Figure 5

Co-expression of FXN and ISCU in Irp1 or 2 deficient MEFs rescues the mitochondrial function. (a) Activities of ETC CI, CII, and CIII were determined in Irp1 or Irp2 deficient MEFs after co-transfection with pcDNA3.1-FXN-myc and pXS-ISCU-myc (same plasmids as used in Fig. 4). Values represent mean ± SEM, n = 3, each duplicates. *p < 0.05, **p < 0.01, ***p < 0.001 compared with WT. ^#p < 0.05, ^##p < 0.01 compared + FXN + ISCU with -FXN-ISCU. (b) Western blot analysis of endogenous and exogenous FXN and ISCU, and mitochondrial respiratory chain proteins including Ndufs3 (a subunit of CI), SdhB (a subunit of CII), Uqcrc1 (a subunit of CIII) in MEFs after co-transfection with pcDNA3.1-FXN-myc and pXS-ISCU-myc. The arrows indicate the precursor and mature forms of exogenous ISCU. A representative dataset is presented. (c) The relative levels of cytosolic and mitochondrial LIP were measured with Calcein-AM and RPA, respectively. Values represent mean ± SEM (n = 3, each duplicates). ***p < 0.001 vs. WT. ^##p < 0.01, ^###p < 0.001, +TfR1 vs. −TfR1. (d) Western blot analysis of iron related proteins including TfR1, Irp1 or Irp2, Fxn, IscU, and mitochondrial respiratory chain proteins including Ndufs1 (a subunit of CI), SdhB (a subunit of CII), Uqcrfs1 (a subunit of CIII) in MEFs after transfection with plasmid pcMV3-TfR1. A representative dataset is presented.