title: Gonadotropin regulation and role of ovarian osteopontin in the periovulatory period.
abstract: Osteopontin (OPN), a secreted glycoprotein, has multiple physiological functions. This study investigated the regulation and roles of OPN in the mouse ovary during the periovulatory stages. Immature female mice were treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) to simulate follicle maturation and ovulation. In situ hybridization and real-time RT-PCR were performed to assess expression of Opn in the periovulatory ovary. Granulosa cells (GCs) from PMSG-primed immature mice were cultured with or without hCG in the presence or absence of OPN, and effects on expression of Opn, progesterone synthesis, and vascular endothelial growth factor (VEGF) signaling were assessed by real-time RT-PCR, ELISA, and western blotting analysis. Opn transcripts were significantly upregulated 3 h after hCG treatment, followed by a peak at 16 h, and the transcripts localized to GCs. Incubation with hCG significantly increased quantities of Opn transcripts in GCs and OPN levels in the culture medium at 12 and 24 h. Furthermore, OPN treatment caused a significant increase in the levels of Star protein, P 450 cholesterol side-chain cleavage enzyme (p450scc), 3-beta-hydroxysteroid dehydrogenase (Hsd3b), and progesterone in the culture medium. OPN treatment promoted Vegf expression in GCs, which was significantly suppressed by a phosphoinositide 3-kinase (PI3K) inhibitor. In addition, OPN treatment stimulated phosphorylation of AKT, a downstream PI3K signaling molecule. In conclusion, expression of Opn was upregulated in mouse ovarian GCs in response to a gonadotropin surge through epidermal growth factor receptor signaling, which enhances progesterone synthesis and Vegf expression during the early-luteal phase.
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan kuwa@nms.ac.jp.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Kuwabara
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Katayama
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Tomiyama
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Hu
authors.initials: H
authors.lastname: Piao
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Kurihara
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ono
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Mine
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Akira
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Orimo
authors.affiliation: Departments of Obstetrics and GynecologyBiochemistry and Molecular BiologyNippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takeshita
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006062:Gonadotropins / Q000378:metabolism* / Q000494:pharmacology; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D053495:Osteopontin / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D010060:Ovulation / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D006062:Gonadotropins; D006064:Gonadotropins, Equine; C506896:Spp1 protein, mouse; D053495:Osteopontin
keywords: corpus luteum; epidermal growth factor; gonadotropin; progesterone