Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Mol Hum Reprod. 2020 Jun 1;26(6):402-412. doi: 10.1093/molehr/gaaa031.
The connecting pieces of the sperm neck link the flagellum and the sperm head, and they are important for initiating flagellar beating. The connecting pieces are important building blocks for the sperm neck; however, the mechanism of connecting piece assembly is poorly understood. In the present study, we explored the role of septins in sperm motility and found that Sept12D197N knock-in (KI) mice produce acephalic and immotile spermatozoa. Electron microscopy analysis showed defective connecting pieces in sperm from KI mice, indicating that SEPT12 is required for the establishment of connecting pieces. We also found that SEPT12 formed a complex with SEPT1, SEPT2, SEPT10 and SEPT11 at the sperm neck and that the D197N mutation disrupted the complex, suggesting that the SEPT12 complex is involved in the assembly of connecting pieces. Additionally, we found that SEPT12 interacted and colocalized with γ-tubulin in elongating spermatids, implying that SEPT12 and pericentriolar materials jointly contribute to the formation of connecting pieces. Collectively, our findings suggest that SEPT12 is required for the formation of striated columns, and the capitulum and for maintaining the stability of the sperm head-tail junction.
精子颈的连接片段连接着鞭毛和精子头部，对于启动鞭毛的摆动至关重要。连接片段是精子颈的重要组成部分；然而，其组装的机制尚不清楚。在本研究中，我们探讨了 septin 在精子运动中的作用，发现 Sept12D197N 敲入 (KI) 小鼠产生无头和不动精子。电子显微镜分析显示，KI 小鼠精子中的连接片段存在缺陷，表明 SEPT12 对于连接片段的建立是必需的。我们还发现 SEPT12 在精子颈部与 SEPT1、SEPT2、SEPT10 和 SEPT11 形成复合物，而 D197N 突变破坏了复合物，表明 SEPT12 复合物参与了连接片段的组装。此外，我们发现 SEPT12 在伸长的精母细胞中与 γ-微管蛋白相互作用并共定位，暗示 SEPT12 和中心体周围物质共同参与连接片段的形成。总之，我们的研究结果表明 SEPT12 对于形成横纹柱、顶体以及维持精子头尾部连接的稳定性是必需的。
