Hu Tingwenyi, Tang Xiangrong, Ruan Tiechao, Long Shunhua, Liu Guicen, Ma Jing, Li Xueqi, Zhang Ruoxuan, Huang Guoning, Shen Ying, Lin Tingting
Chongqing Key Laboratory of Human Embryo Engineering and Precision Medicine, Center for Reproductive Medicine, Women and Children's Hospital of Chongqing Medical University, Chongqing, 400010, China.
Chongqing Clinical Research Center for Reproductive Medicine, Chongqing Health Center for Women and Children, Chongqing, 400010, China.
Cell Commun Signal. 2025 Jan 23;23(1):41. doi: 10.1186/s12964-025-02043-z.
Asthenozoospermia (ASZ) accounts for about 20-40% of male infertility, and genetic factors, contributing to 30-40% of the causes of ASZ, still need further exploration. Radial spokes (RSs), a T-shaped macromolecular complex, connect the peripheral doublet microtubules (DMTs) to a central pair (CP), forming a CP-RS-DMT structure to regulate the beat frequency and amplitude of sperm flagella. To date, many components of RSs and their functions in human sperm flagella remain unclear.
We recruited a cohort of 323 infertile males with ASZ between August 2019 and June 2024. Genetic mutations were identified by whole-exome sequencing. Computer-aided sperm analysis, Papanicolaou staining, and electron microscopy were applied to evaluate the motility, morphology, and ultrastructure of spermatozoa, respectively. Protein mass spectrometry, western blotting, and bioinformatic analyses were performed to identify critical components of mammalian RS1 to model its structure and explore the pathological mechanism of IQUB deficiency. Intracytoplasmic sperm injection (ICSI) was applied for the patient and Iqub mice.
We identified a novel homozygous IQUB mutation [c.842del (p.L281Pfs*28)] in an ASZ male with normal sperm morphology (ANM), which resulted in the complete loss of IQUB in sperm flagella. Deficiency of RS1, but not RS2 or RS3, was observed in both IQUB patient and Iqub mice, and resulted in the reduction of sperm kinetic parameters, indicating the critical role of IQUB in regulating mammalian RS1 assembly and sperm flagellar beat. More importantly, we identified twelve critical components of RS1 in humans and mice, among which RSPH3, RSPH6A, RSPH9 and DYDC1 constituting the head, DYDC1, NME5, DNAJB13 and PPIL6 assembling into the head-neck complex, AK8, ROPN1L, RSPH14, DYNLL1, and IQUB forming the stalk of RS1. Along with the RS1 defect, the IQUB deficiency caused significant down-regulation of the inner dynein arms of DNAH7 and DNAH12, highlighting their nearby location with RS1. Finally, ICSI can effectively resolve the male infertility caused by IQUB genetic defects.
We demonstrate that IQUB may serve as an adapter for sperm flagellar RS1 in both humans and mice and consolidated the causal relationship between IQUB genetic mutations and ANM, further enriching the genetic spectrum of male infertility.
弱精子症（ASZ）约占男性不育症的20%-40%，而导致ASZ病因的30%-40%的遗传因素仍有待进一步探索。辐条（RSs）是一种T形大分子复合物，将外周双联微管（DMTs）与中央微管对（CP）相连，形成CP-RS-DMT结构，以调节精子鞭毛的摆动频率和幅度。迄今为止，RSs的许多组成成分及其在人类精子鞭毛中的功能仍不清楚。
我们招募了一组在2019年8月至2024年6月期间患有ASZ的323名不育男性。通过全外显子组测序鉴定基因突变。应用计算机辅助精子分析、巴氏染色和电子显微镜分别评估精子的活力、形态和超微结构。进行蛋白质质谱分析、蛋白质印迹分析和生物信息学分析，以鉴定哺乳动物RS1的关键成分，构建其结构模型，并探索IQUB缺陷的病理机制。对患者和Iqub小鼠应用卵胞浆内单精子注射（ICSI）。
我们在一名精子形态正常（ANM）的ASZ男性中鉴定出一种新的纯合IQUB突变[c.842del（p.L281Pfs*28）]，该突变导致精子鞭毛中IQUB完全缺失。在IQUB患者和Iqub小鼠中均观察到RS1缺乏，但未观察到RS2或RS3缺乏，这导致精子动力学参数降低，表明IQUB在调节哺乳动物RS1组装和精子鞭毛摆动中起关键作用。更重要的是，我们鉴定出人类和小鼠中RS1的十二个关键成分，其中RSPH3、RSPH6A、RSPH9和DYDC1构成头部，DYDC1、NME5、DNAJB13和PPIL6组装成头颈复合体，AK8、ROPN1L、RSPH14、DYNLL1和IQUB形成RS1的柄部。随着RS1缺陷，IQUB缺乏导致DNAH7和DNAH12内动力臂显著下调，突出了它们与RS1的邻近位置。最后，ICSI可以有效解决由IQUB基因缺陷引起的男性不育问题。
我们证明IQUB在人类和小鼠中可能作为精子鞭毛RS1的衔接蛋白，并巩固了IQUB基因突变与ANM之间的因果关系，进一步丰富了男性不育的遗传谱。
