Journal: iScience
Article Title: Fusobacterium nucleatum subsp. nucleatum RadD binds Siglec-7 and inhibits NK cell-mediated cancer cell killing
doi: 10.1016/j.isci.2024.110157
Figure Lengend Snippet: RadD of F. nucleatum subsp. nucleatum is the bacterial ligand for Siglec-7 Lysates prepared from (A) F. nucleatum subsp. nucleatum ATCC 23726 WT ( Fnn 23726 WT) or (B) F. nucleatum subsp. nucleatum ATCC 23726 ΔRadD ( Fnn 23726 ΔRadD) were immunoprecipitated using Siglec-7-Ig, CEACAM1-Ig, or CEACAM1 ΔN-Ig. Immunoprecipitates were visualized by Coomassie blue and immunoprecipitated bands were analyzed by mass spectrometry. RadD levels were quantified relative to the negative control. RQ, relative quantification. (C) FITC-labeled Fnn 23726 WT or its ΔRadD mutant was stained with Siglec-7-Ig. Filled gray histograms represent staining with secondary antibody only. One representative experiment out of eight is shown. (D) Quantification of Siglec-7-Ig binding to Fnn 23726 WT and the ΔRadD mutant shown as fold change in median fluorescent intensity (MFI) relative to Fnn 23726 WT. Bars represent means of eight independent experiments. Statistical significance was assessed using a two-tailed unpaired t test (∗ p ≤ 0.05; ∗∗ p ≤ 0.01; ∗∗∗ p ≤ 0.001).
Article Snippet: F. nucleatum subp. nucleatum is known to bind to several immune receptors such as CEACAM1 and TIGIT to circumvent the immune response., , , Here, we assessed binding of FITC-labeled F. nucleatum subsp. nucleatum strain ATCC 23726 (subsequently abbreviated as Fnn 23726) to several different NK cell receptor fusion proteins in which the extracellular domain of the respective immune receptor is fused to the Fc portion of human IgG1 (containing the N297A mutation to abrogate Fc receptor binding).
Techniques: Immunoprecipitation, Mass Spectrometry, Negative Control, Labeling, Mutagenesis, Staining, Binding Assay, Two Tailed Test