Calcium Signaling in Health and Disease

National Institute Of Environmental Health Sciences

Investigators

Linked publications & trials

Abstract

The broad aim of this project is to understand at the molecular, cellular and systems levels the mechanisms involved in regulation of store-operated calcium entry across the plasma membrane in non-excitable cells. Store-operated calcium entry is a highly conserved and ubiquitous calcium entry pathway that is indispensable for the function of non-excitable cells, particularly those in the immune system, where it controls a large variety of cell processes, including secretion, contraction, motility, growth, differentiation and apoptosis. Store-operated calcium entry is potentially vulnerable to environmental intervention by chemical and physical agents (such as EMF) and is a direct target for air-borne allergens including those derived form house dust mite. Store-operated calcium entry is activated by a signal generated in the endoplasmic reticulum when Ca2+ is released from the store by IP3 and which then interacts with the plasma membrane to activate calcium channels. The endoplasmic reticulum-spanning proteins Stim1 and Stim2 act as sensors for endoplasmic reticulum calcium, and Orai1 functions as the pore-forming unit of the store-operated calcium channel. We are interested in how calcium entry through Orai1 selectively activates downstream signalling pathways, including exocytosis, mitochondrial metabolism and calcium-dependent gene expression. We have recently discovered a dynamic interaction between Orai1 and the scaffolding protein AKAP79, which orchestrates the formation of a signalling complex adjacent to the calcium channel. We are currently dissecting out the molecular basis for the interaction between Orai1 and AKAP79, with the view to developing small molecules that selectively disrupt this interaction and thereby prevent cytokine production. Another major aim of our research is to understand the role of Orai1 in vivo, and how it contributes to disorders such as allergy and asthma. To address these questions, we used a multi-disciplinary approach including patch clamp electrophysiology, techniques of single cell fluorescence imaging, confocal microscopy, total internal reflection microscopy, FRET studies, immuno-cytochemistry, biochemical measurements, molecular biology including site-directed mutagenesis and mathematical modelling. We are currently using mouse models to evaluate the role of store-operated calcium entry in various physiological processes, including skin development and lung function and how it might be targeted in asthma and atopic dermatitis.