title: Mitochondrial contagion induced by Parkin deficiency in Drosophila hearts and its containment by suppressing mitofusin.
abstract: BACKGROUND
  Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood.
  
  
  OBJECTIVE
  We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes.
  
  
  RESULTS
  Transcriptional profiling of Parkin knockout mouse hearts revealed compensatory upregulation of multiple related E3 ubiquitin ligases. Because Drosophila lack most of these redundant genes, we examined heart tubes of parkin knockout flies and observed accumulation of enlarged hollow donut mitochondria with dilated cardiomyopathy, which could be rescued by cardiomyocyte-specific Parkin expression. Identical abnormalities were induced by cardiomyocyte-specific Parkin suppression using 2 different inhibitory RNAs. Parkin-deficient cardiomyocyte mitochondria exhibited dysmorphology, depolarization, and reactive oxygen species generation without calcium cycling abnormalities, pointing to a primary mitochondrial defect. Suppressing cardiomyocyte mitochondrial fusion in Parkin-deficient fly heart tubes completely prevented the cardiomyopathy and corrected mitochondrial dysfunction without normalizing mitochondrial dysmorphology, demonstrating a central role for mitochondrial fusion in the cardiomyopathy provoked by impaired mitophagy.
  
  
  CONCLUSIONS
  Parkin deficiency and resulting mitophagic disruption produces cardiomyopathy in part by contamination of the cardiomyocyte mitochondrial pool through fusion between improperly retained dysfunctional/senescent and normal mitochondria. Limiting mitochondrial contagion by inhibiting organelle fusion shows promise for minimizing organ dysfunction produced by defective mitophagic signaling.
authors.affiliation: From the Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO (P.B., M.S., Y.C., G.W.D.); and Department of Biomedical Sciences, University of Montreal, Quebec, Canada (Y.B.).
authors.forename: Poonam
authors.initials: P
authors.lastname: Bhandari
authors.forename: Moshi
authors.initials: M
authors.lastname: Song
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.forename: Yan
authors.initials: Y
authors.lastname: Burelle
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Dorn
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002311:Cardiomyopathy, Dilated / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D029721:Drosophila Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics; D020869:Gene Expression Profiling; D005838:Genotype; D006333:Heart Failure / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D008565:Membrane Proteins / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000473:pathology; D063154:Mitochondrial Dynamics; D063306:Mitophagy; D009154:Mutation; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000473:pathology; D010641:Phenotype; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D044767:Ubiquitin-Protein Ligases / Q000172:deficiency* / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; C527117:Marf protein, Drosophila; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D044767:Ubiquitin-Protein Ligases; C487430:park protein, Drosophila
keywords: cardiomyopathies; mitochondrial degradation; mitochondrial dynamics