Regulation of airway epithelial cell-mediated inflammation by CRAC channels

Ca2+ is a ubiquitous signaling messenger mediating many essential functions such as excitability, exocytosis and transcription. In the airway epithelial cells (AECs) lining the conducting airways of the lung, Ca2+ signals are implicated in numerous cellular functions through effects on enzymatic cascades and transcriptional factors. Ca2+ homeostasis is also closely integrated with other signaling systems including that of reactive oxygen species (ROS), which has many cellular functions of its own and is implicated in allergic lung diseases and injury. However, the role of CRAC channels expressed in AECs for mediating airway inflammation and their potential crosstalk with other ROS and other inflammatory signaling pathways remains unknown. We have recently shown that store-operated Ca2+ release-activated Ca2+ (CRAC) channels serve as the main pathway for Ca2+ entry in bronchial epithelial cells and their activation leads to increases in levels of numerous proinflammatory cytokines. We hypothesize that CRAC channels are a major mechanism for controlling the generation of inflammatory mediators from AECs in response to stimulation of cell surface G-protein coupled receptors such as protease activated and ATP receptors, to drive pulmonary inflammation in diseases such as asthma. We will address this hypothesis through the following specific aims: 1) examine the physiological contributions of CRAC channels for allergen-mediated release of ATP and determine how this release stimulates inflammatory cytokines in AECs, 2) investigate the functional interactions between CRAC channels and mitochondrial ROS signaling and assess the impact of this crosstalk for inflammatory cytokine generation, and 3) evaluate the contribution of CRAC channels for mediating airway inflammation in vivo in a mouse model of house dustmite-induced asthma. Together, these studies will advance our understanding of how CRAC channels regulate cellular Ca2+-dependent signaling pathways to modulate allergen-stimulated inflammatory mediators in the airways, and advance the quest for developing novel treatments for allergic airway diseases.