Exosome Adherence and Internalization by Hepatic Stellate Cells Triggers Sphingosine 1-Phosphate-dependent Migration

作者：Ruisi Wang, Qian Ding, Usman Yaqoob, Thiago M. de Assuncao, Vikas Verma, Petra Hirsova, Sheng Cao, Debabrata Mukhopadhyay, Robert C. Huebert, Vijay H. Shah · 发表于：Journal of Biological Chemistry · 年份：2015 · DOI：10.1074/jbc.m115.671735 · 被引用次数：230 · 研究领域：Extracellular vesicles in disease、Phagocytosis and Immune Regulation、Sphingolipid Metabolism and Signaling

Exosomes are cell-derived extracellular vesicles thought to promote intercellular communication by delivering specific content to target cells. The aim of this study was to determine whether endothelial cell (EC)-derived exosomes could regulate the phenotype of hepatic stellate cells (HSCs). Initial microarray studies showed that fibroblast growth factor 2 induced a 2.4-fold increase in mRNA levels of sphingosine kinase 1 (SK1). Exosomes derived from an SK1-overexpressing EC line increased HSC migration 3.2-fold. Migration was not conferred by the dominant negative SK1 exosome. Incubation of HSCs with exosomes was also associated with an 8.3-fold increase in phosphorylation of AKT and 2.5-fold increase in migration. Exosomes were found to express the matrix protein and integrin ligand fibronectin (FN) by Western blot analysis and transmission electron microscopy. Blockade of the FN-integrin interaction with a CD29 neutralizing antibody or the RGD peptide attenuated exosome-induced HSC AKT phosphorylation and migration. Inhibition of endocytosis with transfection of dynamin siRNA, the dominant negative dynamin GTPase construct Dyn2K44A, or the pharmacological inhibitor Dynasore significantly attenuated exosome-induced AKT phosphorylation. SK1 levels were increased in serum exosomes derived from mice with experimental liver fibrosis, and SK1 mRNA levels were up-regulated 2.5-fold in human liver cirrhosis patient samples. Finally, S1PR2 inhibition protected mice from CCl4-induce...