title: Small molecule structure correctors abolish detrimental effects of apolipoprotein E4 in cultured neurons.
abstract: Apolipoprotein E4 (apoE4), the major genetic risk factor for late onset Alzheimer disease, assumes a pathological conformation, intramolecular domain interaction. ApoE4 domain interaction mediates the detrimental effects of apoE4, including decreased mitochondrial cytochrome c oxidase subunit 1 levels, reduced mitochondrial motility, and reduced neurite outgrowth in vitro. Mutant apoE4 (apoE4-R61T) lacks domain interaction, behaves like apoE3, and does not cause detrimental effects. To identify small molecules that inhibit domain interaction (i.e. structure correctors) and reverse the apoE4 detrimental effects, we established a high throughput cell-based FRET primary assay that determines apoE4 domain interaction and secondary cell- and function-based assays. Screening a ChemBridge library with the FRET assay identified CB9032258 (a phthalazinone derivative), which inhibits domain interaction in neuronal cells. In secondary functional assays, CB9032258 restored mitochondrial cytochrome c oxidase subunit 1 levels and rescued impairments of mitochondrial motility and neurite outgrowth in apoE4-expressing neuronal cells. These benefits were apoE4-specific and dose-dependent. Modifying CB9032258 yielded well defined structure-activity relationships and more active compounds with enhanced potencies in the FRET assay (IC(50) of 23 and 116 nm, respectively). These compounds efficiently restored functional activities of apoE4-expressing cells in secondary assays. An EPR binding assay showed that the apoE4 structure correction resulted from direct interaction of a phthalazinone. With these data, a six-feature pharmacophore model was constructed for future drug design. Our results serve as a proof of concept that pharmacological intervention with apoE4 structure correctors negates apoE4 detrimental effects in neuronal cells and could be further developed as an Alzheimer disease therapeutic.
authors.affiliation: Gladstone Center for Translational Research, San Francisco, California 94158, USA.
authors.forename: Hung-Kai
authors.initials: HK
authors.lastname: Chen
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Liu
authors.forename: Anke
authors.initials: A
authors.lastname: Meyer-Franke
authors.forename: Jens
authors.initials: J
authors.lastname: Brodbeck
authors.forename: Rene D
authors.initials: RD
authors.lastname: Miranda
authors.forename: James G
authors.initials: JG
authors.lastname: McGuire
authors.forename: Michael A
authors.initials: MA
authors.lastname: Pleiss
authors.forename: Zhong-Sheng
authors.initials: ZS
authors.lastname: Ji
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Balestra
authors.forename: David W
authors.initials: DW
authors.lastname: Walker
authors.forename: Qin
authors.initials: Q
authors.lastname: Xu
authors.forename: Dah-eun
authors.initials: DE
authors.lastname: Jeong
authors.forename: Madhu S
authors.initials: MS
authors.lastname: Budamagunta
authors.forename: John C
authors.initials: JC
authors.lastname: Voss
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Freedman
authors.forename: Karl H
authors.initials: KH
authors.lastname: Weisgraber
authors.forename: Yadong
authors.initials: Y
authors.lastname: Huang
authors.forename: Robert W
authors.initials: RW
authors.lastname: Mahley
mesh_terms: D053327:Apolipoprotein E4 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D004353:Drug Evaluation, Preclinical; D057166:High-Throughput Screening Assays; D006801:Humans; D008958:Models, Molecular; D009474:Neurons / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D010793:Phthalazines / Q000737:chemistry / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D015203:Reproducibility of Results; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D053327:Apolipoprotein E4; D010793:Phthalazines; D054852:Small Molecule Libraries; C043388:phthalazine