Co-expression of genes that physically cluster together is a common characteristic of eukaryotic transcriptomes. Identifying these groups of co-expressed genes is important to the functional annotation of genomes and understanding the evolutionary fates of the clustered genes.
Coordinated evolution of co-expressed gene clusters in the Drosophila transcriptome.
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View SamplesCystatin A (gene: CSTA), is up-regulated in non-small-cell lung cancer (NSCLC) and dysplastic vs normal human bronchial epithelium. In the context that chronic obstructive pulmonary disease (COPD), a small airway epithelium (SAE) disorder, is independently associated with NSCLC (especially squamous cell carcinoma, SCC), but only occurs in a subset of smokers, we hypothesized that genetic variation, smoking and COPD modulate CSTA gene expression levels in SAE, with further up-regulation in SCC. Gene expression was assessed by microarray in SAE of 178 individuals [healthy nonsmokers (n=60), healthy smokers (n=82), and COPD smokers (n=36)], with corresponding large airway epithelium (LAE) data in a subset (n=52). Blood DNA was genotyped by SNP microarray. Twelve SNPs upstream of the CSTA gene were all significantly associated with CSTA SAE gene expression (p<0.04 to 5 x 10-4). CSTA gene expression levels in SAE were higher in COPD smokers (28.4 2.0) than healthy smokers (19.9 1.4, p<10-3), who in turn had higher levels than nonsmokers (16.1 1.1, p<0.04). CSTA LAE gene expression was also smoking-responsive (p<10-3). Using comparable publicly available NSCLC expression data, CSTA was up-regulated in SCC vs LAE (p<10-2) and down-regulated in adenocarcinoma vs SAE (p<10-7). All phenotypes were associated with significantly different proportional gene expression of CSTA to cathepsins. The data demonstrate that regulation of CSTA expression in human airway epithelium is influenced by genetic variability, smoking, and COPD, and is further up-regulated in SCC, all of which should be taken into account when considering the role of CSTA in NSCLC pathogenesis.
Modulation of cystatin A expression in human airway epithelium related to genotype, smoking, COPD, and lung cancer.
Race
View SamplesMotivation: Identification of eQTL, the genetic loci that contribute to heritable variation in gene expression, can be obstructed by factors that produce variation in expression profiles if these factors are unmeasured or hidden from direct analysis.
HEFT: eQTL analysis of many thousands of expressed genes while simultaneously controlling for hidden factors.
Disease, Race
View SamplesAirway remodelling in chronic obstructive pulmonary disease (COPD) originates, in part, from smoking-induced changes in airway basal stem/progenitor cells (BCs). Based on the knowledge that bone morphogenetic protein 4 (BMP4) influences epithelial progenitor function in the developing and adult mouse lung, we hypothesised that BMP4 signalling may regulate the biology of adult human airway BCs relevant to COPD.
Expression of the SARS-CoV-2 ACE2 Receptor in the Human Airway Epithelium.
Specimen part
View SamplesThe toll-like receptors (TLRs) are important components of the respiratory epithelium host innate defense, enabling the airway surface to recognize and respond to a variety of insults in inhaled air. Based on the knowledge that smokers are more susceptible to pulmonary infection and the airway epithelium of smokers with chronic obstructive pulmonary disease (COPD) is characterized by bacterial colonization and acute exacerbation of airway infections, we assessed whether smoking alters the expression of TLRs in human small airway epithelium, the primary site of smoking-induced disease. Microarrays were used to survey the TLR family gene expression in small airway (10th-12th order) epithelium from healthy nonsmokers (n=60), healthy smokers (n=73) and smokers with COPD (n=36). Using the criteria of detection call of present in 50%, 6 of 10 TLRs (1, 2, 3, 4, 5 and 8) were expressed. Compared to nonsmokers, the most strikingly changed gene is TLR5, which down-regulated in healthy smokers (1.4-fold decrease, p<10-13) and in smokers with COPD (1.6-fold, p<10-14). TaqMan RT-PCR confirmed these observations. Bronchial biopsies immunofluorescence showed that TLR5 protein was expressed mainly on the apical side of the human airway epithelium and decreased in healthy smokers and smokers with COPD. In vitro studies showed that the level of TLR5 downstream genes, IL-6 and IL-8 were highly induced in TLR5 high-expressing cells compared to TLR5 low-expressing cells after flagellin exposure. In the context that TLR5 functions to recognize pathogens and activate innate immune responses, the smoking-induced down-regulation of TLR5 likely contributes to smoking-related susceptibility to airway infection.
Airway epithelial expression of TLR5 is downregulated in healthy smokers and smokers with chronic obstructive pulmonary disease.
Race
View SamplesTo help define the genes associated with mucus synthesis and secretion in the human small airway epithelium, we hypothesized that comparison of the transcriptomes of the small airway epithelium of individuals that express high vs low levels of MUC5AC, a major secretory mucin and the major component of airway mucus, could be used as a probe to identify the genes related to human small airway mucus production / secretion. Genome-wide comparison between healthy nonsmokers grouped as high MUC5AC expressors vs low MUC5AC expressors identified significantly up-regulated and down-regulated genes in the high vs low expressors. Based on the literature, genes in the up-regulated list were used to identify a 73 MUC5AC-associated core gene list with 9 categories: mucus components; mucus-producing cell differentiation-related transcription factor; mucus-producing cell differentiation-related pathway or mediator; post-translational modification of mucin; vesicle transport; endoplasmic reticulum stress-related; secretory granule-associated; mucus secretion-related regulator and mucus hypersecretory-related ion channel. The identification of the genes associated with increased small airway mucin production in humans should be useful in identifying therapeutic targets to treat small airway mucus hypersecretion.
Genes associated with MUC5AC expression in small airway epithelium of human smokers and non-smokers.
Specimen part, Race, Time
View SamplesNuclear factor erythroid 2-related factor 2 (NFE2L2, Nrf2) is an oxidant responsive transcription factor known to induce phase 2 detoxifying and antioxidant genes to protect cells from oxidative stress. Cigarette smoke, with its large oxidant content, is a major stressor to the small airway epithelium, the cells of which are vulnerable to oxidant damage and consequent malignant transformation. In this study, we assessed the role of cigarette smoke in activation of Nrf2 in the human small airway epithelium in vivo. Fiberoptic bronchoscopy was used to sample a pure population of small airway epithelium in 38 healthy nonsmokers and 45 healthy smokers, and gene expression was assessed using Affymetrix HG-U133 Plus 2.0 microarrays. Compared to that of healthy nonsmokers, Nrf2 protein was significantly activated in the small airway epithelium of healthy normal smokers and localized in the nucleus (p<0.05). Of the human homologs of 201 known murine Nrf2-mediated genes, 13 highly smoking-responsive genes were identified (p<10-4, all comparisons smokers to nonsmokers). Using a Nrf2-index to quantify the extent of expression in the small airway epithelium of these 13 known Nrf2 genes, variability in the level of expression was observed among the 45 healthy smokers, but the variability was coordinately modulated among the 13 genes, an observation confirmed by TaqMan quantitative PCR. This variability in the coordinate level of expression of the 13 Nrf2-mediated genes was independent of the smoking history. Based on these observations, the Nrf2 index was used to evaluate whether other genes modulated by smoking in the small airway epithelium were also coordinately up- or down- modulated among the 45 healthy smokers. Two genes, pirin (PIR) and UDP glucuronosyltransferase 1 family polypeptide A4 (UGT1A4), not previously known to be modulated by Nrf2 were identified as being coordinately modulated among the 45 smokers. Both genes contain several functional antioxidant response elements in the promoter region. Using an electrophoretic mobility shift assay, these antioxidant response elements in the promoters of PIR and UGT1A4 responded in vitro to activated Nrf2. These observations are consistent with the concept that Nrf2 plays an important role in regulating cellular defenses against smoking in the highly vulnerable small airway epithelium cell population, and that there is variability among the population in the relative Nrf2 responsiveness to a similar oxidant burden.
Coordinate control of expression of Nrf2-modulated genes in the human small airway epithelium is highly responsive to cigarette smoking.
Sex, Age
View SamplesEpidemiological studies have demonstrated that exposure to particulate matter (PM) ambient pollution has adverse effects on lung health, exacerbated by cigarette smoking. Fine airborne particles <2.5 m (PM2.5) are the most harmful of the urban pollutants, and the most closely linked to respiratory disease. Based on the knowledge that the small airway epithelium (SAE) plays a central role in pathogenesis of smoking-related lung disease, we hypothesized that elevated PM2.5 levels are associated with dysregulation of SAE gene expression.
Ambient Pollution-related Reprogramming of the Human Small Airway Epithelial Transcriptome.
Specimen part
View SamplesBackground: High mobility group AT-hook1 (HMGA1) is essential for airway basal cell mucociliary differentiation, barrier integrity and wound repair. HMGA1 expression suppresses the abnormal basal cell differentiation to squamous, inflammatory and epithelial-mesenchymal transition phenotype commonly observed in association with cigarette smoking and chronic obstructive pulmonary disease (COPD). Results: HMGA1 knockdown experiments indicate that when HMGA1 expression is suppressed, the airway basal cells cannot normally differentiate into a mucociliary epithelium, form an intact barrier, and repair following injury. Instead, airway basal cell differentiation was skewed to an abnormal squamous EMT-like phenotype associated with airway remodeling in COPD. This study demonstrates that HMGA1 plays a key role in normal airway differentiation, regeneration of the normal airway epithelium following injury, and suppression of expression of genes related to squamous metaplasia, EMT and inflammation. Overall design: [RNA-seq] Non-smoker large airway epithelium cells, large airway basal cells, small airway epithelial cells, small airway basal cells. Smoker large airway basal cells, COPD smoker large airway basal cells,.
Mandatory role of HMGA1 in human airway epithelial normal differentiation and post-injury regeneration.
Specimen part, Subject
View SamplesBackground: Healthy individuals exposed to low levels of cigarette smoke have a decrement in lung function and higher risk for lung disease compared to unexposed individuals. We hypothesized that healthy individuals exposed to low levels of tobacco smoke must have biologic changes in the small airway epithelium compared to healthy unexposed individuals. Methods: Small airway epithelium was obtained by bronchoscopy from 121 individuals; microarrays assessed genome wide gene expression, and urine nicotine and cotinine were used to categorized subjects as nonsmokers, active smokers, and low exposure. The gene expression data was used to determine the threshold and ID50 of urine nicotine and cotinine at which the small airway epithelium showed abnormal responses. Results: There was no threshold of urine nicotine without an abnormal small airway epithelial response, and only a slightly above detectable threshold abnormal response for cotinine. The nicotine ID50 for nicotine was 25 ng/ml and cotinine 104 ng/ml. Conclusions: The small airway epithelium detects and responds to low levels of tobacco smoke with transcriptome modifications. This provides biologic correlates of epidemiologic studies linking low level tobacco smoke exposure to lung health risk, health, identifies genes in the lung cells most sensitive to tobacco smoke and defines thresholds at the lung epithelium responds to inhaled tobacco smoke.
Threshold of biologic responses of the small airway epithelium to low levels of tobacco smoke.
Sex, Age
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