Identification of biologically active, HIV TAR RNA-binding small molecules using small molecule microarrays

J Am Chem Soc. 2014 Jun 11;136(23):8402-10. doi: 10.1021/ja502754f. Epub 2014 May 28.

Abstract

Identifying small molecules that selectively bind to structured RNA motifs remains an important challenge in developing potent and specific therapeutics. Most strategies to find RNA-binding molecules have identified highly charged compounds or aminoglycosides that commonly have modest selectivity. Here we demonstrate a strategy to screen a large unbiased library of druglike small molecules in a microarray format against an RNA target. This approach has enabled the identification of a novel chemotype that selectively targets the HIV transactivation response (TAR) RNA hairpin in a manner not dependent on cationic charge. Thienopyridine 4 binds to and stabilizes the TAR hairpin with a Kd of 2.4 μM. Structure-activity relationships demonstrate that this compound achieves activity through hydrophobic and aromatic substituents on a heterocyclic core, rather than cationic groups typically required. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) analysis was performed on a 365-nucleotide sequence derived from the 5' untranslated region (UTR) of the HIV-1 genome to determine global structural changes in the presence of the molecule. Importantly, the interaction of compound 4 can be mapped to the TAR hairpin without broadly disrupting any other structured elements of the 5' UTR. Cell-based anti-HIV assays indicated that 4 inhibits HIV-induced cytopathicity in T lymphocytes with an EC50 of 28 μM, while cytotoxicity was not observed at concentrations approaching 1 mM.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-HIV Agents / chemistry*
  • Anti-HIV Agents / pharmacology
  • Cell Line, Tumor
  • Cytopathogenic Effect, Viral
  • Drug Discovery
  • Fluorometry
  • HIV Long Terminal Repeat / drug effects*
  • HIV Long Terminal Repeat / genetics
  • HIV-1 / drug effects
  • HIV-1 / pathogenicity
  • Humans
  • Molecular Structure
  • Nucleotide Motifs / genetics
  • RNA, Viral / chemistry*
  • Small Molecule Libraries / chemistry*
  • Small Molecule Libraries / pharmacology
  • T-Lymphocytes / virology

Substances

  • Anti-HIV Agents
  • RNA, Viral
  • Small Molecule Libraries