u2os  (ATCC)

Journal: Journal of Cell Science

Article Title: OptoLoop – an optogenetic tool to probe the functional role of genome organization

doi: 10.1242/jcs.264574

Figure Lengend Snippet: Optogenetic manipulation of proximity between repetitive genomic loci. (A) Scheme of OptoLoop consisting of a fusion between dCas9 and the optogenetic protein CRY2. OptoLoop is targeted to specific genomic loci by introducing specific sgRNAs. CRY2–CRY2 interactions activated by blue light bridge targeted loci to form a chromatin loop. (B) Left panel, region of chromosome 19 showing sgIDR3 and sgTCF3 target sites, representative Hi-C contact map (data from ) and BACs used in DNA-FISH to label the IDR3 (magenta) and TCF3 loci (green). Right panel, mCherry channel images of U2OS dCas9–3XmCherry–CRY2 cells transfected with sgIDR3 and sgTCF3, kept in dark or illuminated with blue light for 3 h (1 s pulses every 10 s), and fixed. Scale bars: 5 µm. (C) Left panel, representative image of DNA-FISH for IDR3 and TCF3 with specific BAC FISH probes in U2OS cells. Right panel represents a single cell highlighted in left panel (yellow box); the expansion shows a single allele in this cell. Dashed line denotes the distance between the two FISH signals. Scale bars: 20 µm (left panel), 5 µm (right panel), 1 µm (expansion). (D) IDR3–TCF3 distances, calculated for U2OS dCas9–mCherry–CRY2 polyclonal cells transfected with indicated combinations of sgIDR3 and sgTCF3, kept under dark or illuminated for 3 h (1 s pulses every 10 s). Violin plot corresponds to a representative experiment, with black lines representing median distances. Bar plot represents means of two independent experiments. Each dot represents the median of typically 5000–10,000 alleles analyzed per experiment. (E) Fraction of alleles with IDR3-TCF3 distance <0.27 µm measured from DNA-FISH images for U2OS dCas9–mCherry–CRY2 polyclonal cells and three clones of U2OS dCas9–3XmCherry–CRY2 cells, transfected with indicated combinations of sgIDR3 and sgTCF3, and kept in dark or illuminated for 3 h (1 s pulses every 10 s). Each dot represents the fraction of typically 5000–10,000 alleles analyzed per experiment. Bars represent means of two or three independent experiments. (F) Measurement of cell-to-cell heterogeneity in loop formation. Bars with green shades: observed fraction of cells with none, one or both alleles with IDR3–TCF3 distance <0.27 µm obtained from a representative experiment shown in E with 2500–5000 cells analyzed per sample. Bars with magenta shades: expected fraction of cells with none, one or both alleles with IDR3–TCF3 distance <0.27 µm assuming that alleles from a same cell are independent between each other (Eqn 2). * P <0.05; *** P <0.001; ns, not significant [two-way ANOVAs followed by post-hoc Tukey tests (D,E); paired two-tailed t -test (E); chi-squared test (F)].

Article Snippet: NIH3T3 (mouse fibroblasts, ATCC #CRL-1658), U2OS (from human osteosarcoma, ATCC #HTB-96), HeLa (from human cervical adenocarcinoma, ATCC #CRM-CCL-2) and Lenti-X HEK-293T (from human embryonic kidney, cat. #632180 from Takara Bio, Japan) cell lines were cultured in Dulbecco's modified Eagle's medium (Gibco, Waltham, MA, USA) supplemented with 10% (15% for NIH3T3) fetal bovine serum (Gibco, Waltham, MA, USA) plus 100 IU/ml penicillin and 100 μg/ml streptomycin (Gibco, Waltham, MA, USA) at 37°C in a humidified atmosphere with 5% CO 2 .

Techniques: Hi-C, Transfection, Single Cell, Clone Assay, Two Tailed Test

Journal: Journal of Cell Science

Article Title: OptoLoop – an optogenetic tool to probe the functional role of genome organization

doi: 10.1242/jcs.264574

Figure Lengend Snippet: Benchmarking OptoLoop against a previous optogenetic manipulation tool. (A) Scheme of LADL consisting of soluble CRY2wt and a fusion between dCas9 and the CRY2 partner CIBN. dCas9–CIBN tethers specific genomic loci and light-activation induces both CRY2–CRY2 and CRY2–CIBN interactions bridging the targeted loci to form a loop. (B) Images of U2OS cells expressing dCas9–3XGFP–CIBN and mCherry fused to CRY2wt or CRY2olig, transfected with sgIDR3 and sgTCF3, and fixed after being kept under dark or illuminated with blue light pulses for 3 h (1 s pulses every 10 s). White arrows indicate FISH signals corresponding to IDR3–TCF3 loci. Scale bar: 5 µm. (C) Fraction of alleles with IDR3–TCF3 distance <0.27 µm measured from DNA-FISH images of U2OS cell lines stably expressing dCas9-3XGFP-CRY2 and mCherry-CRY2olig (LADL, clone #7) or dCas9-3XmCherry-CRY2 (OptoLoop, clone #3), transfected with sgIDR3 and sgTCF3, and kept under dark or illuminated with blue light for 3 h (1 s pulses every 10 s). Each dot represents the fraction of 5000–7000 alleles analyzed per experiment. Bars represent the means of three independent experiments. * P <0.05; ** P <0.01; *** P <0.001 (two-way ANOVA followed by post-hoc Tukey test).

Article Snippet: NIH3T3 (mouse fibroblasts, ATCC #CRL-1658), U2OS (from human osteosarcoma, ATCC #HTB-96), HeLa (from human cervical adenocarcinoma, ATCC #CRM-CCL-2) and Lenti-X HEK-293T (from human embryonic kidney, cat. #632180 from Takara Bio, Japan) cell lines were cultured in Dulbecco's modified Eagle's medium (Gibco, Waltham, MA, USA) supplemented with 10% (15% for NIH3T3) fetal bovine serum (Gibco, Waltham, MA, USA) plus 100 IU/ml penicillin and 100 μg/ml streptomycin (Gibco, Waltham, MA, USA) at 37°C in a humidified atmosphere with 5% CO 2 .

Techniques: Activation Assay, Expressing, Transfection, Stable Transfection

Journal: The Journal of Biological Chemistry

Article Title: Biosensor-guided discovery of peptide inhibitors targeting the ribosomal protein uS5-PDCD2 chaperone interaction

doi: 10.1016/j.jbc.2026.111415

Figure Lengend Snippet: Inhibition of the uS5-PDCD2 interaction using residues 21 to 50 of uS5. A , Western blot analysis of total extracts (Input, Top ) and anti-Flag purifications (IP:Flag, Bottom ) prepared from HeLa cells that stably expressed Flag-PDCD2 and that were previously transfected with constructs encoding either GFP alone (lane 1), wild-type (WT, lane 2) or F29Y (MT, lane 3) versions of uS5 21-50 -GFP. The blots were analyzed for GFP, Actin, uS5, and Flag-PDCD2. B , quantification of relative uS5 levels copurified from anti-Flag precipitates normalized to Flag-PDCD2 levels. Values were expressed relative to the GFP control vector, which was set to 1.0. The data and error bars represent the average and SD from at least three independent experiments. p -value is indicated, as determined by a one-way ANOVA with Dunnett’s multiple comparisons test. ( C ) U2OS cells that conditionally express Flag-PDCD2 were transfected with either GFP control vector (panels a-d), wild-type (panels e-h) or F29Y (panels i-l) versions of uS5 21-50 -GFP. At the time of transfection, doxycycline was added to the media to induce the expression of Flag-PDCD2. 48 h post-transfection, cells were fixed and simultaneously analysed by direct fluorescence (b, f and j) and immunostaining for Flag-PDCD2 (c, g and k). DNA staining with DAPI shows the nucleus of each cell (a, e and i). Scale bars correspond to 20 μm. D , quantification of nucleus-to-cytoplasmic ratios of Flag-PDCD2 shows a significant decrease in cells that expressed the wild-type version of uS5 21-50 -GFP. More than 60 cells were analyzed for each condition from three independent immunofluorescence experiments. Statistical differences were calculated using a one-way ANOVA with Dunnett’s multiple comparisons test. p -value is indicated. E , Peptide sequences corresponding to residues 21 to 50 of uS5, showing conserved phenylalanines in blue (WT) and substitutions to alanine residues in the mutant in red (MT). F , schematic of the peptide competition experiments using purified uS5-GFP/PDCD2 complex. See text for details. G , Western blot analysis of an uS5-GFP immunoprecipitate that were washed, divided, and treated with increasing concentrations of either wild-type ( Top , WT) or mutant ( Bottom , MT) uS5 21-50 peptides (lanes 2–5) or with no peptide (lane 1). Blots were analyzed for uS5-GFP and endogenous PDCD2. ( H ) Quantification of PDCD2 levels copurified from anti-GFP precipitates normalized to uS5-GFP levels. The values were then set to 1.0 for the control purification in the absence of peptide. Solid lines mark the average binding from three independent replicates, with error bars corresponding to standard deviations. Statistical differences were calculated using a one-way ANOVA with Dunnett’s multiple comparisons test. p -value is indicated.

Article Snippet: Human MOLT-4, HEK293T, HeLa, and U2OS cell lines were acquired from ATCC.

Techniques: Inhibition, Western Blot, Stable Transfection, Transfection, Construct, Control, Plasmid Preparation, Expressing, Fluorescence, Immunostaining, Staining, Immunofluorescence, Mutagenesis, Purification, Binding Assay

Journal: Clinical Cancer Research

Article Title: A Novel Potent and Selective GCN2 Inhibitor, APL-4098, Has Antileukemic Activity through Dysregulation of Mitochondrial Function

doi: 10.1158/1078-0432.CCR-25-1444

Figure Lengend Snippet: APL-4098 is a potent inhibitor of GCN2. A, APL-4098 molecular structure. B, Crystal structure of APL-4098 bound to human GCN2. Backbone of the GCN2 catalytic site (blue ribbon) and binding of APL-4098, with the extensive interaction network in the ATP site shown with dashed red lines (hydrogen bonds) and yellow lines (hydrophobic contacts). C, Biochemical, ADME, and PK profile of APL-4098. *All data generated from a rat intravenous/oral study: 1 mg/kg i.v. and 3 mg/kg orally. 1 Data generated from the i.v. study and 2 data generated from the oral study. D, APL-4098 inhibition of GCN2 kinase activity, measured as the level of eIF2α phosphorylation, using LanthaScreen FRET-based assay. Plot shows mean ± SEM from three representative experiments conducted in duplicate. E, U2OS cells were treated with APL-4098 in the presence or absence of borrelidin as indicated for 4 hours. Cell lysates were analyzed for phosphorylation of eIF2α using HTRF assay. Plot shows mean ± SEM from four individual experiments conducted in duplicate. F, U2OS cells were grown in glutamine-depleted medium and treated with APL-4098 as indicated for 4 hours. Cell lysates were analyzed by Western blotting.

Article Snippet: The osteosarcoma cell line U2OS (HTB-96, RRID: CVCL_0042) was obtained from ATCC and cultured in DMEM high glucose (Gibco, #41965-039) with 10% FBS (Gibco, #10270-106), 1 mmol/L sodium pyruvate (Gibco, #11360-039), 1% nonessential amino acids (Gibco, #11140-035), and antibiotics (penicillin/streptomycin 100 U/mL and 100 μg/mL; Gibco, #15140-122).

Techniques: Binding Assay, Generated, Inhibition, Activity Assay, Phospho-proteomics, HTRF Assay, Western Blot

Journal: Clinical Cancer Research

Article Title: A Novel Potent and Selective GCN2 Inhibitor, APL-4098, Has Antileukemic Activity through Dysregulation of Mitochondrial Function

doi: 10.1158/1078-0432.CCR-25-1444

Figure Lengend Snippet: APL-4098 is a selective inhibitor of GCN2. A, Eurofins KINOMEScan selectivity panel assay Treespot results for APL-4098 tested at 1 μmol/L. B, Eurofins biochemical K d concentration–response assay. C, U2OS cells were treated with APL-4098 or positive control dabrafenib (bioRxiv 2024.08.14.607626) in the presence of BtdCPU for 4 hours. Cell lysates were analyzed for phosphorylation of eIF2α using HTRF assay. Plot shows mean ± SEM from three individual experiments conducted in duplicate. D, U2OS cells were treated with APL-4098 or positive control GSK2606414 in the presence of thapsigargin for 4 hours. Cell lysates were analyzed for phosphorylation of eIF2α using HTRF assay. Plot shows mean ± SEM from three individual experiments.

Article Snippet: The osteosarcoma cell line U2OS (HTB-96, RRID: CVCL_0042) was obtained from ATCC and cultured in DMEM high glucose (Gibco, #41965-039) with 10% FBS (Gibco, #10270-106), 1 mmol/L sodium pyruvate (Gibco, #11360-039), 1% nonessential amino acids (Gibco, #11140-035), and antibiotics (penicillin/streptomycin 100 U/mL and 100 μg/mL; Gibco, #15140-122).

Techniques: Concentration Assay, Positive Control, Phospho-proteomics, HTRF Assay

Journal: The Journal of Biological Chemistry

Article Title: BARD1 recognizes pre-rRNA for DNA damage repair and rRNA biogenesis

doi: 10.1016/j.jbc.2026.111406

Figure Lengend Snippet: The R705 residue in human BARD1 is critical for pre-rRNA binding. A , SDS-PAGE analysis of purified human BARD1-BRCT protein and the R705T mutant. B , AF3-predicted structural models contrast pre-rRNA recognition by wild-type BARD1 ( left ) with the loss of binding in the R705T mutant ( right ). C , the R705T mutation in HsBARD1 drastically reduces its binding affinity for pre-RNA. The binding affinities between the HsBARD1-BRCT domains and 25-nt biotin-labeled RNA oligos were measured by BLI assays. D , the R705T mutation attenuates BARD1-BRCT aggregation within the nucleolus of U2OS cells. NPM1 was used as a nucleolar marker. The nucleolar density of BARD1 per cell was analyzed (n = 30 cells). Scale bar: 10 μm. E , the R705T mutation impairs pre-rRNA binding. The association between the HsBARD1-BRCT domains (residues 554–777; UniProt # Q99728 ) and pre-rRNA was examined by protein pull-down and RT-qPCR assays. Data are shown as mean ± SD (n = 3).

Article Snippet: 293T, HCT116, and U2OS cells were purchased from American Type Culture Collection.

Techniques: Residue, Binding Assay, SDS Page, Purification, Mutagenesis, Labeling, Marker, Quantitative RT-PCR

Journal: Chembiochem

Article Title: Monoclonal Antibodies Accessing the Cytosol of Living Cells and Binding to Polo‐Like Kinase 1 Interdomain Linker Affect Mitotic Behavior

doi: 10.1002/cbic.202500858

Figure Lengend Snippet: Anti‐PLK1 mAbs characterization. (A) Clones 35‐206, 3F8, and 13E8 were raised against full‐length PLK1, fragment 300–600, or fragment 300–400, respectively. KD: Kinase Domain; IDL: Interdomain Linker; PBD: Polo Box Domain. (B) Epitope mapping by Western blot. Lane 1: protein ladder; Lanes 2‐4: U2OS cells expressing 68 kDa PLK1, 14 kDa IDL (300–400), or 35 kDa IDL‐PBD (300–603), respectively.

Article Snippet: Human cervical carcinoma cells HeLa (ATCC Cat# CCL‐2, RRID:CVCL_0030), histone‐green fluorescent protein expressing HeLa cells H2BGFP‐HeLa (SCC117, Merck Millipore, RRID:CVCL_ZM02), human osteosarcoma cells U2OS (ATCC HTB‐96) U2OS (RRID:CVCL_0042) and human osteosarcoma cells expressing both luciferase (LUC) and green fluorescent protein (EGFP) (EGFPLuc‐U2OS, produced in our laboratory) were cultured adherently on plastic substrates (75 cm 2 Falcon tissue culture flasks) in high‐glucose Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) (Perbio, Brebières, France), 2 mM L‐glutamine, 100 U/mL penicillin G, and 100 μg/mL streptomycin.

Techniques: Clone Assay, Western Blot, Expressing