Department of Obstetrics and Gynecology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei 111, Taiwan.
College of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
Medicina (Kaunas). 2022 Oct 7;58(10):1408. doi: 10.3390/medicina58101408.
Background and Objectives: Septins (SEPTs) are highly conserved GTP-binding proteins and the fourth component of the cytoskeleton. Polymerization of SEPTs contributes to several critical cellular processes such as cytokinesis, cytoskeletal remodeling, and vesicle transportation. In our previous study, we found that SEPT14 mutations resulted in teratozoospermia with >87% sperm morphological defects. SEPT14 interactors were also identified through proteomic assays, and one of the peptides was mapped to RAB3B and RAB3C. Most studies on the RAB3 family have focused on RAB3A, which regulates the exocytosis of neurotransmitters and acrosome reactions. However, the general expression and patterns of the RAB3 family members during human spermatogenesis, and the association between RAB3 and teratozoospermia owing to a SEPT14 mutation, are largely unknown. Materials and Methods: Human sperm and murine male germ cells were collected in this study and immunofluorescence analysis was applied on the collected sperm. Results: In this study, we observed that the RAB3C transcripts were more abundant than those of RAB3A, 3B, and 3D in human testicular tissues. During human spermatogenesis, the RAB3C protein is mainly enriched in elongated spermatids, and RAB3B is undetectable. In mature human spermatozoa, RAB3C is concentrated in the postacrosomal region, neck, and midpiece. The RAB3C signals were delocalized within human spermatozoa harboring the SEPT14 mutation, and the decreased signals were accompanied by a defective head and tail, compared with the healthy controls. To determine whether RAB3C is involved in the morphological formation of the head and tail of the sperm, we separated murine testicular tissue and isolated elongated spermatids for further study. We found that RAB3C is particularly expressed in the manchette structure, which assists sperm head shaping at the spermatid head, and is also localized at the sperm tail. Conclusions: Based on these results, we suggest that the localization of RAB3C proteins in murine and human sperm is associated with SEPT14 mutation-induced morphological defects in sperm.
Septins（SEPTs）是高度保守的 GTP 结合蛋白，是细胞骨架的第四成分。SEPTs 的聚合有助于许多关键的细胞过程，如胞质分裂、细胞骨架重塑和囊泡运输。在我们之前的研究中，我们发现 SEPT14 突变导致畸形精子症，精子形态缺陷超过 87%。通过蛋白质组学分析还鉴定了 SEPT14 的相互作用物，其中一个肽段被映射到 RAB3B 和 RAB3C。大多数关于 RAB3 家族的研究都集中在 RAB3A 上，它调节神经递质的胞吐作用和顶体反应。然而，RAB3 家族成员在人类精子发生过程中的普遍表达和模式，以及 SEPT14 突变导致的 RAB3 和畸形精子症之间的关联，在很大程度上是未知的。材料和方法：本研究收集了人类精子和雄性小鼠生殖细胞，并对收集的精子进行免疫荧光分析。结果：在本研究中，我们观察到 RAB3C 转录本在人睾丸组织中的丰度高于 RAB3A、3B 和 3D。在人类精子发生过程中，RAB3C 蛋白主要富集在长形精子中，而 RAB3B 不可检测。在成熟的人精子中，RAB3C 集中在后顶体区、颈部和中段。在携带 SEPT14 突变的人精子中，RAB3C 信号发生弥散，与健康对照组相比，信号减少伴随着头部和尾部缺陷。为了确定 RAB3C 是否参与精子头部和尾部的形态形成，我们分离了雄性小鼠睾丸组织并分离出长形精子进行进一步研究。我们发现 RAB3C 特别表达在帽状结构中，有助于精子头部的精子头形状形成，也定位于精子尾部。结论：基于这些结果，我们认为 RAB3C 蛋白在小鼠和人精子中的定位与 SEPT14 突变诱导的精子形态缺陷有关。
