Transforming growth factor beta 1-responsive element: closely associated binding sites for USF and CCAAT-binding transcription factor-nuclear factor I in the type 1 plasminogen activator inhibitor gene.

Abstract

Transforming growth factor 13 (TGF-3) is the name of a group of closely related polypeptides characterized by a multiplicity of effects, including regulation of extracellular proteolysis and turnover of the extracellular matrix. Its cellular mechanism of action is largely unknown. TGF-131 is a strong and fast inducer of type 1 plasminogen activator inhibitor gene transcription. We have identified a TGF-131-responsive element in the 5'-flanking region of the human type 1 plasminogen activator inhibitor gene and shown that it is functional both in its natural context and when fused to a heterologous nonresponsive promoter. Footprinting and gel retardation experiments showed that two different nuclear factors, present in extracts from both TGF-131-treated and nontreated cells, bind to adjacent sequences contained in the responsive unit. A palindromic sequence binds a trans-acting factor(s) of the CCAAT-binding transcription factor-nuclear factor I family. A partially overlapping dyad symmetry interacts with a second protein that much evidence indicates to be USF. USF is a transactivator belonging to the basic helix-loop-helix family of transcription factors. Mutations which abolish the binding of either CCAAT-binding transcription factor-nuclear factor I or USF result in reduction of transcriptional activation upon exposure to TGF-131, thus showing that both elements of the unit are necessary for the TGF-131 response. We discuss the possible relationship of these findings to the complexity of the TGF-13 action.Transforming growth factor I0 (TGF-3) is a general regulator of cellular activities with a multiplicity of effects in the normal organism. TGF-ps include a group of chemically closely related 25,000-Mr dimeric polypeptides, TGF-pl, , with largely identical effects. (Unless otherwise specified, "TGF-P3" will refer to TGF-fi1 heterodimers throughout the rest of the text.) TGF-,B can be synthesized by most cells of the organism and is stored in large quantities in blood platelets. It acts presumably in an autocrine and paracrine manner. Besides affecting cellular proliferation, TGF-3 influences the differentiation of several cell types; for instance, it inhibits myogenesis and adipogenesis and stimulates chondrogenesis. TGF-, regulates the turnover of the extracellular matrix. It stimulates production by fibroblasts of extracellular matrix components, such as type I, II, and III procollagen, fibronectin, and proteoglycans, and of cellular receptors for such proteins. TGF-1 inhibits production of enzymes catalyzing degradation of the extracellular matrix and stimulates production of inhibitors of such enzymes (22,27,31,41,47).It has previously been demonstrated that TGF-p induces type 1 inhibitor of plasminogen activators (PAI-1) in cultured human fibroblasts (24,26). PAI-1 is an important regulator of plasminogen activation and thus of extracellular proteolytic events, including fibrinolysis and degradation of the extracellular matrix (1, 6). The induction of PAI-1 protein by * Corresponding author. TGF-0 was la...

Regulation of human myocilin/TIGR gene transcription in trabecular meshwork cells and astrocytes: role of upstream stimulatory factor

“…Examples for this are the insulin-mediated transcriptional activation of the fatty acid synthase gene (Wang & Sul 1995), and the glucose response of L-pyruvate kinase and Spot 14 transcription, which are both mediated by USF (Vallet et al 1997). USF is also involved in the contractile-induced expression of the cardiac a-myosin heavy chain (Ojamaa et al 1995), the injury-induced osteopontin expression of smooth muscle cells (Malyankar et al 1999), the TGF-b1 mediated induction of the human type 1 plasminogen inhibitor gene (Riccio et al 1992) and the induction of the metallthionein-I gene in response to H 2 O 2 and cadmium (Li et al 1998). H 2 O 2 and cadmium can induce oxidative stress, and the involvement of USF in oxidative stress could be related to the fact that USF can be functionally regulated in a redox-dependent manner (Pognonec et al 1992).…”

Binding of Upstream Stimulatory Factor and a Cell-specific Activator to the Calcitonin/Calcitonin Gene-related Peptide Enhancer

“…We have previously demonstrated this point by showing that retinoic acid (42), dexamethasone (15), and a serotonergic agonist 3 all can repress CT/CGRP gene expression through the CT/CGRP HLH-OB2 enhancer. The possibility that USF activity can be regulated has been suggested by Riccio et al (32), who have shown that transforming growth factor-␤ can regulate gene expression through overlapping USF-CTF/NF-I sites in the type 1 plasminogen activator inhibitor gene (32). Mutations in either the USF or CTF/NF-1 sites reduced transcriptional activation upon exposure to transforming growth factor-␤.…”

“…For example, the insulin gene has been proposed to be controlled by the combinatorial actions of E47 HLH proteins and cell-specific homeodomain proteins (22,23). The USF HLH proteins have also been shown to functionally interact with other DNA binding proteins to activate transcription, including in a cell-specific manner (32,33,38). In the case of the CT/CGRP enhancer, we propose that cell specificity is provided by the OB2 protein.…”

Activation of Peroxisome Proliferator-Activated Receptor-γ Decreases Pancreatic Cancer Cell Invasion through Modulation of the Plasminogen Activator System

“…The precise mechanisms by which PPAR-g ligands modulate PAI-1 and uPA transcription remain to be defined. The PAI-1 promoter, which lacks a consensus PPAR response element (PPRE), contains cis-acting elements for CAAT/enhancer-binding protein and signal transducers and activators of transcription (35,36). It is conceivable that activation of PPAR-g induces the expression of other transcription factors, which in turn regulate PAI-1 gene transcription (37,38).…”