Absence of connexin43 and connexin45 does not disturb pre- and peri-implantation development

Gap junctional intercellular communication is assumed to play an important role during pre- and peri-implantation development. In this study, we eliminated connexin43 (Cx43) and connexin45 (Cx45), major gap junctional proteins in the pre- and peri-implantation embryo. We generated Cx43(-/-)Cx45(-/-) embryos by Cx43(+/-)Cx45(+/-) intercrossing, because mice deficient in Cx43 (Cx43(-/-)) exhibit perinatal lethality and those deficient in Cx45 (Cx45(-/-)) exhibit early embryonic lethality. Wild-type, Cx43(-/-), Cx45(-/-), and Cx43(-/-)Cx45(-/-) blastocysts all showed similar outgrowths in in vitro culture. Moreover, Cx43(-/-)Cx45(-/-) embryos were obtained at the expected Mendelian ratio up to embryonic day 9.5, when the Cx45(-/-) mutation proved lethal. The Cx43(-/-)Cx45(-/-) embryos seemed to have no additional developmental abnormalities in comparison with the single knockout strains. Thus, pre- and peri-implantation development does not require Cx43 and Cx45. Other gap junctional proteins are expressed around these stages and these may compensate for the lack of Cx43 and Cx45.