title: Microvillar size and espin expression in principal cells of the adult rat epididymis are regulated by androgens.
abstract: Principal cells of the epididymis are the most prominent cell type and are noted for an apical cell surface studded with microvilli. The latter contain channel proteins that condition the microenvironment of epididymal lumen and promote sperm maturation; however, the regulation of the structure and integrity of microvilli is not well known. Espins are a family of proteins implicated in microvillar growth. The objectives of this study were to assess the regulation of espin in epididymal principal cells both in vitro and in vivo. Treatment of immortalized rat caput epididymal (RCE) cells with increasing doses of a homogenized testicular extract revealed a dose-dependent increase in the size of microvilli. Reverse transcriptase-polymerase chain reaction (RT-PCR) of adult rat epididymal RNA using espin-specific primers indicated the presence of a band at about 290 base pairs (bp) in all regions. Western blot analysis using affinity-purified espin antibody confirmed the presence of an approximately 110-kDa band in the epididymis, corresponding to espin isoform 1. In adult rats, immunocytochemistry revealed espin expression over principal cells. In orchidectomized rats, espin expression was significantly reduced, whereas ligation of the efferent ducts resulted in a decrease of espin expression but not to the extent of orchidectomy. The fact that espin expression was restored to control levels in orchidectomized rats supplemented with high levels of testosterone indicated that its expression was dependent on androgens and not on other lumicrine factors derived from the testis. Taken together, these data indicate that espin is expressed in the epididymis and is regulated by androgens.
authors.affiliation: Department of Anatomy and Cell Biology, McGill University, 3640 University St, Montreal, Quebec, H3A 2B2, Canada.
authors.forename: Nadia
authors.initials: N
authors.lastname: Primiani
authors.forename: Mary
authors.initials: M
authors.lastname: Gregory
authors.forename: Julie
authors.initials: J
authors.lastname: Dufresne
authors.forename: Charles E
authors.initials: CE
authors.lastname: Smith
authors.forename: Ye Lauren
authors.initials: YL
authors.lastname: Liu
authors.forename: James R
authors.initials: JR
authors.lastname: Bartles
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Cyr
authors.forename: Louis
authors.initials: L
authors.lastname: Hermo
mesh_terms: D000728:Androgens / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D004822:Epididymis / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure*; D015870:Gene Expression; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D020033:Protein Isoforms; D051381:Rats; D017207:Rats, Sprague-Dawley; D013737:Testis / Q000378:metabolism*
chemical_list: D000728:Androgens; C472022:Espn protein, rat; D008840:Microfilament Proteins; D020033:Protein Isoforms