Figure 3. Mitochondrial STAT3 augments electron transport chain activity.
(A) Mitochondrial membrane potential measured with TMRE and recorded as mean fluorescence intensity (MFI) by flow cytometry in wild type (WT) or STAT3-deficient (KO) cells with or without H-RasV12. (B) Mitochondrial membrane potential of H-RasV12-expressing cells with wild type (WT), vector (KO), mitochondrially-targeted wild type (MTS-WT) or S727A-mutant STAT3. Activities of electron transport chain complexes II (C) and V (D) compared between H-RasV12-expressing wild type (WT) or STAT3-deficient (KO) cells. Unit activity of individual complexes normalized to citrate synthase activity from equivalent numbers of mitochondria. Statistical significance with p value <0.05* or <0.001*** by student’s t-test. (E) Lactate dehydrogenase activity in wild type (WT), STAT3-deficient (KO), and H-RasV12-expressing wild type (WT), STAT3-deficient (KO), mitochondrially-targeted wild type (MTS-WT), or mutant STAT3 (MTS-S/A) expressing cells. Results are means of 3 replicates. Error bars indicate SD.