Store-operated Ca2+ entry through ORAI1 is critical for T cell-mediated autoimmunity and allograft rejection.
ORAI1 is the pore-forming subunit of the Ca(2+) release-activated Ca(2+) (CRAC) channel, which is responsible for store-operated Ca(2+) entry in lymphocytes. A role for ORAI1 in T cell function in vivo has been inferred from in vitro studies of T cells from human immunodeficient patients with mutations in ORAI1 and Orai1(-/-) mice, but a detailed analysis of T cell-mediated immune responses in vivo in mice lacking functional ORAI1 has been missing. We therefore generated Orai1 knock-in mice (Orai1(KI/KI)) expressing a nonfunctional ORAI1-R93W protein. Homozygosity for the equivalent ORAI1-R91W mutation abolishes CRAC channel function in human T cells resulting in severe immunodeficiency. Homozygous Orai1(KI/KI) mice die neonatally, but Orai1(KI/KI) fetal liver chimeric mice are viable and show normal lymphocyte development. T and B cells from Orai1(KI/KI) mice display severely impaired store-operated Ca(2+) entry and CRAC channel function resulting in a strongly reduced expression of several key cytokines including IL-2, IL-4, IL-17, IFN-γ, and TNF-α in CD4(+) and CD8(+) T cells. Cell-mediated immune responses in vivo that depend on Th1, Th2, and Th17 cell function were severely attenuated in ORAI1-deficient mice. Orai1(KI/KI) mice lacked detectable contact hypersensitivity responses and tolerated skin allografts significantly longer than wild-type mice. In addition, T cells from Orai1(KI/KI) mice failed to induce colitis in an adoptive transfer model of inflammatory bowel disease. These findings reaffirm the critical role of ORAI1 for T cell function and provide important insights into the in vivo functions of CRAC channels for T cell-mediated immunity.
McCarl
Christie-Ann
CA
Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA.
Khalil
Sara
S
Ma
Jian
J
Oh-hora
Masatsugu
M
Yamashita
Megumi
M
Roether
Jens
J
Kawasaki
Takumi
T
Jairaman
Amit
A
Sasaki
Yoshiteru
Y
Prakriya
Murali
M
Feske
Stefan
S
D000818:Animals; D015551:Autoimmunity / Q000276:immunology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020013:Calcium Signaling / Q000235:genetics / Q000276:immunology; D002469:Cell Separation; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D031541:Fluorescence Resonance Energy Transfer; D055879:Gene Knock-In Techniques; D006084:Graft Rejection / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D000071740:ORAI1 Protein; D018408:Patch-Clamp Techniques; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018183:Transplantation Chimera; D014184:Transplantation, Homologous
D015220:Calcium Channels; D016207:Cytokines; D000071740:ORAI1 Protein; C520430:Orai1 protein, mouse; D002118:Calcium