scholarly journals Glucocorticoids can activate the α-ENaC gene promoter independently of SGK1

2009 ◽  
Vol 423 (2) ◽  
pp. 189-197 ◽  
Author(s):  
Niall McTavish ◽  
Jennet Getty ◽  
Ann Burchell ◽  
Stuart M. Wilson
Keyword(s):  
Transcriptional Activity ◽  
Transcriptional Response ◽  
Gene Promoter ◽  
Airway Epithelial Cells ◽  
Na Channel ◽  
Airway Epithelial ◽  
Transcriptional Responses ◽  
Α Subunit ◽  
Inactive Form ◽  
Phosphoinositide 3 Kinase

The role of SGK1 (serum- and glucocorticoid-induced protein kinase 1) in the glucocorticoid induction of α-ENaC (epithelial Na+ channel α subunit) gene transcription was explored by monitoring the transcriptional activity of a luciferase-linked, α-ENaC reporter gene construct (pGL3-KR1) expressed in H441 airway epithelial cells. Dexamethasone evoked a concentration-dependent (EC50∼4 μM) increase in transcriptional activity dependent upon a glucocorticoid response element in the α-ENaC sequence. Although dexamethasone also activated endogenous SGK1, artificially increasing cellular SGK1 activity by expressing a constitutively active SGK1 mutant (SGK1-S422D) in hormone-deprived cells did not activate pGL3-KR1. Moreover, expression of catalytically inactive SGK1 (SGK1-K127A) suppressed the activation of endogenous SGK1 without affecting the transcriptional response to dexamethasone. Increasing cellular PI3K (phosphoinositide 3-kinase) activity by expressing a membrane-anchored form of the catalytic PI3K-P110α subunit [CD2 (cluster of differentiation 2)-P110α] also activated endogenous SGK1 without affecting pGL3-KR1activity. A catalytically inactive form of CD2-P110α (R1130P), on the other hand, prevented the dexamethasone-induced activation of SGK1, but did not inhibit the activation of pGL3-KR1. However, expression of SGK1-S422D or CD2-P110α enhanced the transcriptional responses to maximally effective concentrations of dexamethasone and this effect occurred with no change in EC50. Dexamethasone-induced (0.3–300 nM) activation of pGL3-KR1 was unaffected by inhibitors of PI3K (PI-103 and wortmanin) and by rapamycin, a selective inhibitor of the TORC1 (target of rapamycin complex 1) signalling complex. Dexamethasone-induced activation of the α-ENaC gene promoter can thus occur independently of SGK1/PI3K, although this pathway does provide a mechanism that allows this transcriptional response to dexamethasone to be enhanced.

Immune responses of porcine airway epithelial cells to poly(I:C), a synthetic analogue of viral double-stranded RNA

2015 ◽  
Vol 95 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Xiu-qin Yang ◽  
Liang Wang ◽  
Hai-tao Li ◽  
Di Liu
Keyword(s):  
Epithelial Cells ◽  
Immune Responses ◽  
Digital Gene Expression ◽  
Enrichment Analysis ◽  
Airway Epithelial Cells ◽  
Poly I:C ◽  
Synthetic Analogue ◽  
Airway Epithelial ◽  
Transcriptional Responses ◽  
Double Stranded Rna

Yang, X.-q., Wang, L., Li, H.-t. and Liu, D. 2015. Immune responses of porcine airway epithelial cells to poly(I:C), a synthetic analogue of viral double-stranded RNA. Can. J. Anim. Sci. 95: 13–20. Swine respiratory disease (SRD) is one of the most economically important diseases affecting the pig industry. The main infectious agents that cause SRD are viruses, but the molecular pathogenesis of viral SRD has not been extensively studied. Here, using digital gene expression tag profiling, the global transcriptional responses to poly(I:C), a synthetic analogue of viral double-stranded RNA, was analyzed in porcine airway epithelial cells (PAECs). The profiling analysis revealed numerous differentially expressed genes (DEGs), including unknown sequences in the porcine nucleotide databases. Gene ontology enrichment analysis showed that DEGs were mainly enriched in response to stress (GO: 0006950), of which, defense response is one sub-process. Poly(I:C) challenge induced a general inflammation response as indicated by marked upregulation of a variety of pathogen recognition receptors, interferon-stimulated genes, proinflammatory cytokines, and chemokines, together with the significant downregulation of anti-inflammatory molecules. Furthermore, the antiapoptotic pathway was triggered, as demonstrated by the significant suppression of molecules involved in the induction of apoptosis, together with the significant stimulation of putative inhibitor of apoptosis. The results indicate that PAECs initiated defense against poly(I:C) challenge through the inflammation responses, whereas poly(I:C) can utilize antiapoptotic pathway to evade host defense.

scholarly journals Individual Matrix Metalloproteinases Control Distinct Transcriptional Responses in Airway Epithelial Cells Infected with Pseudomonas aeruginosa

2007 ◽  
Vol 75 (12) ◽  
pp. 5640-5650 ◽  
Author(s):  
Sean Y. Kassim ◽  
Sina A. Gharib ◽  
Brigham H. Mecham ◽  
Timothy P. Birkland ◽  
William C. Parks ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Initial Point ◽  
Global Gene Expression ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Transcriptional Responses ◽  
Matrix Metalloproteinase 7 ◽  
Node Network ◽  
Global Gene Expression Analysis

ABSTRACT Airway epithelium is the initial point of host-pathogen interaction in Pseudomonas aeruginosa infection, an important pathogen in cystic fibrosis and nosocomial pneumonia. We used global gene expression analysis to determine airway epithelial transcriptional responses dependent on matrilysin (matrix metalloproteinase 7 [MMP-7]) and stromelysin-2 (MMP-10), two MMPs induced by acute P. aeruginosa pulmonary infection. Extraction of differential gene expression (EDGE) analysis of gene expression changes in P. aeruginosa-infected organotypic tracheal epithelial cell cultures from wild-type, Mmp7 −/−, and Mmp10 −/− mice identified 2,091 matrilysin-dependent and 1,628 stromelysin-2-dependent genes that were differentially expressed. Key node network analysis showed that these MMPs controlled distinct gene expression programs involved in proliferation, cell death, immune responses, and signal transduction, among other host defense processes. Our results demonstrate discrete roles for these MMPs in regulating epithelial responses to Pseudomonas infection and show that a global genomics strategy can be used to assess MMP function.

scholarly journals Nascent RNA sequencing defines dynamic aryl hydrocarbon receptor signaling responses to wood smoke particles

2021 ◽  
Author(s):  
Arnav Gupta ◽  
Sarah K. Sasse ◽  
Lynn Sanford ◽  
Margaret A. Gruca ◽  
Robin D. Dowell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Airway Epithelial Cells ◽  
Wood Smoke ◽  
Primary Role ◽  
Airway Epithelial ◽  
Transcriptional Responses ◽  
Wildfire Smoke ◽  
Smoke Particles ◽  
Aryl Hydrocarbon

AbstractTranscriptional responses to wildfire smoke, an increasingly important cause of human morbidity, are poorly understood. Here, using a combination of precision nuclear run-on sequencing (PRO-seq) and the assay for transposase-accessible chromatin using sequencing (ATAC-seq), we identify rapid and dynamic changes in transcription and chromatin structure in Beas-2B airway epithelial cells after exposure to wood smoke particles (WSP). By comparing 30 and 120 minutes of WSP exposure, we defined three distinct temporal patterns of transcriptional induction and chromatin responses to WSP. Whereas transcription of canonical targets of the aryl hydrocarbon receptor (AHR), such as CYP1A1 and AHRR, was robustly increased after 30 minutes of WSP exposure, transcription of these genes and associated enhancers returned to near baseline at 120 minutes. ChIP-qPCR assays and AHR knockdown confirmed a role for AHR in regulating these transcriptional responses, and we applied bioinformatics approaches to identify novel AHR-regulated pathways and targets including the DNA methyltransferase, DNMT3L, and its interacting factor, SPOCD1. Our analysis also defined a role for NFkB as a primary transcriptional effector of WSP-induced changes in gene expression. The kinetics of AHR- and NFkB-regulated responses to WSP were distinguishable based on the timing of both transcriptional responses and chromatin remodeling, with induction of several cytokines implicated in maintaining the NFkB response. In aggregate, our data establish a direct and primary role for AHR in mediating airway epithelial responses to WSP and identify crosstalk between AHR and NFkB signaling in controlling pro-inflammatory gene expression.

scholarly journals Looping of upstream cis-regulatory elements is required for CFTR expression in human airway epithelial cells

2020 ◽  
Vol 48 (7) ◽  
pp. 3513-3524 ◽  
Author(s):  
Monali NandyMazumdar ◽  
Shiyi Yin ◽  
Alekh Paranjapye ◽  
Jenny L Kerschner ◽  
Hannah Swahn ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Molecular Mechanisms ◽  
Gene Promoter ◽  
Regulatory Elements ◽  
Airway Epithelial Cells ◽  
Control Mechanisms ◽  
Airway Epithelial ◽  
Cell Type ◽  
Long Range Interactions ◽  
Cell Type Specific

Abstract The CFTR gene lies within an invariant topologically associated domain (TAD) demarcated by CTCF and cohesin, but shows cell-type specific control mechanisms utilizing different cis-regulatory elements (CRE) within the TAD. Within the respiratory epithelium, more than one cell type expresses CFTR and the molecular mechanisms controlling its transcription are likely divergent between them. Here, we determine how two extragenic CREs that are prominent in epithelial cells in the lung, regulate expression of the gene. We showed earlier that these CREs, located at −44 and −35 kb upstream of the promoter, have strong cell-type-selective enhancer function. They are also responsive to inflammatory mediators and to oxidative stress, consistent with a key role in CF lung disease. Here, we use CRISPR/Cas9 technology to remove these CREs from the endogenous locus in human bronchial epithelial cells. Loss of either site extinguished CFTR expression and abolished long-range interactions between these sites and the gene promoter, suggesting non-redundant enhancers. The deletions also greatly reduced promoter interactions with the 5′ TAD boundary. We show substantial recruitment of RNAPII to the −35 kb element and identify CEBPβ as a key activator of airway expression of CFTR, likely through occupancy at this CRE and the gene promoter.

scholarly journals TRAIL (CD253) Sensitizes Human Airway Epithelial Cells to Toxin-Induced Cell Death

2018 ◽  
Author(s):  
Yinghui Rong ◽  
Jennifer Westfall ◽  
Dylan Ehrbar ◽  
Timothy LaRocca ◽  
Nicholas J. Mantis
Keyword(s):  
Cell Death ◽  
Epithelial Cell ◽  
Airway Epithelial Cell ◽  
Cell Damage ◽  
Transcriptional Response ◽  
Airway Epithelial Cells ◽  
Epithelial Cell Line ◽  
Airway Epithelial ◽  
Ricin Toxin ◽  
Human Airway

ABSTRACTInhalation of ricin toxin is associated with the onset of acute respiratory distress syndrome (ARDS), characterized by hemorrhage, inflammatory exudates, and tissue edema, as well as the near complete destruction of the lung epithelium. Here we report that the Calu-3 human airway epithelial cell line is relatively impervious to the effects of ricin, with little evidence of cell death even upon exposure to microgram amounts of toxin. However, the addition of exogenous soluble TNF-Related Apoptosis Inducing Ligand (TRAIL; CD253) dramatically sensitized Calu-3 cells to ricin-induced apoptosis. Calu-3 cell killing in response to ricin and TRAIL was reduced upon the addition of caspase-8 and caspase-3/7 inhibitors, but not caspase 9 inhibitors, consistent with involvement of extrinsic apoptotic pathways in cell death. We employed nCounter Technology to define the transcriptional response of Calu-3 cells to ricin, TRAIL, and the combination of ricin plus TRAIL. An array of genes associated with inflammation-and cell death were significantly up regulated upon treatment with ricin toxin, and further amplified upon addition of TRAIL. Of particular note was IL-6, whose expression in Calu-3 cells increased 300-fold upon ricin treatment and more than 750-fold upon ricin and TRAIL treatment. IL-6 secretion by Calu-3 cells was confirmed by cytometric bead array. Based on these finding, we speculate that the severe airway epithelial cell damage observed in animal models following ricin exposure is a result of a positive feedback loop driven by pro-inflammatory cytokines like TRAIL and IL-6.

Defining an inhibitory domain in the α-subunit of the epithelial sodium channel

2008 ◽  
Vol 294 (1) ◽  
pp. F47-F52 ◽  
Author(s):  
Marcelo D. Carattino ◽  
Christopher J. Passero ◽  
Carlos A. Steren ◽  
Ahmad B. Maarouf ◽  
Joseph M. Pilewski ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Collecting Duct ◽  
Airway Epithelial Cells ◽  
Xenopus Laevis Oocytes ◽  
Airway Epithelial ◽  
Wild Type ◽  
Epithelial Sodium Channels ◽  
Α Subunit ◽  
Collecting Duct Cells ◽  
Inhibitory Domain

Epithelial sodium channels (ENaC) are processed by proteases as they transit the biosynthetic pathway. We recently observed that furin-dependent processing of the α-subunit of ENaC at two sites within its extracellular domain is required for channel activation due to release of a 26-residue inhibitory domain. While channels with α-subunits lacking the furin sites are not cleaved and have very low activity, channels lacking the furin consensus sites as well as the tract between these sites (αD206–R231) are active. We analyzed channels with a series of deletions in the tract αD206–R231 and lacking the α-subunit furin consensus sites in Xenopus laevis oocytes. We found an eight-residue tract that, when deleted, restored channel activity to the level found in oocytes expressing wild-type ENaC. A synthetic peptide, LPHPLQRL, representing the tract αL211–L218, inhibited wild-type ENaC expressed in oocytes with an IC50 of 0.9 μM, and inhibited channels expressed in collecting duct cells and human primary airway epithelial cells with an IC50s of between ∼50 and 100 μM. Analyses of peptides with deletions within this inhibitory tract indicate that eight residues is the minimal backbone length that is required for ENaC inhibition. Analyses of 8-mer peptides with conserved and nonconserved substitutions suggest that L1, P2, H3, P4, and L8 are required for inhibitory activity. Our findings suggest that this eight-residue tract is a key conserved inhibitory domain that provides epithelial cells with a reserve of inactive channels that can be activated as required by proteases.

scholarly journals Glucocorticoid receptor activation induces gene-specific transcriptional memory and universally reversible changes in chromatin accessibility

2021 ◽  
Author(s):  
Melissa Bothe ◽  
René Buschow ◽  
Sebastiaan H. Meijsing
Keyword(s):  
Glucocorticoid Receptor ◽  
Transcriptional Repression ◽  
Single Gene ◽  
Transcriptional Response ◽  
Receptor Activation ◽  
Chromatin Accessibility ◽  
Airway Epithelial Cells ◽  
Transcriptional Responses ◽  
Transcriptional Memory ◽  
Induced Changes

AbstractGlucocorticoids are stress hormones that elicit cellular responses by binding to the glucocorticoid receptor (GR), a ligand-activated transcription factor. The exposure of cells to this hormone induces wide-spread changes in the chromatin landscape and gene expression. Previous studies have suggested that some of these changes are reversible whereas others persist even when the hormone is no longer around. However, when we examined chromatin accessibility in human airway epithelial cells after hormone washout, we found that the hormone-induced changes were universally reversed after one day. Reversibility of hormone-induced changes are found for GR-occupied opening sites and also for closing sites that typically lack GR occupancy. These closing sites are enriched near repressed genes, suggesting that transcriptional repression by GR does not require nearby GR binding. Mirroring what we say in terms of chromatin accessibility, we found that transcriptional responses to hormone are universally reversable. Moreover, priming of cells by a previous exposure to hormone, in general, did not alter the transcriptional response to a subsequent encounter of the same cue. Interestingly, despite the short-lived nature of hormone-induced changes in the chromatin landscape, we identified a single gene, ZBTB16, that displays transcriptional memory manifesting itself as a more robust transcriptional response upon repeated hormone stimulation. Single-cell analysis revealed that the more robust response is driven by a higher probability of primed cells to activate ZBTB16 and by a subset of cells that express the gene at levels that are higher than the induction levels observed for naïve cells. Although our study shows that hormone-induced changes are typically reversable, exposure to hormone can induce gene-specific changes in the response to subsequent exposures which may play a role in habituation to stressors and changes in glucocorticoid sensitivity.

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