Tissue transglutaminase promotes PDGF/PDGFR-mediated signaling and responses in vascular smooth muscle cells.

ABSTRACT: Although the pivotal role of platelet derived growth factor (PDGF)-mediated signaling in vascular diseases was demonstrated, the pathophysiological mechanisms driving its over-activation remain incompletely understood. Tissue transglutaminase (tTG) is a multifunctional protein expressed in the vasculature, including smooth muscle cells (SMCs), and implicated in several vascular pathologies. The goal of this study is to define the regulation of PDGF-BB/PDGFR?-induced signaling pathways and cell responses by tTG in vascular SMCs. We find that in human aortic SMCs, shRNA-mediated depletion and over-expression of tTG reveals its ability to down-regulate PDGFR? levels and induce receptor clustering. In these cells, tTG specifically amplifies the activation of PDGFR? and its multiple downstream signaling targets in response to PDGF-BB. Furthermore, tTG promotes dedifferentiation and increases survival, proliferation, and migration of human aortic SMCs mediated by this growth factor. Finally, PDGF-BB stimulates tTG expression in human aortic SMCs in culture and in the blood vessels in response to injury. Together, our results show that tTG in vascular SMCs acts as a principal enhancer within the PDGF-BB/PDGFR? signaling axis involved in phenotypic modulation of these cells, thereby suggesting a novel role for this protein in the progression of vascular diseases.

SUBMITTER: Zemskov EA 

PROVIDER: S-EPMC3210882 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature