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

Background and Purpose: It has been proposed that genomic mechanisms contribute to adverse effects often experienced by asthmatic subjects who take regular, inhaled beta(2)-adrenoceptor agonists as a monotherapy. Moreover, data from preclinical models of asthma suggest that these gene expression changes are mediated by p-arrestin-2 rather than PKA. Herein, we tested this hypothesis by comparing the genomic effects of formoterol, a beta(2)-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 p-arrestin-2 and PKA. Key Results: The formoterol-regulated transcriptome in HBEC treated concurrently with TNF alpha was defined by 1480 unique gene expression changes. TNF alpha-induced transcripts modulated by formoterol were annotated with enriched gene ontology terms related to inflammation and proliferation, notably GO:0070374 similar to positive regulation of ERK1 and ERK2 cascade, which is an apparent beta-arrestin-2 target. However, expression of the formoterol- and forskolin-regulated transcriptomes were highly rank-order correlated and the effects of formoterol on TNF alpha-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 beta-arrestin-2 were comparable with those expressed by their parental counterparts. Contrariwise, gene expression was partially inhibited in clones lacking the alpha-catalytic subunit (C alpha) of PKA and abolished following the additional knockdown of the beta-catalytic subunit (C beta) paralogue. Conclusions: The effects of formoterol on inflammatory gene expression in airway epithelia are mediated by PKA and involve the cooperation of PKA-C alpha and PKA-C beta.

Automated summary

This study found that 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.