Characterization of growth factor activity produced by fetal mouse osteoblasts.
Bone matrix contains a variety of growth factors, but little is known of osteoblastic production of such materials. The present study assesses growth factor activity, chromatographed on acidic Bio-Gel P-100, secreted into conditioned media of primary cultures of fetal mouse calvaria. The cultures produced insulin-like growth factor-I (IGF-I), determined by radioimmuno-assay of molecular weights 20 and 10 kDa. IGF-II, determined by radioreceptor assay, was present at 20-29 and 7 kDa. The IGF peaks at 20, 10 and 7 kDa were all mitogenic in MCF-7 cells. Proteins of several different molecular weights were also present that specifically bound IGF-I and IGF-II. Transforming growth factor-beta (TGF-beta), assayed in a system for inhibition of growth, was also produced. Both activated and latent forms were present, and part of the TGF-beta was TGF-beta 2. The absence of mitogenic activity in the bmolecular range of platelet-derived growth factor, assayed in 3T3 fibroblasts, makes it unlikely that mouse osteoblasts produce this growth factor.
Slootweg
M C
MC
Department of Internal Medicine, University Hospital, Utrecht, The Netherlands.
van Buul-Offers
S C
SC
Hoogerbrugge
C M
CM
Herrmann-Erlee
M P
MP
van den Eijnden-van Raaij
A J
AJ
Duursma
S A
SA
van Zoelen
E J
EJ
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis; D002478:Cells, Cultured; D005333:Fetus; D006133:Growth Substances / Q000032:analysis* / Q000096:biosynthesis; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D015291:Transforming Growth Factors / Q000032:analysis
D002352:Carrier Proteins; D006133:Growth Substances; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D015291:Transforming Growth Factors