scholarly journals Plasmin cleaves betaglycan and releases a 60 kDa transforming growth factor-β complex from the cell surface

1994 ◽  
Vol 302 (1) ◽  
pp. 199-205 ◽  
Author(s):  
J Lamarre ◽  
J Vasudevan ◽  
S L Gonias
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Type I ◽  
Type Ii ◽  
Tgf Beta ◽  
Beta Receptor ◽  
Cell Extracts ◽  
Beta 2

Plasmin regulates the activity and distribution of transforming growth factor beta (TGF-beta) and other growth factors. The purpose of the present investigation was to determine the effects of plasmin on cellular receptors for TGF-beta. AKR-2B fibroblasts were affinity-labelled with 125I-TGF-beta 1 and 125I-TGF-beta 2, demonstrating betaglycan, the type-I TGF-beta receptor and the type-II TGF-beta receptor. Treatment of TGF-beta-affinity-labelled cells with plasmin (10-100 nM) for 1 h profoundly and selectively decreased recovery of TGF-beta-betaglycan complex. The type-I and type-II receptors were not plasmin substrates. A radiolabelled complex with an apparent mass of 60 kDa was detected by SDS/PAGE in both the medium and cell extracts of plasmin-treated affinity-labelled cells. In order to demonstrate that plasmin cleavage of betaglycan did not require prior exposure of the betaglycan to cross-linking agent, AKR-2B cells were treated with plasmin first and then affinity-labelled. Markedly decreased TGF-beta binding to cellular betaglycan was observed. Although plasmin treatment of AKR-2B cells decreased overall binding of 125I-TGF-beta 1 and 125I-TGF-beta 2, the rate at which the cells degraded bound 125I-TGF-beta at 37 degrees C was not changed. AKR-2B cells treated with plasmin demonstrated slightly increased [3H]thymidine incorporation; the plasmin-treated cells retained their ability to respond to TGF-beta. Conditioned medium from plasmin-treated AKR-2B cells contained increased amounts of active TGF-beta as determined in Mv 1 Lu epithelial-cell-proliferation assays. Specific cleavage of betaglycan represents a novel mechanism whereby plasmin may regulate the assortment of receptors available for TGF-beta. In addition, plasmin may facilitate transfer of active TGF-beta between neighbouring cells by releasing the active growth factor from the cell surface.

scholarly journals The types II and III transforming growth factor-beta receptors form homo-oligomers.

1994 ◽  
Vol 126 (1) ◽  
pp. 139-154 ◽  
Author(s):  
Y I Henis ◽  
A Moustakas ◽  
H Y Lin ◽  
H F Lodish
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Type Ii ◽  
Tgf Beta ◽  
Double Labeling ◽  
Beta Receptors ◽  
Growth Factor Beta ◽  
In Cells

Affinity-labeling experiments have detected hetero-oligomers of the types I, II, and III transforming growth factor beta (TGF-beta) receptors which mediate intracellular signaling by TGF-beta, but the oligomeric state of the individual receptor types remains unknown. Here we use two types of experiments to show that a major portion of the receptor types II and III forms homo-oligomers both in the absence and presence of TGF-beta. Both experiments used COS-7 cells co-transfected with combinations of these receptors carrying different epitope tags at their extracellular termini. In immunoprecipitation experiments, radiolabeled TGF-beta was bound and cross-linked to cells co-expressing two differently tagged type II receptors. Sequential immunoprecipitations using anti-epitope monoclonal antibodies showed that type II TGF-beta receptors form homo-oligomers. In cells co-expressing epitope-tagged types II and III receptors, a low level of co-precipitation of the ligand-labeled receptors was observed, indicating that some hetero-oligomers of the types II and III receptors exist in the presence of ligand. Antibody-mediated cross-linking studies based on double-labeling immunofluorescence explored co-patching of the receptors at the cell surface on live cells. In cells co-expressing two differently tagged type II receptors or two differently tagged type III receptors, forcing one receptor into micropatches by IgG induced co-patching of the receptor carrying the other tag, labeled by noncross-linking monovalent Fab'. These studies showed that homo-oligomers of the types II and III receptors exist on the cell surface in the absence or presence of TGF-beta 1 or -beta 2. In cells co-expressing types II and III receptors, the amount of heterocomplexes at the cell surface was too low to be detected in the immunofluorescence co-patching experiments, confirming that hetero-oligomers of the types II and III receptors are minor and probably transient species.

scholarly journals mRNA expression of type I and type II receptors for activin, transforming growth factor-beta, and bone morphogenetic protein in the murine erythroleukemic cell line, F5-5.fl

2000 ◽  
pp. 705-710 ◽  
Author(s):  
H Machida ◽  
K Ogawa ◽  
M Funaba ◽  
T Mizutani ◽  
M Tsujimoto
Keyword(s):  
Growth Factor ◽  
Mrna Expression ◽  
Bone Morphogenetic Protein ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Type I ◽  
Type Ii ◽  
Tgf Beta ◽  
Morphogenetic Protein ◽  
Growth Factor Beta

OBJECTIVE: Intracellular signaling of activin and transforming growth factor-beta (TGF-beta) is thought to be mediated by the same molecules (Smad2/3 and Smad4). Although differentiation of murine erythroleukemia F5-5.fl cells is induced by activin, it is not induced by TGF-beta, suggesting that at some point TGF-beta signaling is defective. The aim of this study was to investigate the unresponsiveness of F5-5.fl cells to TGF-beta. DESIGN: mRNA expression of ligands, receptors, and signal mediators for the TGF-beta family was examined in F5-5.fl cells using RT-PCR. RESULTS: Activin induced erythrodifferentiation of F5-5.fl cells in a dose-dependent manner. Neither TGF-beta1 nor bone morphogenetic protein (BMP)-4 affected the differentiation of F5-5.fl cells in the presence or absence of activin. Although mRNAs of TGF-betas (TGF-beta1, TGF-beta2 and TGF-beta3) were detected, those of inhibin/activin (alpha-, betaA- and betaB-subunits) and BMPs (BMP-2, BMP-4 and BMP-7) could not be detected in the cells, suggesting that neither activins nor BMPs are produced in F5-5.fl cells. The expression of both type I (ALK-4/ActRIB) and type II (ActRII) receptors for activin was detected in F5-5.fl cells. In contrast, while the expression of type I receptor for TGF-beta (ALK-5/TbetaRI) was detected, that of type II receptor (TbetaRII) was not. The mRNA of all Smads examined was detected in F5-5.fl cells. CONCLUSIONS: A defect in the type II receptor might cause unresponsiveness to TGF-beta in F5-5.fl cells. An erythrodifferentiation assay using F5-5.fl cells would be useful for measuring net activin activity because it would not be necessary to consider endogenous activins and BMPs.

scholarly journals A glycosylation-deficient endothelial cell mutant with modified responses to transforming growth factor-beta and other growth inhibitory cytokines: evidence for multiple growth inhibitory signal transduction pathways.

1993 ◽  
Vol 4 (2) ◽  
pp. 135-144 ◽  
Author(s):  
V Fafeur ◽  
B O'Hara ◽  
P Böhlen
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Tnf Alpha ◽  
Type I ◽  
Tgf Beta ◽  
Ifn Gamma ◽  
Beta Receptor ◽  
Growth Inhibitory ◽  
Growth Factor Beta

An endothelial cell line (M40) resistant to growth inhibition by transforming growth factor-beta type 1 (TGF beta 1) was isolated by chemical mutagenesis and growth in the presence of TGF beta 1. Like normal endothelial cells, this mutant is characterized by high expression of type II TGF beta receptor and low expression of type I TGF beta receptor. However, the mutant cells display a type II TGF beta receptor of reduced molecular weight as a result of a general defect in N-glycosylation of proteins. The alteration does not impair TGF beta 1 binding to cell surface receptors or the ability of TGF beta 1 to induce fibronectin or plasminogen activator inhibitor-type I production. M40 cells were also resistant to growth inhibition by tumor necrosis factor alpha (TNF alpha) and interleukin-1 alpha (IL-1 alpha) but were inhibited by interferon-gamma (IFN gamma) and heparin. These results imply that TGF beta 1, TNF alpha, and IL-1 alpha act through signal transducing pathways that are separate from pathways for IFN gamma and heparin. Basic fibroblast growth factor was still mitogenic for M40, further suggesting that TGF beta 1, TNF alpha, and IL-1 alpha act by direct inhibition of cell growth rather than by interfering with growth stimulatory pathways.

scholarly journals Formation of hetero-oligomeric complexes of type I and type II receptors for transforming growth factor-beta.

1994 ◽  
Vol 269 (31) ◽  
pp. 20172-20178 ◽  
Author(s):  
H. Yamashita ◽  
P. ten Dijke ◽  
P. Franzén ◽  
K. Miyazono ◽  
C.H. Heldin
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Type I ◽  
Type Ii ◽  
Growth Factor Beta
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