Effects of a Sertoli cell specific knockout of the connexin43-gene on the regulation of spermatogenesis in transgenis mice using the Cre/IoxP-recombination system

睾丸缝隙连接蛋白Cx43(Cx43)位于相邻的支持细胞(SC)之间以及SC和生殖细胞之间。它参与了睾丸发育、生殖细胞分化、精子发生的启动和维持。由于Cx43基因的完全破坏会导致围产儿死亡，我们使用Cre/loxP重组系统产生了一个条件性Cx43基因敲除(KO)小鼠，该系统在SC(SCCx43KO)中唯一缺乏Cx43基因，以评估Cx43在体内精子发生中的SC特异性功能。成年SCCx43KO~A小鼠表现出正常的睾丸下降和泌尿生殖道发育，但与杂合子和野生型(WT)小鼠相比，睾丸的大小和重量显著降低。组织学分析和生殖细胞特异性标记基因的mRNA表达定量分析显示，精原细胞数量显著减少，仅剩下少数小管显示正常精子发生。因此，Cx43的SC特异性缺失主要导致精原细胞或SC综合征水平的精子发生停止，并导致小管内SC·簇。我们的数据表明，Cx43在SC中的表达是正常睾丸发育和精子发生的绝对必要条件。

The predominant testicular gap junctional protein connexin43 (cx43) is located « between neighboring Sertoli cells (SC) and between SC and germ cells. It is involved in • testicular development, germ cell differentiation, initiation and maintenance of spermatogenesis. As total disruption of the cx43 gene leads to perinatal death, we generated a « conditional cx43 knockout (KO) mouse using the Cre/loxP recombination system which | lacks the cx43 gene solely in SC (SCCx43KO) to evaluate the SC specific functions of cx43 on spermatogenesis in-vivo. Adult SCCx43KO~A mice showed normal testis descent and • development of the urogenital tract, but testis size and weight was drastically lower when | compared with heterozygous and wild-type (WT) littermates. Histological analysis and quantitation of mRNA expression of germ cell-specific marker genes revealed a significant , • reduction in the number of spermatogonia with only a few tubules left showing normal spermatogenesis. Thus, SC-specific deletion of cx43 mostly .resulted in an arrest of spermatogenesis at the level of spermatogonia or SC-only syndrome and to intratubular SC • clusters. Our data demonstrate that cx43 expression in SC is an absolute requirement for normal testicular development and spermatogenesis.