Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Torun, Poland.
Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK.
Histochem Cell Biol. 2021 Mar;155(3):323-340. doi: 10.1007/s00418-020-01954-x. Epub 2021 Jan 2.
Spermiogenesis is the final stage of spermatogenesis, a differentiation process during which unpolarized spermatids undergo excessive remodeling that results in the formation of sperm. The actin cytoskeleton and associated actin-binding proteins play crucial roles during this process regulating organelle or vesicle delivery/segregation and forming unique testicular structures involved in spermatid remodeling. In addition, several myosin motor proteins including MYO6 generate force and movement during sperm differentiation. MYO6 is highly unusual as it moves towards the minus end of actin filaments in the opposite direction to other myosin motors. This specialized feature of MYO6 may explain the many proposed functions of this myosin in a wide array of cellular processes in animal cells, including endocytosis, secretion, stabilization of the Golgi complex, and regulation of actin dynamics. These diverse roles of MYO6 are mediated by a range of specialized cargo-adaptor proteins that link this myosin to distinct cellular compartments and processes. During sperm development in a number of different organisms, MYO6 carries out pivotal functions. In Drosophila, the MYO6 ortholog regulates actin reorganization during spermatid individualization and male KO flies are sterile. In C. elegans, the MYO6 ortholog mediates asymmetric segregation of cytosolic material and spermatid budding through cytokinesis, whereas in mice, this myosin regulates assembly of highly specialized actin-rich structures and formation of membrane compartments to allow the formation of fully differentiated sperm. In this review, we will present an overview and compare the diverse function of MYO6 in the specialized adaptations of spermiogenesis in flies, worms, and mammals.
精子发生是精子发生的最后阶段,是一个未极化精子发生经历过度重塑的分化过程,导致精子的形成。肌动蛋白细胞骨架和相关的肌动蛋白结合蛋白在这个过程中起着至关重要的作用,调节细胞器或囊泡的输送/分离,并形成参与精子发生重塑的独特睾丸结构。此外,几种肌球蛋白马达蛋白,包括 MYO6,在精子分化过程中产生力和运动。MYO6 非常不寻常,因为它朝着肌动蛋白丝的负端移动,与其他肌球蛋白马达的方向相反。MYO6 的这种特殊特征可能解释了这种肌球蛋白在动物细胞中广泛的细胞过程中的许多提议的功能,包括内吞作用、分泌、高尔基体复合体的稳定以及肌动蛋白动力学的调节。MYO6 的这些不同作用是由一系列专门的货物衔接蛋白介导的,这些蛋白将这种肌球蛋白与不同的细胞区室和过程联系起来。在许多不同生物体的精子发生过程中,MYO6 发挥着关键作用。在果蝇中,MYO6 同源物调节精子发生个体化过程中的肌动蛋白重排,雄性 KO 蝇是不育的。在秀丽隐杆线虫中,MYO6 同源物通过胞质物质的不对称分离和有丝分裂中的精子芽生来介导不对称分离,而在小鼠中,这种肌球蛋白调节高度特化的富含肌动蛋白的结构的组装和膜区室的形成,以允许完全分化的精子的形成。在这篇综述中,我们将概述并比较 MYO6 在果蝇、蠕虫和哺乳动物的精子发生特化适应中的不同功能。