Abstract
We have previously shown that bone organ cultures produce large amounts of latent transforming growth factor beta (TGF beta), which lacks latent TGF beta-binding protein (LTBP). In this study we used the known osteoblast-like cell lines UMR-106, ROS 17/2.8, and MG63 as models to further examine latent TGF beta expression in bone. We found that the osteosarcoma cell line UMR-106 secreted latent TGF beta almost exclusively as a 100-kDa complex lacking LTBP. ROS 17/2.8 cells produced both the 100-kDa complex and also a 290-kDa complex containing the fibroblastic (190 kDa) form of LTBP. MG63 cells (like human foreskin fibroblasts) expressed almost exclusively the 290-kDa complex. To investigate the regulation of latent TGF beta complexes in bone cells we assessed the effects of TGF beta 1 treatment on expression of active and latent TGF beta. TGF beta 1 induced secretion of latent but not active TGF beta in all cell types examined. In human foreskin fibroblast cells, TGF beta 1 and LTBP mRNA were expressed concomitantly. In contrast, in osteosarcoma cell lines autoinduction of TGF beta 1 mRNA was associated with either a delayed increase or no change in LTBP mRNA. In UMR-106 cells LTBP message was virtually undetectable. We postulate that the expression of different latent TGF beta forms by osteoblast-like cells may reflect their maturation states and that different latent TGF beta complexes may have different functions, for example as secretory forms or as matrix storage forms.
Highlights
From the $Department of Medicine, Division of Endocrinology and Metabolism, University of n x a s Health Science Center, Sun Antonio, Texas 78284-7877,llL.udwig Znstitute for Cancer Research, Uppsala, Sweden, J1Bristol-MeyerslSquibb (D.R.T), Seattle, Washington 98121,**Department of Cellular and Structural Biology, University of Texas Health Science Center at Sun Antonio
We have previously shown that bone organ cultures era1 latent TGFp complexes produced by different cell types produce large amounts of latent transforming growth have beendescribed
We have previously found that TGFpproduced by fibroblasts confactor j3 (TGFP) in conditioned medium from bone organ cultures exists in several laftoernmt s (Bonewald et al, 1991).The major formis a 100-kDa precursor complex, which lacks LTBP and appears identical tao100-kDa recombinant form of latent TGFpexpressed in CHO cells (Genwith either a delayed increase or no change in LTBP try et al, 1987)
Summary
(Received forpublication, March 16, 1993, and in revised form, October 6 , 1993). Sarah L. We have previously found that TGFP in conditioned medium from bone organ cultures exists in several laftoernmt s (Bonewald et al, 1991).The major formis a 100-kDa precursor complex, which lacks LTBP and appears identical tao100-kDa recombinant form of latent TGFpexpressed in CHO cells (Genwith either a delayed increase or no change in LTBP try et al, 1987). T h e probe for human latent TGFp1-hindlng protein different forms of latent TGFB in osteosarcoma cell lines with TGFPl treatment to determine (i)which types of latent complex were stimulated and (ii) whetheexrpression ofTGFPl and consisted of a 0.73-kilobase cDNA spanning base pair2s90G3H.74of the human fibroblast form of LTRP Theywere tested for TGFp activity as described above following acidactivation of the latent TGFP
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
