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

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.

• 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
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 290 Issue 52 Pg. 30684-96 (Dec 25 2015) ISSN: 1083-351X [Electronic] United States
• PMID: 26534962 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Integrins
• Lysophospholipids
• Receptors, Lysosphingolipid
• Sphingosine-1-Phosphate Receptors
• sphingosine-1-phosphate receptor-2, mouse
• sphingosine 1-phosphate
• Sphingosine

Topics

• Animals
• Cell Movement
• Exosomes (metabolism)
• Hepatic Stellate Cells (cytology, metabolism)
• Humans
• Integrins (genetics, metabolism)
• Liver Cirrhosis (genetics, metabolism, physiopathology)
• Lysophospholipids (metabolism)
• Mice
• Mice, Inbred C57BL
• Receptors, Lysosphingolipid (genetics, metabolism)
• Sphingosine (analogs & derivatives, metabolism)
• Sphingosine-1-Phosphate Receptors