School of Mathematics and Statistics - Research Publications

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    Blimp-1 controls plasma cell function through the regulation of immunoglobulin secretion and the unfolded protein response
    Tellier, J ; Shi, W ; Minnich, M ; Liao, Y ; Crawford, S ; Smyth, GK ; Kallies, A ; Busslinger, M ; Nutt, SL (NATURE PUBLISHING GROUP, 2016-03)
    Plasma cell differentiation requires silencing of B cell transcription, while it establishes antibody-secretory function and long-term survival. The transcription factors Blimp-1 and IRF4 are essential for the generation of plasma cells; however, their function in mature plasma cells has remained elusive. We found that while IRF4 was essential for the survival of plasma cells, Blimp-1 was dispensable for this. Blimp-1-deficient plasma cells retained their transcriptional identity but lost the ability to secrete antibody. Blimp-1 regulated many components of the unfolded protein response (UPR), including XBP-1 and ATF6. The overlap in the functions of Blimp-1 and XBP-1 was restricted to that response, with Blimp-1 uniquely regulating activity of the kinase mTOR and the size of plasma cells. Thus, Blimp-1 was required for the unique physiological ability of plasma cells that enables the secretion of protective antibody.
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    Whole transcriptome analysis for T cell receptor-affinity and IRF4-regulated clonal expansion of T cells.
    Shi, W ; Man, K ; Smyth, GK ; Nutt, SL ; Kallies, A (Elsevier BV, 2014-12)
    Clonal population expansion of T cells during an immune response is dependent on the affinity of the T cell receptor (TCR) for its antigen [1]. However, there is little understanding of how this process is controlled transcriptionally. We found that the transcription factor IRF4 was induced in a manner dependent on TCR-affinity and was critical for the clonal expansion and maintenance of effector function of antigen-specific CD8(+) T cells. We performed a genome-wide expression profiling experiment using RNA sequencing technology (RNA-seq) to interrogate global expression changes when IRF4 was deleted in CD8(+) T cells activated with either a low or high affinity peptide ligand. This allowed us not only to determine IRF4-dependent transcriptional changes but also to identify transcripts dependent on TCR-affinity [2]. Here we describe in detail the analyses of the RNA-seq data, including quality control, read mapping, quantification, normalization and assessment of differential gene expression. The RNA-seq data can be accessed from Gene Expression Omnibus database (accession number GSE49929).
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    Attenuation of TCR-induced transcription by Bach2 controls regulatory T cell differentiation and homeostasis
    Sidwell, T ; Liao, Y ; Garnham, AL ; Vasanthakumar, A ; Gloury, R ; Blume, J ; Teh, PP ; Chisanga, D ; Thelemann, C ; Rivera, FDL ; Engwerda, CR ; Corcoran, L ; Kometani, K ; Kurosaki, T ; Smyth, GK ; Shi, W ; Kallies, A (NATURE PUBLISHING GROUP, 2020-01-14)
    Differentiation and homeostasis of Foxp3+ regulatory T (Treg) cells are strictly controlled by T-cell receptor (TCR) signals; however, molecular mechanisms that govern these processes are incompletely understood. Here we show that Bach2 is an important regulator of Treg cell differentiation and homeostasis downstream of TCR signaling. Bach2 prevents premature differentiation of fully suppressive effector Treg (eTreg) cells, limits IL-10 production and is required for the development of peripherally induced Treg (pTreg) cells in the gastrointestinal tract. Bach2 attenuates TCR signaling-induced IRF4-dependent Treg cell differentiation. Deletion of IRF4 promotes inducible Treg cell differentiation and rescues pTreg cell differentiation in the absence of Bach2. In turn, loss of Bach2 normalizes eTreg cell differentiation of IRF4-deficient Treg cells. Mechanistically, Bach2 counteracts the DNA-binding activity of IRF4 and limits chromatin accessibility, thereby attenuating IRF4-dependent transcription. Thus, Bach2 balances TCR signaling induced transcriptional activity of IRF4 to maintain homeostasis of thymically-derived and peripherally-derived Treg cells.