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Myosin VI maintains the actin-dependent organization of the tubulobulbar complexes required for endocytosis during mouse spermiogenesis

Accepted version
Peer-reviewed

Type

Article

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Authors

Zakrzewski, Przemysław 
Suwińska, Anna 
Lenartowski, Robert 
Rędowicz, Maria Jolanta 

Abstract

Myosin VI (MYO6) is an actin-based motor that has been implicated in a wide range of cellular processes, including endocytosis and the regulation of actin dynamics. MYO6 is crucial for actin/membrane remodeling during the final step of Drosophila spermatogenesis, and MYO6-deficient males are sterile. This protein also localizes to actin-rich structures involved in mouse spermiogenesis. Although loss of MYO6 in Snell’s waltzer knock-out (KO) mice causes several defects and show reduced male fertility, no studies have been published to address the role of MYO6 in sperm development in mouse. Here we demonstrate that MYO6 and some of its binding partners are present at highly specialized actin-based structures, the apical tubulobulbar complexes (TBCs), which mediate endocytosis of the intercellular junctions at the Sertoli cell-spermatid interface, an essential process for sperm release. Using electron and light microscopy and biochemical approaches we show that MYO6, GIPC1 and TOM1/L2 form a complex in testis and localize predominantly to an early endocytic APPL1-positive compartment of the TBCs that is distinct from EEA1-positive early endosomes. These proteins also associate with the TBC actin-free bulbular region. Finally, our studies using testis from Snell’s waltzer males show that loss of MYO6 causes disruption of the actin cytoskeleton and disorganization of the TBCs, and leads to defects in the distribution of the MYO6-positive early APPL1-endosomes. Taken together, we report here for the first time that lack of MYO6 in mouse testis reduces male fertility and disrupts spatial organization of the TBC-related endocytic compartment during the late phase of spermiogenesis.

Description

Keywords

actin cytoskeleton, actin dynamics, fertility, myosin VI, spermiogenesis, tubulobulbar complexes, Actin Cytoskeleton, Actins, Adaptor Proteins, Signal Transducing, Animals, Endocytosis, Infertility, Male, Intracellular Signaling Peptides and Proteins, Male, Mice, Mice, Knockout, Myosin Heavy Chains, Spermatogenesis

Journal Title

Biology of Reproduction

Conference Name

Journal ISSN

0006-3363
1529-7268

Volume Title

Publisher

Oxford University Press

Rights

All rights reserved
Sponsorship
Medical Research Council (MR/S007776/1)
Medical Research Council (MR/K000888/1)
Biotechnology and Biological Sciences Research Council (BB/R001316/1)
This project was supported by PRELUDIUM grant from National Science Centre (Poland), the grant number 2017/25/N/NZ3/00487 (to P.Z.); ETIUDA doctoral scholarship from National Science Centre (Poland), the grant number 2018/28/T/NZ3/00002 (to P.Z.); a travelling fellowship funded by The Company of Biologists, the grant number JCSTF-171105 (to P.Z.), and a Medical Research Council grant, grant number MR/K000888/1 (to F.B.)