The protein kinase C (PKC) family of serine-threonine kinases plays a central role in T lymphocyte activation. Here, we identify NR2F6, a nuclear zinc-finger orphan receptor, as a critical PKC substrate and essential regulator of CD4(+) T cell activation responses. NR2F6 potently antagonized the ability of T helper 0 (Th0) and Th17 CD4(+) T cells to induce expression of key cytokine genes such as interleukin-2 (IL-2) and IL-17. Mechanistically, NR2F6 directly interfered with the DNA binding of nuclear factor of activated T cells (NF-AT):activator protein 1 (AP-1) but not nuclear factor kappaB (NF-kappa B) and, subsequently, transcriptional activity of the NF-AT-dependent IL-17A cytokine promoter. Consistent with our model, Nr2f6-deficient mice had hyperreactive lymphocytes, developed a late-onset immunopathology, and were hypersusceptible to Th17-dependent experimental autoimmune encephalomyelitis. Our study establishes NR2F6 as a transcriptional repressor of IL-17 expression in Th17-differentiated CD4(+) T cells in vitro and in vivo.

The orphan nuclear receptor Ear2 (Nr2f6) is transiently expressed in the rostral part of the rhombic lip in which the locus coeruleus (LC) arises. LC development, regulated by a signaling cascade (Mash1 → Phox2b → Phox2a), is disrupted in Ear2 −/− embryos as revealed by an approximately threefold reduction in the number of Phox2a-and Phox2b-expressing LC progenitor cells. Mash1 expression in the rhombic lip, however, is unaffected, placing Ear2 in between Mash1 and Phox2a/b. Dopamine-␤-hydroxylase and tyrosine hydroxylase staining demonstrate that >70% of LC neurons are absent in the adult with agenesis affecting primarily the dorsal division of the LC. Normally, this division projects noradrenergic efferents to the cortex that appear to be diminished in Ear2 −/− since the cortical concentration of noradrenaline is four times lower in these mice. The rostral region of the cortex is known to contain a circadian pacemaker regulating adaptability to light-and restricted food-driven entrainment. In situ hybridization establishes that the circadian expression pattern of the clock gene Period1 is abolished in the Ear2 −/− forebrain. Behavioral experiments reveal that Ear2 mutants have a delayed entrainment to shifted light-dark cycles and adapt less efficiently to daytime feeding schedules. We propose that neurons in the dorsal division of LC contribute to the regulation of the forebrain clock, at least in part, through targeted release of noradrenaline into the cortical area.[Keywords: Circadian rhythm; Ear2; forebrain clock; locus coeruleus; nociception; nuclear orphan receptor] Supplemental material is available at http://www.genesdev.org.

Automated in situ hybridization enables the construction of comprehensive atlases of gene expression patterns in mammals. Such atlases can become Web-searchable digital expression maps of individual genes and thus offer an entryway to elucidate genetic interactions and signaling pathways. Towards this end, an atlas housing ∼1,000 spatial gene expression patterns of the midgestation mouse embryo was generated. Patterns were textually annotated using a controlled vocabulary comprising >90 anatomical features. Hierarchical clustering of annotations was carried out using distance scores calculated from the similarity between pairs of patterns across all anatomical structures. This process ordered hundreds of complex expression patterns into a matrix that reflects the embryonic architecture and the relatedness of patterns of expression. Clustering yielded 12 distinct groups of expression patterns. Because of the similarity of expression patterns within a group, members of each group may be components of regulatory cascades. We focused on the group containing Pax6, an evolutionary conserved transcriptional master mediator of development. Seventeen of the 82 genes in this group showed a change of expression in the developing neocortex of Pax6-deficient embryos. Electromobility shift assays were used to test for the presence of Pax6-paired domain binding sites. This led to the identification of 12 genes not previously known as potential targets of Pax6 regulation. These findings suggest that cluster analysis of annotated gene expression patterns obtained by automated in situ hybridization is a novel approach for identifying components of signaling cascades.

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