Figure 6

Mitochondrial fragmentation induced by calcium overload was prevented by inhibition of mPTP in mutant huntingtin cells. A, striatal cells transfected with Mito-GFP protein were treated with 1 μM thapsigargin (Th) during 60 min before live fluorescence images were taken. Images were acquired from full resolution images obtained with 63X objective in a Zeiss Axiovert LED fluorescence microscope. Thapsigargin treatment induced a significant fragmentation of mitochondria in mutant compared with wild type cells. Bar = 10 μm. B, magnification of boxed regions from A to emphasize differences of mitochondrial morphology in striatal cells. Bar = 5 μm. C, striatal cells transfected with Mito-GFP protein were treated with thapsigargin (Th) plus cyclosporine A (CsA) during 60 min and live fluorescence images were obtained. Images were acquired from full resolution images obtained with 63X objective in a Zeiss Axiovert LED fluorescence microscope. Thapsigargin treatment induced significant fragmentation of mitochondria in mutant compared with wild type cells. Mitochondria fragmentation produced by calcium stress was abolished by mPTP closure induced by 0.5 μM CsA treatment for 2 h. Bar = 10 μm. D, magnification of boxed regions from A to emphasize differences of mitochondrial morphology in striatal cells. Bar = 5 μm. E, quantitation of mitochondrial length of 4 independent experiments showed significant mitochondria fragmentation in mutant cells exposed to thapsigargin and this effect was prevented by co-treatment with CsA. Data correspond to the mean ± S.E.M. of 4 independent experiments. * p < 0.05 compared with wild type treated with thapsigargin. ** p < 0.05 compared with mutant cells treated with thapsigargin.