title: Release of transforming growth factor-beta 1 from the pericellular matrix of cultured fibroblasts and fibrosarcoma cells by plasmin and thrombin.
abstract: A sensitive immunoblotting assay was developed for the detection of transforming growth factor (TGF)-beta 1 from cell extracts and culture medium. HT-1080 human fibrosarcoma cells and human fibroblasts were used as models for the secretion and proteolytic release of pericellular matrix-associated TGF-beta 1. Analysis of the pericellular matrices of the cells indicated that the majority of cell-layer associated TGF-beta 1 was associated with the pericellular matrix. Treatment of the cells with plasmin or thrombin released the matrix-associated TGF-beta 1 to the culture medium. Assays for the biological activity of plasmin-released TGF-beta 1 by Mv1Lu cell growth inhibition assays indicated that the majority was in the latent form. Northern hybridization analyses indicated that the mRNA levels of TGF-beta 1 were not elevated during the proteinase treatment. Experiments using radiolabeled TGF-beta 1 indicated that exogenous active TGF-beta 1 associates mainly with the presumed TGF-beta 1 receptors that were not retained in the extracellular matrix preparations. These results indicate that a major fraction of latent TGF-beta 1 that is produced by the cells is deposited to and remains associated with the pericellular matrices of cultured fibroblasts and fibrosarcoma cells, and that matrix-associated TGF-beta 1 is very susceptible to release by various proteolytic enzymes.
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005341:Fibrinolysin / Q000494:pharmacology*; D005354:Fibrosarcoma; D006801:Humans; D015151:Immunoblotting; D007457:Iodine Radioisotopes; D007700:Kinetics; D008168:Lung; D008907:Mink; D011061:Poly A / Q000302:isolation & purification / Q000378:metabolism; D012313:RNA / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D007457:Iodine Radioisotopes; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D011061:Poly A; D012313:RNA; D013917:Thrombin; D005341:Fibrinolysin