Involvement of a membrane skeletal protein, 4.1G, for Sertoli/germ cell interaction.
We previously reported that a membrane skeletal protein, 4.1G (also known as EPB41L2), is immunolocalized in mouse seminiferous tubules. In this study, the 4.1G immunolocalizaiton was precisely evaluated at various stages of the mouse seminiferous epithelial cycle with 'in vivo cryotechnique' and also with pre-embedding immunoelectron microscopy in testicular tissues whose ultrastructures were well preserved with glycerol treatment before cryosectioning. In addition, 4.1G-deficient mice were produced, and the morphology of their seminiferous tubules was also evaluated. The 4.1G immunolocalization was different among stages, indicating that it was not only along cell membranes of Sertoli cells, but also those of spermatogonia and early spermatocytes. To confirm the 4.1G immunolocalization in germ cells, in vitro culture of spermatogonial stem cells (SSCs) was used for immunocytochemistry and immunoblotting analysis. In the cultured SSCs, 4.1G was clearly expressed and immunolocalized along cell membranes, especially at mutual attaching regions. In testicular tissues, cell adhesion molecule-1 (CADM1), an intramembranous adhesion molecule, was colocalized on basal parts of the seminiferous tubules and immunoprecipitated with 4.1G in the tissue lysate. Interestingly, in the 4.1G-deficient mice, histological manifestation of the seminiferous tubules was not different from that in wild-type mice, and the CADM1 was also immunolocalized in the same pattern as that in the wild-type. Moreover, the 4.1G-deficient male mice were fertile. These results were probably due to functional redundancy of unknown membrane skeletal molecules in germ cells. Thus, a novel membrane skeletal protein, 4.1G, was found in germ cells, and considering its interaction with CADM family, it probably has roles in attachment of both Sertoli-germ and germ-germ cells.
Terada
Nobuo
N
Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-City, Yamanashi 409-3898, Japan. nobuot@yamanashi.ac.jp
Ohno
Nobuhiko
N
Saitoh
Sei
S
Saitoh
Yurika
Y
Komada
Masayuki
M
Kubota
Hiroshi
H
Ohno
Shinichi
S
D000818:Animals; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002450:Cell Communication; D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D007136:Immunoglobulins / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012670:Seminiferous Epithelium / Q000166:cytology / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000378:metabolism*; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism; D013093:Spermatogonia / Q000166:cytology / Q000378:metabolism; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D016707:Tissue Fixation / Q000379:methods
C498598:Cadm1 protein, mouse; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D007136:Immunoglobulins; D008565:Membrane Proteins; C028841:erythrocyte membrane band 4.1 protein