IGF regulation of neutral amino acid transport in the BeWo choriocarcinoma cell line (b30 clone): evidence for MAP kinase-dependent and MAP kinase-independent mechanisms.

摘要: Abstract Objective IGF-1 and receptors are major determinants of fetal growth expressed primarily on the maternal-facing surface syncytiotrophoblast cell membrane in human placenta. regulates growth, part, by regulating amino acid transport across The objective these studies was to study role its signaling pathway neutral a trophoblast culture model. Design regulation studied cultured BeWo b30 choriocarcinoma cells using non-metabolizing analog, [ 3 H]-α-aminoisobutyric (AIB). Transport absence Na used distinguish system L from total AIB transport. Similarly, Na-dependent presence excess methyl-AIB (MeAIB) permitted discrimination systems A (MeAIB-sensitive) ASC (MeAIB-insensitive). Specific inhibitors intracellular pathways were then determine utilized IGFs regulate each system. Specificity inhibition assessed specific markers p70 S6 kinase activity MAP activation. Results Maximal stimulating concentrations IGF-I (100ng/ml) stimulated 30–40% exclusively through A. Wortmannin (100nM), an inhibitor PI-3-kinase activity, inhibited all IGF-I-stimulated Rapamycin (100ng/ml), kinase, bisindolylmaleimide, protein C (PKC), had no effect. PD-098059 (50μM), activation, 20–30% basal but did not inhibit under conditions studied. increase steady state mRNA levels transporters, SNAT1 SNAT2, suggesting stimulates via post-transcriptional mechanisms. Conclusions These data demonstrate that PI3-kinase dependent, line. Additionally, appear be sensitive kinase-dependent regulated IGFs.