Exosomes from uninfected cells activate transcription of latent HIV-1

Abstract

HIV-1 infection causes AIDS, infecting millions worldwide. The virus can persist in a state of chronic infection due to its ability to become latent. We have previously shown a link between HIV-1 infection and exosome production. Specifically, we have reported that exosomes transport viral proteins and RNA from infected cells to neighboring uninfected cells. These viral products could then elicit an innate immune response, leading to activation of the Toll-like receptor and NF-κB pathways. In this study, we asked whether exosomes from uninfected cells could activate latent HIV-1 in infected cells. We observed that irrespective of combination antiretroviral therapy, both short- and long-length viral transcripts were increased in wild-type HIV-1-infected cells exposed to purified exosomes from uninfected cells. A search for a possible mechanism for this finding revealed that the exosomes increase RNA polymerase II loading onto the HIV-1 promoter in the infected cells. These viral transcripts, which include trans-activation response (TAR) RNA and a novel RNA that we termed TAR-, can then be packaged into exosomes and potentially be exported to neighboring uninfected cells, leading to increased cellular activation. To better decipher the exosome release pathways involved, we used siRNA to suppress expression of ESCRT (endosomal sorting complex required for transport) proteins and found that ESCRT II and IV significantly control exosome release. Collectively, these results imply that exosomes from uninfected cells activate latent HIV-1 in infected cells and that true transcriptional latency may not be possible , especially in the presence of combination antiretroviral therapy.

Macrophage‐derived extracellular vesicles mediate smooth muscle hyperplasia: role of altered miRNA cargo in response to HIV infection and substance abuse

“…Furthermore, the role of HIV infection in formation and secretion of EVs is well known (57, 58). It has been reported that HIV-1 modulates the secretion and packaging of EVs to promote its infection (43, 57, 59, 60). Also, HIV-1 virions can get packaged within the EVs to escape immune surveillance and replicate.…”

Large‐scale, cross‐flow based isolation of highly pure and endocytosis‐competent extracellular vesicles

“…EVs were resuspended in proportional volumes of PBS (see methods). The tetraspanin molecules CD9 and CD63 [8,25,26,38,41], the ESCRT-I associated tumour suppressor gene 101 (TSG101) [19,20,25,42–44], and the late-endosome/lipid raft protein Flotillin-2 [7,45–47] were selected as markers. All were present in EV obtained by these three methods, but not the intracellular control Tubulin (Figure 2(a)).…”

Specific packaging and circulation of cytochromes P450, especially 2E1 isozyme, in human plasma exosomes and their implications in cellular communications

“…The cells were cultured for 7 days to achieve peak CYP expression. Then the HepaRG maintenance media was replaced with DMEM media supplemented with exosome-free FBS, sodium bicarbonate, non-essential amino acids, and gentamycin, and was further grown for 4 days for optimal secretion of exosomes [14,15]. U937 monocytic cells were differentiated into macrophages followed by culture in exosome-free FBS in RPMI media for 4 days.…”