Fig. 2: CISD1/CISD mediates Parkin-dependent regulation of ER calcium release.

a Genetic scheme to screen new genes that alleviate defective ER calcium release of PINK1 (PINK1^B9) and Parkin (park¹) null mutants. To measure ER calcium release in Drosophila larval muscle, mef2-GAL4 were used to express ERGCaMP6-210, an ER calcium indicator. After dissection of the third instar larvae, fluorescence images of larval muscle were acquired by confocal microscope with a perfusion system. Some elements of the figure were created using images from BioRender.com. b Measurement of ER calcium release for control (mef2>Luci, black) and Parkin null mutants (red), CISD KD flies (blue), and Parkin null mutants expressing CISD RNAi (green). Here, we used CISDi #1 flies (#33925 from the Vienna Drosophila Resource Center) for CISD KD. 5 mM ATP was delivered to initiate ER calcium release. The right side bar graphs indicate the quantification of the normalized calcium traces using AUC of calcium release during ATP treatment. n = 10 flies. c Measurement of ER calcium modulations in WT (black) and Parkin KO (red) MEF cells. Similar experiments were also conducted when WT (blue) and Parkin KO (green) MEF cells were expressing CISD1 siRNA (siCISD1) or control siRNA (siControl). The right side bar graphs indicate the quantification of the normalized calcium traces using AUC of calcium release during ATP treatment. n = 158–195 cells. d Measurement of ER calcium release through IP₃R in WT (black, n = 72 cells) and CISD1 KO (red, n = 79 cells.) MEF cells. The bar graphs indicate the magnitude of the change during IP₃ treatment. Three independent experiments were conducted and were quantified (b–d). One-way ANOVA with Tukey’s multiple comparisons test was used (b, c), and two-tailed unpaired Student’s t test was used (d). ****p < 0.0001. Source data, the exact p values, and n number of each experiment are included within the Source Data file. All data are presented as mean ± SD.