Ligands for glaucoma-associated myocilin discovered by a generic binding assay

ACS Chem Biol. 2014 Feb 21;9(2):517-25. doi: 10.1021/cb4007776. Epub 2013 Dec 9.

Abstract

Mutations in the olfactomedin domain of myocilin (myoc-OLF) are the strongest link to inherited primary open angle glaucoma. In this recently identified protein misfolding disorder, aggregation-prone disease variants of myocilin hasten glaucoma-associated elevation of intraocular pressure, leading to vision loss. Despite its well-documented pathogenic role, myocilin remains a domain of unknown structure or function. Here we report the first small-molecule ligands that bind to the native state of myoc-OLF. To discover these molecules, we designed a general label-free, mix-and-measure, high throughput chemical assay for restabilization (CARS), which is likely readily adaptable to discover ligands for other proteins. Of the 14 hit molecules identified from screening myoc-OLF against the Sigma-Aldrich Library of Pharmacologically Active Compounds using CARS, surface plasmon resonance binding studies reveal three are stoichiometric ligand scaffolds with low micromolar affinity. Two compounds, GW5074 and apigenin, inhibit myoc-OLF amyloid formation in vitro. Structure-activity relationship-based soluble derivatives reduce aggregation in vitro as well as enhance secretion of full-length mutant myocilin in a cell culture model. Our compounds set the stage for a new chemical probe approach to clarify the biological function of wild-type myocilin and represent lead therapeutic compounds for diminishing intracellular sequestration of toxic mutant myocilin.

Publication types

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

MeSH terms

  • Cytoskeletal Proteins / chemistry
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Drug Evaluation, Preclinical
  • Extracellular Matrix Proteins / chemistry
  • Eye Proteins / chemistry
  • Eye Proteins / genetics
  • Eye Proteins / metabolism*
  • Glaucoma, Open-Angle / genetics
  • Glaucoma, Open-Angle / metabolism
  • Glycoproteins / chemistry
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • Humans
  • Ligands
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Protein Structure, Tertiary
  • Small Molecule Libraries / chemistry*
  • Small Molecule Libraries / pharmacology*
  • Structure-Activity Relationship
  • Surface Plasmon Resonance

Substances

  • Cytoskeletal Proteins
  • Extracellular Matrix Proteins
  • Eye Proteins
  • Glycoproteins
  • Ligands
  • Small Molecule Libraries
  • olfactomedin
  • trabecular meshwork-induced glucocorticoid response protein