title: Regulatory role of kit ligand-c-kit interaction and oocyte factors in steroidogenesis by rat granulosa cells.
abstract: Although kit ligand (KL)-c-kit interaction is known to be critical for oogenesis and folliculogenesis, its role in ovarian steroidogenesis has yet to be elucidated. We studied the impact of KL-c-kit interaction in regulation of steroidogenesis using rat oocyte/granulosa cell co-culture. In the presence of oocytes, soluble KL suppressed FSH-induced estradiol production and aromatase mRNA expression without affecting FSH-induced progesterone production. The KL effect on steroidogenesis was interrupted by an anti-c-kit neutralizing antibody, suggesting that KL-c-kit interaction is involved in suppression of estrogen by granulosa cells through oocyte c-kit action. The cAMP-PKA pathway activity was not directly involved in the estrogen regulation by KL-c-kit action. It was of note that KL treatment increased the expression levels of oocyte-derived FGF-8, GDF-9 and BMP-6, while it reduced the expression levels of oocyte-derived BMP-15 in the oocyte-granulosa cell co-culture. Given the findings that FGF-8, but not GDF-9, BMP-6 or -15, suppressed FSH-induced estrogen production by granulosa cells, oocyte-derived FGF-8 is linked to suppression of FSH-induced estrogen production through the KL-c-kit interaction. Furthermore, the suppression of FSH-induced estrogen production by KL in the co-culture was reversed by a FGF receptor kinase inhibitor and the effect of the inhibitor was enhanced in combination with extracellular-domain protein of BMPRII, which interferes with BMP-15 and GDF-9 activities. Thus, the actions of endogenous oocyte factors including FGF-8 and BMP-15/GDF-9 were involved in the KL activity that inhibited FSH-induced estradiol production. Collectively, the results indicate that KL-c-kit interaction plays a role in estrogenic regulation through oocyte-granulosa cell communication.
authors.affiliation: Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Miyoshi
authors.forename: Fumio
authors.initials: F
authors.lastname: Otsuka
authors.forename: Eri
authors.initials: E
authors.lastname: Nakamura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Inagaki
authors.forename: Kanako
authors.initials: K
authors.lastname: Ogura-Ochi
authors.forename: Naoko
authors.initials: N
authors.lastname: Tsukamoto
authors.forename: Masaya
authors.initials: M
authors.lastname: Takeda
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Makino
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing; D001141:Aromatase / Q000235:genetics; D055430:Bone Morphogenetic Protein 15 / Q000096:biosynthesis / Q000378:metabolism; D055418:Bone Morphogenetic Protein 6 / Q000378:metabolism; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D051524:Fibroblast Growth Factor 8 / Q000378:metabolism; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D055429:Growth Differentiation Factor 9 / Q000096:biosynthesis / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D011374:Progesterone / Q000096:biosynthesis; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019089:Stem Cell Factor / Q000276:immunology / Q000378:metabolism*; D013256:Steroids / Q000096:biosynthesis
chemical_list: D057134:Antibodies, Neutralizing; C525816:BMP6 protein, human; D055430:Bone Morphogenetic Protein 15; D055418:Bone Morphogenetic Protein 6; C496456:FGF8 protein, human; D055429:Growth Differentiation Factor 9; D012333:RNA, Messenger; D019089:Stem Cell Factor; D013256:Steroids; D051524:Fibroblast Growth Factor 8; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D001141:Aromatase; D019009:Proto-Oncogene Proteins c-kit; D017868:Cyclic AMP-Dependent Protein Kinases; C498218:BMPR2 protein, human; D052006:Bone Morphogenetic Protein Receptors, Type II