Published online before print August 27, 2009, doi: 10.1161/CIRCRESAHA.109.205120
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Submitted on May 22, 2008
Revised on August 17, 2009
Accepted on August 19, 2009
S100A4 and Bone Morphogenetic Protein-2 Codependently Induce Vascular Smooth Muscle Cell Migration via Phospho–Extracellular Signal-Regulated Kinase and Chloride Intracellular Channel 4
Edda Spiekerkoetter ;
From the Department of Pediatrics (E.S., C.G., V.d.J.P., T.-P.A., J.M.P., L.W., M.R.), Stanford University School of Medicine, Calif; School of Medicine and Biomedical Sciences (A.L.), University Sheffield, United Kingdom; Danish Cancer Society (N.A.), Copenhagen, Denmark; Department of Physiology (A.-M.S.), Medicine and Surgery, Columbia University, New York; Department of Biomedical Sciences (M.B.), Ohio University College of Osteopathic Medicine, Athens; and Centre for Integrative Physiology (R.H.A.), University of Edinburgh Medical School, United Kingdom.
* To whom correspondence should be addressed. E-mail: marlener{at}stanford.edu.
Rationale: S100A4/Mts1 is implicated in motility of human pulmonary artery smooth muscle cells (hPASMCs), through an interaction with the RAGE (receptor for advanced glycation end products).
Objective: We hypothesized that S100A4/Mts1-mediated hPASMC motility might be enhanced by loss of function of bone morphogenetic protein (BMP) receptor (BMPR)II, observed in pulmonary arterial hypertension.
Methods and Results: Both S100A4/Mts1 (500 ng/mL) and BMP-2 (10 ng/mL) induce migration of hPASMCs in a novel codependent manner, in that the response to either ligand is lost with anti-RAGE or BMPRII short interference (si)RNA. Phosphorylation of extracellular signal-regulated kinase is induced by both ligands and is required for motility by inducing matrix metalloproteinase 2 activity, but phospho–extracellular signal-regulated kinase 1/2 is blocked by anti-RAGE and not by BMPRII short interference RNA. In contrast, BMPRII short interference RNA, but not anti-RAGE, reduces expression of intracellular chloride channel (CLIC)4, a scaffolding molecule necessary for motility in response to S100A4/Mts1 or BMP-2. Reduced CLIC4 expression does not interfere with S100A4/Mts1 internalization or its interaction with myosin heavy chain IIA, but does alter alignment of myosin heavy chain IIA and actin filaments creating the appearance of vacuoles. This abnormality is associated with reduced peripheral distribution and/or delayed activation of RhoA and Rac1, small GTPases required for retraction and extension of lamellipodia in motile cells.
Conclusions: Our studies demonstrate how a single ligand (BMP-2 or S100A4/Mts1) can recruit multiple cell surface receptors to relay signals that coordinate events culminating in a functional response, ie, cell motility. We speculate that this carefully controlled process limits signals from multiple ligands, but could be subverted in disease.
Key words: bone morphogenetic protein • S100 protein • vascular smooth muscle cells • intracellular chloride channel • migration