title: PARK2-mediated mitophagy is involved in regulation of HBEC senescence in COPD pathogenesis.
abstract: Cigarette smoke (CS)-induced mitochondrial damage with increased reactive oxygen species (ROS) production has been implicated in COPD pathogenesis by accelerating senescence. Mitophagy may play a pivotal role for removal of CS-induced damaged mitochondria, and the PINK1 (PTEN-induced putative kinase 1)-PARK2 pathway has been proposed as a crucial mechanism for mitophagic degradation. Therefore, we sought to investigate to determine if PINK1-PARK2-mediated mitophagy is involved in the regulation of CS extract (CSE)-induced cell senescence and in COPD pathogenesis. Mitochondrial damage, ROS production, and cell senescence were evaluated in primary human bronchial epithelial cells (HBEC). Mitophagy was assessed in BEAS-2B cells stably expressing EGFP-LC3B, using confocal microscopy to measure colocalization between TOMM20-stained mitochondria and EGFP-LC3B dots as a representation of autophagosome formation. To elucidate the involvement of PINK1 and PARK2 in mitophagy, knockdown and overexpression experiments were performed. PINK1 and PARK2 protein levels in lungs from patients were evaluated by means of lung homogenate and immunohistochemistry. We demonstrated that CSE-induced mitochondrial damage was accompanied by increased ROS production and HBEC senescence. CSE-induced mitophagy was inhibited by PINK1 and PARK2 knockdown, resulting in enhanced mitochondrial ROS production and cellular senescence in HBEC. Evaluation of protein levels demonstrated decreased PARK2 in COPD lungs compared with non-COPD lungs. These results suggest that PINK1-PARK2 pathway-mediated mitophagy plays a key regulatory role in CSE-induced mitochondrial ROS production and cellular senescence in HBEC. Reduced PARK2 expression levels in COPD lung suggest that insufficient mitophagy is a part of the pathogenic sequence of COPD.
authors.affiliation: a Division of Respiratory Diseases; Department of Internal Medicine ; Jikei University School of Medicine ; Tokyo , Japan.
authors.forename: Saburo
authors.initials: S
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Araya
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kurita
authors.forename: Kenji
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Naoki
authors.initials: N
authors.lastname: Takasaka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Hara
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Minagawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wakui
authors.forename: Satoko
authors.initials: S
authors.lastname: Fujii
authors.forename: Jun
authors.initials: J
authors.lastname: Kojima
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Shimizu
authors.forename: Takanori
authors.initials: T
authors.lastname: Numata
authors.forename: Makoto
authors.initials: M
authors.lastname: Kawaishi
authors.forename: Makoto
authors.initials: M
authors.lastname: Odaka
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Morikawa
authors.forename: Toru
authors.initials: T
authors.lastname: Harada
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Nishimura
authors.forename: Yumi
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Nakayama
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kuwano
mesh_terms: D000328:Adult; D000368:Aged; D001343:Autophagy; D001980:Bronchi / Q000166:cytology; D016922:Cellular Senescence; D004847:Epithelial Cells / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000503:physiopathology; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D008928:Mitochondria / Q000473:pathology; D063306:Mitophagy; D011494:Protein Kinases / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000276:immunology / Q000503:physiopathology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects; D062789:Tobacco Products; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*; D000099202:PTEN-Induced Putative Kinase
chemical_list: D011494:Protein Kinases; D017382:Reactive Oxygen Species; D044767:Ubiquitin-Protein Ligases; D000099202:PTEN-Induced Putative Kinase; C111567:parkin protein
keywords: Baf A1, bafilomycin A1; COPD; COPD, chronic obstructive pulmonary disease; CS, cigarette smoke; CSE, cigarette smoke extract; EM, electron microscopy; FEV1, forced expiratory volume in one second; FVC, forced vital capacity; HBEC, human bronchial epithelial cell; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; NAC, N-acetylcysteine; PARK2; PCD, programmed cell death; PINK1, PTEN-induced putative kinase 1; ROS; ROS, reactive oxygen species; SA-β-Gal, senescence-associated β-galactosidase; TLR, toll-like receptor; WB, western blotting; mitophagy; senescence