Cytokines alter glucocorticoid receptor phosphorylation in airway cells : role of phosphatases

Corticosteroid insensitivity (CSI) represents a profound challenge in managing patients with asthma. We recently demonstrated that short exposure of airway smooth muscle cells (ASMCs) to proasthmatic cytokines drastically reduced their responsiveness to glucocorticoids (GCs), an effect that was partially mediated via interferon regulatory factor-1, suggesting the involvement of additional mechanisms (Am J Respir Cell Mol Biol 2008;38:463-472). Although GC receptor (GR) can be phosphorylated at multiple serines in the N-terminal region, the major phosphorylation sites critical for GR transcriptional activity are serines 211 (Ser211) and 226 (Ser226). We tested the novel hypothesis that cytokine-induced CSI in ASMCs is due to an impaired GR phosphorylation. Cells were treated with TNF-α (10 ng/ml) and IFN-γ (500 UI/ml) for 6 hours and/or fluticasone (100 nm) added 2 hours before. GR was constitutively phosphorylated at Ser226 but not at Ser211 residues. Cytokines dramatically suppressed fluticasone-induced phosphorylation of GR on Ser211 but not on Ser226 residues while increasing the expression of Ser/Thr protein phosphatase (PP)5 but not that of PP1 or PP2A. Transfection studies using a reporter construct containing GC responsive elements showed that the specific small interfering RNA-induced mRNA knockdown of PP5, but not that of PP1 or PP2A, partially prevented the cytokine suppressive effects on GR-meditated transactivation activity. Similarly, cytokines failed to inhibit GC-induced GR-Ser211 phosphorylation when expression of PP5 was suppressed. We propose that the novel mechanism that proasthmatic cytokine-induced CSI in ASMCs is due, in part, to PP5-mediated impairment of GR-Ser211 phosphorylation.

Medienart:

E-Artikel

Erscheinungsjahr:

2012

Erschienen:

2012

Enthalten in:

Zur Gesamtaufnahme - volume:47

Enthalten in:

American journal of respiratory cell and molecular biology - 47(2012), 4 vom: 25. Okt., Seite 464-73

Sprache:

Englisch

Beteiligte Personen:

Bouazza, Belaid [VerfasserIn]
Krytska, Kateryna [VerfasserIn]
Debba-Pavard, Manel [VerfasserIn]
Amrani, Yassine [VerfasserIn]
Honkanen, Richard E [VerfasserIn]
Tran, Jennifer [VerfasserIn]
Tliba, Omar [VerfasserIn]

Links:

Volltext

Themen:

Androstadienes
CUT2W21N7U
Cytokines
EC 3.1.3.16
Fluticasone
Glucocorticoids
Journal Article
Nuclear Proteins
Phosphoprotein Phosphatases
Protein phosphatase 5
Receptors, Glucocorticoid
Research Support, N.I.H., Extramural

Anmerkungen:

Date Completed 07.12.2012

Date Revised 21.10.2021

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1165/rcmb.2011-0364OC

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM217855679