Journal: bioRxiv
Article Title: The phosphate exporter XPR1 regulates a gasdermin D–independent mature IL-1β secretion pathway in LPS-stimulated human monocytic cells
doi: 10.64898/2025.12.23.695886
Figure Lengend Snippet: (A) Schematic overview of the CRISPR/Cas9 library screening strategy. The genome-wide human library Brunello, encoding Cas9 and 77,441 single guide (sg)RNAs, was packaged into lentiviruses produced by HEK293 cells and immediately used to transduce GSDMD -/- THP-1 cells. Three independent batches of THP-1 cells were infected on the same day with the same pool of viruses. After 19 days of culture, transduced cells were differentiated with PMA and stimulated with LPS for 24 h. After intracellular labeling of mature IL-1β, the cells of each batch displaying the highest staining were sorted by flow cytometry. Genomic DNA of sorted cells, together with control DNA from unselected transduced cells, was used as a template for sgRNA PCR amplification, followed by high-throughput sequencing. sgRNA abundance and enrichment were analyzed with MAGeCK. See also Dataset S1 and S2 and Figure S4. (B) Volcano plot showing gene enrichment and depletion in the screen. For each gene, the x axis shows its enrichment or depletion, calculated as the mean of all four sgRNAs targeting the gene, in the three sorted mIL-1β positive populations relative to the corresponding unsorted populations (paired analysis). The y axis shows statistical significance. Significantly enriched genes are highlighted in red. (C) Representative immunofluorescence images of WT, GSDMD -/- , and GSDMD -/- XPR1 -/- THP-1 cells differentiated with PMA and labeled with anti-XPR1 (green) and DAPI (blue). Magnification 63×; scale bar, 10 µm. (D) Cell viability following LPS stimulation of XPR1-invalidated THP-1 cells. GSDMD -/- XPR1 -/- THP-1 cells were differentiated with PMA and stimulated or not with LPS for 24 h. Metabolic activity was assessed with the MTS/PMS assay. As a positive control for cell death, pyroptosis was induced by addition of nigericin (Nig) (10 µM) 4 h after LPS stimulation. Data are represented as means ± SEM of biological triplicates. Data shown are representative of at least three independent experiments. The results shown for gene-invalidated cells in panels C and D were reproduced with two different clones generated with distinct gRNAs (Table S1), and complete gene invalidation was verified by targeted sequencing (Table S1).
Article Snippet: We used a rabbit IgG Isotype Control (Alexa Fluor 488 conjugate) (Cell Signaling #4340) as negative control (Isoctrl), a rabbit Alexa Fluor 488 coupled antibody against cleaved IL-1β (Cell Signaling – custom) and a mouse FITC anti-human IL-1β antibody (BioLegend #508206, clone JK1B-1) which recognizes both pro- and mature IL-1β.
Techniques: CRISPR, Library Screening, Genome Wide, Produced, Transduction, Infection, Labeling, Staining, Flow Cytometry, Control, Amplification, Next-Generation Sequencing, Immunofluorescence, Activity Assay, Positive Control, Clone Assay, Generated, Sequencing