Exosomes are nanometer-sized vesicles with the function of intercellular communication, and they are released by various cell types. To reveal the knowledge about the exosomes from osteoblast, and explore the potential functions of osteogenesis, researchers at Fudan University isolated microvesicles from supernatants of mouse Mc3t3 by ultracentrifugation, characterized exosomes by electron microscopy and immunoblotting and presented the protein profile by proteomic analysis. The result demonstrated that microvesicles were between 30 and 100 nm in diameter, round shape with cup-like concavity and expressed exosomal marker tumor susceptibility gene (TSG) 101 and flotillin (Flot) 1. The researchers identified a total number of 1069 proteins among which 786 proteins overlap with ExoCarta database. Gene Oncology analysis indicated that exosomes mostly derived from plasma membrane and mainly involved in protein localization and intracellular signaling. The Ingenuity Pathway Analysis showed pathways are mostly involved in exosome biogenesis, formation, uptake and osteogenesis. Among the pathways, eukaryotic initiation factor 2 pathways played an important role in osteogenesis. This study identified osteoblast-derived exosomes, unveiled the content of them, presented potential osteogenesis-related proteins and pathways and provided a rich proteomics data resource that will be valuable for further studies of the functions of individual proteins in bone diseases.
Identification of exosomes. (A) Transmission electron microscope images of exosomes from Mc3t3 cells. (B) Western-blotting analysis of specific proteins isolated from Mc3t3-derived microvesicle and cytoplasm. (C) Nanoparticle tracking analysis for particle size concentration.
- Researchers identified exosomes from mouse osteoblastfor the first time.
- Osteoblasts-derived exosomes contain osteoblast peculiar proteins.
- Proteins from osteoblasts-derived exosomes are intently involved in EIF2 pathway.
- EIF2α from the EIF2 pathway plays an important role in osteogenesis.