Exosome Adherence and Internalization by Hepatic Stellate Cells Triggers Sphingosine 1-Phosphate-dependent Migration |
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Authors: | Ruisi Wang Qian Ding Usman Yaqoob Thiago M de Assuncao Vikas K Verma Petra Hirsova Sheng Cao Debabrata Mukhopadhyay Robert C Huebert Vijay H Shah |
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Institution: | From the Departments of ‡Molecular Pharmacology and Experimental Therapeutics and ;¶Biochemistry and Molecular Biology and ;§Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55902 |
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Abstract: | 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-induced liver fibrosis. Therefore, EC-derived SK1-containing exosomes regulate HSC signaling and migration through FN-integrin-dependent exosome adherence and dynamin-dependent exosome internalization. These findings advance our understanding of EC/HSC cross-talk and identify exosomes as a potential target to attenuate pathobiology signals. |
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Keywords: | adhesion endocytosis exosome (vesicle) fibrosis hepatic stellate cell (HSC) liver |
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