title: Role of Cigarette Smoke-Induced Aggresome Formation in Chronic Obstructive Pulmonary Disease-Emphysema Pathogenesis.
abstract: Cigarette smoke (CS) exposure is known to induce proteostasis imbalance that can initiate accumulation of ubiquitinated proteins. Therefore, the primary goal of this study was to determine if first- and secondhand CS induces localization of ubiquitinated proteins in perinuclear spaces as aggresome bodies. Furthermore, we sought to determine the mechanism by which smoke-induced aggresome formation contributes to chronic obstructive pulmonary disease (COPD)-emphysema pathogenesis. Hence, Beas2b cells were treated with CS extract (CSE) for in vitro experimental analysis of CS-induced aggresome formation by immunoblotting, microscopy, and reporter assays, whereas chronic CS-exposed murine model and human COPD-emphysema lung tissues were used for validation. In preliminary analysis, we observed a significant (P < 0.01) increase in ubiquitinated protein aggregation in the insoluble protein fraction of CSE-treated Beas2b cells. We verified that CS-induced ubiquitin aggregrates are localized in the perinuclear spaces as aggresome bodies. These CS-induced aggresomes (P < 0.001) colocalize with autophagy protein microtubule-associated protein 1 light chain-3B(+) autophagy bodies, whereas U.S. Food and Drug Administration-approved autophagy-inducing drug (carbamazepine) significantly (P < 0.01) decreases their colocalization and expression, suggesting CS-impaired autophagy. Moreover, CSE treatment significantly increases valosin-containing protein-p62 protein-protein interaction (P < 0.0005) and p62 expression (aberrant autophagy marker; P < 0.0001), verifying CS-impaired autophagy as an aggresome formation mechanism. We also found that inhibiting protein synthesis by cycloheximide does not deplete CS-induced ubiquitinated protein aggregates, suggesting the role of CS-induced protein synthesis in aggresome formation. Next, we used an emphysema murine model to verify that chronic CS significantly (P < 0.0005) induces aggresome formation. Moreover, we observed that autophagy induction by carbamazepine inhibits CS-induced aggresome formation and alveolar space enlargement (P < 0.001), confirming involvement of aggresome bodies in COPD-emphysema pathogenesis. Finally, significantly higher p62 accumulation in smokers and severe COPD-emphysema lungs (Global Initiative for Chronic Obstructive Lung Disease Stage III/IV) as compared with normal nonsmokers (Global Initiative for Chronic Obstructive Lung Disease Stage 0) substantiates the pathogenic role of autophagy impairment in aggresome formation and COPD-emphysema progression. In conclusion, CS-induced aggresome formation is a novel mechanism involved in COPD-emphysema pathogenesis.
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|2 Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Ian
authors.initials: I
authors.lastname: Tran
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|2 Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Changhoon
authors.initials: C
authors.lastname: Ji
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|2 Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Inzer
authors.initials: I
authors.lastname: Ni
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|2 Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Taehong
authors.initials: T
authors.lastname: Min
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|2 Biomedical Engineering, the Johns Hopkins University School of Medicine, Baltimore, Maryland; and.
authors.forename: Danni
authors.initials: D
authors.lastname: Tang
authors.affiliation: Departments of 1 Pediatric Respiratory Science and.|3 College of Medicine, Central Michigan University, Mount Pleasant, Michigan.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Vij
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001343:Autophagy; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008810:Mice, Inbred C57BL; D066263:Protein Aggregation, Pathological / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D021381:Protein Transport; D011656:Pulmonary Emphysema / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D016601:RNA-Binding Proteins / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects*; D057149:Ubiquitinated Proteins / Q000378:metabolism*; D000074405:Valosin Containing Protein
chemical_list: D018797:Cell Cycle Proteins; C118585:P62 protein, human; D016601:RNA-Binding Proteins; D057149:Ubiquitinated Proteins; D000251:Adenosine Triphosphatases; C000614178:VCP protein, human; D000074405:Valosin Containing Protein; C000614179:Vcp protein, mouse
keywords: aggresomes; autophagy; chronic obstructive pulmonary disease; cigarette smoke; ubiquitin