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Abstract：
The annulus is a septin-based ring structure located at the junction of the midpiece (MP) and the principal piece (PP) of spermatozoa flagellum. In the mouse, deletion of Septin 4, a structural component of the sperm annulus, prevents annulus formation and leads to MP-PP disjunction, flagellar bending, asthenozoospermia and male sterility. Testis anion transporter 1 (Tat1) is a germ cell-specific member of the SLC26 anion transporter family and is co-expressed with Septin 4 at the sperm annulus. Interestingly, Tat1 null sperm bear an atrophic annulus, causing a phenotype similar to that of Sept4 null sperm. We searched for Tat1 misexpression and/or mislocalization in spermatozoa from asthenozoospermic subjects (n = 75) and controls by performing an immunofluorescence detection assay on sperm smear preparations. We found one patient showing moderate asthenozoospermia, with 97% of sperm lacking Tat1, Septin 4 and Septin 7 proteins at the annulus. We confirmed the absence of the annulus structure by transmission electron microscopy and observed that spermatozoa from the patient displayed MP-PP disjunction and abnormal mitochondrial organization. We show that the structural defects in sperm are not caused by abnormal transcription or point mutations of the TAT1 and SEPT4 genes; however, although both proteins are expressed, they are not properly localized at sperm annulus. The case we studied, so far unreported in human, confirms the involvement of Tat1 and Septin proteins in the constitution of the annulus, but also raises questions about the function of this structure in human sperm motility.
摘要：
环是基于隔膜的环结构，位于精子鞭毛的中段（MP）和主段（PP）的交界处。在老鼠身上，精子环的结构成分Septin4的缺失，防止环空形成并导致MP-PP分离，鞭毛弯曲，弱精子症和雄性不育。睾丸阴离子转运蛋白1（Tat1）是SLC26阴离子转运蛋白家族的生殖细胞特异性成员，与Septin4在精子环共表达。有趣的是,Tat1空精子有一个萎缩性环，导致类似于9月4日无精子的表型。我们通过对精子涂片制剂进行免疫荧光检测分析，从弱精子症受试者（n=75）和对照组的精子中搜索了Tat1的错误表达和/或错误定位。我们发现一名患者表现为中度弱精子症，97%的精子环缺乏Tat1、Septin4和Septin7蛋白。我们通过透射电子显微镜证实了环结构的不存在，并观察到患者的精子表现出MP-PP分离和异常的线粒体组织。我们证明精子的结构缺陷不是由TAT1和SEPT4基因的异常转录或点突变引起的；然而，尽管这两种蛋白质都被表达，它们不能正确定位在精子环。我们研究的案例,到目前为止，在人类中没有报道，证实Tat1和Septin蛋白参与环的构成，但也提出了关于这种结构在人类精子运动中的功能的问题。
