Identification of small molecule inhibitors of the mitotic kinase haspin by high-throughput screening using a homogeneous time-resolved fluorescence resonance energy transfer assay.
Haspin/Gsg2 is a kinase that phosphorylates histone H3 at Thr-3 (H3T3ph) during mitosis. Its depletion by RNA interference results in failure of chromosome alignment and a block in mitosis. Haspin, therefore, is a novel target for development of antimitotic agents. We report the development of a high-throughput time-resolved fluorescence resonance energy transfer (TR-FRET) kinase assay for haspin. Histone H3 peptide was used as a substrate, and a europium-labeled H3T3ph phosphospecific monoclonal antibody was used to detect phosphorylation. A library of 137632 small molecules was screened at K(m) concentrations of ATP and peptide to allow identification of diverse inhibitor types. Reconfirmation of hits and IC( 50) determinations were carried out with the TR-FRET assay and by a radiometric assay using recombinant histone H3 as the substrate. A preliminary assessment of specificity was made by testing inhibition of 2 unrelated kinases. EC( 50) values in cells were determined using a cell-based ELISA of H3T3ph. Five compounds were selected as leads based on potency and chemical structure considerations. These leads form the basis for the development of specific inhibitors of haspin that will have clear utility in basic research and possible use as starting points for development of antimitotic anticancer therapeutics.
Patnaik
Debasis
D
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Jun Xian
Glicksman
Marcie A
MA
Cuny
Gregory D
GD
Stein
Ross L
RL
Higgins
Jonathan M G
JM
D000595:Amino Acid Sequence; D001681:Biological Assay / Q000379:methods*; D004795:Enzyme Stability / Q000187:drug effects; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006801:Humans; D020128:Inhibitory Concentration 50; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors*; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D047428:Protein Kinase Inhibitors / Q000032:analysis* / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D011874:Radiometry; D019311:Staurosporine / Q000494:pharmacology; D013379:Substrate Specificity / Q000187:drug effects; D013997:Time Factors
D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D047428:Protein Kinase Inhibitors; C530656:HASPIN protein, human; D017346:Protein Serine-Threonine Kinases; D019311:Staurosporine