TGF{beta}2-mediated production of hyaluronan is important for the induction of epicardial cell differentiation and invasion
- Department of Pharmacology and Toxicology, The University of Arizona, Tucson, AZ (United States)
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States)
In the developing heart, the epicardium is a major source of progenitor cells that contribute to the formation of the coronary vessel system. These epicardial progenitors give rise to the different cellular components of the coronary vasculature by undergoing a number of morphological and physiological changes collectively known as epithelial to mesenchymal transformation (EMT). However, the specific signaling mechanisms that regulate epicardial EMT are yet to be delineated. In this study we investigated the role of TGF{beta}2 and hyaluronan (HA) during epicardial EMT and how signals from these two molecules are integrated during this important process. Here we show that TGF{beta}2 induces MEKK3 activation, which in turn promotes ERK1/2 and ERK5 phosphorylation. TGF{beta}2 also increases Has2 expression and subsequent HA production. Nevertheless, inhibition of MEKK3 kinase activity, silencing of ERK5 or pharmacological disruption of ERK1/2 activation significantly abrogates this response. Thus, TGF{beta}2 promotes Has2 expression and HA production through a MEKK3/ERK1/2/5-dependent cascade. Furthermore, TGF{beta}2 is able to induce epicardial cell invasion and differentiation but not proliferation. However, inhibition of MEKK3-dependent pathways, degradation of HA by hyaluronidases or blockade of CD44, significantly impairs the biological response to TGF{beta}2. Taken together, these findings demonstrate that TGF{beta}2 activation of MEKK3/ERK1/2/5 signaling modulates Has2 expression and HA production leading to the induction of EMT events. This is an important and novel mechanism showing how TGF{beta}2 and HA signals are integrated to regulate changes in epicardial cell behavior.
- OSTI ID:
- 22209936
- Journal Information:
- Experimental Cell Research, Vol. 316, Issue 20; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0014-4827
- Country of Publication:
- United States
- Language:
- English
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