Characterization of insulin-like growth factor-binding proteins in rat serum, lymph, cerebrospinal and amniotic fluids, and in media conditioned by liver, bone and muscle cells.
Insulin-like growth factor-binding proteins (IGFBPs) in rat serum, lymph, amniotic fluid and cerebrospinal fluid (CSF), and in rat cell-conditioned media were characterized using a combination of gel-permeation chromatography, Western immunoblots and Western-ligand analysis. Adult serum and abdominal lymph contained a 200 kDa IGFBP (the putative type-II IGF receptor) and a 150 kDa IGFBP that contained subunits of 40-50 kDa aligning with porcine IGFBP-3 on Western-ligand blots. In addition, both fluids contained the smaller IGFBPs: a 30 kDa IGFBP which was immunoreactive with IGFBP-2 antiserum, a 28 kDa IGFBP which electrophoresed with human IGFBP-1, and a 24 kDa IGFBP. In contrast, fetal serum and amniotic fluid lacked the 150 kDa and the 28 kDa IGFBPs. CSF contained only a 30 kDa IGFBP, but this was not IGFBP-2. Several IGFBPs were detected in media conditioned by liver, bone and muscle cells. Liver-derived cells and some hepatoma cell lines produced similar patterns upon ligand blot analysis, i.e. IGFBPs of 30 kDa (which reacted with IGFBP-2 antiserum), 28 kDa and 24 kDa. A hepatoma cell line, HTC, and a smooth muscle cell line contained only an IGFBP of 26 kDa. Skeletal muscle-derived cells (L6 myoblasts) produced a 28 kDa, a 26 kDa and a 24 kDa IGFBP. Both calvarial osteoblasts and osteogenic sarcoma cells produced an IGFBP of 30 kDa that cross-reacted with IGFBP-2 antisera. In addition, osteogenic sarcoma cells produced a 28 kDa and a 24 kDa IGFBP. These results allow us partially to classify and to compare the IGFBPs in rat fluids and those produced by cultured cells.
Gargosky
S E
SE
Department of Biochemistry, University of Adelaide, South Australia.
Walton
P E
PE
Wallace
J C
JC
Ballard
F J
FJ
D000653:Amniotic Fluid / Q000737:chemistry*; D000818:Animals; D015153:Blotting, Western; D001842:Bone and Bones / Q000378:metabolism; D002352:Carrier Proteins / Q000097:blood / Q000134:cerebrospinal fluid / Q000737:chemistry*; D002850:Chromatography, Gel; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D018969:Insulin-Like Growth Factor Binding Proteins; D008099:Liver / Q000378:metabolism; D008196:Lymph / Q000737:chemistry*; D009132:Muscles / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000134:cerebrospinal fluid / Q000737:chemistry* / Q000378:metabolism
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins