Fig. 4
From: MICU1 controls cristae junction and spatially anchors mitochondrial Ca2+ uniporter complex
OPA1 and MICU1 tighten the CJ to restrict cytochrome c release from the cristae lumen. a The upper panel shows a single TEM image of a mitochondrion of HeLa cells transfected with control-siRNA (Control si). To analyze the topology of the cristae junction the cristae width was measured in 2 nm increments starting at the thought prolongation of the IBM and measured into the cristae as indicated with red boxes and arrows in a–c. In the lower panel the distance of the CM to the cristae center is plotted against the distance from the IBM (n = 2/24/117 with preparations/cells/CJ). b Same experiment as in a but with OPA1-siRNA (OPA1si) (n = 2/22/97 with preparations/cells/CJ). c Same experiment as in a but with MICU1-siRNA (MICU1si) (n = 2/23/106 with preparations/cells/CJ). d Comparative analysis of the cristae junction topology of Control (a, black), MICU1 (c, magenta) and OPA1 (b, blue) siRNA transfected cells. Data points represent the mean ± SEM (nControl si = 117; nOPA1 si = 97; nMICU1 si = 106). e Representative images of HeLa cells transfected with Control, OPA1, or MICU1 siRNA, stained with MTRCMX, PFA-fixed and immunostained for cytochrome c. f Quantitative analysis of the sub-mitochondrial distribution of cytochrome c in HeLa cells transfected with Control, OPA1, or MICU1 siRNA (n = 12). Horizontal lines represent the median, the lower and upper hinge show respectively first quartile and third quartile, and lower and upper whisker encompass minimal and maximal values. g Schematic representation of the impact of the loss of MICU1 or OPA1 on mitochondrial cytochrome c redistribution caused by enlarged cristae junction. *P < 0.05 vs. respective control conditions carried out with analysis of variance (ANOVA) with Bonferroni post hoc test. Source data are provided as a Source Data file
