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Nucleotide-binding oligomerization domain 2 (Nod2) is required for sensing of intracellular bacteria and subsequent inflammatory responses. Unexpectedly, new evidence suggests that Nod2 influences T helper cell signaling, proliferation and differentiation and effector responses against Toxoplasma gondii.
The differentiation of interleukin 17–producing helper T cells is controlled by a complex network of cytokines, signaling pathways and transcription factors. Regulation by microRNA particles can now be added to this list.
Antigen-driven selection in germinal centers lays the foundation of effective B cell memory. Two reports in this issue reveal novel mechanisms that control effective formation of germinal centers and their long-term persistence in vivo.
Mammalian cells ubiquitinate bacteria that erroneously enter the cytosol and target these intruding microbes for destruction by autophagy. New work shows that the protein NDP52 directly binds to ubiquitinated bacteria and facilitates the assembly of an autophagic membrane that surrounds these invaders.
Regulatory T cells that express the transcription factor Foxp3 are pivotal in suppressing autoimmune responses. A report in this issue describes a key role for interleukin 10 produced by lamina propria macrophages in maintaining Foxp3 expression during inflammatory responses in the intestine.
The induction of type I interferon is a critical checkpoint in antiviral immunity. Toll-like receptor 2 can unexpectedly induce type I interferon in the subset of inflammatory monocytes during infection with vaccinia virus.
Peptides able to positively select major histocompatibility complex class II–restricted thymocytes have not yet been defined. Two new reports identify and ascribe important extrathymic functions to several positively selecting peptides for CD4+ T cells.
Ariadne is the legendary Minoan goddess of the Labyrinth. The term 'Ariadne's thread' is used to describe the understanding of complex issues. Immunologists attending the 5th Leukocyte Signal Transduction Workshop discussed the Ariadne's thread woven about intracellular signaling pathways.
Agonist encounter can divert thymocytes into several unconventional T cell subsets, many of which exhibit regulatory properties. Unexpected findings indicate that agonist selection can drive the differentiation of interleukin 17–producing cells in the thymus.
Transcription factors are critical regulators of cell fate in the hemato-lymphoid system. New evidence indicates that the basic leucine zipper transcription factor E4BP4 (also known as NFIL3) is essential for natural killer cell specification.
Cytosolic DNA sensors have remained poorly defined so far. Two recent studies identify a previously undefined cytosolic DNA-sensing pathway that depends on the RNA polymerase III–mediated conversion of microbial DNA into 5′-triphosphate double-stranded RNA that activates the RNA helicase RIG-I.
Nod2 is a cytoplasmic Nod-like receptor protein that detects the peptidoglycan subfragment muramyl dipeptide. New work shows that Nod2 also has an important role in recognizing viruses and in triggering interferon production during viral infection.