Research Article

Parkin-mediated mitophagy directs perinatal cardiac metabolic maturation in mice

See allHide authors and affiliations

Science  04 Dec 2015:
Vol. 350, Issue 6265, aad2459
DOI: 10.1126/science.aad2459
  • Mitochondrial maturation fails when mitophagy is interrupted.

    Normal perinatal mitochondrial maturation is shown on the left: Heart sections from neonatal and 5-week-old hearts are superimposed on their electron micrographs. To the right are similar images from hearts expressing the dominant negative mitochondrial Parkin receptor, Mfn2 AA. Retention of fetal cardiomyocyte mitochondria in mitophagically impaired hearts was lethal.

  • Fig. 1 Early lethality of perinatal cardiomyocyte-specific Parkin-deficient mice.

    (A) Transmission electron microscopy (TEM) showing normal cardiomyocyte mitochondria on the first (P1) and 21st (P21) day of life. Enlargement shows structural details at P1. (B) PCR genotyping of floxed Park2 gene (top) and tamoxifen-inducible cardiac Cre (bottom) of surviving mice from a representative litter at P21; three mice died before weaning. KO indicates Cre recombined Park2 fl/fl allele. T is tail DNA; H is heart DNA. (C and D) Representative (of three) hearts, histological sections, and TEMs from P21 cardiac Parkin–deficient (top) and control (bottom) mice. Scale bars for hearts are 2 mm.

  • Fig. 2 Mitochondrial Parkin mobilization directed by pseudo-PINK1 phosphorylated Mfn2.

    (A) Phosphorylation of Mfn2 by recombinant PINK1 in a cell-free system. First three panels show enrichment of FLAG-Mfn2 by immunoprecipitation (IP) with antibody to FLAG (anti-FLAG); left is Coomassie blue stained gel, middle is anti-Mfn2 immunoblot, right is anti-FLAG immunoblot. Fourth panel shows anti-Mfn2 Phos-tag immunoblot of in vitro PINK1 phosphorylation reactants; KD is kinase dead PINK1; CIP is calf intestinal phosphatase. Arrowheads show FLAG-Mfn2; bold arrow indicates phospho-Mfn2. (B) Spontaneous maraschino cherry (mc) Parkin translocation in MEFs provoked by adeno-Mfn2 EE, and FCCP-mediated mcParkin translocation suppressed by adeno-Mfn2 AA. To the left is an immunoblot of Mfn2. (C) Lysosomal-mitochondrial interactions (white squares) provoked by adeno-Mfn2 EE and suppressed by adeno-Mfn2 AA. (D) Mitochondrial elongation (aspect ratio) inhibited by adeno-Mfn2 EE and stimulated by adeno-Mfn2 AA. WT is wild-type adeno-Mfn2. In (B) and (C), gray bars are basal; the black bars are 60 min after FCCP or antimycin A. In (D), gray bars are 24 hours and black bars are 48 hours after adeno-Mfn2 virus infection. *, P < 0.05 versus adeno β-gal control (Ctrl); #, P < 0.05 versus same condition WT adeno-Mfn2.

  • Fig. 3 Perinatal cardiomyopathy evoked by nonphosphorylated Mfn2 AA.

    (A) Immunoblot analysis of Mfn2 expression (top) and mitochondrial Parkin localization (bottom) in transgenic mouse hearts. (Top) Top pair is cardiac homogenate; bottom pair is mitochondrial-enriched 10,000 g pellet (cytochrome oxidase IV; COX IV) and postmitochondrial supernatant [glyceraldehyde-3-phosphate dehydrogenase (GAPDH)]. (Bottom) Immunoblot analysis of mitochondrial-associated Parkin and downstream mitophagy events and their modulation by cardiac-expressed Mfn2 EE and Mfn2 AA. (B) Representative hearts of 6-week-old mice. (C) Survival. (D) Serial echocardiographic data of 4- to 6-week-old mice; white bars are Ctrl, gray is WT Mfn2, and black is Mfn2 AA. (E) Heart (top) and lung (bottom) weights of 6-week-old mice indexed to body weight (BW). (F) Histological studies of cardiomyocyte cross-sectional area (top) and myocardial fibrosis (bottom); quantitative data are on the right. *, P < 0.05 versus WT Mfn2 and nontransgenic (NTG) control.

  • Fig. 4 Abnormalities in mitophagy and mitochondria induced by perinatal cardiac Mfn2 AA.

    (A) Immunoreactive Parkin and p62/SQSTM1 in 2- to 3-week-old mitochondrial-enriched mouse heart fractions (mito-) of fed mice (top) and food-deprived mice (bottom). Cyto-p62 is p62/SQSTM1 in the cytosolic fraction. (B) Substrate-stimulated (left) and maximum uncoupled (right) respiration of isolated cardiac mitochondria. (C) Isolated mitochondrial O2 (MitoSOX; left) and H2O2 (Amplex red; right) production studies. (D) Cardiac mitochondrial protein content. (E) Flow cytometric mitochondrial forward scatter. (F) Ultrastructural studies of cardiomyocyte mitochondria. Mitochondrial content is the percentage of cell area occupied by mitochondria; mitochondrial area is the mean area of individual organelles; mitochondrial aspect ratio is long axis/short axis. (G) Immunoblot analysis of respiratory complex proteins. Quantitative data to right are n = 4 individual mouse hearts. *, P < 0.05 versus Ctrl; #, P < 0.05 versus WT Mfn2.

  • Fig. 5 Fetal mitochondria persist in young adult Mfn2 AA mouse hearts.

    (A) Representative four-chamber heart sections and transmission electron micrographs of cardiomyocyte mitochondria from P1, P21, and 5-week-old mouse hearts. NTG controls are top row, WT Mfn2 middle row, Mfn2 AA bottom row. Quantitative data for heart weights are in (B) and for mitochondrial ultrastructure in (C). *, P < 0.05 versus P1; #, P < 0.05 versus WT Mfn2 at the same stage.

  • Fig. 6 Failure of metabolic gene reprogramming after perinatal Mfn2 AA expression.

    (A) Heat map of mitochondrial gene expression in P1, P21, and 5-week-old mouse hearts; functional annotation of Mfn2 AA gene clusters is to the right. (B) Postnatal reprogramming of mitochondrial genes by metabolic function. Bars are mean values from results in Fig. 4B; log(2) gene expression at 5 weeks versus P1 for Ctrl (top), WT Mfn2 (middle), and Mfn2 AA (bottom) hearts. Blue and red bars are significantly down- and up-regulated, respectively [1.25-fold; false discovery (FDR) < 0.02]; black bars are not significantly regulated. (C) Regulated expression of mitochondrial biogenesis and replication genes during the perinatal-adult transition. *, FDR < 0.02 versus littermate control mice (TO); #, P < 0.0001 versus WT Mfn2 [two-way analysis of variance (ANOVA)].

  • Fig. 7 Adult Mfn2 AA hearts retain a fetal-like glycolytic metabolism.

    (A)Palmitoylcarnitine-stimulated (top) and pyruvate-stimulated (bottom) respiration of isolated permeabilized cardiomyocytes. (B and C) Standardized heat map showing unsupervised clustering of myocardial acylcarnitine (B) and organic acid (C) metabolite content in P1 NTG and 5-week-old NTG, WT Mfn2, and Mfn2 AA mouse hearts. Vertical lines to the right of (B) indicate significantly dysregulated metabolites in 5-week-old Mfn2 AA hearts versus contemporaneous controls. (D) Quantitative data for absolute myocardial content of dysregulated metabolites in (B). -DC and -OH designate monohydroxylated and dicarboxylic acid acylcarnitine species, respectively. Common names for parent species are in parentheses. *, P < 0.05 versus WT Mfn2 (ANOVA).

Supplementary Materials

  • Parkin-mediated mitophagy directs perinatal cardiac metabolic maturation in mice

    Guohua Gong, Moshi Song, Gyorgy Csordas, Daniel P. Kelly, Scot J. Matkovich, Gerald W. Dorn II

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

    Download Supplement
    • Materials and Methods
    • Figs. S1 to S19
    • References
    Data set S1
    Gene lists by functional category
    Data set S2
    Regulated gene details

Navigate This Article