Adenosine-specific transcriptional programs in murine connective tissue type mast cells
Mast cells are tissue-resident immune cells that are critical for the pathogenesis of allergic and inflammatory disorders. In addition to classic host defense against parasites, food quality control through antigen avoidance has been recently elucidated as additional physiological mast cell function. The purine nucleoside adenosine (ADO), like other mast cell activators, such as antigens or Mrgprb2 agonists, increases intracellular Ca2+ concentration; however, it fails to induce degranulation of preformed mediators when applied to isolated mast cells alone, and there is limited knowledge of whether ADO evokes the de novo synthesis and release of inflammatory mediators such as cytokines in tissue mast cells. An unbiased genome-wide analysis of gene expression triggered by various mast cell activators should enable identification of the gene program specifically activated by adenosine in mast cells and thereby reveal new components of the associated inflammatory responses. To this end, we performed bulk RNA sequencing (RNA-Seq) in primary murine peritoneal mast cells (PMCs) as connective tissue mast cells. By comparing responses evoked by ADO stimulation with those of the Mrgprb2 compound 48/80 and antigens that activate Fc{varepsilon}RI receptors, we identified 393 genes whose expression was uniquely regulated by ADO, including upregulation of genes encoding de novo synthesized mediators such as Tgfa and Il7. Transcription factor activity inference, protein classification, functional enrichment analysis, protein-protein interaction network, and topology analysis revealed that these genes play roles in phosphoinositide signaling, vesicle trafficking, glycolysis, mitochondrial activity, and cell cycle arrest. In summary, our work elucidates a distinct ADO-triggered response and identifies a set of proteins including de novo synthesized mediators whose functional relevance in adenosine-evoked mast cell activation and inflammatory reactions can be evaluated in future studies.