title: Discovery of MINC1, a GTPase-activating protein small molecule inhibitor, targeting MgcRacGAP.
abstract: The Rho family of Ras superfamily small GTPases regulates a broad range of biological processes such as migration, differentiation, cell growth and cell survival. Therefore, the availability of small molecule modulators as tool compounds could greatly enhance research on these proteins and their biological function. To this end, we designed a biochemical, high throughput screening assay with complementary follow-up assays to identify small molecule compounds inhibiting MgcRacGAP, a Rho family GTPase activating protein involved in cytokinesis and transcriptionally upregulated in many cancers. We first performed an in-house screen of 20,480 compounds, and later we tested the assay against 342,046 compounds from the NIH Molecular Libraries Small Molecule Repository. Primary screening hit rates were about 1% with the majority of those affecting the primary readout, an enzyme-coupled GDP detection assay. After orthogonal and counter screens, we identified two hits with high selectivity towards MgcRacGAP, compared with other RhoGAPs, and potencies in the low micromolar range. The most promising hit, termed MINC1, was then examined with cell-based testing where it was observed to induce an increased rate of cytokinetic failure and multinucleation in addition to other cell division defects, suggesting that it may act as an MgcRacGAP inhibitor also in cells.
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: van Adrichem
authors.forename: Annika
authors.initials: A
authors.lastname: Fagerholm
authors.forename: Laura
authors.initials: L
authors.lastname: Turunen
authors.forename: Anna
authors.initials: A
authors.lastname: Lehto
authors.forename: Jani
authors.initials: J
authors.lastname: Saarela
authors.forename: Ari
authors.initials: A
authors.lastname: Koskinen
authors.forename: Gretchen A
authors.initials: GA
authors.lastname: Repasky
authors.affiliation: Institute for Molecular Medicine Finland FIMM, Nordic EMBL Partnership for Molecular Medicine, Biomedicum Helsinki 2U, P.O. Box 20 (Tukholmankatu 8), FI- 00014, University of Helsinki, Finland. krister.wennerberg@fimm.fi.
authors.forename: Krister
authors.initials: K
authors.lastname: Wennerberg
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D055808:Drug Discovery; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006367:HeLa Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D054852:Small Molecule Libraries / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D054852:Small Molecule Libraries; C115995:mgcRacGAP