α and β catalytic subunits of cAMP‐dependent protein kinase regulate formoterol‐induced inflammatory gene expression changes in human bronchial epithelial cells

• Published in: British journal of pharmacology Vol. 179; no. 18; pp. 4593 - 4614
• Main Authors: Hamed, Omar, Joshi, Radhika, Mostafa, Mahmoud M., Giembycz, Mark A.
• Format: Journal Article
• Language: English
• Published: London Blackwell Publishing Ltd 01.09.2022
• Subjects: Adrenergic receptors; Agonists; airway epithelial cells; Arrestin; Asthma; cAMP‐dependent protein kinase; Catalytic subunits; Cloning; Epithelial cells; Extracellular signal-regulated kinase; Formoterol; Forskolin; Gene expression; Gene silencing; Genome editing; Genomics; Inflammation; Kinases; Protein kinase A; RNA-mediated interference; Transcriptomes; Tumor necrosis factor-α; β2‐adrenoceptor agonists; β‐Arrestin 2
• ISSN: 0007-1188; 1476-5381; 1476-5381
• DOI: 10.1111/bph.15901

Background and Purpose It has been proposed that genomic mechanisms contribute to adverse effects often experienced by asthmatic subjects who take regular, inhaled β2‐adrenoceptor agonists as a monotherapy. Moreover, data from preclinical models of asthma suggest that these gene expression changes are mediated by β‐arrestin‐2 rather than PKA. Herein, we tested this hypothesis by comparing the genomic effects of formoterol, a β2‐adrenoceptor agonist, with forskolin in human primary bronchial epithelial cells (HBEC). Experimental Approach Gene expression changes were determined by RNA‐sequencing. Gene silencing and genome editing were employed to explore the roles of β‐arrestin‐2 and PKA. Key Results The formoterol‐regulated transcriptome in HBEC treated concurrently with TNFα was defined by 1480 unique gene expression changes. TNFα‐induced transcripts modulated by formoterol were annotated with enriched gene ontology terms related to inflammation and proliferation, notably “GO:0070374~positive regulation of ERK1 and ERK2 cascade,” which is an apparent β‐arrestin‐2 target. However, expression of the formoterol‐ and forskolin‐regulated transcriptomes were highly rank‐order correlated and the effects of formoterol on TNFα‐induced inflammatory genes were abolished by an inhibitor of PKA. Furthermore, formoterol‐induced gene expression changes in BEAS‐2B bronchial epithelial cell clones deficient in β‐arrestin‐2 were comparable with those expressed by their parental counterparts. Contrariwise, gene expression was partially inhibited in clones lacking the α‐catalytic subunit (Cα) of PKA and abolished following the additional knockdown of the β‐catalytic subunit (Cβ) paralogue. Conclusions The effects of formoterol on inflammatory gene expression in airway epithelia are mediated by PKA and involve the cooperation of PKA‐Cα and PKA‐Cβ.