Fig. 4: Spatial loss of ΔΨm after ER Ca2+ release is modulated by MICU1 and UCP2.
a Binarized labeling of HeLa cells at T = 28 s, 32 s, and 36 s showing thresholded mitochondrial (TMRM; red), endoplasmic reticulum (ERAT 4.0 NA; green) and MAMs (yellow) structures as well as positive (+∆TMRM) or negative (−∆TMRM) local TMRM intensity changes (white). b Quantification of spatial restricted drops in membrane potential defined as −∆/+∆TMRM over time in HeLa cells challenged with or without histamine in the complete mitochondria and (upper panel) in spatial proximity to MAMs (lower panel). The red arrows point to the addition of histamine. Statistical quantification in whole mitochondria in c and regions with close proximity to MAMs in d of basal (left panel) and maximum delta (right panel) −Δ/+ΔTMRM ratios in HeLa cell transfected with siRNA against control, MICU1, or UCP2. e Schematic depiction of CJ opening or closing and redistribution of local membrane potential upon knockdown of UCP2, MICU1, or OPA1 as well as the influence of PRMT1 expression and high local Ca2+ concentrations. Data information: data are shown as the mean +/− SEM (nControl si, control = 9/23, nControl si, hist = 10/29, nMICU1 si, control = 8/24, nMICU1 si, hist = 9/26, nUCP2 si, control = 8/20, nUCP2 si, hist = 9/24, with days/cells). *P < 0.05 vs. respective untreated (CaB) control conditions carried out with unpaired double-sided T test.
