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Cell Signal. 2011 Nov;23(11):1785-93. doi: 10.1016/j.cellsig.2011.06.013. Epub 2011 Jun 25.

Nuclear presence of nuclear factor of activated T cells (NFAT) c3 and c4 is required for Toll-like receptor-activated innate inflammatory response of monocytes/macrophages.

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1
Center for Orthopaedic Research, Department of Orthopaedic Surgery, Columbia University, 650 West 168th Street BB14-1412, New York, NY 10032, USA.

Abstract

Nuclear factor of activated T cells (NFATs) are crucial transcription factors that tightly control proinflammatory cytokine expression for adaptive immunity in T and B lymphocytes. However, little is known about the role of NFATs for innate immunity in macrophages. In this study, we report that NFAT is required for Toll-like receptor (TLR)-initiated innate immune responses in bone marrow-derived macrophages (BMMs). All TLR ligand stimulation including LPS, a TLR4 ligand, and Pam(3)CSK(4), a TLR1/2 ligand, induced expression of TNF which was inhibited by VIVIT, an NFAT-specific inhibitor peptide. BMMs from NFATc4 knock-out mouse expressed less TNF than wild type. Despite apparent association between NFAT and TNF, LPS did not directly activate NFAT based on NFAT-luciferase reporter assay, whereas NF-κB was inducibly activated by LPS. Instead, macrophage exhibited constitutive NFAT activity which was not increased by LPS and was decreased by VIVIT. Immunocytochemical examination of NFATc1-4 of BMMs exhibited nuclear localization of NFATc3/c4 regardless of LPS stimulation. LPS stimulation did not cause nuclear translocation of NFATc1/c2. Treatment with VIVIT resulted in nuclear export of NFATc3/c4 and inhibited TLR-activated TNF expression, suggesting that nuclear residence of NFATc is required for TLR-related innate immune response. Chromatin immunoprecipitation (ChIP) assay using anti-RNA polymerase II (PolII) antibody suggested that VIVIT decreased PolII binding to TNF gene locus, consistent with VIVIT inhibition of LPS-induced TNF mRNA expression. This study identifies a novel paradigm of innate immune regulation rendered by NFAT which is a well known family of adaptive immune regulatory proteins.

PMID:
21726630
PMCID:
PMC3169434
DOI:
10.1016/j.cellsig.2011.06.013
[Indexed for MEDLINE]
Free PMC Article

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