While IkB-kinase-ε (IKKε) induces immunomodulatory genes following viral stimuli, its upregulation by inflammatory cytokines remains under-explored. Since airway epithelial cells respond to airborne insults and potentiate inflammation, IKKε expression was characterized in pulmonary epithelial cell lines (A549, BEAS-2B) and primary human bronchial epithelial cells (pHBECs) grown as submersion or differentiated air-liquid interface (ALI) cultures. IKKε expression was upregulated by the pro-inflammatory cytokines, IL-1β and TNF⍺. Thus, mechanistic interrogations in A549 cells were used to demonstrate the NF-κB dependence of cytokine-induced IKKε. Furthermore, chromatin immunoprecipitation in A549 and BEAS-2B cells revealed robust recruitment of the NF-κB subunit, p65, to one 5′ and two intronic regions within the IKKε locus (IKBKE). In addition, IL-1β and TNFα induced strong RNA polymerase 2 recruitment to the 5′ region, the first intron, and the transcription start site. Stable transfection of the p65-binding regions into A549 cells revealed IL-1β- and TNFα-inducible reporter activity that required NF-κB, but was not repressed by glucocorticoid. While critical NF-κB motifs were identified in the 5′ and downstream intronic regions, the first intronic region did not contain functional NF-κB motifs. Thus, IL-1β- and TNFα-induced IKKε expression involves three NF-κB-binding regions, containing multiple functional NF-κB motifs, and potentially other mechanisms of p65 binding through non-classical NF-κB binding motifs. By enhancing IKKε expression, IL-1β may prime, or potentiate, responses to alternative stimuli, as modeled by IKKε phosphorylation induced by phorbol 12-myristate 13-acetate. However, since IKKε expression was only partially repressed by glucocorticoid, IKKε-dependent responses could contribute to glucocorticoid-resistant disease.
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Research Article|
June 28 2024
Inducible gene expression of IκB-kinase ε (IKKε) is dependent on nuclear factor-κB (NF-κB) in human pulmonary epithelial cells
Amandah Necker-Brown;
Amandah Necker-Brown
University of Calgary Cumming School of Medicine, Calgary, Canada
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Cora Kooi;
Cora Kooi
University of Calgary Cumming School of Medicine, Calgary, Canada
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Andrew J Thorne;
Andrew J Thorne
University of Calgary Cumming School of Medicine, Calgary, Canada
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Akanksha Bansal;
Akanksha Bansal
University of Calgary Cumming School of Medicine, Calgary, Canada
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Mahmoud M Mostafa;
Mahmoud M Mostafa
University of Calgary Cumming School of Medicine, Calgary, Canada
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Priyanka Chandramohan;
Priyanka Chandramohan
University of Calgary Cumming School of Medicine, Calgary, Canada
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Alex Gao;
Alex Gao
University of Calgary Cumming School of Medicine, Calgary, Canada
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Keerthana Kalyanaraman;
Keerthana Kalyanaraman
University of Calgary Cumming School of Medicine, Calgary, Canada
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Arya Milani;
Arya Milani
University of Calgary Cumming School of Medicine, Calgary, Canada
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Sachman Gill;
Sachman Gill
University of Calgary Cumming School of Medicine, Calgary, Canada
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Andrei Georgescu;
Andrei Georgescu
University of Calgary Cumming School of Medicine, Calgary, Canada
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Sarah K Sasse;
Sarah K Sasse
National Jewish Health, Denver, Colorado, United States
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Richard Leigh;
Richard Leigh
University of Calgary, Canada
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Robert Newton
University of Calgary Cumming School of Medicine, Calgary, Canada
* Corresponding Author; email: rnewton@ucalgary.ca
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Publisher: Portland Press Ltd
Received:
November 02 2023
Revision Received:
June 14 2024
Accepted:
June 28 2024
Online ISSN: 1470-8728
Print ISSN: 0264-6021
Funding
Funding Group:
- Award Group:
- Funder(s):
- Award Id(s): 156310
- Principal Award Recipient(s): RobertNewton
- Funder(s):
- Award Group:
- Funder(s):
- Award Id(s): RGPIN-2016-04549
- Principal Award Recipient(s): RobertNewton
- Funder(s):
- Award Group:
- Funder(s):
- Award Id(s): RGPIN-2023-03763
- Principal Award Recipient(s): RobertNewton
- Funder(s):
Copyright 2024 The Author(s)
2024
This is an Accepted Manuscript; not the final Version of Record. Archiving permitted only in line with the archiving policy of Portland Press Limited.
Biochem J (2024) BCJ20230461.
Article history
Received:
November 02 2023
Revision Received:
June 14 2024
Accepted:
June 28 2024
Citation
Amandah Necker-Brown, Cora Kooi, Andrew J Thorne, Akanksha Bansal, Mahmoud M Mostafa, Priyanka Chandramohan, Alex Gao, Keerthana Kalyanaraman, Arya Milani, Sachman Gill, Andrei Georgescu, Sarah K Sasse, Anthony Gerber, Richard Leigh, Robert Newton; Inducible gene expression of IκB-kinase ε (IKKε) is dependent on nuclear factor-κB (NF-κB) in human pulmonary epithelial cells. Biochem J 2024; BCJ20230461. doi: https://doi.org/10.1042/BCJ20230461
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