Journal: eLife

Article Title: Negative regulation of urokinase receptor activity by a GPI-specific phospholipase C in breast cancer cells

doi: 10.7554/eLife.23649

Figure Lengend Snippet: ( A ) Domain structure of GDE2, GDE3 and GDE6 (left panel), and the transmembrane scheme of GDE3 (right panel). GDPD denotes catalytic glycerophosphodiesterase domain. Asterisk in GDPD domain depicts catalytic His residue in both GDE2 and GDE3. ( B ) Immunoblot analysis of uPAR release into the medium. HEK-uPAR cells transfected with empty vector (control), GDE2 or GDE3. PI-PLC served as positive control. ( C ) Mutant GDE3(H229A) fails to release uPAR. ( D ) Partial loss of uPAR from the plasma membrane by GDE3, as measured by flow cytometry. ( E ) TIRF microscopy reveals loss of uPAR from the basolateral plasma membrane. Box plot shows uPAR-GFP intensity at the ventral membrane (n = 3, mean ±SEM ****p<0001). ( F ) Homology modeling of the GDE2 and GDE3 catalytic domains showing surface charge distributions (blue, positive; red, negative; green line, putative GPI-binding groove; yellow line, proposed substrate-binding surface). The active site is indicated by glycerol-3-phosphate located at the template structure.

Article Snippet: To determine the inositol phosphate content of cleaved uPAR, suPAR was immuno-precipitated from HEK293 cell conditioned medium using anti-GFP beads (ChromoTek).

Techniques: Residue, Western Blot, Transfection, Plasmid Preparation, Control, Positive Control, Mutagenesis, Clinical Proteomics, Membrane, Flow Cytometry, Microscopy, Binding Assay

Journal: eLife

Article Title: Negative regulation of urokinase receptor activity by a GPI-specific phospholipase C in breast cancer cells

doi: 10.7554/eLife.23649

Figure Lengend Snippet: ( A ) Confocal images of HEK293 cells expressing human GDE2-HA, GDE3-HA or GDE6-HA, as indicated; bar, 10 μm. ( B ) GDE3 localizes to distinct microdomains (yellow square, open arrows) and filopodia-like extensions (orange square, solid arrow), as visualized by confocal and super-resolution microscopy. Bars, 10 μm and 1 μm respectively. ( C ) Immunoblot analysis showing that GDE3 reduces the membrane-anchored uPAR pool and competes with PI-PLC. The medium and lysates of HEK-uPAR cells expressing GDE3 or empty vector (EV) were analyzed without or with PI-PLC treatment (45 min.) of the cells, as indicated (left and right panels, respectively). Right lanes refer to wild-type (WT) HEK293 cells. ( D ) Expression and localization of GDE3 and mutant GDE3(H229A), as measured by immunoblotting and confocal microscopy, respectively, at 24 hr after transfection. Actin was used as a loading control. ( E ) uPAR-TM containing the transmembrane domain of EGFR is not released by GDE3, as shown by immunoblotting using anti-uPAR antibody, while uPAR-TM is properly expressed at the plasma membrane (bar, 10 μm).

Article Snippet: To determine the inositol phosphate content of cleaved uPAR, suPAR was immuno-precipitated from HEK293 cell conditioned medium using anti-GFP beads (ChromoTek).

Techniques: Expressing, Super-Resolution Microscopy, Western Blot, Membrane, Plasmid Preparation, Mutagenesis, Confocal Microscopy, Transfection, Control, Clinical Proteomics

Journal: eLife

Article Title: Negative regulation of urokinase receptor activity by a GPI-specific phospholipase C in breast cancer cells

doi: 10.7554/eLife.23649

Figure Lengend Snippet: ( A ) (Left) Scheme showing uPAR cleavage in cis or trans. (Right) GDE3-expressing HEK-uPAR cells were mixed with a GDE3-deficient cell population, as indicated. Immunoblot analysis of uPAR in medium and cell lysates indicates that GDE3 acts in cis; mock refers to empty vector-transfected cells. ( B ) GDE3 expression leads to increased GPI-free suPAR. Conditioned medium from HEK-uPAR cells expressing GDE2 or GDE3 was subjected to Triton X-114 phase separation. suPAR in the aqueous ( A ) and detergent ( D ) fractions was analyzed by immunoblotting. ( C ) GPI-anchor with phospholipase cleavage sites indicated; HONO, nitrous acid. ( D ) Representative LC-MS ion chromatograms (m/z 259.02–259.03); inositol 1-phosphate peaks in red. HONO-treated suPAR contains inositol 1-phosphate (n = 3, mean ±SEM; *p<0.05).

Article Snippet: To determine the inositol phosphate content of cleaved uPAR, suPAR was immuno-precipitated from HEK293 cell conditioned medium using anti-GFP beads (ChromoTek).

Techniques: Expressing, Western Blot, Plasmid Preparation, Transfection, Liquid Chromatography with Mass Spectroscopy

Journal: eLife

Article Title: Negative regulation of urokinase receptor activity by a GPI-specific phospholipase C in breast cancer cells

doi: 10.7554/eLife.23649

Figure Lengend Snippet: ( A ) Endogenous uPAR expression in MDA-MB-231 versus HEK293 cells, as determined by immunoblot. ( B ) Endogenous GDPD2 expression, as determined by qPCR analysis. ( C ) (left) Cell-surface expression of GDE3-mCherry of MDA-MB-231 cells expressing GDE3, as detected by flow cytometry. (Right) Cell-surface expression of uPAR in control (grey) and GDE3-expressing MDA-MB-231 cells (red), as detected by flow cytometry. ( D ) Confocal (top) and dual-color super-resolution microscopy images (bottom) of MDA-MB-231 cells expressing GDE3-GFP or catalytically dead GDE3(H229A)-GFP. Endogenous uPAR was immunostained in red. Merged images show colocalization of uPAR with GDE3(H229A) but not with wild-type GDE3 and uPAR. Scale bars, 10 μm (confocal) and 1 μm (super-resolution). Co-localization analysis (Mander's coefficient) on peripheral uPAR patches in confocal images was done using ImageJ software (n = 30 cells, three independent experiments). ( E ) Endogenous uPAR staining in control, GDE3-overexpressing and GDE3 knockout MDA-MB-231 cells plated on vitronectin. Two distinct GDE3 knockout clones (KO1 and KO2) were examined, as indicated. Scale bar,10 μm. ( F ) Quantification of basolateral uPAR-containing membrane domains referring to the cells in panel ( E ) (n = 3, mean ±SEM, ****p<0.0001). GDE3 suppresses the vitronectin- and uPAR-dependent phenotype of MDA-MB-231 breast cancer cells.

Article Snippet: To determine the inositol phosphate content of cleaved uPAR, suPAR was immuno-precipitated from HEK293 cell conditioned medium using anti-GFP beads (ChromoTek).

Techniques: Expressing, Western Blot, Flow Cytometry, Control, Super-Resolution Microscopy, Software, Staining, Knock-Out, Clone Assay, Membrane

Journal: Genome Biology

Article Title: Experimental characterization of the human non-sequence-specific nucleic acid interactome

doi: 10.1186/gb-2013-14-7-r81

Figure Lengend Snippet: Validation of preferential affinity . (a) GO molecular function term significance in the various sets of proteins inferred to bind preferentially one or several subtypes of nucleic acids. We observe the clear separation between molecular functions enriched in inferred DNA- and RNA-binding proteins. Color log-scale: red = P < 1E-15, light yellow = P < 0.01, gray = P ≥ 0.01. (b) Examples of affinity preferences of selected NABPs represented by P -values in the statistical analysis (table on left) and western blots in the experimental validation (right). We note the strong agreement between preferred versus non-preferred affinities in the statistics and the blots. (C20orf72 was purified with a Myc tag in HEK293 cells instead of a specific antibody in HepG2 cells.) (c) Methylation specificity usually correlates with CG specificity, but UHRF1 and YB-1 were specific to mCG only in the statistical analysis (see reported P -values in the table on the left). Experimental validation confirmed their specificity (right); AIM2 was used as a DNA-binding non-specific control.

Article Snippet: Myc-tagged C20orf72, AIM2, UHRF1 and YB-1 were overexpressed in HEK293 cells and visualized by immunoblotting using anti-Myc-IRDye800 (Rockland Gilbertsville, PA, USA ).

Techniques: Biomarker Discovery, RNA Binding Assay, Western Blot, Purification, Methylation, Binding Assay, Control

Journal: Analytical Chemistry

Article Title: Label-Free Quantitative Thermal Proteome Profiling Reveals Target Transcription Factors with Activities Modulated by MC3R Signaling

doi: 10.1021/acs.analchem.3c03643

Figure Lengend Snippet: Overview of the preparatory and analytical workflows. (A) POMC derived ligands and their downstream signaling cascades. (B) Schematic overview of the thermal proteome profiling (TPP) workflow. MC3R-expressing HEK293 cells were treated with ACTH, α-MSH, or γ-MSH at concentrations of 20, 100, and 500 nM or with DMSO as a vehicle-only negative control. (C) Schematic overview of the TPP data analysis workflow. Protein identification and relative quantification were achieved by direct analysis of the raw LC–MS data, after which various bioinformatics tools were used to infer changes in transcription factor (TF) activity, perform enriched pathway analysis, and identify thermally affected proteins.

Article Snippet: A human embryonic kidney 293 cell line transfected with a tetracycline-regulated expression system to overexpress MC3R (HEK-TREx-MC3R) was provided by Astra Zeneca.

Techniques: Derivative Assay, Expressing, Negative Control, Quantitative Proteomics, Liquid Chromatography with Mass Spectroscopy, Activity Assay

Journal: Analytical Chemistry

Article Title: Label-Free Quantitative Thermal Proteome Profiling Reveals Target Transcription Factors with Activities Modulated by MC3R Signaling

doi: 10.1021/acs.analchem.3c03643

Figure Lengend Snippet: Overview of identified proteins and thermally stabilized or destabilized proteins. (A) Venn diagrams showing the numbers of proteins exhibiting altered melting points, associations with enriched pathways, and phosphorylation in MC3R-expressing HEK293 cells incubated with ACTH, α-MSH, and γ-MSH. (B) Venn diagrams showing the numbers of stabilized, destabilized, and phosphorylated proteins after incubation with ACTH, α-MSH, and γ-MSH. (C) Upset plot representing individual numbers of stabilized and destabilized proteins for each ligand and those common between various combinations of ligands.

Article Snippet: A human embryonic kidney 293 cell line transfected with a tetracycline-regulated expression system to overexpress MC3R (HEK-TREx-MC3R) was provided by Astra Zeneca.

Techniques: Phospho-proteomics, Expressing, Incubation

Journal: Analytical Chemistry

Article Title: Label-Free Quantitative Thermal Proteome Profiling Reveals Target Transcription Factors with Activities Modulated by MC3R Signaling

doi: 10.1021/acs.analchem.3c03643

Figure Lengend Snippet: Characterization of transcription factors. (A) Heat map showing the relative abundance (compared to vehicle-only controls) of the transcription factors CCAR2, HMGB2, DDX21, SRSF7, and TET2 in MC3R-expressing HEK293 cells incubated with ACTH, α-MSH, and γ-MSH at different ligand concentrations and temperatures. (B) Phosphorylation of tryptic peptides derived from the thermally stabilized and destabilized transcription factors shown in panel A whose activity was inferred to change following stimulation with ACTH, α-MSH, or γ-MSH. Phosphorylation sites are indicated by asterisks next to the modified amino acid (shown in parentheses when the exact amino acid is unknown). (C) Transcription factor activities and relational networks inferred from differential expression data using BITFAM. The heatmap shows fold changes in transcription factor activities (relative to vehicle-only treatments) in MC3R-expressing HEK293 cells incubated with ACTH, α-MSH, or γ-MSH. (D) Network showing the interconnectivity of the transcription factors identified within our experimental LC–MS data set.

Article Snippet: A human embryonic kidney 293 cell line transfected with a tetracycline-regulated expression system to overexpress MC3R (HEK-TREx-MC3R) was provided by Astra Zeneca.

Techniques: Expressing, Incubation, Phospho-proteomics, Derivative Assay, Activity Assay, Modification, Quantitative Proteomics, Liquid Chromatography with Mass Spectroscopy