title: Implication of amphiphysin 1 and dynamin 2 in tubulobulbar complex formation and spermatid release.
abstract: Tubulobulbar complexes (TBCs) are composed of several tubular invaginations formed at the plasma membrane of testicular Sertoli cells. TBCs are transiently formed at the contact region with spermatids at spermatogenic stage VII in rat and mouse, and such TBC formation is prerequisite for spermatid release. Since the characteristic structure of TBCs suggests that the molecules implicated in endocytosis could be involved in TBC formation, we here investigated the localization and physiological roles of endocytic proteins, amphiphysin 1 and dynamin 2, at TBCs. We demonstrated by immunofluorescence that the endocytic proteins were concentrated at TBCs, where they colocalized with cytoskeletal proteins, such as actin and vinculin. Immunoelectron microscopy disclosed that both amphiphysin 1 and dynamin 2 were localized on TBC membrane. Next, we histologically examined the testis from amphiphysin 1 deficient {Amph(-/-)} mice. Morphometric analysis revealed that the number of TBCs was significantly reduced in Amph(-/-). The ratio of stage VIII seminiferous tubules was increased, and the ratio of stage IX was conversely decreased in Amph(-/-). Moreover, unreleased spermatids in stage VIII seminiferous tubules were increased in Amph(-/-), indicating that spermatid release and the following transition from stage VIII to IX was prolonged in Amph(-/-) mice. These results suggest that amphiphysin 1 and dynamin 2 are involved in TBC formation and spermatid release at Sertoli cells.
authors.affiliation: Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kusumi
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.forename: Shun-Ai
authors.initials: SA
authors.lastname: Li
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kashiwakura
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsukawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nagai
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Nasu
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kumon
authors.forename: Kohji
authors.initials: K
authors.lastname: Takei
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001814:Blood-Testis Barrier / Q000378:metabolism*; D015153:Blotting, Western; D003598:Cytoskeletal Proteins / Q000276:immunology; D034285:Dynamin II / Q000276:immunology* / Q000378:metabolism* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D051379:Mice; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000276:immunology* / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport; D051381:Rats; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism; D013087:Spermatids / Q000378:metabolism*; D013091:Spermatogenesis / Q000276:immunology