Department of Biomedicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Center of Biomedical Research, Research Center for Human Disease Modeling, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Biol Reprod. 2020 Apr 24;102(5):1134-1144. doi: 10.1093/biolre/ioaa017.
Intercellular bridges (ICBs) connecting germ cells are essential for spermatogenesis, and their deletion causes male infertility. However, the functions and component factors of ICBs are still unknown. We previously identified novel ICB-associated proteins by proteomics analysis using ICB enrichment. Here, we performed immunoprecipitation-proteomics analyses using antibodies specific to known ICB proteins MKLP1, RBM44, and ectoplasmic specialization-associated protein KIAA1210 and predicted protein complexes in the ICB cores. KIAA1210, its binding protein topoisomerase2B (TOP2B), and tight junction protein ZO1 were identified as novel ICB proteins. On the other hand, as well as KIAA1210 and TOP2B, MKLP1 and RBM44, but not TEX14, were localized at the XY body of spermatocytes, suggesting that there is a relationship between ICB proteins and meiotic chromosomes. Moreover, small RNAs interacted with an ICB protein complex that included KIAA1210, RBM44, and MKLP1. These results indicate dynamic movements of ICB proteins and suggest that ICB proteins could be involved not only in the communication between germ cells but also in their epigenetic regulation. Our results provide a novel perspective on the function of ICBs and could be helpful in revealing the biological function of the ICB.
细胞间桥（ICBs）连接生殖细胞对于精子发生是必不可少的，其缺失会导致男性不育。然而，ICBs 的功能和组成因素仍不清楚。我们之前通过使用 ICB 富集的蛋白质组学分析鉴定了新型的 ICB 相关蛋白。在这里，我们使用针对已知的 ICB 蛋白 MKLP1、RBM44 和胞质特化相关蛋白 KIAA1210 以及 ICB 核心中的预测蛋白复合物的特异性抗体进行了免疫沉淀蛋白质组学分析。KIAA1210、其结合蛋白拓扑异构酶 2B（TOP2B）和紧密连接蛋白 ZO1 被鉴定为新型 ICB 蛋白。另一方面，与 KIAA1210 和 TOP2B 一样，MKLP1 和 RBM44 而不是 TEX14 定位于精母细胞的 X-Y 体上，表明 ICB 蛋白与减数分裂染色体之间存在关系。此外，小 RNA 与包括 KIAA1210、RBM44 和 MKLP1 在内的 ICB 蛋白复合物相互作用。这些结果表明 ICB 蛋白的动态运动，并表明 ICB 蛋白不仅参与生殖细胞之间的通讯，而且还参与它们的表观遗传调控。我们的研究结果为 ICB 的功能提供了新的视角，并有助于揭示 ICB 的生物学功能。
