ORAI1, STIM1/2, and RYR1 shape subsecond Ca 2+ microdomains upon T cell activation

• Published in: Science signaling Vol. 11; no. 561
• Main Authors: Diercks, Björn-Philipp, Werner, René, Weidemüller, Paula, Czarniak, Frederik, Hernandez, Lola, Lehmann, Cari, Rosche, Annette, Krüger, Aileen, Kaufmann, Ulrike, Vaeth, Martin, Failla, Antonio V, Zobiak, Bernd, Kandil, Farid I, Schetelig, Daniel, Ruthenbeck, Alexandra, Meier, Chris, Lodygin, Dmitri, Flügel, Alexander, Ren, Dejian, Wolf, Insa M A, Feske, Stefan, Guse, Andreas H
• Format: Journal Article
• Language: English
• Published: United States 18-12-2018
• Subjects: Animals; Calcium - metabolism; Calcium Signaling; Cell Membrane; Cells, Cultured; Female; Fluorescence Resonance Energy Transfer; Lymphocyte Activation; Male; Membrane Microdomains - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; ORAI1 Protein - metabolism; Ryanodine Receptor Calcium Release Channel - metabolism; Stromal Interaction Molecule 1 - metabolism; Stromal Interaction Molecule 2 - metabolism; T-Lymphocytes - cytology; T-Lymphocytes - immunology; T-Lymphocytes - metabolism
• ISSN: 1937-9145
• DOI: 10.1126/scisignal.aat0358

The earliest intracellular signals that occur after T cell activation are local, subsecond Ca
microdomains. Here, we identified a Ca
entry component involved in Ca
microdomain formation in both unstimulated and stimulated T cells. In unstimulated T cells, spontaneously generated small Ca
microdomains required ORAI1, STIM1, and STIM2. Super-resolution microscopy of unstimulated T cells identified a circular subplasmalemmal region with a diameter of about 300 nm with preformed patches of colocalized ORAI1, ryanodine receptors (RYRs), and STIM1. Preformed complexes of STIM1 and ORAI1 in unstimulated cells were confirmed by coimmunoprecipitation and Förster resonance energy transfer studies. Furthermore, within the first second after T cell receptor (TCR) stimulation, the number of Ca
microdomains increased in the subplasmalemmal space, an effect that required ORAI1, STIM2, RYR1, and the Ca
mobilizing second messenger NAADP (nicotinic acid adenine dinucleotide phosphate). These results indicate that preformed clusters of STIM and ORAI1 enable local Ca
entry events in unstimulated cells. Upon TCR activation, NAADP-evoked Ca
release through RYR1, in coordination with Ca
entry through ORAI1 and STIM, rapidly increases the number of Ca
microdomains, thereby initiating spread of Ca
signals deeper into the cytoplasm to promote full T cell activation.