In the mean time, these LMP1(+) exosomes can enhance cell cycle progression in an LMP1-dependent manner
In the mean time, these LMP1(+) exosomes can enhance cell cycle progression in an LMP1-dependent manner. B cells, EBV preferentially undergoes lytic replication in the epithelial tissues instead of latency [31,32]. The pro-lytic propensity of epithelial cells is likely to facilitate the production of high viral titers in the oral epithelium that can be released into the saliva. The B cell-to-epithelium transfer of EBV is usually mediated through the reactivating B cells that infiltrate the oral epithelium. We reasoned that this spontaneous viral reactivation in B cells is usually unlikely to be an efficient way to facilitate the B cell-to-epithelial-cell exchange process and epithelium-derived transmissible brokers capable of inducing reactivation in B cells might actually help this process. The agent should act to trigger viral reactivation in B cells when the optimal environment (epithelium) is usually detected. We as well as others previously reported that miR-200 family microRNAs (miRNAs) can act as a cellular switch that regulates the transition from latency to the lytic cascade [33,34]. Specifically, the miR-200 family miRNAs form a double negative-feedback loop with the ZEB1/ZEB2 (zinc finger E-box binding homeobox 1 and 2) lytic cycle repressors, to facilitate the committed transition of cells between the latent and lytic cycles [33,34,35,36]. Increasing data have shown that miRNAs are important cargos in exosomes and they can alter the signaling pathway in recipient cells (2S)-Octyl-α-hydroxyglutarate [37]. In agreement with it, we showed that the oral epithelium-associated EV pathway, especially the exosome plays a key role in orchestrating EBVs lytic replication in B cells [2]. In blood circulation or other non-epithelial environments, the low levels of endogenous miR-200 family miRNAs in EBV-infected B cells allow the expression of lytic suppressors (2S)-Octyl-α-hydroxyglutarate ZEB1/ZEB2 and inhibit the viral lytic activator Zta (Z transactivator) gene, thus promoting viral latency. In the epithelial environment, the epithelial markers, miRNA-200 family miRNAs, are actively loaded into small EVs including exosomes. Once released, these exosomes create an epithelial microenvironment that favors EBV lytic replication. The internalization of exosomal miR-200s in recipient B cells will subsequently activate lytic replication by relieving ZEB1/ZEB2 mediated suppression of the viral Zta gene. We concluded that miR-200s are ideal exosomal signaling molecules for facilitating sustained pathway alterations. Rabbit Polyclonal to CaMK2-beta/gamma/delta This self-reinforcing opinions mechanism allows a single dose of exosomal miR-200s to not only inhibit ZEB1/ZEB2 expression, but also increase cellular miR-200 expression and help break viral latency in recipient cells [2]. With the assistance of exosomes, EBV stored in the peripheral B cells can be amplified in the oral epithelium and subsequently shed into the saliva. Thus, this microenvironment sensing mechanism can help facilitate the computer virus exchange between B cells and epithelial cells. Further, it also enables such a limited quantity of virally infected B cells (~ one in one million circulating B cells) to maintain constant viral replication foci at oral epithelial sites. Notably, we have focused on one-way communication from oral epithelial cells to virally infected B cells [2]. It is also interesting to consider whether in the microenvironment, the virally infected B cells can simultaneously talk to oral epithelial cells through an exosome-mediated paracrine-like manner and modulate transmission pathways that may facilitate the needs of the computer virus. For instance, uptake of these exosomes may induce the permissiveness of recipient epithelial cells to EBV contamination. In agreement with this hypothesis, Nanbo et al. showed that uptake of exosomes released from EBV(+) B cells enhances the expression of intercellular adhesion molecule-1 (ICAM-1) in epithelial cells, which subsequently facilitates cell-to-cell contact-mediated EBV transmission [38,39]. Further, a recent study from Nanbos group has shown that suppression of exosomes biogenesis in either EBV(+) B cells or uninfected epithelial cells significantly impairs the EBV transmission between B cells and epithelial cells, indicating an important role of exosomes in the regulation of EBVs contamination cycle (2S)-Octyl-α-hydroxyglutarate [40]. 3. EBV-Modified Exosomes and Their Functions in EBVs Life Cycle and Pathogenesis To date, numerous EBV gene products have been detected in the exosomes released from virally infected cells. However, due to the technical limitations,.