Researchers from the University of Texas Health Science Center at Houston discuss the potential use of microRNAs, particularly those located in peripherally-isolated exosomes, as biomarkers in neuropsychiatric disorders. These extracellular vesicles are released as a form of cell-to-cell communication and may mediate the soma-to-germline transmission of brain-relevant information, thereby potentially contributing to the inter- or transgenerational transmission of behavioral traits. Recent novel methods allow for the enrichment of peripheral exosomes specifically released by neurons and astrocytes and may provide valuable brain-relevant biosignatures of disease.
(a) Formation and release of exosomes. Exosomes are generated by the inward budding of the surrounding membrane of the microvesicular bodies. These exosome-filled microvesicle bodies can be either fused with the lysosome (resulting in the degradation of the cargo) or with the plasma membrane for release of exosomes to the circulation. (b) Of particular relevance for neuropsychiatric disorders, exosomes released by brain cells can reach the peripheral circulation and deliver their context to germ cells. This soma-to-germline communication through exosomes has been hypothesized as one of the mechanisms underlying the non-genetic inter- and transgenerational transmission of epigenetic markers (such as DNA methylation), thereby potentially contributing to the transmission of behavioral traits over generations