Fig. 1

Diagrammatic Overview of Extracellular Vesicle Biogenesis and miRNA Processing. Extracellular vesicles (EVs) are a heterogeneous collection of membrane-enveloped nanoparticles that serve as a mass transit mechanism for the packaging and release of complex cargos, including miRNAs. Exosomes (30-150 nm), are commonly spherical in shape and arise via the endocytic pathway via exocytosis from the fusion of the vesicular membrane into the plasma membrane. Microvesicles (100-1000 nm), notably irregularly shaped, are the byproduct of the outward budding/pinching of the plasma membrane. Apoptotic bodies (> 1 µm) are formed through apoptotic cell disassembly or programmed cell death, and released through cell blebbing. The cargo 'selection' or 'sorting' process that ensues, specifically the local enrichment of miRNA cargo molecules during nascent EV formation is largely propagated through the miRNA processing enzymes Drosha and Dicer, required for the maturation of miRNAs that lead to the translational repression or degradation of target mRNAs