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The interaction of GIV with Galpha‐i is a druggable protein‐protein interaction
Author(s) -
DiGiacomo Vincent,
Opakua Alain Ibanez,
Merino Nekane,
BlancoCanosa Juan B.,
Blanco Francisco J.,
GarciaMarcos Mikel
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.823.6
Subject(s) - druggability , heterotrimeric g protein , protein–protein interaction , virtual screening , guanine nucleotide exchange factor , computational biology , g protein , fluorescence anisotropy , binding site , g protein coupled receptor , biology , plasma protein binding , drug discovery , chemistry , receptor , biochemistry , signal transduction , gene , membrane
GIV (a.k.a Girdin) is a non‐receptor Guanine‐nucleotide Exchange Factor (GEF) for heterotrimeric G proteins. Dysregulation of signaling networks dependent on such G proteins is a contributing factor in many human pathologies from cancer to psychiatric disorders. Therapeutic development in this area has been very successful by targeting G protein‐coupled receptors (GPCRs) – the targets of greater than 30% of marketed drugs – but structural and mechanistic insights into regulators such as GIV have opened novel routes to pharmacological intervention. GIV itself is overexpressed in a variety of human cancers and promotes metastatic properties in tumor cells. Moreover, disrupting GIV binding to Gαi blunts this metastatic behavior. These findings situate the GIV‐Gαi interaction as a promising therapeutic target. Despite protein‐protein interactions (PPIs) generally being considered poorly “druggable,” here we provide structural details about the Gαi‐GIV interface and demonstrate its chemical tractability. In testing a collection of >1,000 bioactive compounds with two high‐throughput screening approaches (structure‐guided virtual screening and a fluorescence polarization assay), we discovered two common micromolar potency hits, which were confirmed as true inhibitors by orthogonal assays. We mapped the binding site of the top hit by NMR spectroscopy and biochemical assays, showing that it overlaps with the GIV engagement site on Gαi, thereby validating its mode of action. Moreover, this inhibitor did not block Gβγ binding to Gαi, indicating that GIV binding can be specifically inhibited. This work empirically confirms the Gαi‐GIV PPI as a druggable target and outlines a discovery approach for anti‐metastatic small molecules. We will present our progress to date in screening a larger library of 200,000 compounds. Support or Funding Information Funded by NIH R01GM112631 and the Hartwell Foundation