Master Autophagy Regulator Transcription Factor EB Regulates Cigarette Smoke-Induced Autophagy Impairment and Chronic Obstructive Pulmonary Disease-Emphysema Pathogenesis.
OBJECTIVE
Recent studies have shown that cigarette smoke (CS)-induced oxidative stress impairs autophagy, resulting in aggresome-formation that correlates with severity of chronic obstructive pulmonary disease (COPD)-emphysema, although the specific step in autophagy pathway that is impaired is unknown. Hence, in this study, we aimed to evaluate the role of master autophagy transcription factor EB (TFEB) in CS-induced COPD-emphysema pathogenesis.


RESULTS
We first observed that TFEB accumulates in perinuclear spaces as aggresome-bodies in COPD lung tissues of tobacco smokers and severe emphysema subjects, compared with non-emphysema or nonsmoker controls. Next, Beas2b cells and C57BL/6 mice were exposed to either cigarette smoke extract (CSE) or subchronic-CS (sc-CS), followed by treatment with potent TFEB-inducing drug, gemfibrozil (GEM, or fisetin as an alternate), to experimentally verify the role of TFEB in COPD. Our in vitro results indicate that GEM/fisetin-mediated TFEB induction significantly (p < 0.05) decreases CSE-induced autophagy-impairment (Ub/LC3B reporter and autophagy flux assay) and resulting aggresome-formation (Ub/p62 coexpression/accumulation; immunoblotting and staining) by controlling reactive oxygen species (ROS) activity. Intriguingly, we observed that CS induces TFEB accumulation in the insoluble protein fractions of Beas2b cells, which shows a partial rescue with GEM treatment. Moreover, TFEB knockdown induces oxidative stress, autophagy-impairment, and senescence, which can all be mitigated by GEM-mediated TFEB induction. Finally, in vivo studies were used to verify that CS-induced autophagy-impairment (increased Ub, p62, and valosin-containing protein in the insoluble protein fractions of lung/cell lysates), inflammation (interleukin-6 [IL-6] levels in bronchoalveolar lavage fluid and iNOS expression in lung sections), apoptosis (caspase-3/7), and resulting emphysema (hematoxylin and eosin [H&E]) can be controlled by GEM-mediated TFEB induction (p < 0.05).


METHODS
CS exposure impairs autophagy in COPD-emphysema by inducing perinuclear localization of master autophagy regulator, TFEB, to aggresome-bodies.


CONCLUSIONS
TFEB-inducing drug(s) can control CS-induced TFEB/autophagy-impairment and COPD-emphysema pathogenesis. Antioxid. Redox Signal. 27, 150-167.
1 College of Medicine, Central Michigan University , Mount Pleasant, Michigan.
Manish
M
Bodas
1 College of Medicine, Central Michigan University , Mount Pleasant, Michigan.
Neel
N
Patel
1 College of Medicine, Central Michigan University , Mount Pleasant, Michigan.
David
D
Silverberg
1 College of Medicine, Central Michigan University , Mount Pleasant, Michigan.
Kyla
K
Walworth
1 College of Medicine, Central Michigan University , Mount Pleasant, Michigan.|2 Department of Pediatrics and Pulmonary Medicine, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
Neeraj
N
Vij
D000818:Animals; D001343:Autophagy; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D015248:Gemfibrozil / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D051379:Mice; D011656:Pulmonary Emphysema / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism*; D012906:Smoke / Q000009:adverse effects*
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D012906:Smoke; C064972:TFEB protein, human; D015248:Gemfibrozil
COPD; ROS; TFEB; autophagy; cigarette smoke; emphysema; oxidative stress; tobacco