Fig. 9

Expressing PTPIP51 suppresses mitochondrial fragmentation and Parkin translocation in Mul1-deficient neurons. a Representative images showing the mitochondria-targeting of PTPIP51 in cortical neurons. Neurons were co-transfected with HA-tagged PTPIP51 and DsRed-Mito at DIV7-8 and imaged at DIV10-11 by immunostaining HA-tag. b, c Representative traces and quantitative analysis showing a partial rescue of IP3-induced ER-Mito Ca²⁺ exchange by expressing PTPIP51 in Mul1-deficient neurons. Cortical neurons at DIV7-8 were co-transfected with pcDNA-4mtD3cpv and Flag, or Flag-Mul1ΔRing, or Flag-Mul1ΔRing + HA-PTPIP51. pcDNA-4mtD3cpv is a FRET-based ratiometric calcium probe that targets the mitochondrial matrix. Live neurons were imaged at DIV10-11. The traces represent the average fluorescence ratio signal (525 nm/458 nm) when excited with a 405-nm laser following stimulation with 10 μM histamine. Mitochondrial Ca²⁺ levels were measured from the total number of trials indicated in the bars. Each trial denotes 2–3 neurons per field. d–g PTPIP51 expression suppresses mitochondrial fragmentation and reduces Parkin translocation in Mul1-deficient neurons. Cortical neurons at DIV7-8 were co-transfected with mCherry-Parkin, Flag-Mul1ΔRing, and HA-Vector (d) or HA-PTPIP51 (e), followed by immunostaining with Flag-tag (green) at DIV14-15. The mitochondrial morphology was measured as average mitochondria size and aspect ratio from the total number of neurons indicated in the bars (f); the percentage of neurons with Parkin recruitment to fragmented mitochondria was measured from the total number of neurons indicated in the bars (g). All data were from three experiments using the unpaired Student’s t-test (f, g) and Ordinary one-way ANOVA with Dunnett’s post hoc test (c) and are expressed as mean ± s.e.m. Scale Bars: 10 μm