Isolation and characterization of a novel type of growth factor derived from serum-free conditioned medium of chicken embryo fibroblasts.
A strong mitogenic activity for fibroblastic cells has been found in serum-free medium of growth-arrested primary cultures of chicken embryo fibroblasts (CEF). This serum-free conditioned medium promoted growth of NIH/3T3 cells and primary as well as secondary cultures of CEF. The mitogenic activity was as potent as 5% serum. Half-maximum stimulation was obtained with 20% of the initial concentration of the conditioned medium. The activity eluted at high M(r) (1-2 x 10(5)) from a gel-filtration column under nondenaturing conditions and was trypsin insensitive and thiol insensitive. Treatment with acid or urea converted the mitogen to a low-molecular-mass form, which showed a delayed induction of DNA synthesis. Purification of this factor (10000-fold) to apparent homogeneity was achieved by preparative isoelectric focusing, gel filtration, reverse-phase HPLC and nonreducing SDS/PAGE. The factor, termed CEF-derived growth factor (CDGF) was a 32-kDa, disulfide-linked heterodimer of a 15-kDa and a 17-kDa subunit as judged by SDS/PAGE, with a pI of approximately 7 in 8 M urea. It exhibited partial stability towards heat treatment and was trypsin sensitive. CDGF was active only in its dimeric form and half-maximum stimulation of NIH/3T3 cells was obtained at approximately 10 pM. The mitogenic activity was not suppressible by an antibody neutralizing the activity of transforming growth factor beta 1, 2 and 3 (TGF-beta). The physico-chemical properties suggest that CDGF is not identical with one of the common growth factors like fibroblast growth factor, platelet-derived growth factor, epidermal growth factor, insulin-like growth factor, or TGF-beta but rather represents a novel type of growth factor.
Geistlich
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Biochemisches Institut, Universität Zürich, Switzerland.
Gehring
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D016475:3T3 Cells; D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D002642:Chick Embryo; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D016895:Culture Media, Serum-Free; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D006133:Growth Substances / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D007525:Isoelectric Focusing; D051379:Mice; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D016895:Culture Media, Serum-Free; D006133:Growth Substances; D016212:Transforming Growth Factor beta