ExoCarta: A Web-Based Compendium of Exosomal Cargo

Abstract

Exosomes are membranous vesicles that are released by a variety of cells into the extracellular microenvironment and are implicated in intercellular communication. As exosomes contain RNA, proteins and lipids, there is a significant interest in characterizing the molecular cargo of exosomes. Here, we describe ExoCarta (http://www.exocarta.org), a manually curated Web-based compendium of exosomal proteins, RNAs and lipids. Since its inception, the database has been highly accessed (>54,000 visitors from 135 countries). The current version of ExoCarta hosts 41,860 proteins, >7540 RNA and 1116 lipid molecules from more than 286 exosomal studies annotated with International Society for Extracellular Vesicles minimal experimental requirements for definition of extracellular vesicles. Besides, ExoCarta features dynamic protein-protein interaction networks and biological pathways of exosomal proteins. Users can download most often identified exosomal proteins based on the number of studies. The downloaded files can further be imported directly into FunRich (http://www.funrich.org) tool for additional functional enrichment and interaction network analysis.

Keywords: FunRich; exosomes; extracellular vesicles; protein–protein interactions.

Figure 1. Snapshot of ExoCarta structure and features

ExoCarta database query search results and different types of data including mass spectrometry, Western blotting, biological pathways and protein-protein interaction (PPI) networks pertaining to exosomal proteins are depicted. In addition, exosomes characterization in accordance to ISEV standards is also provided.

Figure 2. Statistics of exosomal studies in last 3 years and list of top 20 most often identified exosomal proteins

A) Statistics of exosomal studies in the last 3 years A search was performed in PubMed on 15 September 2015 to identify articles using the term exosomes and extracellular vesicles. The list was manually validated to remove non-extracellular vesicles studies. The analysis clearly shows a surge in the publication of articles in exosomes and extracellular vesicles in the last 3 years. Other terms such as microvesicles, prostasomes and ectosomes were not used in the PubMed search. B) Top 20 most often identified exosomal proteins and its involvement in number of cancer types. This figure illustrates top 20 most often identified exosomal proteins based on the number of exosomal studies. The grey bar depicts number of exosomal studies and black bar depicts different cancer types in which they are known to be mutated.