Gap junctions in the ovary of Drosophila melanogaster: localization of innexins 1, 2, 3 and 4 and evidence for intercellular communication via innexin-2 containing channels

Abstract

Background: In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the innexin family. In order to reveal the role that innexins play in cell-cell communication during oogenesis, we investigated the localization of innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade.

Bi-directional gap junction-mediated Soma-Germline communication is essential for spermatogenesis

“…This shows that Inx2 is required in the soma to maintain the distribution of Zpg at the somagermline interface, consistent with a coupling of somatic Inx2 with germline Zpg. Moreover, as Zpg is the only fly innexin known to be expressed in the germ line (Bohrmann and Zimmermann, 2008;Stebbings et al, 2002), these results suggest a possible homotypic coupling of Zpg at germline-germline boundaries that competes with the heterotypic coupling of Inx2-Zpg at soma-germline boundaries.…”

“…Furthermore, Inx2 was found to colocalize with Zpg at soma-germline boundaries (Bohrmann and Zimmermann, 2008). Phenotypic analysis of a hypomorphic inx2 mutation in the ovary suggested a role for Inx2 in the soma (Mukai et al, 2011).…”

Developmental Control of Oocyte Maturation and Egg Activation in Metazoan Models

“…Interestingly, the proteins that compose the gap junction channels, innexins (Inx), are widely expressed during Drosophila oogenesis (Stebbings et al 2002). In fact, in vitro injections with antisera against Inx2 (a gap junction protein between oocyte and follicle cells) into stage 10 follicle-enclosed oocytes significantly affected development past stage 10 by blocking follicle cell differentiation, nurse cell regression, and oocyte growth (Bohrmann and Zimmermann 2008). Those oocytes that bypassed the developmental arrest showed defects in chorion formation; however, meiosis was not analyzed in these oocytes (Bohrmann and Zimmermann 2008).…”

“…In fact, in vitro injections with antisera against Inx2 (a gap junction protein between oocyte and follicle cells) into stage 10 follicle-enclosed oocytes significantly affected development past stage 10 by blocking follicle cell differentiation, nurse cell regression, and oocyte growth (Bohrmann and Zimmermann 2008). Those oocytes that bypassed the developmental arrest showed defects in chorion formation; however, meiosis was not analyzed in these oocytes (Bohrmann and Zimmermann 2008). To date, no roles for the Drosophila cAMP transduction pathway during meiosis have been established.…”

Innexin AGAP001476 Is Critical for Mediating Anti-Plasmodium Responses in Anopheles Mosquitoes

“…For instance, AGAP006241 is responsible for gonad development in A. gambiae (26). Innexin 2 in Drosophila ovaries is essential for oogenesis (27). Due to the ubiquitous expression of connexins in all mammalian immune cells, gap junctions have been implicated in various aspects of the immune system, including antigen presentation and transfer of apoptotic signals (28), but these are mostly speculative.…”