Hwang Jae Yeon, Wang Huafeng, Clouser Gillian, Oh Jong-Nam, Finnegan Sarah F, Skakkebaek Niels E, Chung Jean-Ju
Department of Cellular and Molecular Physiology, Yale School of Medicine, CT.
Department of Molecular Biology, Pusan National University, Busan, South Korea.
bioRxiv. 2025 Jan 31:2024.11.18.624146. doi: 10.1101/2024.11.18.624146.
The sperm flagellar-specific CatSper Ca channel is a multiprotein complex critical for successful fertilization. The four ancillary subunits, CATSPERβ, γ, δ, and ε, form a unique canopy structure over the pore-forming channel. However, how the canopy is formed and what it does in the assembled channel complex remains unknown. Here, we report that extracellular domains (ECDs) of CATSPERε are essential for canopy and holo-complex assembly and modulate channel activity during sperm capacitation. CATSPERε-deficient males are sterile due to the absence of the entire channel and defective sperm hyperactivation. Expressing ECDs-truncated CATSPERε during spermatogenesis does not rescue the knockout because it fails to incorporate into the native complex. In contrast, addition of a CATSPERε ECD fragment during sperm capacitation significantly reduces channel activity. These findings provide insight into the underlying molecular and developmental mechanisms of CatSper assembly and how the channel can be modulated in physiological settings and by therapeutic intervention.
精子鞭毛特异性的CatSper钙通道是一种多蛋白复合物，对成功受精至关重要。四个辅助亚基CATSPERβ、γ、δ和ε在形成孔道的通道上形成独特的伞状结构。然而，这种伞状结构是如何形成的以及它在组装好的通道复合物中起什么作用仍然未知。在此，我们报告CATSPERε的细胞外结构域（ECD）对于伞状结构和全复合物组装至关重要，并在精子获能过程中调节通道活性。由于整个通道缺失和精子超激活缺陷，CATSPERε缺陷的雄性动物不育。在精子发生过程中表达截短了ECD的CATSPERε并不能挽救基因敲除，因为它无法整合到天然复合物中。相反，在精子获能过程中添加CATSPERε ECD片段会显著降低通道活性。这些发现为CatSper组装的潜在分子和发育机制以及该通道在生理环境和治疗干预中如何被调节提供了见解。
