title: Pharmacological dimerization and activation of the exchange factor eIF2B antagonizes the integrated stress response.
abstract: The general translation initiation factor eIF2 is a major translational control point. Multiple signaling pathways in the integrated stress response phosphorylate eIF2 serine-51, inhibiting nucleotide exchange by eIF2B. ISRIB, a potent drug-like small molecule, renders cells insensitive to eIF2α phosphorylation and enhances cognitive function in rodents by blocking long-term depression. ISRIB was identified in a phenotypic cell-based screen, and its mechanism of action remained unknown. We now report that ISRIB is an activator of eIF2B. Our reporter-based shRNA screen revealed an eIF2B requirement for ISRIB activity. Our results define ISRIB as a symmetric molecule, show ISRIB-mediated stabilization of activated eIF2B dimers, and suggest that eIF2B4 (δ-subunit) contributes to the ISRIB binding site. We also developed new ISRIB analogs, improving its EC50 to 600 pM in cell culture. By modulating eIF2B function, ISRIB promises to be an invaluable tool in proof-of-principle studies aiming to ameliorate cognitive defects resulting from neurodegenerative diseases.
authors: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
authors: Carmela
authors: C
authors: Sidrauski
authors: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
authors: Jordan C
authors: http://orcid.org/0000-0001-5202-722X
authors: JC
authors: Tsai
authors: Howard Hughes Medical Institution, University of California, San Francisco, San Francisco, United States.
authors: Martin
authors: http://orcid.org/0000-0002-3819-7019
authors: M
authors: Kampmann
authors: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.
authors: Brian R
authors: BR
authors: Hearn
authors: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.
authors: Punitha
authors: P
authors: Vedantham
authors: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.
authors: Priyadarshini
authors: P
authors: Jaishankar
authors: Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, United States.
authors: Masaaki
authors: M
authors: Sokabe
authors: Howard Hughes Medical Institution, University of California, San Francisco, San Francisco, United States.
authors: Aaron S
authors: AS
authors: Mendez
authors: QB3, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
authors: Billy W
authors: BW
authors: Newton
authors: QB3, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
authors: Edward L
authors: EL
authors: Tang
authors: QB3, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
authors: Erik
authors: http://orcid.org/0000-0001-5842-6344
authors: E
authors: Verschueren
authors: QB3, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
authors: Jeffrey R
authors: JR
authors: Johnson
authors: QB3, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
authors: Nevan J
authors: NJ
authors: Krogan
authors: Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, United States.
authors: Christopher S
authors: CS
authors: Fraser
authors: Howard Hughes Medical Institution, University of California, San Francisco, San Francisco, United States.
authors: Jonathan S
authors: JS
authors: Weissman
authors: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.
authors: Adam R
authors: AR
authors: Renslo
authors: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.
authors: Peter
authors: P
authors: Walter
mesh_terms: D000081:Acetamides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003514:Cyclohexylamines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D020717:Eukaryotic Initiation Factor-2B / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D057809:HEK293 Cells; D006367:HeLa Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D020014:K562 Cells; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018696:Neuroprotective Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D018697:Nootropic Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D055503:Protein Multimerization / Q000187:drug effects; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D019284:Thapsigargin / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: C000599093:2-(4-chlorophenoxy)-N-(4-(2-(4-chlorophenoxy)acetamido)cyclohexyl)acetamide; D000081:Acetamides; D001426:Bacterial Proteins; D003514:Cyclohexylamines; D020717:Eukaryotic Initiation Factor-2B; D008164:Luminescent Proteins; D018696:Neuroprotective Agents; D018697:Nootropic Agents; D021122:Protein Subunits; D034741:RNA, Small Interfering; C054562:yellow fluorescent protein, Bacteria; D019284:Thapsigargin
keywords: ISRIB; biochemistry; cell biology; eIF2; eIF2B; human; integrated stress response; protein synthesis; unfolded protein response