FIG. 3.
Mfrn1 and Mfrn2 contribute to mitochondrial iron metabolism in ES cells. (A) Mouse ES cells heterozygous for the loss of Mfrn1 (ESMfrn1+/Mfrn1−) or homozygous for the loss of Mfrn1 (ESMfrn1−/Mfrn1−) were treated for 48 h with oligonucleotides specific to Mfrn2 (siRNA Mfrn2) and/or were transfected with Mfrn1-GFP (CMV-Mfrn1) or Mfrn2-GFP (CMV-Mfrn2). Iron (59Fe) incorporation into heme was measured as cpm/mg protein. The data are expressed as the relative percentages of incorporation compared to that of the nonsilenced cells. (B) Protoporphyrin IX accumulation was measured in ES cells treated as described for panel A. The data are expressed as fluorescence units/mg protein. Error bars represent the standard deviations of the results from three independent experiments.