Department of Functional Anatomy, Reproductive Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, 260-8670, Japan.
Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Sci Rep. 2023 Feb 20;13(1):2969. doi: 10.1038/s41598-023-28177-z.
Normal sperm flagellar shape and movement are essential for fertilization. The integral protein outer dense fiber 4 (ODF4) localizes to ODFs, but its function remains unclear. Adenylate kinase (AK) is a phosphotransferase that catalyzes the interconversion and controls the concentration equilibrium of adenine nucleotides. AK shuttles ATP to energy-consuming sites. Here, we report on the relationship of flagellar shape and movement with ODF4, AK1 and AK2 by using Odf4-deletion (Odf4) mice. Soluble ODF4 is coimmunoprecipitated with AK1 and AK2 in Odf4 spermatozoa. ODF4, AK1 and AK2 localize to whole flagella (plasmalemma, mitochondria, ODFs, and residual cytoplasmic droplets (CDs)), principal pieces, and midpieces, respectively. Odf4 sperm flagella lose ODF4 and reduce AK1 and AK2 but produce ATP. The flagellum is bent (hairpin flagellum) with a large CD in the midpiece. There is no motility in the midpiece, but the principal piece is motile. Odf4 spermatozoa progress backward and fail to ascend in the uterus. Thus, Odf4 males are infertile owing to abnormal flagellar shape and movement caused mainly by the loss of ODF4 with AK1 and AK2. This study is supported by the rescue experiment; the abnormalities and male infertility caused by Odf4 deletion were reversed by Odf4 restoration.
正常的精子鞭毛形态和运动对于受精至关重要。完整的蛋白质外致密纤维 4（ODF4）定位于 ODFs，但它的功能尚不清楚。腺苷酸激酶（AK）是一种磷酸转移酶，可催化相互转化并控制腺嘌呤核苷酸的浓度平衡。AK 将 ATP 穿梭到需要能量的部位。在这里，我们通过使用 Odf4 缺失（Odf4）小鼠报告了鞭毛形态和运动与 ODF4、AK1 和 AK2 的关系。可溶的 ODF4 与 Odf4 精子中的 AK1 和 AK2 共免疫沉淀。ODF4、AK1 和 AK2 分别定位于整条鞭毛（质膜、线粒体、ODFs 和残留的细胞质滴（CDs））、主段和中段。Odf4 精子鞭毛失去 ODF4 并减少 AK1 和 AK2，但产生 ATP。鞭毛弯曲（发夹鞭毛），中段有大的 CD。中段没有运动，但主段有运动。Odf4 精子向后推进并不能在子宫内上升。因此，Odf4 男性由于主要由 ODF4 丢失引起的精子鞭毛形态和运动异常而不育，AK1 和 AK2。这项研究得到了挽救实验的支持；通过 Odf4 恢复，Odf4 缺失引起的异常和男性不育得到逆转。
