title: High-Throughput Screens to Discover Small-Molecule Modulators of Ryanodine Receptor Calcium Release Channels.
abstract: Using time-resolved fluorescence resonance energy transfer (FRET), we have developed and validated the first high-throughput screening (HTS) method to discover compounds that modulate an intracellular Ca2+channel, the ryanodine receptor (RyR), for therapeutic applications. Intracellular Ca2+regulation is critical for striated muscle function, and RyR is a central player. At resting [Ca2+], an increased propensity of channel opening due to RyR dysregulation is associated with severe cardiac and skeletal myopathies, diabetes, and neurological disorders. This leaky state of the RyR is an attractive target for pharmacological agents to treat such pathologies. Our FRET-based HTS detects RyR binding of accessory proteins calmodulin (CaM) or FKBP12.6. Under conditions that mimic a pathological state, we carried out a screen of the 727-compound NIH Clinical Collection, which yielded six compounds that reproducibly changed FRET by >3 SD. Dose-response of FRET and [3H]ryanodine binding readouts reveal that five hits reproducibly alter RyR1 structure and activity. One compound increased FRET and inhibited RyR1, which was only significant at nM [Ca2+], and accentuated without CaM present. These properties characterize a compound that could mitigate RyR1 leak. An excellent Z' factor and the tight correlation between structural and functional readouts validate this first HTS method to identify RyR modulators.
authors.affiliation: 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Robyn T
authors.initials: RT
authors.lastname: Rebbeck
authors.affiliation: 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Maram M
authors.initials: MM
authors.lastname: Essawy
authors.affiliation: 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Florentin R
authors.initials: FR
authors.lastname: Nitu
authors.affiliation: 2 Fluorescence Innovations, Inc., Minneapolis, MN, USA.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Grant
authors.affiliation: 2 Fluorescence Innovations, Inc., Minneapolis, MN, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Gillispie
authors.affiliation: 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Thomas
authors.affiliation: 3 Department of Pharmacology, University of California, Davis, CA, USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Bers
authors.affiliation: 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Razvan L
authors.initials: RL
authors.lastname: Cornea
mesh_terms: D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009422:Nervous System Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022021:Tacrolimus Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D022021:Tacrolimus Binding Proteins; C403484:tacrolimus binding protein 1B
keywords: RyR; calcium channel; calcium leak; fluorescence lifetime; sarco/endoplasmic reticulum