scholarly journals Bromodomain Containing Protein 4 (BRD4) Regulates Expression of its Interacting Coactivators in the Innate Response to Respiratory Syncytial Virus

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiaofang Xu ◽  
Morgan Mann ◽  
Dianhua Qiao ◽  
Yi Li ◽  
Jia Zhou ◽  
...  

Bromodomain-containing protein 4 plays a central role in coordinating the complex epigenetic component of the innate immune response. Previous studies implicated BRD4 as a component of a chromatin-modifying complex that is dynamically recruited to a network of protective cytokines by binding activated transcription factors, polymerases, and histones to trigger their rapid expression via transcriptional elongation. Our previous study extended our understanding of the airway epithelial BRD4 interactome by identifying over 100 functionally important coactivators and transcription factors, whose association is induced by respiratory syncytial virus (RSV) infection. RSV is an etiological agent of recurrent respiratory tract infections associated with exacerbations of chronic obstructive pulmonary disease. Using a highly selective small-molecule BRD4 inhibitor (ZL0454) developed by us, we extend these findings to identify the gene regulatory network dependent on BRD4 bromodomain (BD) interactions. Human small airway epithelial cells were infected in the absence or presence of ZL0454, and gene expression profiling was performed. A highly reproducible dataset was obtained which indicated that BRD4 mediates both activation and repression of RSV-inducible gene regulatory networks controlling cytokine expression, interferon (IFN) production, and extracellular matrix remodeling. Index genes of functionally significant clusters were validated independently. We discover that BRD4 regulates the expression of its own gene during the innate immune response. Interestingly, BRD4 activates the expression of NFκB/RelA, a coactivator that binds to BRD4 in a BD-dependent manner. We extend this finding to show that BRD4 also regulates other components of its functional interactome, including the Mediator (Med) coactivator complex and the SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin (SMARC) subunits. To provide further insight into mechanisms for BRD4 in RSV expression, we mapped 7,845 RSV-inducible Tn5 transposase peaks onto the BRD4-dependent gene bodies. These were located in promoters and introns of cytostructural and extracellular matrix (ECM) formation genes. These data indicate that BRD4 mediates the dynamic response of airway epithelial cells to RNA infection by modulating the expression of its coactivators, controlling the expression of host defense mechanisms and remodeling genes through changes in promoter accessibility.

2006 ◽  
Vol 291 (2) ◽  
pp. C218-C230 ◽  
Author(s):  
Terry E. Machen

The lack of functional cystic fibrosis (CF) transmembrane conductance regulator (CFTR) in the apical membranes of CF airway epithelial cells abolishes cAMP-stimulated anion transport, and bacteria, eventually including Pseudomonas aeruginosa, bind to and accumulate in the mucus. Flagellin released from P. aeruginosa triggers airway epithelial Toll-like receptor 5 and subsequent NF-κB signaling and production and release of proinflammatory cytokines that recruit neutrophils to the infected region. This response has been termed hyperinflammatory because so many neutrophils accumulate; a response that damages CF lung tissue. We first review the contradictory data both for and against the idea that epithelial cells exhibit larger-than-normal proinflammatory signaling in CF compared with non-CF cells and then review proposals that might explain how reduced CFTR function could activate such proinflammatory signaling. It is concluded that apparent exaggerated innate immune response of CF airway epithelial cells may have resulted not from direct effects of CFTR on cellular signaling or inflammatory mediator production but from indirect effects resulting from the absence of CFTRs apical membrane channel function. Thus, loss of Cl−, HCO3−, and glutathione secretion may lead to reduced volume and increased acidification and oxidation of the airway surface liquid. These changes concentrate proinflammatory mediators, reduce mucociliary clearance of bacteria and subsequently activate cellular signaling. Loss of apical CFTR will also hyperpolarize basolateral membrane potentials, potentially leading to increases in cytosolic [Ca2+], intracellular Ca2+, and NF-κB signaling. This hyperinflammatory effect of CF on intracellular Ca2+and NF-κB signaling would be most prominently expressed during exposure to both P. aeruginosa and also endocrine, paracrine, or nervous agonists that activate Ca2+signaling in the airway epithelia.


Virology ◽  
2017 ◽  
Vol 512 ◽  
pp. 144-150 ◽  
Author(s):  
Devi Rajan ◽  
Raghavan Chinnadurai ◽  
Evan L. O'Keefe ◽  
Seyhan Boyoglu-Barnum ◽  
Sean O. Todd ◽  
...  

Biomolecules ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 165 ◽  
Author(s):  
María Martín-Vicente ◽  
Salvador Resino ◽  
Isidoro Martínez

Human respiratory syncytial virus (HRSV) infection is a common cause of severe lower respiratory tract diseases such as bronchiolitis and pneumonia. Both virus replication and the associated inflammatory immune response are believed to be behind these pathologies. So far, no vaccine or effective treatment is available for this viral infection. With the aim of finding new strategies to counteract HRSV replication and modulate the immune response, specific small interfering RNAs (siRNAs) were generated targeting the mRNA coding for the viral fusion (F) protein or nucleoprotein (N), or for two proteins involved in intracellular immune signaling, which are named tripartite motif-containing protein 25 (TRIM25) and retinoic acid-inducible gene-I (RIG-I). Furthermore, two additional bispecific siRNAs were designed that silenced F and TRIM25 (TRIM25/HRSV-F) or N and RIG-I (RIG-I/HRSV-N) simultaneously. All siRNAs targeting N or F, but not those silencing TRIM25 or RIG-I alone, significantly reduced viral titers. However, while siRNAs targeting F inhibited only the expression of the F mRNA and protein, the siRNAs targeting N led to a general inhibition of viral mRNA and protein expression. The N-targeting siRNAs also induced a drastic decrease in the expression of genes of the innate immune response. These results show that both virus replication and the early innate immune response can be regulated by targeting distinct viral products with siRNAs, which may be related to the different role of each protein in the life cycle of the virus.


2017 ◽  
Vol 30 (8) ◽  
pp. 576-581 ◽  
Author(s):  
Vesla I. Kullaya ◽  
Quirijn de Mast ◽  
Andre van der Ven ◽  
Hicham elMoussaoui ◽  
Gibson Kibiki ◽  
...  

2021 ◽  
Author(s):  
Xinhui Yuan ◽  
Li-li Pang ◽  
Jing Yang ◽  
Yu Jin

Abstract Background: Human rhinovirus C (HRV-C) accounts for a large proportion of HRV-related illnesses, but the immune response to HRV-C infection has not been elucidated. Our objective was to assess the effect of HRV-C on cytokine secretion in human bronchial epithelial (HBE) cells grown at air–liquid interface (ALI) and compare it with that of respiratory syncytial virus (RSV). Methods: HBE cells were differentiated at ALI culture and the full-length cDNA clones of HRV-C651 and HRV-C15, clinical isolates of HRV-C79 and HRV-C101, and two RSV isolates were inoculated in the HBE cells. The effect of HRV-C on cytokine secretion were assessed and compared with that of RSV.Results: HRV-Cs infects and propagates in fully differentiated HBE cells and significantly increased the secretion of IFN-λ1, CCL5, IP10, IL-6, IL-8, and MCP-1. The virus load positively correlated with the levels of the cytokines. HRV-C induced lower secretion of CCL5 (P=0.048), IL-6 (P=0.016), MCP-1 (P=0.008), and IL-8 (P=0.032), and similar secretion of IP10 (P=0.214) and IFN-λ1 (P=0.214) when compared with RSV. Conclusion: HBE ALI culture system supported HRV-C infection and propagation and HRV-C induced relatively weaker cytokine expression than RSV.


2019 ◽  
Vol 129 (11) ◽  
pp. 4875-4884 ◽  
Author(s):  
Daniel Menendez ◽  
Joyce Snipe ◽  
Jacqui Marzec ◽  
Cynthia L. Innes ◽  
Fernando P. Polack ◽  
...  

2021 ◽  
Author(s):  
Vincent Basse ◽  
Jiawei Dong ◽  
Andressa Peres de Oliveira ◽  
Pierre-Olivier Vidalain ◽  
Frédéric Tangy ◽  
...  

Respiratory syncytial virus has evolved a unique strategy to evade host immune response by coding for two non-structural proteins NS1 and NS2. Recently it was shown that in infected cells, nuclear NS1 could be involved in transcription regulation of host genes linked to innate immune response, via an interaction with chromatin and the Mediator complex. Here we identified the MED25 Mediator subunit as an NS1 interactor in a yeast two-hybrid screen. We demonstrate that NS1 directly interacts with MED25 in vitro and in cellula, and that this interaction involves the C-terminal α3 helix of NS1 and the MED25 ACID domain. More specifically we showed by NMR that the NS1 α3 sequence primarily binds to the MED25 ACID H2 face, which is a transactivation domain (TAD) binding site for transcription regulators such as ATF6α, a master regulator of ER stress response activated upon viral infection. Moreover, we found out that the NS1 α3 helix could compete with ATF6α TAD binding to MED25. This finding points to a mechanism of NS1 interfering with innate immune response by impairing recruitment by cellular TADs of the Mediator via MED25 and hence transcription of specific genes by RNA polymerase II.


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