Biology subjects

Thomes, P.

Publications and source records attributed to Thomes, P..

3 recordsLinked to original sources

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↗

bioRxiv2020

Mucin granules are degraded in the autophagosome-lysosome pathway as a means of resolving airway mucous cell metaplasia

Exacerbations of muco-obstructive airway diseases such as COPD and asthma are associated with epithelial changes termed mucous cell metaplasia (MCM). The molecular pathways triggering MCM have been identified; however, the factors that regulate resolution are less well understood. We hypothesized that the autophagosome-lysosome pathway is required for resolution of MCM by degrading cytoplasmic mucins. We found increased intracellular levels of Muc5ac and Muc5b in autophagy-deficient mice. This difference was not due to defective mucin secretion. Instead, we found that Lamp1-labeled lysosomes surrounded mucin granules of mucous cells indicating that granules were being degraded. Using a model of resolution of mucous cell metaplasia in mice, we found increased lysosomal proteolytic activity that peaked in the days after inflammation. Autophagy-deficient mice had persistent accumulation of mucin granules that failed to decline due to reduced mucin degradation. We applied these findings in vitro to human airway epithelial cells (AECs). Activation of autophagy by mTOR inhibition led to degradation of mucin granules in AECs. Our findings indicate that during peak and resolution phases of MCM, mucin granules can be degraded by autophagy. The addition of mucin degradation to the existing paradigm of production and secretion may more fully explain how the secretory cells handle excess amounts of cytoplasmic mucin and offers a therapeutic target to speed resolution of MCM in airway disease exacerbations. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/130534v2_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@94239org.highwire.dtl.DTLVardef@1dac6dforg.highwire.dtl.DTLVardef@368161org.highwire.dtl.DTLVardef@680b7d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2018

Golgi Renaissance: the pivotal role of the largest Golgi protein giantin

Golgi undergoes disorganization in response to the drugs or alcohol, but it is able to restore compact structure under recovery. This self-organization mechanism remains mostly elusive, as does the role of giantin, the largest Golgi matrix dimeric protein. Here, we found that in cells treated with Brefeldin A (BFA) or ethanol (EtOH), Golgi disassembly is associated with giantin de-dimerization, which was restored to the dimer form after BFA or EtOH washout. Cells lacking giantin are disabled for the restoration of the classical ribbon Golgi, and they demonstrate altered trafficking of proteins to the cell surface. The fusion of the nascent Golgi membranes is mediated by the cross-membrane interaction of Rab6a GTPase and giantin. Giantin is involved in the formation of long intercisternal connections, which in giantin-depleted cells was replaced by the short bridges that formed via oligomerization of GRASP65. This phenomenon occurs in advanced prostate cancer cells, in which a fragmented Golgi phenotype is maintained by the dimerization of GRASP65. Thus, we provide a model of Golgi Renaissance, which is impaired in aggressive prostate cancer.

cell biology↗