Redox-Sensitive Regulation of Myocardin-Related Transcription Factor (MRTF-A) Phosphorylation via Palladin in Vascular Smooth Muscle Cell Differentiation Marker Gene Expression

• Published in: PloS one 2016-04, Vol.11 (4), p.e0153199-e0153199
• Main Authors: Lee, Minyoung, San Martín, Alejandra, Valdivia, Alejandra, Martin-Garrido, Abel, Griendling, Kathy K
• Format: Article
• Language: English
• Subjects: Actin; Actins - metabolism; Arteriosclerosis; Atherosclerosis; Biology and Life Sciences; Calcium-Binding Proteins - metabolism; Calponin; Calponins; Cardiology; Cardiovascular diseases; Cell differentiation; Cell Differentiation - drug effects; Cell Differentiation - physiology; Cells, Cultured; Cytoskeletal Proteins - genetics; Cytoskeletal Proteins - metabolism; Cytoskeleton; Differentiation (biology); Extracellular matrix; Fibroblasts; Gene expression; Gene Expression Regulation; Gene regulation; Genes; Genetic aspects; Genetic Markers; Heart diseases; Humans; Hydrogen peroxide; Kinases; Medicine; Microfilament Proteins - metabolism; Motility; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Muscles; NAD(P)H oxidase; NADPH Oxidase 4; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; NOX4 protein; Oxidases; Oxidation-Reduction; Oxygen; Phosphoproteins - genetics; Phosphoproteins - metabolism; Phosphorylation; Physiological aspects; Proteins; Reactive oxygen species; Regulations; Research and Analysis Methods; Restenosis; Rho-associated kinase; rho-Associated Kinases - metabolism; Rocks; Signal transduction; Signaling; siRNA; Smooth muscle; Trans-Activators - genetics; Trans-Activators - metabolism; Transcription factors; Transforming growth factor; Transforming Growth Factor beta - metabolism; Transforming Growth Factor beta - pharmacology; Transforming growth factor-b
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0153199

Vascular smooth muscle cells (VSMCs) undergo a phenotypic switch from a differentiated to synthetic phenotype in cardiovascular diseases such as atherosclerosis and restenosis. Our previous studies indicate that transforming growth factor-β (TGF-β) helps to maintain the differentiated phenotype by regulating expression of pro-differentiation genes such as smooth muscle α-actin (SMA) and Calponin (CNN) through reactive oxygen species (ROS) derived from NADPH oxidase 4 (Nox4) in VSMCs. In this study, we investigated the relationship between Nox4 and myocardin-related transcription factor-A (MRTF-A), a transcription factor known to be important in expression of smooth muscle marker genes. Previous work has shown that MRTF-A interacts with the actin-binding protein, palladin, although how this interaction affects MRTF-A function is unclear, as is the role of phosphorylation in MRTF-A activity. We found that Rho kinase (ROCK)-mediated phosphorylation of MRTF-A is a key event in the regulation of SMA and CNN in VSMCs and that this phosphorylation depends upon Nox4-mediated palladin expression. Knockdown of Nox4 using siRNA decreases TGF-β -induced palladin expression and MRTF-A phosphorylation, suggesting redox-sensitive regulation of this signaling pathway. Knockdown of palladin also decreases MRTF-A phosphorylation. These data suggest that Nox4-dependent palladin expression and ROCK regulate phosphorylation of MRTF-A, a critical factor in the regulation of SRF responsive gene expression.