Expression of steroidogenic acute regulatory protein (StAR) in rat granulosa cells.
Steroidogenic acute regulatory protein (StAR) is a vital mitochondrial protein that is indispensable for the synthesis of steroids. To study the mechanisms of regulation of StAR in rat granulosa cells, we used granulosa cells obtained from diethylstilbestrol-treated immature rats. Northern blot analysis revealed two major transcripts of about 3.6 kb and 1.6 kb of rat StAR mRNA. Rat StAR mRNA had strongly increased within 2 h due to the treatment of FSH or 8-Br-cAMP in this culture, a parallel increase of transcripts of both sizes was observed. Compared to the control, StAR mRNA levels increased in a dose-dependent manner in the presence of increasing concentrations of FSH (1-100 ng/ ml) and 8-Br-cAMP (0.25-5 mM). Although co-treatment of rat granulosa cells with FSH and TGF-beta did not change FSH-induced StAR mRNA levels, these levels in granulosa cells were markedly increased by pretreatment with TGF-beta before being acutely (2 h) stimulated with an effective dose of FSH. The stimulatory effect of TGF-beta was time- and concentration-dependent (1-30 ng/ml).
Minegishi
T
T
Department of Obstetrics and Gynecology, School of Medicine, Gunma University, Maebashi, Japan. tminegis@sb.gunma-u.ac.jp
Tsuchiya
M
M
Hirakawa
T
T
Abe
K
K
Inoue
K
K
Mizutani
T
T
Miyamoto
K
K
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011962:Receptors, FSH / Q000096:biosynthesis / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D000098682:Steroidogenic Acute Regulatory Protein
D010750:Phosphoproteins; D012333:RNA, Messenger; D011962:Receptors, FSH; D016212:Transforming Growth Factor beta; D000098682:Steroidogenic Acute Regulatory Protein; D015124:8-Bromo Cyclic Adenosine Monophosphate; D005640:Follicle Stimulating Hormone