- Mar 2021
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Homology directed repair (HDR) assayEach variant was introduced into a HA-FLAG-tagged full-length PALB2 complementary DNA (cDNA) expression in the pOZC plasmid by site-directed mutagenesis using pfu turbo. Variants were verified by Sanger sequencing. Cotransfection of PALB2 expression constructs and the I-SceI expression plasmid into B400/DR-GFP reporter cells was performed at a 5:1 molar ratio using Xtremegene 9 transfection reagent (Roche). At least two independent clones containing each variant were analyzed in duplicate. PALB2 expression and transfection efficiency was verified by western blotting. Green fluorescence protein (GFP) expressing cells were quantified by fluorescence-activated cell sorting. Fold increases in GFP-positive cells, which are equivalent to HDR fold change, were normalized and rescaled relative to a 1:5 ratio derived from the p.Y551X pathogenic variant control and the wild-type PALB2 control.
AssayGeneralClass: BAO:0003061 reporter protein
AssayMaterialUsed: CLO:0036938 tumor-derived cell line
AssayDescription: Stable expression of wild type and variant PALB2 cDNA constructs in Trp53 and Palb2-null mouse cell line containing DR-GFP reporter; I-SceI endonuclease introduces a double-stranded break in the reporter construct and efficient repair results in GFP expression, which is detected by flow cytometry
AssayReadOutDescription: Homology directed repair (HDR) activity fold change, measured as GFP-positive cells and normalized relative to wild type PALB2 (set to 5.0) and the p.Y551X truncating variant (set to 1.0).
AssayRange: scaled score
AssayNormalRange: >4.4
AssayAbnormalRange: ≤1.7 for "deleterious" variants and ≤2.4 for "hypomorphic"variants
AssayIndeterminateRange: >2.4-<4.4
ValidationControlPathogenic: 7
ValidationControlBenign: 4
Replication: At least 2 independent clones per variant, each analyzed in duplicate
StatisticalAnalysisDescription: Not reported
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Viability assayPALB2 variants were introduced into B400 cells using mCherry-pOZC expression vector and flow cytometry for Cherry-red was performed to select for cells expressing PALB2. Sorted cells were plated in 96-well plates and exposed to increasing amounts of Olaparib or cisplatin and incubated for a period of 5 days. Presto Blue (Invitrogen) was added and incubated for 1–2 hours before measuring fluorescence intensity on a Cytation 3 microplate reader (BioTek).
AssayGeneralClass: BAO:0003009 cell viability assay
AssayMaterialUsed: CLO:0036938 tumor-derived cell line
AssayDescription: Transient expression of wild type and variant mCherry-tagged PALB2 cDNA constructs in Trp53 and Palb2-null mouse cell line; exposure to increasing concentrations of cisplatin for 5 days induces interstrand-crosslink DNA damage; cell survival is determined by measuring fluorescence intensity after staining with a cell viability reagent.
AssayReadOutDescription: Percent cell survival after treatment with cisplatin
AssayRange: %
AssayNormalRange: Cisplatin resistance levels comparable to that of cells expressing wild type PALB2; no numeric threshold given
AssayAbnormalRange: Not reported
AssayIndeterminateRange: Not reported
ValidationControlPathogenic: 0
ValidationControlBenign: 0
Replication: Not reported
StatisticalAnalysisDescription: Not reported
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Viability assayPALB2 variants were introduced into B400 cells using mCherry-pOZC expression vector and flow cytometry for Cherry-red was performed to select for cells expressing PALB2. Sorted cells were plated in 96-well plates and exposed to increasing amounts of Olaparib or cisplatin and incubated for a period of 5 days. Presto Blue (Invitrogen) was added and incubated for 1–2 hours before measuring fluorescence intensity on a Cytation 3 microplate reader (BioTek).
AssayGeneralClass: BAO:0003009 cell viability assay
AssayMaterialUsed: CLO:0036938 tumor-derived cell line
AssayDescription: Transient expression of wild type and variant mCherry-tagged PALB2 cDNA constructs in Trp53 and Palb2-null mouse cell line; exposure to increasing concentrations of PARP inhibitor Olaparib for 5 days inhibits end-joining mediated by PARP and sensitizes cells to DNA damage; cell survival is determined by measuring fluorescence intensity after staining with a cell viability reagent.
AssayReadOutDescription: Percent cell survival after treatment with Olaparib
AssayRange: %
AssayNormalRange: Olaparib resistance levels comparable to that of cells expressing wild type PALB2; no numeric threshold given
AssayAbnormalRange: Not reported
AssayIndeterminateRange: Not reported
ValidationControlPathogenic: 0
ValidationControlBenign: 0
Replication: Not reported
StatisticalAnalysisDescription: Not reported
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