During spermiogenesis in mammals actin filaments and a variety of actin-binding proteins are involved in the formation and function of highly specialized testis-specific structures. Actin-based motor proteins, such as myosin Va and VIIa, play a key role in this complex process of spermatid transformation into mature sperm. We have previously demonstrated that myosin VI (MYO6) is also expressed in mouse testes. It is present in actin-rich structures important for spermatid development, including one of the earliest events in spermiogenesis-acrosome formation. Here, we demonstrate using immunofluorescence, cytochemical and ultrastructural approaches that MYO6 is involved in maintaining the structural integrity of these specialized actin-rich structures during acrosome biogenesis in mouse. We show that MYO6 together with its binding partner TOM1/L2 is present at/around the spermatid Golgi complex and the nascent acrosome. Depletion of MYO6 in Snell's waltzer mice causes structural disruptions of the Golgi complex and affects the acrosomal granule positioning within the developing acrosome. In summary, our results suggest that MYO6 plays an anchoring role during the acrosome biogenesis mainly by tethering of different cargo/membranes to highly specialized actin-related structures..

中文翻译：

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肌球蛋白 VI 表达的缺失会影响小鼠精子发生过程中的顶体/顶体复合体形态†。

在哺乳动物的精子发生过程中，肌动蛋白丝和多种肌动蛋白结合蛋白参与高度特化的睾丸特异性结构的形成和功能。基于肌动蛋白的运动蛋白，如肌球蛋白 Va 和 VIIa，在精子细胞向成熟精子的这一复杂过程中发挥着关键作用。我们之前已经证明肌球蛋白 VI (MYO6) 也在小鼠睾丸中表达。它存在于对精子细胞发育很重要的富含肌动蛋白的结构中，包括精子发生 - 顶体形成中最早的事件之一。在这里，我们使用免疫荧光、细胞化学和超微结构方法证明 MYO6 参与维持小鼠顶体生物发生过程中这些专门的富含肌动蛋白结构的结构完整性。我们表明 MYO6 及其结合伙伴 TOM1/L2 存在于精子细胞高尔基复合体和新生顶体处/周围。在 Snell 的 waltzer 小鼠中 MYO6 的消耗会导致高尔基复合体的结构破坏，并影响发育中的顶体内的顶体颗粒定位。总之，我们的结果表明 MYO6 在顶体生物发生过程中主要通过将不同的货物/膜束缚到高度特化的肌动蛋白相关结构上而发挥锚定作用。