HIV proviral transcription and infectivity are enhanced by neddylation

A spreading infection can quickly restart from the persistent reservoir of cells harboring HIV proviruses if antiretroviral therapy (ART) is stopped. HIV transcription can also be increased by latency-reversing agents (LRAs) during ART. Neddylation is a post-translational modification that activates Cullin-RING ligases (CRLs), which ubiquitinate several proteins that regulate HIV transcription and infectivity, marking these regulators for proteasomal degradation. We studied how inhibiting neddylation affects HIV gene expression ex vivo after three LRAs: TNFα, PMA and ionomycin, and JQ1. In provirus-containing T cells, broad inhibition of CRL-mediated ubiquitination using MLN4924 (MLN) with the above LRAs reduced HIV transcriptional initiation, decreased virus production, and diminished virion infectivity by increasing A3G incorporation. Decreased degradation of inhibitor of kB alpha (IkBα) was implicated in reducing LRA-stimulated HIV transcription. MLN also decreased HIV reactivation after PMA and ionomycin treatment of CD4+ T cells from ART-suppressed people living with HIV. Results indicate that neddylation can enhance HIV proviral transcription and reactivated virion infectivity. IMPORTANCE Results indicate that neddylation contributes to reactivating HIV provirus transcription and antigen expression, as well as enhancing infectivity of resulting virions. This suggests hypotheses to test in the future that may inform a novel strategy for research to enable antiretroviral therapy (ART)-free remission of HIV infection, including whether inhibiting neddylation when ART stops reduces spontaneous provirus reactivation and increases virus A3G content to help control HIV rebound from latent reservoirs post-ART.