Phosphorylated insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) inhibits while non-phosphorylated IGFBP-1 stimulates IGF-I-induced amino acid uptake by cultured trophoblast cells.
The effects of phosphorylated insulin-like growth factor-binding protein (pIGFBP-1) and non-phosphorylated (npIGFBP-1) IGFBP-1 on amino acid uptake induced by IGF-I were studied using cultured trophoblast cells. Trophoblast cells obtained from term pregnancy were incubated with indicated concentrations of pIGFBP-1 or npIGFBP-1 for 24 h and further incubated with 10 nM IGF-I for 3 h. Cells were then incubated with 3H-alpha-amino isobutyric acid (3H-AIB) for 30 min. Both pIGFBP-1 and npIGFBP-1 alone had no effect on 3H-AIB uptake; however, pIGFBP-1 inhibited IGF-I-stimulated 3H-AIB uptake with an ED50 of 0.26 nM while npIGFBP-1 potentiated 3H-AIB uptake with an ED50 of 0.27 nM. Maternal IGF-I promotes fetal growth by stimulating nutrient transport in the placenta. As shown in this study, pIGFBP-1 inhibits while npIGFBP-1 stimulates this IGF-I action in the placenta. Thus, it is suggested that IGFBP-1 phosphoisoforms are also involved in fetal growth by modulating IGF-I action in the placenta.
Yu
J
J
Department of Obstetrics and Gynecology, Tokyo Women's Medical College, Japan.
Iwashita
M
M
Kudo
Y
Y
Takeda
Y
Y
D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000653:Amniotic Fluid / Q000737:chemistry; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011247:Pregnancy; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D000596:Amino Acids; D000621:Aminoisobutyric Acids; D018970:Insulin-Like Growth Factor Binding Protein 1; D020033:Protein Isoforms; C100049:2-aminoisobutyric acid