The Acroplaxome Is the Docking Site of Golgi-Derived Myosin Va/Rab27a/b- Containing Proacrosomal Vesicles in Wild-Type and Hrb Mutant Mouse Spermatids

摘要: Acrosome biogenesis involves the transport and fusion of Golgi-derived proacrosomal vesicles along acroplaxome, an F-actin/keratin 5-containing cytoskeletal plate anchored to spermatid nucleus. A significant issue is whether acroplaxome develops in acrosomeless mutant mice. Male mice with a Hrb null mutation are infertile both spermatids sperm round-headed lack acrosome. Hrb, protein that contains several NPF motifs (Asn-Pro-Phe) interacts proteins Eps15 homology domains, regarded as critical for docking and/or vesicles. Here we report acrosome does not prevent development acroplaxome. Yet F-actin but deficient keratin 5. We also show actin-based motor myosin Va its receptor, Rab27a/b, known be involved vesicle transport, present Golgi wild-type mouse spermatids. In mutant, myosin-Va-bound proacrosome tether where they flatten form flat sac, designated pseudoacrosome. As spermiogenesis advances, round-shaped nuclei display nuclear protrusions, nucleopodes. Nucleopodes consistently found at acroplaxome- pseudoacrosome site. Our findings support interpretation provides focal point myosin-Va/ Rab27a/b-driven accumulate, coalesce, suggest nucleopodes develop site 5-deficient may withstand tension forces operating during shaping.