HIV-1 Vpr induces ciTRAN to prevent transcriptional silencing of the provirus
The functional relevance of circular RNA (circRNA) expression in HIV-1 infection remains unclear. By developing a customized protocol involving direct RNA nanopore sequencing here, we captured circRNAs in their native state from HIV-1 infected T cells and identified ciTRAN, a circRNA modulator of HIV-1 Transcription. We show that HIV-1 infection of monocytic, T cell lines and primary CD4+ T cells induces ciTRAN expression in a Vpr-dependent manner. ciTRAN protein interactome analysis by proximity biotinylation and mass spectrometry identified SRSF-1 as a prominent interactor of the circular RNA. SRSF-1 is known to negatively regulate HIV-1 transcription, which the virus overcomes by a yet unknown mechanism. We demonstrate that HIV-1 Vpr induced ciTRAN sequesters SRSF1 away from the viral transcriptional complex to promote efficient viral transcription. Accordingly, ciTRAN depletion by CRISPR-Cas phenocopied the effects of SRSF1 overexpression and improved SRSF1 association with HIV-1 transcriptional complex. Finally, we show that an SRSF-1-inspired competing peptide can inhibit HIV-1 transcription regardless of ciTRAN induction. The hijacking of a host circRNA thus represents a new facet of primate lentiviruses in overcoming transmission bottlenecks.