title: TGFβ1 and SGK1-sensitive store-operated Ca2+ entry and Orai1 expression in endometrial Ishikawa cells.
abstract: The serum-and-glucocorticoid-inducible-kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress, hormones and further mediators. A most powerful stimulator of SGK1 expression is transforming growth factor TGFβ1. SGK1 is activated by insulin and growth factors via phosphatidylinositol-3-kinase and the 3-phosphoinositide-dependent kinase PDK1. As shown recently, SGK1 increases the store-operated Ca(2+) entry (SOCE), which is accomplished by the pore-forming ion channel unit Orai. Most recent observations further revealed that SGK1 plays a critical role in the regulation of fertility. SGK1 is up-regulated in the luminal epithelium of women with unexplained infertility but down-regulated in decidualizing stromal cells of patients with recurrent pregnancy loss. The present study explored whether Orai1 is expressed in endometrium and sensitive to regulation by SGK1 and/or TGFβ1. To this end, Orai1 protein abundance was determined by western blotting and SOCE by fura-2 fluorescence. As a result, Orai1 was expressed in human endometrium and in human endometrial Ishikawa cells. Orai1 expression and SOCE in Ishikawa cells were increased by transfection with constitutively active (S422D)SGK1 but not by transfection with inactive (K127N)SGK1. The difference of SOCE between (S422D)SGK1 and (K127N)SGK1-transfected cells was virtually abrogated in the presence of Orai1 inhibitor 2-aminoethoxydiphenyl borate (2-APB, 50 µM). Similar to (S422D)SGK1 transfection TGFβ1 treatment up-regulated both Orai1 protein abundance and SOCE. In conclusion, Orai1 is expressed in the human endometrium and is up-regulated by SGK1 and TGFβ1. The present observations thus uncover a novel element in SGK1-sensitive regulation of endometrial cells.
authors.affiliation: Department of Physiology, University of Tübingen, D72076 Tübingen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Schneider
authors.forename: W
authors.initials: W
authors.lastname: Yang
authors.forename: G
authors.initials: G
authors.lastname: Liu
authors.forename: E-M
authors.initials: EM
authors.lastname: Schmidt
authors.forename: E
authors.initials: E
authors.lastname: Schmid
authors.forename: S
authors.initials: S
authors.lastname: Mia
authors.forename: S
authors.initials: S
authors.lastname: Brucker
authors.forename: C
authors.initials: C
authors.lastname: Stournaras
authors.forename: D
authors.initials: D
authors.lastname: Wallwiener
authors.forename: J J
authors.initials: JJ
authors.lastname: Brosens
authors.forename: F
authors.initials: F
authors.lastname: Lang
mesh_terms: D000328:Adult; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D004717:Endometrium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D017136:Ion Transport; D000071740:ORAI1 Protein; D017697:Premenopause; D061251:Primary Cell Culture; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D001896:Boron Compounds; D002118:Calcium; D015220:Calcium Channels; D017874:Immediate-Early Proteins; D000071740:ORAI1 Protein; D017346:Protein Serine-Threonine Kinases; D053773:Transforming Growth Factor beta1; D000099184:Serum-Glucocorticoid Regulated Kinases; C510746:ORAI1 protein, human; C109986:2-aminoethoxydiphenyl borate
keywords: Ca2+ release activated Ca2+ channel; endometrium; serum and glucocorticoid inducible kinase 1; tumor growth factor beta