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NLRC5 deficiency selectively impairs MHC class I- dependent lymphocyte killing by cytotoxic T cells.

Nucleotide-binding oligomerization domain-like receptors (NLRs) are intracellular proteins involved in innate-driven inflammatory responses. The function of the family member NLR caspase recruitment domain containing protein 5 (NLRC5) remains a matter of debate, particularly with respect to NF-κB activation, type I IFN, and MHC I expression. To address the role of NLRC5, we generated Nlrc5-deficient mice (Nlrc5(Δ/Δ)). In this article we show that these animals exhibit slightly decreased CD8(+) T cell percentages, a phenotype compatible with deregulated MHC I expression. Of interest, NLRC5 ablation only mildly affected MHC I expression on APCs and, accordingly, Nlrc5(Δ/Δ) macrophages efficiently primed CD8(+) T cells. In contrast, NLRC5 deficiency dramatically impaired basal expression of MHC I in T, NKT, and NK lymphocytes. NLRC5 was sufficient to induce MHC I expression in a human lymphoid cell line, requiring both caspase recruitment and LRR domains. Moreover, endogenous NLRC5 localized to the nucleus and occupied the proximal promoter region of H-2 genes. Consistent with downregulated MHC I expression, the elimination of Nlrc5(Δ/Δ) lymphocytes by cytotoxic T cells was markedly reduced and, in addition, we observed low NLRC5 expression in several murine and human lymphoid-derived tumor cell lines. Hence, loss of NLRC5 expression represents an advantage for evading CD8(+) T cell-mediated elimination by downmodulation of MHC I levels-a mechanism that may be exploited by transformed cells. Our data show that NLRC5 acts as a key transcriptional regulator of MHC I in lymphocytes and support an essential role for NLRs in directing not only innate but also adaptive immune responses.

Pubmed ID: 22412192

Authors

  • Staehli F
  • Ludigs K
  • Heinz LX
  • Seguín-Estévez Q
  • Ferrero I
  • Braun M
  • Schroder K
  • Rebsamen M
  • Tardivel A
  • Mattmann C
  • MacDonald HR
  • Romero P
  • Reith W
  • Guarda G
  • Tschopp J

Journal

Journal of immunology (Baltimore, Md. : 1950)

Publication Data

April 15, 2012

Associated Grants

None

Mesh Terms

  • Adaptive Immunity
  • Animals
  • Antigen-Presenting Cells
  • Bone Marrow
  • Cell Differentiation
  • Cell Line, Tumor
  • Cell Nucleus
  • Cell Proliferation
  • Gene Expression Regulation
  • Genes, MHC Class I
  • Humans
  • Immunity, Innate
  • Intracellular Signaling Peptides and Proteins
  • Killer Cells, Natural
  • Macrophages
  • Mice
  • Mice, Knockout
  • NF-kappa B
  • T-Lymphocytes, Cytotoxic