Fig. 4 | Nature Communications

Fig. 4

From: Engineered proteins with sensing and activating modules for automated reprogramming of cellular functions

Fig. 4

The activation and function of SIRPα Syk-iSNAP in macrophages. a Schematic representation of the drawing of the SIRPα Syk-iSNAP and its putative activation mechanism upon CD47 engagement. bc Images of RAW264.7 macrophages expressing b SIRPα Syk-iSNAP or c non-fluorescent SIRPα Syk-iSNAP together with Ca2+ or Erk FRET biosensors, before and after incubation with CD47-coated beads. d Images of phagocytosis of opsonized RBCs by a representative RAW264.7 macrophage expressing SIRPα Syk-iSNAP. e Dot plot of normalized phagocytic rate (mean ± s.e.m.) of RAW264.7 macrophages expressing SIRPα Syk-iSNAP or control constructs against opsonized RBCs (K402R, a kinase-dead mutant K402R in Syk kinase domain; other constructs are the same as described in Fig. 3) (n = 7, 4, 3, 7, 7). f Schematic drawing of the engineered macrophage for mAbs-guided cancer cell eradication. In native macrophages, pro-phagocytic activity mediated by the antigen-recognizing antibody and FcγR is inhibited by CD47-SIRPα signal pathway via the recruitment of negative regulator Shp1. In engineered macrophages, the anti-phagocytic signal of CD47-SIRPα axis is rewired by SIRPα iSNAPs to promote phagocytic activities for the cancer cell eradication *P < 0.05 (two-sided Mann–Whitney U-test adjusted for multiple group comparison). Scale bars, 20 μm

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