Histone deacetylase 6–mediated selective autophagy regulates COPD-associated cilia dysfunction
Hilaire C. Lam, … , Stefan W. Ryter, Augustine M.K. Choi
Hilaire C. Lam, … , Stefan W. Ryter, Augustine M.K. Choi
Published November 8, 2013
Citation Information: J Clin Invest. 2013;123(12):5212-5230. https://doi.org/10.1172/JCI69636.
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Research Article Pulmonology

Histone deacetylase 6–mediated selective autophagy regulates COPD-associated cilia dysfunction

Abstract

Chronic obstructive pulmonary disease (COPD) involves aberrant airway inflammatory responses to cigarette smoke (CS) that are associated with epithelial cell dysfunction, cilia shortening, and mucociliary clearance disruption. Exposure to CS reduced cilia length and induced autophagy in vivo and in differentiated mouse tracheal epithelial cells (MTECs). Autophagy-impaired (Becn1+/– or Map1lc3B–/–) mice and MTECs resisted CS-induced cilia shortening. Furthermore, CS increased the autophagic turnover of ciliary proteins, indicating that autophagy may regulate cilia homeostasis. We identified cytosolic deacetylase HDAC6 as a critical regulator of autophagy-mediated cilia shortening during CS exposure. Mice bearing an X chromosome deletion of Hdac6 (Hdac6–/Y) and MTECs from these mice had reduced autophagy and were protected from CS-induced cilia shortening. Autophagy-impaired Becn1–/–, Map1lc3B–/–, and Hdac6–/Y mice or mice injected with an HDAC6 inhibitor were protected from CS-induced mucociliary clearance (MCC) disruption. MCC was preserved in mice given the chemical chaperone 4-phenylbutyric acid, but was disrupted in mice lacking the transcription factor NRF2, suggesting that oxidative stress and altered proteostasis contribute to the disruption of MCC. Analysis of human COPD specimens revealed epigenetic deregulation of HDAC6 by hypomethylation and increased protein expression in the airways. We conclude that an autophagy-dependent pathway regulates cilia length during CS exposure and has potential as a therapeutic target for COPD.

Authors

Hilaire C. Lam, Suzanne M. Cloonan, Abhiram R. Bhashyam, Jeffery A. Haspel, Anju Singh, J. Fah Sathirapongsasuti, Morgan Cervo, Hongwei Yao, Anna L. Chung, Kenji Mizumura, Chang Hyeok An, Bin Shan, Jonathan M. Franks, Kathleen J. Haley, Caroline A. Owen, Yohannes Tesfaigzi, George R. Washko, John Quackenbush, Edwin K. Silverman, Irfan Rahman, Hong Pyo Kim, Ashfaq Mahmood, Shyam S. Biswal, Stefan W. Ryter, Augustine M.K. Choi

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Figure 5

HDAC6 deficiency is associated with impaired autophagic protein clearance.

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HDAC6 deficiency is associated with impaired autophagic protein clearanc...
(A) The global ubiquitin pattern was assessed in Hdac6+/Y and Hdac6–/Y MTEC cultures 24 hours after treatment with 50 mg/m3 CS. Samples are presented in duplicate. β-Actin served as the standard. (B) Protein aggregates (PA; shown in red) were analyzed in MTEC cultures derived from Hdac6+/Y and Hdac6–/Y mice 24 hours after exposure to CS (50 mg/m3). Scale bar: 10 μm (n = 3 MTEC cultures; 5 fields analyzed/culture) (C) Quantification of protein aggregate puncta in MTEC cultures, which were pretreated with 50 mg/m3 CS followed 15 minutes later by CQ (25 μm) in the basal media and harvested 2 hours later (n = 2–3 MTEC cultures; 3–4 fields analyzed per culture). (D) Nrf2–/– and WT mice (n = 4 mice/group) were exposed to RA or CS for 2 weeks. (E) Global protein ubiquitination was quantified by densitometry in Nrf2–/– and WT mouse lungs after exposure to RA or CS (n = 2 mice/group). All data are the mean ± SEM. *P < 0.05 by an unpaired Student’s t test (C), and *P < 0.05, **P < 0.01, and ***P < 0.001 by one- or two-way ANOVA and Bonferroni’s post tests (D and E).