title: Non-classical testosterone signaling mediated through ZIP9 stimulates claudin expression and tight junction formation in Sertoli cells.
abstract: In the classical signaling pathway, testosterone regulates gene expression by activating the cytosolic/nuclear androgen receptor. In the non-classical pathway, testosterone activates cytosolic signaling cascades that are normally triggered by growth factors. The nature of the receptor involved in this signaling pathway is a source of controversy. In the Sertoli cell line 93RS2, which lacks the classical AR, we determined that testosterone stimulates the non-classical signaling pathway, characterized by the phosphorylation of Erk1/2 and transcription factors CREB and ATF-1. We also demonstrated that testosterone increases the expression of the tight junction (TJ) proteins claudin-1 and claudin-5. Both of these proteins are known to be essential constituents of TJs between Sertoli cells, and as a consequence of their increased expression transepithelial resistance across Sertoli cell monolayers is increased. ZIP9 is a Zn(2+)transporter that was recently shown to be a membrane-bound testosterone receptor. Silencing its expression in 93RS2 Sertoli cells by siRNA completely prevents Erk1/2, CREB, and ATF-1 phosphorylation as well the stimulation of claudin-1 and -5 expression and TJ formation between neighboring cells. The study presented here demonstrates for the first time that in Sertoli cells testosterone acts through the receptor ZIP9 to trigger the non-classical signaling cascade, resulting in increased claudin expression and TJ formation. Since TJ formation is a prerequisite for the maintenance of the blood-testis barrier, the testosterone/ZIP9 effects might be significant for male physiology. Further assessment of these interactions will help to supplement our knowledge concerning the mechanism by which testosterone plays a role in male fertility.
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin Justus-Liebig-Universität, Giessen, Germany.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Bulldan
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin Justus-Liebig-Universität, Giessen, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Dietze
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin Justus-Liebig-Universität, Giessen, Germany.
authors.forename: Mazen
authors.initials: M
authors.lastname: Shihan
authors.affiliation: Institut für Veterinär-Physiologie und -Biochemie, Fachbereich Veterinärmedizin Justus-Liebig-Universität, Giessen, Germany. Electronic address: Georgios.Scheiner-Bobis@vetmed.uni-giessen.de.
authors.forename: Georgios
authors.initials: G
authors.lastname: Scheiner-Bobis
mesh_terms: D051697:Activating Transcription Factor 1 / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000378:metabolism*; D062445:Claudin-1 / Q000378:metabolism*; D062507:Claudin-5 / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D020868:Gene Silencing / Q000187:drug effects; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013739:Testosterone / Q000378:metabolism* / Q000494:pharmacology; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism*
chemical_list: D051697:Activating Transcription Factor 1; D027682:Cation Transport Proteins; D062445:Claudin-1; D062507:Claudin-5; D017362:Cyclic AMP Response Element-Binding Protein; D034741:RNA, Small Interfering; C543108:Slc39a9 protein, human; D013739:Testosterone; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Androgen receptor; Claudin; Testosterone; Tight junction; ZIP9