Fig. 7
MIEF self-association is required for MIEF-induced mitochondrial fusion. a, b Confocal images of mitochondrial fusion from the PEG-based fusion assay in WT 293T polykaryons transfected with empty vector, MIEF2-V5 (WT), MIEF2Δ1-49-V5, or MIEF2Δ50-104-V5. Cells with stable expression of mitoRFP or mitoGFP were co-cultured, transfected with empty vector, MIEF2-V5, MIEF2Δ1-49-V5, or MIEF2Δ50-104-V5 as indicated and then subjected to the PEG cell fusion assay. Mitochondrial fusion is indicated by co-localization of mitoRFP and mitoGFP (i.e., yellow mitochondria) (a, upper panels). As indicated by V5-tag staining, the MIEF2Δ1-49 mutant localizes in the cytosol, whereas MIEF2Δ50-104 is mainly on mitochondria (a, lower panels). The extent of mitochondrial fusion in individual hybrid cells was analyzed via the Pearson’s correlation coefficient (PCC, mean ± SEM) in three independent experiments for each condition and data are summarized in (b) (n represents the total number of cells analyzed for each condition). c, d The mito-PAGFP-based mitochondrial fusion assay confirmed that the cytosolic mutant MIEF2Δ1-49 and the self-association-deficient mutant MIEF1Δ50-104 lost the ability to enhance mitochondrial fusion. n represents the number of cells analyzed. ***P < 0.001; **P < 0.01; *P < 0.05 (d)