The XPB Subunit of the TFIIH Complex Plays a Critical Role in HIV-1 Transcription, and XPB Inhibition by Spironolactone Prevents HIV-1 Reactivation from Latency

Abstract

HIV transcription requires assembly of cellular transcription factors at the HIV-1promoter. The TFIIH general transcription factor facilitates transcription initiation by opening the DNA strands around the transcription start site and phosphorylating the C-terminal domain for RNA polymerase II (RNAPII) for activation. Spironolactone (SP), an FDA approved aldosterone antagonist, triggers the proteasomal degradation of the XPB subunit of TFIIH, and concurrently suppresses acute HIV infection in vitro. Here we investigated SP as a possible block-and-lock agent for a functional cure aimed at the transcriptional silencing of the viral reservoir. The long-term activity of SP was investigated in primary and cell line models of HIV-1 latency and reactivation. We show that SP rapidly inhibits HIV-1 transcription by reducing RNAPII recruitment to the HIV-1 genome. shRNA knockdown of XPB confirmed XPB degradation as the mechanism of action. Unfortunately, long-term pre-treatment with SP does not result in epigenetic suppression of HIV upon SP treatment interruption, since virus rapidly rebounds when XPB reemerges; however, SP alone without ART maintains the transcriptional suppression. Importantly, SP inhibits HIV reactivation from latency in both cell line models and resting CD4+T cells isolated from aviremic infected individuals upon cell stimulation with latency reversing agents. Furthermore, long-term treatment with concentrations of SP that potently degrade XPB does not lead to global dysregulation of cellular mRNA expression. Overall, these results suggest that XPB plays a key role in HIV transcriptional regulation and XPB degradation by SP strengthens the potential of HIV transcriptional inhibitors in block-and-lock HIV cure approaches. IMPORTANCE Antiretroviral therapy (ART) effectively reduces an individual’s HIV loads to below the detection limit, nevertheless rapid viral rebound immediately ensues upon treatment interruption. Furthermore, virally suppressed individuals experience chronic immune activation from ongoing low-level virus expression. Thus, the importance of identifying novel therapeutics to explore in block-and-lock HIV functional cure approaches, aimed at the transcriptional and epigenetic silencing of the viral reservoir to block reactivation from latency. We investigated the potential of repurposing the FDA-approved spironolactone (SP), as one such drug. SP treatment rapidly degrades a host transcription factor subunit, XPB, inhibiting HIV transcription and blocking reactivation from latency. Long-term SP treatment does not affect cellular viability, cell cycle progression or global cellular transcription. SP alone blocks HIV transcription in the absence of ART but does not delay rebound upon drug removal as XPB rapidly reemerges. This study highlights XPB as a novel drug target in block-and-lock therapeutic approaches.

Lenalidomide potentially reduced the level of cell- associated HIV RNA and improved persistent inflammation in patients with HIV-associated cryptococcal meningitis a pilot study

“…Mori et al. demonstrated that spironolactone treatment achieved an average of 1.4 log (27.6-fold) per million cell reduction of HIV-1 reactivation ( Mori et al., 2020 ). CA HIV-1 RNA decreased in both the spleen (17.7-fold) and bone marrow (4.4-fold) in HIV-1-infected mice treated with IFN-α/β receptor (IFNAR) antibody ( Cheng et al., 2017 ).…”

“…Similarly, didehydro-cortistatin A (dCA) reduced the mean viral RNA level per 10 5 CD4 + T cells from BLT mouse tissues by 3.8-fold (Kessing et al, 2017). Mori et al demonstrated that spironolactone treatment achieved an average of 1.4 log (27.6-fold) per million cell reduction of HIV-1 reactivation (Mori et al, 2020). CA HIV-1 RNA decreased in both the spleen (17.7-fold) and bone marrow (4.4-fold) in HIV-1-infected mice treated with IFN-a/b receptor (IFNAR) antibody (Cheng et al, 2017).…”

“…Despite combination antiretroviral therapy (cART) reducing the morbidity and mortality of AIDS, HIV-1 infection remains an incurable disease ( Sengupta and Siliciano, 2018 ; Ahlenstiel et al., 2020 ; Cohn et al., 2020 ). HIV-1 latent provirus is the major barrier to a cure, resulting in residual viremia during cART and viral rebound upon treatment cessation ( Mori et al., 2020 ; Vansant et al., 2020 ). Therefore, further efforts should be expended to completely eradicate the latent provirus for a HIV-1 cure or remission.…”

HIV-1 transcriptional modulation: novel host factors and prospective therapeutic strategies

“…Spironolactone, a Food and Drug Administration (FDA)-approved drug for the treatment of hypertension and heart failure, was reported to degrade the xeroderma pigmentosum type B (XPB) subunit of TFIIH and inhibit HIV transcription [95][96][97]. TFIIH is involved in DNA opening at the TSS and RNAPII promoter escape during transcriptional initiation [98,99].…”

Toward a Functional Cure for HIV-1 Infection: The Block and Lock Therapeutic Approach

“…The transcription factor TFIIH enhances transcription initiation by inducing the DNA strands to open up near the transcription start site and phosphorylating and activating the carboxyl terminal domain of RNA Pol II. The aldosterone, spironolactone, mediates the proteasomal degradation of the XPB subunit of TFIIH as well as represses acute HIV-1 infection in vitro (44). While spironolactone readily inhibits HIV-1 transcription by decreasing Pol II recruitment to the HIV-1 genome, perpetual pretreatment with the drug was not able to maintain sustained epigenetic suppression of HIV-1 upon interruption of the drug, since the virus is reactivated when XPB reemerges.…”