Sridharan Santhi, Simon Liz, Meling Daryl D, Cyr Daniel G, Gutstein David E, Fishman Glenn I, Guillou Florian, Cooke Paul S
Department of Veterinary Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
Biol Reprod. 2007 May;76(5):804-12. doi: 10.1095/biolreprod.106.059212. Epub 2007 Jan 17.
GJA1 (also known and referred to here as connexin 43 and abbreviated CX43) is the predominant testicular gap junction protein, and CX43 may regulate Sertoli cell maturation and spermatogenesis. We hypothesized that lack of CX43 would inhibit Sertoli cell differentiation and extend proliferation. To test this, a Sertoli cell-specific Cx43 knockout (SC-Cx43 KO) mouse was generated using Cre-lox technology. Immunohistochemistry indicated that CX43 was not expressed in the Sertoli cells of SC-Cx43 KO mice, but was normal in organs such as the heart. Testicular weight was reduced by 41% and 76% in SC-Cx43 KO mice at 20 and 60 days, respectively, vs. wild-type (wt) mice. Seminiferous tubules of SC-Cx43 KO mice contained only Sertoli cells and actively proliferating early spermatogonia. Sertoli cells normally cease proliferation at 2 wk of age in mice and become terminally differentiated. However, proliferating Sertoli cells were present in SC-Cx43 KO but not wt mice at 20 and 60 days of age. Thyroid hormone receptor alpha (THRA) is high in proliferating Sertoli cells, then declines sharply in adulthood. Thra mRNA expression was increased in 20-day SC-Cx43 KO vs. wt mice, and it showed a trend toward an increase in 60-day mice, indicating that loss of CX43 in Sertoli cells inhibited their maturation. In conclusion, we have generated mice lacking CX43 in Sertoli cells but not other tissues. Our data indicate that CX43 in Sertoli cells is essential for spermatogenesis but not spermatogonial maintenance/proliferation. SC-Cx43 KO mice showed continued Sertoli cell proliferation and delayed maturation in adulthood, indicating that CX43 plays key roles in Sertoli cell development.
GJA1（在这里也被称为连接蛋白43，缩写为CX43）是睾丸中主要的间隙连接蛋白，CX43可能调节支持细胞的成熟和精子发生。我们假设CX43的缺失会抑制支持细胞的分化并延长其增殖。为了验证这一点，利用Cre-lox技术构建了支持细胞特异性Cx43基因敲除（SC-Cx43 KO）小鼠。免疫组织化学表明，CX43在SC-Cx43 KO小鼠的支持细胞中不表达，但在心脏等器官中表达正常。与野生型（wt）小鼠相比，SC-Cx43 KO小鼠在20天和60天时睾丸重量分别降低了41%和76%。SC-Cx43 KO小鼠的生精小管中仅含有支持细胞和活跃增殖的早期精原细胞。在小鼠中，支持细胞通常在2周龄时停止增殖并最终分化。然而，在20天和60天时，增殖的支持细胞存在于SC-Cx43 KO小鼠而非wt小鼠中。甲状腺激素受体α（THRA）在增殖的支持细胞中含量较高，成年后则急剧下降。与wt小鼠相比，20天龄的SC-Cx43 KO小鼠中Thra mRNA表达增加，60天龄小鼠中也有增加的趋势，这表明支持细胞中CX43的缺失抑制了它们的成熟。总之，我们构建了支持细胞中缺乏CX43而其他组织中不缺乏的小鼠。我们的数据表明，支持细胞中的CX43对精子发生至关重要，但对精原细胞的维持/增殖并非必需。SC-Cx43 KO小鼠在成年期表现出支持细胞持续增殖和成熟延迟，表明CX43在支持细胞发育中起关键作用。
