title: Induction of Ski protein expression upon luteinization in rat granulosa cells without a change in its mRNA expression.
abstract: The Ski protein is implicated in the proliferation/differentiation of a variety of cells. We previously reported that the Ski protein is present in granulosa cells of atretic follicles, but not in preovulatory follicles, suggesting that Ski has a role in apoptosis of granulosa cells. However, granulosa cells cannot only undergo apoptosis but can alternatively differentiate into luteal cells. It is unknown whether Ski is expressed and has a role in granulosa cells undergoing luteinization. Thus, the aim of the present study was to determine the localization of the Ski protein in the rat ovary during luteinization to examine if Ski might play a role in this process. In order to examine the Ski protein expression during the progression of luteinization, follicular growth was induced in immature female rats by administration of equine chorionic gonadotropin, and luteinization was induced by human chorionic gonadotropin treatment to mimic the luteinizing hormone (LH) surge. While no Ski-positive granulosa cells were present in the preovulatory follicle, Ski protein expression was induced in response to the LH surge and was maintained after formation of the corpus luteum (CL). Although the Ski protein is absent from the granulosa cells of the preovulatory follicle, its mRNA (c-ski) was expressed, and the level of c-ski mRNA was unchanged even after the LH surge. The combined results demonstrated that Ski protein expression is induced in granulosa cells upon luteinization, and suggested that its expression is regulated posttranscriptionally.
authors.affiliation: Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.forename: Keitaro
authors.initials: K
authors.lastname: Yamanouchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuwaki
authors.forename: Masugi
authors.initials: M
authors.lastname: Nishihara
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003338:Corpus Luteum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007016:Hypophysectomy; D007150:Immunohistochemistry; D034461:Luteinization / Q000187:drug effects / Q000378:metabolism*; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation; D013997:Time Factors; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C525545:Ski protein, rat; C550853:Rnf111 protein, rat; D044767:Ubiquitin-Protein Ligases