1E7‐03, a low MW compound targeting host protein phosphatase‐1, inhibits HIV‐1 transcription

Abstract

BACKGROUND AND PURPOSEHIV-1 transcription is activated by the Tat protein which recruits the cyclin-dependent kinase CDK9/cyclin T1 to TAR RNA. Tat binds to protein phosphatase-1 (PP1) through the Q 35 VCF 38 sequence and translocates PP1 to the nucleus. PP1 dephosphorylates CDK9 and activates HIV-1 transcription. We have synthesized a low MW compound 1H4, that targets PP1 and prevents HIV-1 Tat interaction with PP1 and inhibits HIV-1 gene transcription. Here, we report our further work with the 1H4-derived compounds and analysis of their mechanism of action. EXPERIMENTAL APPROACHUsing the 1H4-PP1 complex as a model, we iteratively designed and synthesized follow-up libraries that were analysed for the inhibition of HIV-1 transcription and toxicity. We also confirmed the mechanism of action of the PP1-targeting molecules by determining the affinity of binding of these molecules to PP1, by analysing their effects on PP1 activity, disruption of PP1 binding to Tat and shuttling of PP1 to the nucleus. KEY RESULTSWe identified a tetrahydroquinoline derivative, compound 7, which disrupted the interaction of Tat with PP1. We further optimized compound 7 and obtained compound 7c, renamed 1E7-03, which inhibited HIV-1 with low IC50 (fivefold lower than the previously reported compound, 1H4), showed no cytotoxicity and displayed a plasma half-life greater than 8 h in mice. 1E7-03 bound to PP1 in vitro and prevented shuttling of PP1 into the nucleus. CONCLUSIONS AND IMPLICATIONSOur study shows that low MW compounds that functionally mimic the PP1-binding RVxF peptide can inhibit HIV-1 transcription by deregulating PP1. AbbreviationsCTD, C-terminal domain of RNA polymerase II; HEXIM1, hexamethylene bis-acetamide-inducible protein 1; LTR, long terminal repeats; PP1, protein phosphatase 1; P-TEFb, positive transcription elongation factor b BJP British Journal of Pharmacology

Role of Protein Phosphatase 1 in Dephosphorylation of Ebola Virus VP30 Protein and Its Targeting for the Inhibition of Viral Transcription

“…5D). Our recent study showed that mice injected with 25 mg/kg 1E7-03 accumulated 90 M plasma concentration of the compound up to 8 h (25). Thus, concentrations of 10 and 3 M, which effectively suppress replication of EBOV in vitro (Fig.…”

“…First, our recent study showed that PP1-targeted compound 1H4 did not prevent the interaction of PP1 with major regulatory subunits, such as NIPP1 or PNUTS (13). Second, we recently demonstrated that high doses of 1E7-03 administered to mice by injections do not result in a toxic effect (25). Third, a stable expression of PP1-sequestering cdNIPP1, although inhibitory for HIV-1, did not compromise cell growth (10).…”

“…In total, 42 compounds were generated. Based on the ability of the compounds to inhibit HIV-1, which is sensitive to PP1 inhibition (25), three compounds were selected for the current study: 1E7, 1E7-03, and 1E7-04 (Fig. 3A).…”

Therapeutics for Postexposure Treatment of Ebola Virus Infection

“…We recently developed a library of PP1-targeting small molecules that were modeled to fit the RVxF-accommodating cavity of PP1 [69]. Our virtual screening of 300,000 compounds identified a tetrahydroquinoline derivative, 1E7-03 [70], that was devoid of toxicity, and displayed a half-life greater than 8 h when administered to mice. 1E7-03 bound to PP1 in vitro and prevented shuttling of PP1 into the nucleus [70].…”

“…Our virtual screening of 300,000 compounds identified a tetrahydroquinoline derivative, 1E7-03 [70], that was devoid of toxicity, and displayed a half-life greater than 8 h when administered to mice. 1E7-03 bound to PP1 in vitro and prevented shuttling of PP1 into the nucleus [70]. 1E7-03 increased EBOV VP30 phosphorylation and effectively suppressed replication of EBOV particles in cultured cells [59].…”