Physiological and physiopathological aspects of connexins and communicating gap junctions in spermatogenesis.
Gap junctions are made of connexin (Cx) molecules and provide communications between adjacent cells through which small molecules (<1kDa) move between cytoplasms. The connexin gene family consists of at least 17 members. Gap junctions play important roles in ovarian and testicular function. Connexin 43 (Cx43) knockout mouse is a model for developmentally impaired fetal gonads. The aim of the current study was twofold: (a) to analyze mRNA expression pattern of multiple members of connexin gene family in normal fetal gonads; (b) to investigate any alteration of mRNA expression of connexins in developmentally impaired fetal gonads. The study was conducted in normal gonads obtained from 17.5 dpc wildtype (Cx43+/+) and heterozygote (Cx43+/-) fetuses and in developmentally impaired gonads obtained from 17.5 dpc knockout (Cx43-/-) fetuses. The mRNA expression pattern of connexins (Cx26, Cx30.3, Cx31, Cx31.1, Cx32, Cx37, Cx40, Cx43, Cx45, Cx46 and Cx50) was analyzed by RT-PCR. The mRNA transcripts for Cx32 and Cx50 were absent in fetal testis of all the genotypes, and the transcripts for Cx26, Cx30.3, Cx31.1, Cx32, Cx40, Cx46 and Cx50 were absent in fetal ovary of all the genotypes. The transcripts for Cx43 showed expression in Cx43+/+ and Cx43+/- gonads and were absent in Cx43-/- gonads, as expected. Additionally, the mRNA transcripts for 8 more connexins (Cx26, Cx30.3, Cx31, Cx31.1, Cx37, Cx40, Cx45 and Cx46) showed expression in Cx43+/+ and Cx43+/- fetal testes, but the transcripts for only 4 connexins (Cx26, Cx37, Cx40 and Cx45) showed expression in Cx43-/- fetal testis. In fetal ovary, the mRNA transcripts for 3 more connexins (Cx31, Cx37 and Cx45) were expressed in all the genotypes. In summary, from the mRNA expression analysis of 11 members of connexin, gene family in 17.5 dpc fetal gonads, besides the expression of Cx43, 8 additional connexins were expressed in normal fetal testis but only 4 connexins were expressed in developmentally impaired testis. The fetal ovary showed the expression of 3 additional connexins besides the expression of Cx43. In developmentally impaired fetal ovary, only Cx43 was not expressed as expected but other three connexins were expresed. The study may be useful in interpreting human testis defects in infertility cases.