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T cells critically depend on reprogramming of metabolic signatures to meet the bioenergetic demands during activation and clonal expansion. Here we identify the transcription factor Nur77 as a cell-intrinsic modulator of T cell activation. Nur77-deficient T cells are highly proliferative, and lack of Nur77 is associated with enhanced T cell activation and increased susceptibility for T cell-mediated inflammatory diseases, such as CNS autoimmunity, allergic contact dermatitis and collagen-induced arthritis. Importantly, Nur77 serves as key regulator of energy metabolism in T cells, restricting mitochondrial respiration and glycolysis and controlling switching between different energy pathways. Transcriptional network analysis revealed that Nur77 modulates the expression of metabolic genes, most likely in close interaction with other transcription factors, especially estrogen-related receptor α. In summary, we identify Nur77 as a transcriptional regulator of T cell metabolism, which elevates the threshold for T cell activation and confers protection in different T cell-mediated inflammatory diseases.

Female pattern hair loss (FPHL) is a common disorder with a complex mode of inheritance. Although understanding of its etiopathogenesis is incomplete, an interaction between genetic and hormonal factors is assumed to be important. The involvement of an androgen-dependent pathway and sex steroid hormones is the most likely hypothesis. We therefore selected a total of 21 variants from the steroid-5-alpha-reductase isoforms SRD5A1 and SRD5A2, the sex steroid hormone receptors ESR1, ESR2 (oestrogen receptor) and PGR (progesterone receptor) and genotyped these in a case-control sample of 198 patients (145 UK; 53 German patients) and 329 controls (179 UK; 150 German). None of these variants showed any significant association, either in the overall UK and German samples or in the subgroup analyses. In summary, the present results, while based on a limited selection of gene variants, do not point to the involvement of SRD5A1, SRD5A2, ESR1, ESR2 or PGR in FPHL.

Deregulated MAP kinase (MAPK) signaling plays key roles in developmental and adult disease processes, but the experimental activation of MAPK is a currently unresolved task. For the reversible induction of MAPK signaling, we generated transgenic mice harboring a tamoxifen inducible BRAF(V637E)ER(T2) fusion protein. The expression of the inducible BRAF kinase can be directed by Cre/loxP-mediated recombination to selected cell types and enables the highly specific activation of MAPK signalling in vivo. We show that MAPK signaling can be transiently activated in the brain, liver, or kidney of Braf(V637E)ER(T2) mice by a single injection of tamoxifen. Braf(V637E)ER(T2) mice provide a new versatile tool to study disease mechanisms elicited by MAPK activation, complementing gene knockout technology that is restricted to the analysis of loss-of-function phenotypes.