An imbalance in the lineages of immunosuppressive regulatory T cells (T cells) and the inflammatory T17 subset of helper T cells leads to the development of autoimmune and/or inflammatory disease. Here we found that TAZ, a coactivator of TEAD transcription factors of Hippo signaling, was expressed under T17 cell-inducing conditions and was required for T17 differentiation and T17 cell-mediated inflammatory diseases. TAZ was a critical co-activator of the T17-defining transcription factor RORγt. In addition, TAZ attenuated T cell development by decreasing acetylation of the T cell master regulator Foxp3 mediated by the histone acetyltransferase Tip60, which targeted Foxp3 for proteasomal degradation. In contrast, under T cell-skewing conditions, TEAD1 expression and sequestration of TAZ from the transcription factors RORγt and Foxp3 promoted T cell differentiation. Furthermore, deficiency in TAZ or overexpression of TEAD1 induced T cell differentiation, whereas expression of a transgene encoding TAZ or activation of TAZ directed T17 cell differentiation. Our results demonstrate a pivotal role for TAZ in regulating the differentiation of T cells and T17 cells.

Follicular helper T cells (TFH cells) are responsible for effective B cell–mediated immunity, and Bcl-6 is a central factor for the differentiation of TFH cells. However, the molecular mechanisms that regulate the induction of TFH cells remain unclear. Here we found that the E3 ubiquitin ligase Itch was essential for the differentiation of TFH cells, germinal center responses and immunoglobulin G (IgG) responses to acute viral infection. Itch acted intrinsically in CD4+ T cells at early stages of TFH cell development. Itch seemed to act upstream of Bcl-6 expression, as Bcl-6 expression was substantially impaired in Itch−/− cells, and the differentiation of Itch−/− T cells into TFH cells was restored by enforced expression of Bcl-6. Itch associated with the transcription factor Foxo1 and promoted its ubiquitination and degradation. The defective TFH differentiation of Itch−/− T cells was rectified by deletion of Foxo1. Thus, our results indicate that Itch acts as an essential positive regulator in the differentiation of TFH cells.

Here, we describe an N-ethyl-N-nitrosourea (ENU)-induced missense error in the membrane-bound transcription factor peptidase site 1 (S1P)-encoding gene (Mbtps1) that causes enhanced susceptibility to dextran sodium sulfate (DSS)-induced colitis. S1P cleaves and activates cAMP response element binding protein/ATF transcription factors, the sterol regulatory element-binding proteins (SREBPs), and other proteins of both endogenous and viral origin. Because S1P has a nonredundant function in the ATF6-dependent unfolded protein response (UPR), woodrat mice show diminished levels of major endoplasmic reticulum chaperones GRP78 (BiP) and GRP94 in the colon upon DSS administration. Experiments with bone marrow chimeric mice reveal a requirement for S1P in nonhematopoietic cells, without which a diminished UPR and colitis develop.ER stress ͉ UPR ͉ site 1 protease ͉ inflammatory bowel disease

SUMMARY Classical genetic approaches to examine the requirements of genes for T cell differentiation during infection are time-consuming. Here we developed a pooled approach to screen 30–100+ genes individually in separate antigen-specific T cells during infection using short hairpin RNAs in a microRNA context (shRNAmir). Independent screens using T cell receptor (TCR)-transgenic CD4+ and CD8+ T cells responding to lymphocytic choriomeningitis virus (LCMV) identified multiple genes that regulated development of follicular helper (Tfh) and T helper-1 (Th1) cells, and short-lived effector and memory precursor cytotoxic T lymphocytes (CTL). Both screens revealed roles for the positive transcription elongation factor (P-TEFb) component Cyclin T1 (Ccnt1). Inhibiting expression of Cyclin T1, or its catalytic partner Cdk9, impaired development of Th1 cells and protective short-lived effector CTL, and enhanced Tfh and memory precursor CTL formation in vivo. This pooled shRNA screening approach should have utility in numerous immunological studies.

TNF␣ is a powerful inflammatory stimulus, central both to the control of infection, and as an agent of inflammatory disease. The most potent inducers of TNF␣ secretion signal through the Toll-like receptors, and we describe here a chemically-induced mutation that impairs this response in macrophages. A missense mutation was revealed in the gene encoding the inactive rhomboid protease iRhom2, which was not complemented by a null allele of the same gene. Neither the missense nor the null allele affected TLR-induced secretion of IL-6. Moreover, unlike a mutation in TNF␣, the iRhom2 missense mutation did not cause enhanced susceptibility to colitis induced by dextran sodium sulfate. These results establish a specific role for iRhom2 in the secretion of TNF␣, and present a new target for the modulation of inflammation. (Blood. 2012; 119(24):5769-5771) IntroductionTLR activation triggers a signaling pathway that culminates in the activation of NF-B and the synthesis of proinflammatory cytokines such as TNF␣. TNF␣, which is synthesized as a membranebound precursor, is liberated from the cell surface by the TNF␣ converting enzyme (TACE, also known as ADAM17). 1,2 Mammalian TACE is also required for the cleavage of other membranebound ligands, including the EGFR ligand TGF␣, 3 whose counterpart in Drosophila is cleaved by the unrelated protease rhomboid-1. 4,5 The rhomboid protease family is also present in mammals, and includes members with no predicted catalytic function, known as iRhoms. 6 Until very recently, the physiologic function of these proteins was unknown.To reveal new regulators of TLR-induced TNF␣, we have stimulated peritoneal macrophages from the progeny of chemicallymutagenized mice. 7 This screen has revealed mutant alleles throughout the pathway, from TLRs and the proteins that control their expression, 8 to TNF␣ itself. 9 Here we describe a new mutation affecting TLR-induced TNF␣ secretion that did not affect secretion of IL-6. The causative mutation lay in the gene encoding iRhom2, a catalytically inactive member of the rhomboid protease family. Methods Mice and positional cloningRhbdf2 sinecure was generated on a C57BL/6J background by N-ethyl-N-nitrosourea mutagenesis as previously described. 10 The index sinecure mutant (C57BL/6J, male) was outcrossed to C57BL/10J females (The Jackson Laboratory) for mapping, and F1 daughters were backcrossed to their father. Mice were grouped into mutant and wild-type cohorts (20 and 15 mice, respectively) based on TNF␣ secretion in response to MALP-2. Individual mice were typed at 70 polymorphic markers across the genome, and genotype frequencies were used to calculate LOD scores at each position. Rhbdf2 amplicons from wild-type and sinecure genomic DNA were sequenced using an ABI 3730xl capillary sequencer. C57BL/6J mice used for mutagenesis were obtained from The Jackson Laboratory. All other mice were obtained from the TSRI breeding colony. Ticam1 Lps2 and Irak2 otiose mutants have been described previously. 11,12 Rhbdf2 tm1a(KOMP)Wtsi ES cells (MGI:4362881, ...