Regulation of mitochondrial and lysosomal contacts with the ER. (A and B) Confocal microscopy image of ER contacts with mitochondria (inset in B) in live HeLa cells (ER, red [mCherry-ER]; mitochondria, green [mEmerald-TOMM20]). Scale bars, 5 μm (A); 1 μm (B). (C–E) Effect of TBC1D15 (WT vs. D397A), Fis1 (WT vs. LA), and Drp1 (WT vs. K38A) on ER-mitochondria contacts. C, n = 45 cells (TBC1D15(WT)); n = 57 cells (TBC1D15(D397A)); D, n = 33 cells (Fis1(WT)); n = 27 cells (Fis1(LA)); E, n = 29 cells (Drp1(WT)); n = 38 cells (Drp1(K38A)). (F and G) Confocal microscopy image of ER contacts with lysosomes (inset in G) in live HeLa cells (ER, red [mCherry-ER]; lysosome, green [mTagBFP2-Lysosomes-20]). Scale bars, 5 μm (F); 1 μm (G). (H–J) Effect of TBC1D15 (WT vs. D397A), Fis1 (WT vs. LA), and Drp1 (WT vs. K38A) on ER-lysosome contacts. H, n = 45 cells (TBC1D15(WT)); n = 57 cells (TBC1D15(D397A)); I, n = 33 cells (Fis1(WT)); n = 27 cells (Fis1(LA)); J, n = 19 cells (Drp1(WT)); n = 23 cells (Drp1(K38A)). Mean ± SEM; unpaired two-tailed t test (C–E and H–J); N.S., not significant (D, E, H, and I); *, P = 0.0157 (C); *, P = 0.0432 (J).