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. 2021 Apr 6;12(2):e03491-20. doi: 10.1128/mBio.03491-20

FIG 1.

FIG 1

Expression of full-length MUC1 on cells enhances E. coli inv invasion. (A) Schematic model showing that the transmembrane mucin MUC1 contains an extracellular domain (ED), a SEA (sea-urchin sperm protein, enterokinase, and agrin) domain, a transmembrane domain (TD), and a cytoplasmic tail (CT). Recognition sites of antibodies 139H2, 214D4, 232A1, and CT2 are depicted. (B) Immunofluorescence confocal microscopy of HeLa-MUC1 cells induced with 10 μg/ml doxycycline for 24 h and stained with α-MUC1-ED antibody 139H2 (green) and DAPI to stain the nuclei (blue). (C) Immunofluorescence confocal microscopy of DOX+ MUC1 cells induced with 10 μg/ml doxycycline for 24 h, infected with E. coli inv (mCherry, red) at MOI 40 for 2 h and stained with α-MUC1-ED antibody 139H2 (green) and DAPI to stain the nuclei (blue). (D) Flow cytometry of representative DOX− MUC1 cells and DOX+ MUC1 cells infected with E. coli inv (GFP) at MOI 20 for 2 h and stained with α-MUC1-ED antibody 139H2. (E) Percentage of E. coli inv (GFP)-infected cells in DOX− MUC1 cells (Q3/Q3+Q4) and DOX+ MUC1 cells (Q2/Q1+Q2) calculated from (D). (F) Percentage of E. coli inv (GFP)-infected cells in MUC1-positive cells (Q2/Q1+Q2) and MUC1-negative cells (Q3/Q3+Q4) in DOX+ MUC1 cells calculated from (D). Each pair of data points represents the result from a single independent experiment. Three independent experimental replicates are shown. Statistical significance was determined by Student’s t test using GraphPad Prism software. *, P < 0.05; **, P < 0.01; ns, not significant. White scale bars represent 20 μm.