Receptors for epidermal growth factor and insulin-like growth factor-I on preimplantation trophoderm of the pig.
125I-labelled epidermal growth factor (125I-EGF) and 125I-labelled insulin-like growth factor-I (125I-IGF-I) bound to trophoderm cells from pig blastocysts obtained on days 15-19 of pregnancy. Specific binding was detected on freshly isolated cell suspensions and on cells cultured for several days. The binding of 125I-EGF was inhibited by increasing concentrations of EGF, but not by various other growth factors and hormones. Chemical cross-linking of 125I-EGF to its receptors using disuccinimidyl suberate (DSS) revealed a radiolabelled band of relative molecular mass 160,000, similar to that identified as the EGF receptor in other cell types. The binding of 125I-IGF-I was inhibited by both IGF-I and insulin, indicating that the receptors were either type I IGF receptors or insulin receptors. Cross-linking of 125I-IGF-I to serum-free supernatants from trophoderm cultures showed that the cells secreted an IGF-binding protein, giving a complex of relative molecular mass about 45,000. The presence of receptors for EGF and IGF/insulin suggests that these factors could be involved in regulating the growth and development of the early blastocyst.
Corps
A N
AN
Department of Biochemistry, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Brigstock
D R
DR
Littlewood
C J
CJ
Brown
K D
KD
D000818:Animals; D001756:Blastoderm / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000378:metabolism*; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013552:Swine / Q000196:embryology* / Q000378:metabolism
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I; D066246:ErbB Receptors