Fig. 6. Mitochondrial fusion is inhibited upon silencing of SENP5. (A) COS-7 cells stably transfected with shRNA vector alone (top panels) or to shRNA targeting SENP5 (bottom panels) were transfected with pOCT:PAGFP and the regions of interest indicated were activated at 405 nm. Stacks were obtained by imaging cells at 488 nm every 10 minutes for 40 minutes, after which all of the mitochondria containing PAGFP were activated. Masks were obtained where each voxel having a fluorescent signal above the threshold was scored as white and single slices taken from the stacks are shown at 1 minute post activation, at 40 minutes and after complete activation. Bars, 10 µm. (B) Quantification of the data obtained from control cells (n=10) and from SENP5-silenced cells (n=13). The percent increase in the spread of the activated signal is shown for each cell. The circled data points represent the cell whose corresponding images are shown in A. The data show that there is an average of 21% of mitochondrial fusion within 40 minutes in COS-7 cells, whereas SENP5-silenced cells have significantly reduced rates of fusion (P<0.001).