Identification of small-molecule antagonists that inhibit an activator:coactivator interaction

doi:10.1073/pnas.0406374101

Identification of small-molecule antagonists that inhibit an activator:coactivator interaction

^*Department of Peptide Biology and ^§Regulatory Biology Laboratories, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037-1002; ^†Departments of Biochemistry and Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038; ^‡Experimental Medicine II, Nikolaus Fiebiger Center for Molecular Medicine, Glueckstrasse 6, 91054 Erlangen, Germany; and^¶Department of Molecular Biology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037

Edited by Peter K. Vogt, The Scripps Research Institute, La Jolla, CA, and approved November 1, 2004 (received for review August 29, 2004)

Abstract

Phosphorylation of the cAMP response element binding protein (CREB) at Ser-133 in response to hormonal stimuli triggers cellular gene expression via the recruitment of the histone acetylase coactivator paralogs CREB binding protein (CBP) and p300 to the promoter. The NMR structure of the CREB:CBP complex, using relevant interaction domains called KID and KIX, respectively, reveals a shallow hydrophobic groove on the surface of KIX that accommodates an amphipathic helix in phospho (Ser-133) KID. Using an NMR-based screening approach on a preselected small-molecule library, we identified several compounds that bind to different surfaces on KIX. One of these, KG-501 (2-naphthol-AS-E-phosphate), targeted a surface distal to the CREB binding groove that includes Arg-600, a residue that is required for the CREB:CBP interaction. When added to live cells, KG-501 disrupted the CREB: CBP complex and attenuated target gene induction in response to cAMP agonist. These results demonstrate the ability of small molecules to interfere with second-messenger signaling cascades by inhibiting specific protein–protein interactions in the nucleus.

Footnotes

↵ ∥ To whom correspondence should be addressed. E-mail: montminy{at}salk.edu.
Author contributions: J.L.B., L.F., C.M.M., B.E., T.Z., K.H.G., and M.M. designed research; J.L.B., C.A.A., B.M., L.F., C.M.M., T.Z., and K.H.G. performed research; J.L.B., C.A.A., B.M., L.F., C.M.M., B.E., K.H.G., and M.M. analyzed data; and J.L.B., C.A.A., K.H.G., and M.M. wrote the paper.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: CREB, cAMP response element binding protein; CBP, CREB binding protein; HAT, histone acetyl transferase; TORC, transducer of regulated CREB activity.