Fig. 6. Ser¹⁵ in Beclin1 and targeting autophagosomes to damaged mitochondria.

A) Protein domains of Beclin1 and Beclin2. Phosphorylation sites in the N-terminal region of Beclin1 and the kinase targeting these sites are indicated. B) Representative images of WT and Becn1^−/− MEFs transfected with Beclin1 or Beclin1 phosphorylation resistant mutants plus GFP-LC3 and mCherry-Parkin prior to treatment with 10 μM FCCP for 6h. Cells were stained for HA. White boxes indicate magnified regions. C) Quantification of GFP-LC3 and mCherry-Parkin colocalization events per cell (n=90 cells/group from 3 experiments). D) Representative images of WT and Becn1^−/− MEFs overexpressing MTS-mCherry-pHluorin2 plus Beclin1 or Beclin1 mutants and treated with 10 μM FCCP for 12h. White boxes indicate magnified regions. E) Quantification of the number of mitophagy events per cell, as measured by the number of red puncta after subtraction of yellow signal (n=90 cells/group from 3 experiments). Data are presented as means ± SEM. Statistical test: **p<0.01, ***p<0.001, and ****p<0.0001 by two-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison test. Scale bars = 10 μm.