Induction of Exosome Release in Primary B Cells Stimulated via CD40 and the IL-4 Receptor

Abstract

Exosomes are lipid-bound nanovesicles formed by inward budding of the endosomal membrane and released following fusion of the endosomal limiting membrane with the plasma membrane. We show here that primary leukocytes do not release exosomes unless subjected to potent activation signals, such as cytokine or mitogen stimulation. In particular, high levels of exosomes were released when murine splenic B cells were stimulated via CD40 and the IL-4 receptor. This property was shared by B cells from different anatomic locations, as newly formed, marginal zone and follicular B cells were capable of secreting exosomes upon CD40/IL-4 triggering. B cell exosomes expressed high levels of MHC class I, MHC class II, and CD45RA (B220), as well as components of the BCR complex, namely, surface Ig, CD19, and the tetraspanins CD9 and CD81. Ig on the plasma membrane of primary B cells was targeted to the exosome pathway, demonstrating a link between the BCR and this exocytic pathway. IgD and IgM were the predominant Ig isotypes associated with CD40/IL-4 elicited exosomes, though other isotypes (IgA, IgG1, IgG2a/2b, and IgG3) were also detected. Together, these results suggest that exosome release is not R constitutive activity of B cells, but may be induced following cell: cell signaling.

Modulation of hypoxia-signaling pathways by extracellular long non-coding RNA regulator of reprogramming

“…We have also identified lncRNAs, such as TUC339, that can be selectively enriched within these vesicles (Kogure et al, 2013). These observations support the presence of highly selective mechanisms for incorporating ncRNA into extracellular vesicles and support a role for ncRNAs as effectors of intercellular signaling (Valadi et al, 2007;Saunderson et al, 2008;Skog et al, 2008). However, the involvement of extracellular RNA during tumor-cell responses to hypoxia is unknown.…”

Exosomes: mediators of communication in eukaryotes

“…For example, B cells secrete detectable levels of exosomes only following the activation of a cell surface receptor (Saunderson et al, 2008) while most tumor cells constitutively secrete exosomes (Record et al, 2011). Importantly, distinct subpopulations of exosomes are secreted from polarized cells; apical and basolateral exosomes (Tauro et al, 2012).…”

The Herpes Simplex Virus-1 Encoded Glycoprotein B Diverts HLA-DR into the Exosome Pathway

“…To remove cellular debris, the cell supernatant was precleared by centrifugation for 30 min at 10 000 g (16). Subsequently, the supernatant was filtered (0.2 mm) and exosomes were pelleted for 2 h at 100 000g.…”

“…Subsequently, cells were washed three times and analyzed using a BD Biosciences FACScan unit (Mountain View, CA). Exosomes were attached to beads for conducting flow cytometry by incubation with aldehyde-activated microspheres (Invitrogen) overnight at 4˚C as previously described (16). Beads were blocked with 50 mg/ml BSA/PBS for 15 min on ice, quenched for 30 min with 100 mM glycine in PBS pH 7.4, and resuspended in FACS buffer (PBS containing 2% FCS and 0.1% sodium azide).…”