scholarly journals Distinct Endocytic Responses of Heteromeric and Homomeric Transforming Growth Factor β Receptors

1997 ◽  
Vol 8 (11) ◽  
pp. 2133-2143 ◽  
Author(s):  
Robert A. Anders ◽  
Sandra L. Arline ◽  
Jules J.E. Doré ◽  
Edward B. Leof
Keyword(s):  
Growth Factor ◽  
Ligand Binding ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Cell Surface Receptor ◽  
Type I ◽  
Type Ii ◽  
Down Regulation ◽  
Tgfβ Receptors ◽  
Tgfβ Receptor

Transforming growth factor β (TGFβ) family ligands initiate a cascade of events capable of modulating cellular growth and differentiation. The receptors responsible for transducing these cellular signals are referred to as the type I and type II TGFβ receptors. Ligand binding to the type II receptor results in the transphosphorylation and activation of the type I receptor. This heteromeric complex then propagates the signal(s) to downstream effectors. There is presently little data concerning the fate of TGFβ receptors after ligand binding, with conflicting reports indicating no change or decreasing cell surface receptor numbers. To address the fate of ligand-activated receptors, we have used our previously characterized chimeric receptors consisting of the ligand binding domain from the granulocyte/macrophage colony-stimulating factor α or β receptor fused to the transmembrane and cytoplasmic domain of the type I or type II TGFβ receptor. This system not only provides the necessary sensitivity and specificity to address these types of questions but also permits the differentiation of endocytic responses to either homomeric or heteromeric intracellular TGFβ receptor oligomerization. Data are presented that show, within minutes of ligand binding, chimeric TGFβ receptors are internalized. However, although all the chimeric receptor combinations show similar internalization rates, receptor down-regulation occurs only after activation of heteromeric TGFβ receptors. These results indicate that effective receptor down-regulation requires cross-talk between the type I and type II TGFβ receptors and that TGFβ receptor heteromers and homomers show distinct trafficking behavior.

scholarly journals Mechanisms of Transforming Growth Factor-β Receptor Endocytosis and Intracellular Sorting Differ between Fibroblasts and Epithelial Cells

2001 ◽  
Vol 12 (3) ◽  
pp. 675-684 ◽  
Author(s):  
Jules J.E. Doré ◽  
Diying Yao ◽  
Maryanne Edens ◽  
Nandor Garamszegi ◽  
Elizabeth L. Sholl ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Ligand Binding ◽  
Transforming Growth Factor ◽  
Point Mutations ◽  
Type I ◽  
Receptor Complex ◽  
Type Ii ◽  
Down Regulation ◽  
Β Receptor

Transforming growth factor-βs (TGF-β) are multifunctional proteins capable of either stimulating or inhibiting mitosis, depending on the cell type. These diverse cellular responses are caused by stimulating a single receptor complex composed of type I and type II receptors. Using a chimeric receptor model where the granulocyte/monocyte colony-stimulating factor receptor ligand binding domains are fused to the transmembrane and cytoplasmic signaling domains of the TGF-β type I and II receptors, we wished to describe the role(s) of specific amino acid residues in regulating ligand-mediated endocytosis and signaling in fibroblasts and epithelial cells. Specific point mutations were introduced at Y182, T200, and Y249 of the type I receptor and K277 and P525 of the type II receptor. Mutation of either Y182 or Y249, residues within two putative consensus tyrosine-based internalization motifs, had no effect on endocytosis or signaling. This is in contrast to mutation of T200 to valine, which resulted in ablation of signaling in both cell types, while only abolishing receptor down-regulation in fibroblasts. Moreover, in the absence of ligand, both fibroblasts and epithelial cells constitutively internalize and recycle the TGF-β receptor complex back to the plasma membrane. The data indicate fundamental differences between mesenchymal and epithelial cells in endocytic sorting and suggest that ligand binding diverts heteromeric receptors from the default recycling pool to a pathway mediating receptor down-regulation and signaling.

scholarly journals Activation of Key Profibrotic Mechanisms in Transgenic Fibroblasts Expressing Kinase-deficient Type II Transforming Growth Factor-β Receptor (TβRIIΔk)

2005 ◽  
Vol 280 (16) ◽  
pp. 16053-16065 ◽  
Author(s):  
Christopher P. Denton ◽  
Gisela E. Lindahl ◽  
Korsa Khan ◽  
Xu Shiwen ◽  
Voon H. Ong ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transgene Expression ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Type I ◽  
Myofibroblast Differentiation ◽  
Type Ii ◽  
Wild Type ◽  
Tgfβ Receptor ◽  
High Level

We have generated transgenic mice expressing a kinase-deficient type II transforming growth factor-β (TGFβ) receptor selectively on fibroblasts (TβRIIΔk-fib). These mice develop dermal and pulmonary fibrosis. In the present study we explore activation of TGFβ signaling pathways in this strain and examine the profibrotic properties of explanted transgenic fibroblasts including myofibroblast differentiation and abnormal metalloproteinase production. Gene expression profiles of littermate wild type or transgenic fibroblasts were compared using high-density gene arrays and validated by Taqman reverse transcriptase-PCR, Northern and Western blotting. Using a specific inhibitor (SD-208) we demonstrate that the abnormal phenotype of these cells is dependent upon TβRI kinase (ALK5) activity, and that transgenic fibroblasts show enhanced expression and activation of TGFβ together with increased levels of wild type TβRII. Moreover, we confirm that transgene expression is itself regulated by TGFβ and that expression at low levels facilitates signaling, whereas high level expression is inhibitory. For a subset of TGFβ responsive genes basal up-regulation is normalized or suppressed by exogenous recombinant TGFβ1 at time points coincident with increased transgene expression. These findings explain the profound refractoriness of TβRIIΔk-fib fibroblasts to exogenous TGFβ1, despite their activated phenotype. Thus, transgenic fibroblasts recapitulate many hallmark biochemical properties of fibrotic cells, including high level CTGF (CCN2) expression and type I collagen overproduction, altered MMP production, and myofibroblast differentiation. These cells also show an enhanced ability to contract collagen gel matrices. Our study demonstrates that altered high affinity TGFβ receptor function may lead to ligand-dependent activation of downstream signaling, and provides further evidence of a pivotal role for sustained TGFβ overactivity in fibrosis.

scholarly journals Integrin β1Signaling Is Necessary for Transforming Growth Factor-β Activation of p38MAPK and Epithelial Plasticity

2001 ◽  
Vol 276 (50) ◽  
pp. 46707-46713 ◽  
Author(s):  
Neil A. Bhowmick ◽  
Roy Zent ◽  
Mayshan Ghiassi ◽  
Maureen McDonnell ◽  
Harold L. Moses
Keyword(s):  
Extracellular Matrix ◽  
Growth Factor ◽  
Transcriptional Activation ◽  
Intracellular Signaling ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Dominant Negative ◽  
Receptor Expression ◽  
Type I ◽  
Type Ii

Transforming growth factor-β (TGF-β) can induce epithelial to mesenchymal transdifferentiation (EMT) in mammary epithelial cells. TGF-β-meditated EMT involves the stimulation of a number of signaling pathways by the sequential binding of the type II and type I serine/threonine kinase receptors, respectively. Integrins comprise a family of heterodimeric extracellular matrix receptors that mediate cell adhesion and intracellular signaling, hence making them crucial for EMT progression. In light of substantial evidence indicating TGF-β regulation of various β1integrins and their extracellular matrix ligands, we examined the cross-talk between the TGF-β and integrin signal transduction pathways. Using an inducible system for the expression of a cytoplasmically truncated dominant negative TGF-β type II receptor, we blocked TGF-β-mediated growth inhibition, transcriptional activation, and EMT progression. Dominant negative TGF-β type II receptor expression inhibited TGF-β signaling to the SMAD and AKT pathways, but did not block TGF-β-mediated p38MAPK activation. Interestingly, blocking integrin β1function inhibited TGF-β-mediated p38MAPK activation and EMT progression. Limiting p38MAPK activity through the expression of a dominant negative-p38MAPK also blocked TGF-β-mediated EMT. In summary, TGF-β-mediated p38MAPK activation is dependent on functional integrin β1, and p38MAPK activity is required but is not sufficient to induce EMT.

scholarly journals A Novel Transforming Growth Factor-β Receptor-interacting Protein That Is Also a Light Chain of the Motor Protein Dynein

2002 ◽  
Vol 13 (12) ◽  
pp. 4484-4496 ◽  
Author(s):  
Qian Tang ◽  
Cory M. Staub ◽  
Guofeng Gao ◽  
Qunyan Jin ◽  
Zhengke Wang ◽  
...  
Keyword(s):  
Growth Factor ◽  
Light Chain ◽  
Transforming Growth Factor ◽  
Motor Protein ◽  
Transforming Growth Factor Β ◽  
Cytoplasmic Dynein ◽  
Epithelial Cell Line ◽  
Tgfβ Receptors ◽  
Tgfβ Receptor ◽  
Intermediate Chain

The phosphorylated, activated cytoplasmic domains of the transforming growth factor-β (TGFβ) receptors were used as probes to screen an expression library that was prepared from a highly TGFβ-responsive intestinal epithelial cell line. One of the TGFβ receptor-interacting proteins isolated was identified to be the mammalian homologue of the LC7 family (mLC7) of dynein light chains (DLCs). This 11-kDa cytoplasmic protein interacts with the TGFβ receptor complex intracellularly and is phosphorylated on serine residues after ligand-receptor engagement. Forced expression of mLC7-1 induces specific TGFβ responses, including an activation of Jun N-terminal kinase (JNK), a phosphorylation of c-Jun, and an inhibition of cell growth. Furthermore, TGFβ induces the recruitment of mLC7-1 to the intermediate chain of dynein. A kinase-deficient form of TGFβ RII prevents both mLC7-1 phosphorylation and interaction with the dynein intermediate chain (DIC). This is the first demonstration of a link between cytoplasmic dynein and a natural growth inhibitory cytokine. Furthermore, our results suggest that TGFβ pathway components may use a motor protein light chain as a receptor for the recruitment and transport of specific cargo along microtublules.

scholarly journals Down-regulation of transforming growth factor-β type II receptor (TGF-βRII) protein and mRNA expression in cervical cancer

2008 ◽  
Vol 7 (1) ◽  
pp. 3 ◽  
Author(s):  
Jose Diaz-Chavez ◽  
Rogelio Hernandez-Pando ◽  
Paul F Lambert ◽  
Patricio Gariglio
Keyword(s):  
Cervical Cancer ◽  
Growth Factor ◽  
Mrna Expression ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Type Ii ◽  
Down Regulation

scholarly journals Transforming Growth Factor-β Induces Formation of a Dithiothreitol-resistant Type I/Type II Receptor Complex in Live Cells

1999 ◽  
Vol 274 (9) ◽  
pp. 5716-5722 ◽  
Author(s):  
Rebecca G. Wells ◽  
Lilach Gilboa ◽  
Yin Sun ◽  
Xuedong Liu ◽  
Yoav I. Henis ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Live Cells ◽  
Type I ◽  
Receptor Complex ◽  
Type Ii

scholarly journals Gestational Changes in the Levels of Transforming Growth Factor-β1 (TGFβ1) and TGFβ Receptor Types I and II in the Human Myometrium1

1998 ◽  
Vol 83 (8) ◽  
pp. 2987-2992 ◽  
Author(s):  
Panadda Hatthachote ◽  
Joanna Morgan ◽  
William Dunlop ◽  
G. Nicholas Europe-Finner ◽  
James I. Gillespie
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Human Myometrium ◽  
Type I ◽  
Signaling System ◽  
Release Channel ◽  
Tgfβ Receptors ◽  
Tgfβ Receptor

abstract As term approaches, a number of key proteins [contraction-associated proteins (CAPs)] are expressed within the human myometrium that are essential for the activation of powerful coordinated contractions during labor. The nature of the signals that switch on the synthesis of CAPs in vivo is not known. The ryanodine-sensitive intracellular Ca2+ release channel (RyR2) is a CAP whose expression in vitro is activated by transforming growth factor-β (TGFβ). The present experiments were performed to determine whether TGFβ and TGFβ receptors are present in the human myometrium at term and to explore the idea that they might form part of a signaling system in vivo. TGFβ receptor types I and II, but not III, were demonstrated in myometrial smooth muscle in tissue taken from nonpregnant, pregnant nonlaboring, and spontaneous laboring women. Western blotting was used subsequently to determine the relative expression of TGFβ receptor types I and II. Using nonpregnant myometrium as a baseline control the levels of expression of receptor types I and II were significantly increased by 168 ± 19% (n = 6) and 162 ± 22% (n = 7) in pregnant nonlaboring myometrium. In spontaneous laboring myometrium the levels of TGFβ receptor type I and II expression were 93 ± 12% (n = 6) and 85 ± 11% (n = 7), respectively, compared to nonpregnant control values and were significantly lower than levels in pregnant nonlaboring tissues. The total TGFβ1 levels in the myometrial tissues were 334 ± 10, 534 ± 73, and 674 ± 106 pg/g tissue wet wt in nonpregnant, pregnant nonlaboring, and spontaneous laboring myometrium (n = 3 in each group), respectively. Thus, the TGFβ signaling system appears to be up-regulated in the myometrium before the onset of parturition. The apparent loss of receptors in the spontaneous laboring samples in the presence of elevated total levels of TGFβ may be indicative of agonist-induced receptor down-regulation. These observations support the idea that cytokines, in particular TGFβ1, may play a role in the normal processes that prepare the myometrium for parturition at term.

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