title: Regulation of ectoplasmic specialization dynamics in the seminiferous epithelium by focal adhesion-associated proteins in testosterone-suppressed rat testes.
abstract: Apical ectoplasmic specialization (ES) is a unique testis-specific cell-cell actin-based adherens junction type restricted to the Sertoli-round/elongating/elongate spermatid interface in the seminiferous epithelium. An endogenous testosterone (T) suppression model was used to study the regulation of apical ES dynamics in the testis. By providing sustained releases of T and estradiol using subdermal implants in rats, this treatment reduced endogenous testicular T level. This in turn led to sloughing of spermatids (step 8 and beyond) from the seminiferous epithelium, which can be reversed by removing the implants, or replacing them with a higher dose of T implants. This model thus allows us to study the restructuring events at the apical ES. It was shown that apical ES restructuring involved proteins that were usually restricted to the cell-matrix focal adhesion site in other epithelia. For instance, the protein levels of beta1-integrin, Tyr-phosphorylated focal adhesion kinase (p-FAK), and c-Src were induced during the T suppression-induced germ cell loss and recovery, implicating that these proteins are putative regulators of ES dynamics. Indeed, the formation of p-FAK/c-Src protein complex, but not their association with beta1-integrin, was stimulated during T suppression-induced germ cell loss. ERK, a MAPK known to regulate focal adhesion turnover, was also activated during the androgen suppression-induced spermatid loss and the early phase of the recovery when germ cells began to repopulate the epithelium. Collectively, these data suggest that the apical ES is a cell-cell adherens junction type with the characteristics of cell-matrix focal contacts. In addition to its role in conferring cell adhesion formation, the p-FAK/c-Src protein complex apparently also regulates apical ES disruption via the ERK signaling pathway.
authors.affiliation: Population Council, Center for Biomedical Research, New York, New York 10021, USA.
authors.forename: Ching-Hang
authors.initials: CH
authors.lastname: Wong
authors.forename: Weiliang
authors.initials: W
authors.lastname: Xia
authors.forename: Nikki P Y
authors.initials: NP
authors.lastname: Lee
authors.forename: Dolores D
authors.initials: DD
authors.lastname: Mruk
authors.forename: Will M
authors.initials: WM
authors.lastname: Lee
authors.forename: C Yan
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D000728:Androgens / Q000378:metabolism; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D002448:Cell Adhesion; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions / Q000378:metabolism; D005854:Germ Cells / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D019012:Integrin beta1 / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012670:Seminiferous Epithelium / Q000378:metabolism*; D015398:Signal Transduction; D013087:Spermatids / Q000378:metabolism; D013091:Spermatogenesis; D013737:Testis / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors; D019061:src-Family Kinases
chemical_list: D000728:Androgens; D000081247:CSK Tyrosine-Protein Kinase; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019012:Integrin beta1; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D013739:Testosterone; D019061:src-Family Kinases; C496052:Ptk2 protein, rat