Dataset Information

Differential RNA packaging into small extracellular vesicles by neurons and astrocytes.

ABSTRACT:

Background

Small extracellular vesicles (sEVs) mediate intercellular communication by transferring RNA, proteins, and lipids to recipient cells. These cargo molecules are selectively loaded into sEVs and mirror the physiological state of the donor cells. Given that sEVs can cross the blood-brain barrier and their composition can change in neurological disorders, the molecular signatures of sEVs in circulation can be potential disease biomarkers. Characterizing the molecular composition of sEVs from different cell types is an important first step in determining which donor cells contribute to the circulating sEVs.

Methods

Cell culture supernatants from primary mouse cortical neurons and astrocytes were used to purify sEVs by differential ultracentrifugation and sEVs were characterized using nanoparticle tracking analysis, transmission electron microscopy and western blot. RNA sequencing was used to determine differential expression and loading patterns of miRNAs in sEVs released by primary neurons and astrocytes. Motif analysis was conducted on enriched miRNAs in sEVs and their respective donor cells.

Results

Sequencing total cellular RNA, and miRNAs from sEVs isolated from culture media of postnatal mouse cortical neurons and astrocytes revealed a distinct profile between sEVs and their corresponding cells. Though the total number of detected miRNAs in astrocytes was greater than neurons, neurons expressed more sEV-associated miRNAs than astrocytes. Only 20.7% of astrocytic miRNAs were loaded into sEVs, while 41.0% of neuronal miRNAs were loaded into sEVs, suggesting differences in the cellular sorting mechanisms. We identified short RNA sequence motifs, or EXOmotifs, on the miRNAs that were differentially loaded or excluded from sEVs. A sequence motif GUAC was enriched in astrocytic sEVs. miRNAs preferably retained in neurons or astrocytes had a similar RNA motif CACACA, suggesting a cell-type-independent mechanism to maintain cellular miRNAs. mRNAs of five RNA-binding proteins associated with passive or active RNA sorting into sEVs were differentially expressed between neurons and astrocytes, one of which, major vault protein was higher in astrocytes than in neurons and detected in astrocytic sEVs.

Conclusions

Our studies suggest differences in RNA sorting into sEVs. These differences in miRNA signatures can be used for determining the cellular sources of sEVs altered in neurological disorders. Video abstract.

SUBMITTER: Luo X

PROVIDER: S-EPMC8272329 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Extracellular RNA in circulation mediates intercellular communication in normal and pathological processes. One mode of circulating miRNA transport in bodily fluids is within 30-150 nm small extracellular vesicles (sEVs) or exosomes. Uptake of sEVs can regulate gene expression in recipient cells enabling circulating miRNAs to exert paracrine and systemic effects. Complex regional pain syndrome (CRPS) is a debilitating pain disorder characterized by chronic inflammation. Our previous investigations identified a significant decrease of hsa-miR-939 in whole blood from CRPS patients compared to control; we also observed that overexpression of miR-939 can negatively regulate several proinflammatory genes in vitro. Though downregulated in whole blood, miR-939 was significantly upregulated in sEVs isolated from patient serum. Here we investigated miR-939 packaging into sEVs in vitro under inflammation induced by monocyte chemoattractant protein-1 (MCP-1), a chemokine that is upregulated in CRPS patients. Stimulation of THP-1 monocytes by MCP-1 led to elevated levels of miR-939 in sEVs, which was abrogated using inhibitors of exosome secretion. miRNAs loaded into exosomes largely contain short miRNA sequence motifs called EXOmotifs. Mutation analysis of miR-939 showed that EXOmotif is one of the possible cellular mechanisms responsible for packaging miR-939 into sEVs. We confirmed gene expression changes in recipient cells following the uptake of sEVs enriched in miR-939 using RNA sequencing. Additionally, our data from primary immune cell-derived sEVs of CRPS patients and controls demonstrate that while the relative expression of miR-939 is higher in sEVs derived from B cells, T cells and NK cells relative to monocyte-derived sEVs in controls, only the B cell-derived sEVs showed a significantly higher level of miR-939 in CRPS patients. Differential miRNA sorting into exosomes and its functional impact on recipient cells may contribute to the underlying pathophysiology of CRPS.