Dissemin is shutting down on January 1st, 2025

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Elsevier, Journal of Biological Chemistry, 28(289), p. 19747-19757, 2014

DOI: 10.1074/jbc.m114.547273

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Platelet-derived Growth Factor β-Receptor, Transforming Growth Factor β Type I Receptor, and CD44 Protein Modulate Each Other's Signaling and Stability

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Growth factors, such as platelet-derived growth factor BB (PDGF-BB) and transforming growth factor β (TGFβ), are key regulators of cellular functions, including proliferation, migration and differentiation. Growth factor signaling is modulated by context-dependent crosstalk between different signaling pathways. We demonstrate in the present communication that PDGF-BB induces phosphorylation of Smad2, a downstream mediator of the canonical TGFβ pathway, in primary dermal fibroblasts. The PDGF-BB-mediated Smad2 phosphorylation was dependent on the kinase activities of both TGFβ type I receptor (TβRI) and PDGF β-receptor (PDGFRβ), and was prevented by inhibitory antibodies against TGFβ. Inhibition of the activity of the TβRI kinase greatly reduced the PDGF-BB-dependent migration in dermal fibroblasts. Moreover, we demonstrate that the receptors for PDGF-BB and TGFβ interact physically in primary dermal fibroblasts, and that stimulation with PDGF-BB induces internalization not only of PDGFRβ, but also of TβRI. In addition, silencing of PDGFRβ by siRNA decreased the stability of TβRI and delayed TGFβ-induced signaling. We further show that the hyaluronan receptor CD44 interacts with both PDGFRβ and TβRI. Depletion of CD44 by siRNA increased signaling via PDGFRβ and TβRI by stabilizing the receptor proteins. Our data suggest that cross-talk between PDGFRβ and TβRI occurs in dermal fibroblasts, and that CD44 negatively modulates signaling via these receptors.