innexin 2, in Periplaneta americana (Blattodea: Blattidae)

“…It is known that the central nervous systems of fruit flies express innexin 2 (Stebbings et al, 2002), and in our Western blotting, a weak band was detected in extracts of the brain and eyes; however, in our immunohistochemistry, no specific reactions were detected in the cockroach brain. Although the reason remains to be clarified, the specificity of antisera and/or tissue-specific modification of innexin 2 might be related.…”

The Expression of Tubulin and Tektin Genes in Dicyemid Mesozoans (Phylum: Dicyemida)

“…Several, organ-specific innexin genes were reported in a leech, H. medicinalis (Dykes and Macagno, 2006), in Drosophila melanogaster (Drosophilidae) (Stebbings et al, 2002), and in C. elegans (Starich et al, 2003;Chuang et al, 2007;Whitten and Miller, 2007). In embryonic stages, they were exclusively expressed in germ layers, but the dicyemid innexin was expressed in all blastomeres of developing embryos after the 24-cell stage.…”

Astrocytic glutamate transport regulates a Drosophila CNS synapse that lacks astrocyte ensheathment

“…Molecular evidence indicates that fly astrocytes express neurotransmitter transporters (glutamate transporter, Eaat1, and GABA transporter, Gat) (Rival et al, 2004;Thimgan et al, 2006) and receptors (metabotropic GABA receptors) (Mezler et al, 2001;Muthukumar et al, 2014), as well as gap-junction forming innexins (Stebbings et al, 2002), much like their mammalian counterparts (Kimelberg and Nedergaard, 2010). Several complex behaviors have been shown to be influenced by genes expressed in Drosophila astrocytes.…”