Fig. 1

Identification of the nuclear localization of TfR1 and characterization of its nuclear translocation mechanism. a Representative IHC images (×10 magnification) of TfR1 staining in tumor tissues from different types of cancer (n = 204). Scale bar = 50 μm. b, c Fractionation of the nuclear and cytoplasmic components of HCT-116 cells in (b) and HCT-116 cells transfected with empty vector (EV) or Flag-TfR1 in (c). Lamin B1 was used as a nuclear (Nu) loading control. Tubulin was used as non-nuclear fraction (NNF), and whole cell lysate (WCL) loading control. d, e HCT-116 cells were treated with different concentrations of CPZ for 30 min in (d) or BFA for 6 h in (e) for immunoblot analysis of nuclear and cytoplasmic fractions. The relative abundance of nuclear TfR1 was normalized to that of the CPZ or BFA = 0 controls. Lamin B1 was used as a Nu loading control. Tubulin was used as the loading control for NNF and WCL. f Co-IP analysis of the interactions between Flag-TfR1 and Sec61β. GAPDH was used as a loading control. g HCT-116 cells were transfected with scrambled negative control siRNA (-) or SEC61B-targeted siRNA (+) for 72 h, followed by subcellular fractionation and immunoblot analysis. The relative abundance of nuclear TfR1 was normalized to that of the siRNA (-) control. Lamin B1 and Tubulin were used as equal loading controls for Nu, NNF, and WCL