Follicle-stimulating hormone and insulin-like growth factor I synergistically induce up-regulation of cartilage link protein (Crtl1) via activation of phosphatidylinositol-dependent kinase/Akt in rat granulosa cells.
FSH and IGF-I are both important determinants of follicle development and the process of cumulus cell-oocyte complex expansion. FSH stimulates the phosphorylation of Akt by mechanisms involving phosphatidylinositol 3-kinase (PI3-K), a pattern of response mimicking that of IGF-I. Cartilage link protein (Crtl1) is confined to the cartilaginous lineage and is assembled into a macroaggregate complex essential for hyaluronan-rich matrix stabilization. The present studies were performed to determine the actions of FSH and IGF-I on Crtl1 production in rat granulosa cells. Primary cultures of granulosa cells were prepared from 24-d-old rats. After treatments, cell extracts and media were prepared, and the Crtl1 level was determined by immunoblotting analysis using anti-Crtl1 antibodies. Here we showed that 1) treatment with FSH (> or = 25 ng/ml) or IGF-I (> or = 25 ng/ml) for 4 h increased Crtl1 production; 2) maximal stimulatory effects of FSH or IGF-I were observed at 100 or 50 ng/ml, respectively; 3) FSH caused a concentration-dependent increase in IGF-I-induced Crtl1 production and vice versa; 4) FSH and IGF-I also up-regulate the expression of Crtl1 mRNA; 5) FSH- and IGF-I-dependent Crtl1 production were abrogated by PI3-K inhibitors (LY294002 and wortmannin), and inhibition of Crtl1 production by p38 mitogen-activated protein kinase inhibitor (SB202190) was partial (approximately 30%), suggesting that PI3-K and, to a lesser extent, p38 mitogen-activated protein kinase are critical for the response. Our study represents the first report that FSH amplifies IGF-I-mediated Crtl1 production, possibly via PI3-K-Akt signaling cascades in rat granulosa cells.
Sun
Guang Wei
GW
Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan.
Kobayashi
Hiroshi
H
Suzuki
Mika
M
Kanayama
Naohiro
N
Terao
Toshihiko
T
D000818:Animals; D002478:Cells, Cultured; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D011509:Proteoglycans; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases; D000099249:Proteoglycan Link Protein
D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D005640:Follicle Stimulating Hormone; D007334:Insulin-Like Growth Factor I; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011509:Proteoglycans; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D048051:p38 Mitogen-Activated Protein Kinases; D000099249:Proteoglycan Link Protein; C494920:Akt1 protein, rat