Sphingosine 1-Phosphate Receptor 2 Signals Through Leukemia-Associated RhoGEF (LARG), to Promote Smooth Muscle Cell Differentiation
Copyright policy )Sphingosine 1-Phosphate Receptor 2 Signals Through Leukemia-Associated RhoGEF (LARG), to Promote Smooth Muscle Cell Differentiation
Objective— The goals of this study were to identify the signaling pathway by which sphingosine 1-phosphate (S1P) activates RhoA in smooth muscle cells (SMC) and to evaluate the contribution of this pathway to the regulation of SMC phenotype. Methods and Results— Using a combination of receptor-specific agonists and antagonists we identified S1P receptor 2 (S1PR2) as the major S1P receptor subtype that regulates SMC differentiation marker gene expression. Based on the known coupling properties of S1PR2 and our demonstration that overexpression of Gα 12 or Gα 13 increased SMC-specific promoter activity, we next tested whether the effects of S1P in SMC were mediated by the regulator of G protein-signaling-Rho guanine exchange factors (RGS-RhoGEFs) (leukemia-associated RhoGEF [LARG], PDZ-RhoGEF [PRG], RhoGEF [p115]). Although each of the RGS-RhoGEFs enhanced actin polymerization, myocardin-related transcription factor-A nuclear localization, and SMC-specific promoter activity when overexpressed in 10T1/2 cells, LARG exhibited the most robust effect and was the only RGS-RhoGEF activated by S1P in SMC. Importantly, siRNA-mediated depletion of LARG significantly inhibited the activation of RhoA and SMC differentiation marker gene expression by S1P. Knockdown of LARG had no effect on SMC proliferation but promoted SMC migration as measured by scratch wound and transwell assays. Conclusion— These data indicate that S1PR2-dependent activation of RhoA in SMC is mediated by LARG and that this signaling mechanism promotes the differentiated SMC phenotype.
- Northwestern University United States
- University of North Carolina at Chapel Hill United States
- Northwestern University Philippines
Time Factors, Transcription, Genetic, Myocytes, Smooth Muscle, Cell Differentiation, GTP-Binding Protein alpha Subunits, G12-G13, Cell Line, Enzyme Activation, Mice, Receptors, Lysosphingolipid, Phenotype, Cell Movement, Sphingosine, Animals, Guanine Nucleotide Exchange Factors, RNA Interference, RNA, Messenger, Lysophospholipids, Sphingosine-1-Phosphate Receptors, Rho Guanine Nucleotide Exchange Factors, Signal Transduction
Time Factors, Transcription, Genetic, Myocytes, Smooth Muscle, Cell Differentiation, GTP-Binding Protein alpha Subunits, G12-G13, Cell Line, Enzyme Activation, Mice, Receptors, Lysosphingolipid, Phenotype, Cell Movement, Sphingosine, Animals, Guanine Nucleotide Exchange Factors, RNA Interference, RNA, Messenger, Lysophospholipids, Sphingosine-1-Phosphate Receptors, Rho Guanine Nucleotide Exchange Factors, Signal Transduction
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