Modified expression of testicular gap-junction connexin 43 during normal spermatogenic cycle and in altered spermatogenesis

In order to better understand the implications of gap junction proteins in spermatogenesis, connexin 43 (Cx43), the most abundant connexin in the test is, was evaluated in testes of wild-type mice and of two mutants with impai red spermatogenesis (ebo/ebo and jun-d(-/-) mice). Reverse transcription-po lymerase chain reaction (RT-PCR) amplification revealed a constitutive expr ession of mRNA for Cx43 in both wild-type mice and infertile mutants. In th e seminiferous tubules of wild-type mice, indirect immunofluorescence revea led that Cx43 expression was stage-dependent and that the signal was mainly located in the region of Sertoli cell occluding junctions. Colocalization of Cx43 and of the tight-junction-associated protein zonula occludens 1 (ZO -1) was demonstrated in seminiferous tubules by using dual-label immunofluo rescence in conjunction with confocal microscopy. The Cx43 staining analyze d by high-resolution confocal microscopy appeared as continuous, anastomoze d ribbons and thin dots. The level of Cx43 immunoreactivity was reduced in seminiferous tubules of ebo/ebo and jun-d(-/-) mutants as compared to the r espective willd-type mice. No staining for Cx43 was detected in Sertoli cel l-only seminiferous tubules observed sometimes in jun-d(-/-) mice. The pres ent study represents one of the first in vivo examples of alteration of sem iniferous tubule Cx43 in testes with impaired spermatogenesis.