Biology subjects

Dickinson, J. D.

Publications and source records attributed to Dickinson, J. D..

3 recordsLinked to original sources

bioRxiv2026

Autonomous MTOR activation in COPD airway epithelium impairs resolution through persistent mucus cell metaplasia and lysosome dysfunction

Background: COPD is associated with persistent airway epithelial mucous cell metaplasia (MCM), mucin hypersecretion, and airway obstruction. Cytokines, such as IL-13, are well-known inflammatory drivers of airway MCM development. However, less is known about the factors that contribute to the impaired resolution of MCM in COPD. We hypothesized that MTOR activation in COPD airway epithelial cells (AECs) impairs autophagy and contributes to the delayed resolution of MCM. Methods: AEC from COPD and non-diseased donors were grown under air-liquid interface (ALI) conditions and treated with IL-13 to promote MCM. Airway sections from COPD lung explants or non-diseased lung donors were utilized for immunohistochemical and immunostaining. Lysosomes were assessed using molecular probes and immunostaining. Results: There was persistent MTOR-dependent MUC5AC immunostaining and epithelial hypertrophy in COPD AEC, which did not resolve after IL-13 withdrawal. MTOR substrate phosphorylation of RBS6, S6K1, and ULK1 was significantly elevated under baseline conditions, and at multiple timepoints independent of IL-13. Pharmacologic activation of MTOR led to increased IL-13-mediated MUC5AC levels in normal AEC but less robustly in COPD derived AEC. We hypothesized that persistent MTOR activation would reduce lysosome function and abundance in disease. COPD airways had reduced lysosome markers, LAMP1 and LAMP2 and fewer functional lysosomes by live-cell reporter probes. This lysosome deficiency in COPD AEC was partially rescued with MTOR inhibition. Conclusions: We provide evidence to support an axis of autonomous MTOR activation and impaired lysosome function in the COPD airway epithelium. Persistent MTOR signaling is a molecular driver that contributes to persistent MCM.

pathology↗

bioRxiv2025

Airway Secretory Cells Contain Both a Perinuclear Golgi Ribbon and Dispersed Golgi Satellites

RationaleFinely tuned production and secretion of the polymeric mucins MUC5AC and MUCB are required for lung health, but knowledge of many details between their translation and their packaging into secretory granules is lacking. ObjectivesTo analyze the structure and function of the Golgi apparatus, a key site of mucin glycosylation, folding, polymerization and packaging, in airway epithelial secretory cells. MethodsLung tissue was obtained from mice stimulated or not with IL-13 to upregulate mucin production, and from normal human lungs. Golgi elements in mouse and human tissue were imaged by high-resolution immunofluorescence microscopy and electron microscopy. Tissue from mice with deletion of both polymeric mucins was also examined. Measurements and Main ResultsBy immunofluorescence microscopy, both mouse and human airway secretory cells contained [~]100 dispersed puncta labeled by markers of medial and trans Golgi cisternae and the trans-Golgi network (TGN), but only a few perinuclear puncta were labeled by markers of cis-Golgi cisternae. By electron microscopy, secretory cells contained both a perinuclear Golgi ribbon and numerous dispersed Golgi stacks, termed satellites. In mucous metaplastic cells, satellites were concentrated among immature mucin granules. Increasing mucin production by cytokine stimulation did not increase the number of TGN puncta, nor did preventing polymeric mucin production by gene deletion reduce TGN puncta. ConclusionsMucin-producing airway secretory cells express an unusual Golgi structure consisting of a conventional perinuclear Golgi ribbon as well as dispersed satellites. While the Golgi satellites are likely an adaptation for mucin production and packaging, their presence is specified developmentally, independent of mucin production.

cell biology↗

bioRxiv2024

mTOR signaling regulates aberrant epithelial cell proliferative and migratory behaviors characteristic of airway mucous metaplasia in asthma

In asthma, the airway epithelium is hyperplastic, hypertrophied, and lined with numerous large MUC5AC-containing goblet cells (GC). Furthermore, the normal epithelial architecture is disorganized with numerous, what we here describe as, ectopic goblet cells (eGC) deep within the thickened epithelial layer disconnected from the lumenal surface. mTOR is a highly conserved pathway that regulates cell size and proliferation. We hypothesized that the balance between mTOR and autophagy signaling regulates key features of the asthma epithelial layer. Airway histological sections from subjects with asthma had increased frequency of eGC and increased levels of mTOR phosphorylation target-Ribosomal S6. Using human airway epithelial cells (hAECs) with IL-13 stimulation and timed withdrawal to stimulate resolution, we found that multiple key downstream phosphorylation targets downstream from the mTOR complex were increased during early IL-13-mediated mucous metaplasia, and then significantly declined during resolution. The IL-13-mediated changes in mTOR signaling were paralleled by morphologic changes with airway epithelial hypertrophy, hyperplasia, and frequency of eGC. We then examined the relationship between mTOR and autophagy using mice deficient in autophagy protein Atg16L1. Despite having increased cytoplasmic mucins, mouse AECs from Atg16L1 deficient mice had no significant difference in mTOR downstream signaling. mTOR inhibition with rapamycin led to a loss of IL-13-mediated epithelial hypertrophy, hyperplasia, ectopic GC distribution, and reduction in cytoplasmic MUC5AC levels. mTOR inhibition was also associated with a reduction in aberrant IL-13-mediated hAEC proliferation and migration. Our findings demonstrate that mTOR signaling is associated with mucous metaplasia and is crucial to the disorganized airway epithelial structure and function characteristic of muco-obstructive airway diseases such as asthma. Graphical Abstract Key ConceptsO_LIThe airway epithelium in asthma is disorganized and characterized by cellular proliferation, aberrant migration, and goblet cell mucous metaplasia. C_LIO_LImTOR signaling is a dynamic process during IL-13-mediated mucous metaplasia, increasing with IL-13 stimulation and declining during resolution. C_LIO_LImTOR signaling is strongly increased in the asthmatic airway epithelium. C_LIO_LImTOR signaling is associated with the development of key features of the metaplastic airway epithelium including cell proliferation and ectopic distribution of goblet cells and aberrant cellular migration. C_LIO_LIInhibition of mTOR leads to decreased epithelial hypertrophy, reduced ectopic goblet cells, and cellular migration. C_LI

cell biology↗