title: Silent information regulator 2 (Sir2) and Forkhead box O (FOXO) complement mitochondrial dysfunction and dopaminergic neuron loss in Drosophila PTEN-induced kinase 1 (PINK1) null mutant.
abstract: PTEN-induced kinase 1 (PINK1), which is associated with early onset Parkinson disease, encodes a serine-threonine kinase that is critical for maintaining mitochondrial function. Moreover, another Parkinson disease-linked gene, parkin, functions downstream of PINK1 in protecting mitochondria and dopaminergic (DA) neuron. In our fly genetic screening, knockdown of Sir2 blocked PINK1 overexpression-induced phenotypes. Consistently, ectopic expression of Sir2 successfully rescued mitochondrial defects in PINK1 null mutants, but unexpectedly, failed in parkin mutants. In further genetic analyses, deletion of FOXO nullified the Sir2-induced mitochondrial restoration in PINK1 null mutants. Moreover, overexpression of FOXO or its downstream target gene such as SOD2 or Thor markedly ameliorated PINK1 loss-of-function defects, suggesting that FOXO mediates the mitochondrial protecting signal induced by Sir2. Consistent with its mitochondria-protecting role, Sir2 expression prevented the DA neuron loss of PINK1 null mutants in a FOXO-dependent manner. Loss of Sir2 or FOXO induced DA neuron degeneration, which is very similar to that of PINK1 null mutants. Furthermore, PINK1 deletion had no deleterious effect on the DA neuron loss in Sir2 or FOXO mutants, supporting the idea that Sir2, FOXO, and PINK1 protect DA neuron in a common pathway. Overall, these results strongly support the role of Sir2 and FOXO in preventing mitochondrial dysfunction and DA neuron loss, further suggesting that Sir2 and FOXO function downstream of PINK1 and independently of Parkin.
authors.affiliation: Department of Pharmacology, Mitochondria Hub Regulation Center (MHRC), Dong-A University College of Medicine, Busan 602-714, Korea.
authors.forename: Hyongjong
authors.initials: H
authors.lastname: Koh
authors.forename: Hyunjin
authors.initials: H
authors.lastname: Kim
authors.forename: Min Ju
authors.initials: MJ
authors.lastname: Kim
authors.forename: Jeehye
authors.initials: J
authors.lastname: Park
authors.forename: Hye-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Jongkyeong
authors.initials: J
authors.lastname: Chung
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D059290:Dopaminergic Neurons / Q000473:pathology / Q000502:physiology*; D004330:Drosophila / Q000201:enzymology* / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D028361:Mitochondrial Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020734:Parkinsonian Disorders / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D000099202:PTEN-Induced Putative Kinase
chemical_list: D029721:Drosophila Proteins; D051858:Forkhead Transcription Factors; D006655:Histone Deacetylases; D017346:Protein Serine-Threonine Kinases; D037761:Sirtuins; D044767:Ubiquitin-Protein Ligases; C477334:FOXO protein, Drosophila; C534484:PINK1 protein, Drosophila; D000099202:PTEN-Induced Putative Kinase; C447899:Sirt2 protein, Drosophila; C487430:park protein, Drosophila