Liu Tao, Rahim Fazal, Yang Meng-Lei, Uddin Meftah, Ye Jing-Wei, Ali Imtiaz, Raza Yousaf, Mansoor Abu, Shoaib Muhammad, Hussain Mujahid, Khan Ihsan, Shah Basit, Khan Asad, Nisar Ahmad, Ma Hui, Xu Bo, Shah Wasim, Shi Qing-Hua
Institute of Health and Medicine, Hefei Comprehensive National Science Center, Center for Reproduction and Genetics, First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei 230027, China.
Asian J Androl. 2025 Mar 1;27(2):245-253. doi: 10.4103/aja202496. Epub 2024 Dec 17.
Male infertility can result from impaired sperm motility caused by multiple morphological abnormalities of the flagella (MMAF). Distinct projections encircling the central microtubules of the spermatozoal axoneme play pivotal roles in flagellar bending and spermatozoal movement. Mammalian sperm-associated antigen 17 ( SPAG17 ) encodes a conserved axonemal protein of cilia and flagella, forming part of the C1a projection of the central apparatus, with functions related to ciliary/flagellar motility, skeletal growth, and male fertility. This study investigated two novel homozygous SPAG17 mutations (M1: NM_206996.2, c.829+1G>T, p.Asp212_Glu276del; and M2: c.2120del, p.Leu707*) identified in four infertile patients from two consanguineous Pakistani families. These patients displayed the MMAF phenotype confirmed by Papanicolaou staining and scanning electron microscopy assays of spermatozoa. Quantitative real-time polymerase chain reaction (PCR) of patients' spermatozoa also revealed a significant decrease in SPAG17 mRNA expression, and immunofluorescence staining showed the absence of SPAG17 protein signals along the flagella. However, no apparent ciliary-related symptoms or skeletal malformations were observed in the chest X-rays of any of the patients. Transmission electron microscopy of axoneme cross-sections from the patients showed incomplete C1a projection and a higher frequency of missing microtubule doublets 1 and 9 compared with those from fertile controls. Immunofluorescence staining and Western blot analyses of spermatogenesis-associated protein 17 (SPATA17), a component of the C1a projection, and sperm-associated antigen 6 (SPAG6), a marker of the spring layer, revealed disrupted expression of both proteins in the patients' spermatozoa. Altogether, these findings demonstrated that SPAG17 maintains the integrity of spermatozoal flagellar axoneme, expanding the phenotypic spectrum of SPAG17 mutations in humans.
男性不育可能由鞭毛多重形态异常（MMAF）导致的精子活力受损引起。环绕精子轴丝中央微管的独特突起在鞭毛弯曲和精子运动中起关键作用。哺乳动物精子相关抗原17（SPAG17）编码一种保守的纤毛和鞭毛轴丝蛋白，是中央装置C1a突起的一部分，其功能与纤毛/鞭毛运动、骨骼生长和男性生育能力有关。本研究调查了在两个巴基斯坦近亲家庭的四名不育患者中鉴定出的两个新的纯合SPAG17突变（M1：NM_206996.2，c.829+1G>T，p.Asp212_Glu276del；M2：c.2120del，p.Leu707*）。这些患者表现出MMAF表型，通过精子巴氏染色和扫描电子显微镜检测得以证实。对患者精子进行的定量实时聚合酶链反应（PCR）也显示SPAG17 mRNA表达显著降低，免疫荧光染色显示沿鞭毛不存在SPAG17蛋白信号。然而，在任何患者的胸部X光片中均未观察到明显的纤毛相关症状或骨骼畸形。对患者轴丝横截面的透射电子显微镜检查显示，与可育对照相比，C1a突起不完整，微管双联体1和9缺失的频率更高。对C1a突起的一个组成部分生精相关蛋白17（SPATA17）和弹簧层标志物精子相关抗原6（SPAG6）进行免疫荧光染色和蛋白质印迹分析，结果显示这两种蛋白在患者精子中的表达均受到破坏。总之，这些发现表明SPAG17维持精子鞭毛轴丝的完整性，扩展了人类SPAG17突变的表型谱。
