title: 14-3-3 Protein regulates cell adhesion in the seminiferous epithelium of rat testes.
abstract: Polarity proteins have been implicated in regulating and maintaining tight junction (TJ) and cell polarity in epithelia. Here we report 14-3-3theta, the homolog of Caenorhabditis elegans Par5 in mammalian cells, which is known to confer cell polarity at TJ, is found at the apical ectoplasmic specialization (ES), a testis-specific adherens junction type restricted to the Sertoli cell-elongating spermatid interface, in which TJ is absent. 14-3-3theta was shown to play a critical role in conferring cell adhesion at the apical ES. A loss of 14-3-3theta expression at the apical ES was detected in the seminiferous epithelium before spermiation. Involvement of 14-3-3theta in Sertoli cell adhesion was confirmed by its knockdown by RNA interference in Sertoli cells cultured in vitro with established TJ permeability barrier that mimicked the blood-testis barrier (BTB) in vivo. Mislocalization of N-cadherin and zonula occludens-1, but not alpha- and beta-catenins, was observed after 14-3-3theta knockdown in Sertoli cells, moving from the cell-cell interface to cytosol, indicating a disruption of cell adhesion. Studies by endocytosis assay illustrated that this loss of cell adhesion was mediated by an increase in the kinetics of endocytosis of N-cadherin and junctional adhesion molecule-A at the BTB, which may represent a general mechanism by which polarity proteins regulate cell adhesion. In summary, the testis is using 14-3-3theta to regulate cell adhesion at the apical ES to facilitate spermiation and at the BTB to facilitate the transit of preleptotene spermatocytes at stages VIII-IX of the epithelial cycle. 14-3-3theta may act as a molecular switch that coordinates these two cellular events in the seminiferous epithelium during spermatogenesis.
authors.affiliation: Center for Biomedical Research, Population Council, New York, New York 10065, USA.
authors.forename: Elissa W P
authors.initials: EW
authors.lastname: Wong
authors.forename: Shengyi
authors.initials: S
authors.lastname: Sun
authors.forename: Michelle W M
authors.initials: MW
authors.lastname: Li
authors.forename: Will M
authors.initials: WM
authors.lastname: Lee
authors.forename: C Yan
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001814:Blood-Testis Barrier / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion; D004705:Endocytosis; D055785:Gene Knockdown Techniques; D006834:Hydrazines; D007191:Indazoles; D008297:Male; D051381:Rats; D012670:Seminiferous Epithelium / Q000502:physiology*; D012708:Sertoli Cells / Q000502:physiology; D013087:Spermatids / Q000502:physiology; D019108:Tight Junctions / Q000502:physiology
chemical_list: C432482:1-(2,4-dichlorobenzyl)indazole-3-carbohydrazide; D048948:14-3-3 Proteins; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D006834:Hydrazines; D007191:Indazoles; C504908:Pard6a protein, rat