(500.11) Crotonate sensitizes IAPi in the disruption of latent HIV by modulating the ncNF-κB signaling pathway at the step of p100 cleavage into p52

Poster Board Number: A227

Guochun Jiang (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Dajiang Li (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Shane Falcinelli (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Lilly Wong (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Yuyang Tang (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Edward Browne (UNC HIV Cure Center, University of North Carolina at Chapel Hill), Nancie Archin (UNC HIV Cure Center, University of North Carolina at Chapel Hill), David Margolis (UNC HIV Cure Center, University of North Carolina at Chapel Hill)

Background: Antiretroviral therapy (ART) effectively suppresses HIV-1 (HIV) replication to an undetectable level in the periphery; however, the treatment is life-long and HIV reservoirs cannot be eliminated by ART alone in people living with HIV (PLWH). The major obstacle that impedes HIV eradication in ART-treated PLWH is the latent viral reservoir harbors in the resting CD4+ T cells. Recently, the activation of non-canonical (nc) NF-κB pathway via IAP inhibitor (IAPi) or the SMAC mimetic (SMACm) compounds has raised as an attractive mechanism to disrupt HIV from latency. IAPi/SMACm targets IAPs to activate NF-κB inducing kinase (NIK) followed by phosphorylation of IkappaB kinase (IKK), leading to the cleavage of p100 into p52. The latter forms a complex with RelB to stimulate transcription of its target genes after translocation into the nucleus. Previously, we discovered that crotonylation stimulates HIV latency reversal that elicited by PKC/NF-κB agonist. We hypothesize that there may exist a functional interaction between protein crotonylation and ncNF-κB signaling, which may enhance IAPi-induced latency reversal to optiomally disrupt HIV latency for a cure of HIV.

Methods: Multiple HIV latency models were used, including Jurkat cell derived HIV latency models,  the U1 promonocytic model of latency, the primary CD4+ T cell model of HIV latency and the resting CD4+ T cells isolated from ART-suppressed PLWH. HIV expression was determined by flow cytometry and/or real-time PCR. Protein expression and cleavage was determined by Western blot.

Results: We found that IAPi/SMACm can disrupt latent HIV. However, its ability to reactivate latent HIV varied among different HIV latency models, with a lowest efficacy in the primary CD4+ T cell model of latency. Interestingly, IAPi/SMACm-induced disruption of latent HIV was greatly enhanced in the presence of crotonate in all these in vitro and ex vivo models. This was possibly mediated by the enhancement of p100 cleavage into p52 in the ncNF-κB signaling pathway.  

Conclusions: We propose that a blockage of p100 cleavage prevents an efficient activation of ncNF-κB signaling pathway in the latently infected CD4+ T cells in PLWH, which could be relieved by targeting IAP proteins to induce p100 cleavage for the activation of ncNF-κB signaling. Crotonylation, which was recently defined by us as a new epigenetic mark for the active HIV transcription, potentiates the reactivation of HIV from latency by further releasing the blockage at the p100 cleavage step, thereby enhancing ncNF-κB activation to disrupt HIV latency. These data indicate that crotonylation could be exploited to develop novel strategies for HIV cure or remission in the future.

Qura Therapeutics (2019-01) to GJ, NIH 1R01AI143381-01A1 to EPB and Delaney CARE UM1AI126619 to DMM.