Abstract
Orai1 is the pore subunit of Ca(2+) release-activated Ca(2+) (CRAC) channels that stimulate downstream signaling pathways crucial for T cell activation. CRAC channels are an attractive therapeutic target for alleviation of autoimmune diseases. Using high-throughput chemical library screening targeting Orai1, we identified a novel class of small molecules that inhibit CRAC channel activity. One of these molecules, compound 5D, inhibited CRAC channel activity by blocking ion permeation. When included during differentiation, Th17 cells showed higher sensitivity to compound 5D than Th1 and Th2 cells. The selectivity was attributable to high dependence of promoters of retinoic-acid-receptor-related orphan receptors on the Ca(2+)-NFAT pathway. Blocking of CRAC channels drastically decreased recruitment of NFAT and histone modifications within key gene loci involved in Th17 differentiation. The impairment in Th17 differentiation by treatment with CRAC channel blocker was recapitulated in Orai1-deficient T cells, which could be rescued by exogenous expression of retinoic-acid-receptor-related orphan receptors or a constitutive active mutant of NFAT. In vivo administration of CRAC channel blockers effectively reduced the severity of experimental autoimmune encephalomyelitis by suppression of differentiation of inflammatory T cells. These results suggest that CRAC channel blockers can be considered as chemical templates for the development of therapeutic agents to suppress inflammatory responses.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Calcium Channel Blockers / chemistry
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Calcium Channel Blockers / pharmacology
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Calcium Channels / genetics
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Calcium Channels / metabolism*
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Calcium Signaling*
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Cell Differentiation / drug effects
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Cell Line
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Encephalomyelitis, Autoimmune, Experimental / drug therapy
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Encephalomyelitis, Autoimmune, Experimental / genetics
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Encephalomyelitis, Autoimmune, Experimental / immunology
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Encephalomyelitis, Autoimmune, Experimental / metabolism
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Humans
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Ions / metabolism
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Mice
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NFATC Transcription Factors / metabolism
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Nuclear Receptor Subfamily 1, Group F, Member 1 / genetics
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Nuclear Receptor Subfamily 1, Group F, Member 1 / metabolism
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Nuclear Receptor Subfamily 1, Group F, Member 3 / genetics
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Nuclear Receptor Subfamily 1, Group F, Member 3 / metabolism
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ORAI1 Protein
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Orphan Nuclear Receptors / deficiency
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Orphan Nuclear Receptors / genetics
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Orphan Nuclear Receptors / metabolism*
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Promoter Regions, Genetic
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Protein Binding
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Response Elements
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Small Molecule Libraries
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Th1 Cells / cytology
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Th1 Cells / immunology
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Th1 Cells / metabolism
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Th17 Cells / cytology*
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Th17 Cells / immunology
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Th17 Cells / metabolism*
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Th2 Cells / cytology
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Th2 Cells / immunology
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Th2 Cells / metabolism
Substances
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Calcium Channel Blockers
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Calcium Channels
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Ions
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NFATC Transcription Factors
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Nuclear Receptor Subfamily 1, Group F, Member 1
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Nuclear Receptor Subfamily 1, Group F, Member 3
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ORAI1 Protein
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ORAI1 protein, human
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Orphan Nuclear Receptors
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Small Molecule Libraries