Both immunodeficient and wild type NOD mice exhibit defects in control of early T-cell development in the thymus. We show that Rag1-deficient NOD mice fail to enforce both the b-selection checkpoint and an earlier T-cell commitment checkpoint, based on genome-wide genetic and transcriptome analyses. A major QTL peak for the checkpoint breakthrough phenotype mapped to the diabetes susceptibility Idd9/11 region, as confirmed by congenic mouse analysis. Genome-wide RNA deep-sequencing revealed two classes of differences between NOD and B6 Rag1-deficient thymocytes: first, effects of genetic background prior to breakthrough, and second, effects of the breakthrough itself. These genotypes differentially express numerous signal transduction genes, prominently tyrosine kinase and actin-binding genes, some located within QTL regions. Emerging NOD breakthrough cells depart from the expected DN3 phenotype by expressing many stem cell-associated proto-oncogenes, such as Lmo2, Hhex, Lyl1, and Kit which are normally repressed earlier, and by illegitimate activation of post-b-selection genes like Cd2, Cd5, and Cd4. Co-expression of stem cell and T-cell genes persists in thymic lymphoma cells that emerge with high penetrance in these mice. These results imply that NOD thymocytes have defects that can collapse regulatory boundaries at two early T-cell checkpoints, which may predispose them to leukemia and autoimmunity. Overall design: Genetic and transcriptome analyses of early T-cell checkpoint failure and leukemia initiation in Rag1-deficient NOD mice
Loss of T cell progenitor checkpoint control underlies leukemia initiation in Rag1-deficient nonobese diabetic mice.
Specimen part, Cell line, Subject
View SamplesDuring T cell development, multipotent progenitors relinquish competence for other fates and commit to the T cell lineage by turning on Bcl11b, which encodes a transcription factor. To clarify lineage commitment mechanisms, we followed developing T cells at the single-cell level using Bcl11b knock-in fluorescent reporter mice. Notch signaling and Notch activated transcription factors collaborate to activate Bcl11b expression irrespectively of Notch-dependent proliferation. These inputs work via three distinct, asynchronous mechanisms: an early locus ‘poising’ function dependent on TCF-1 and GATA-3, a stochastic-permissivity function dependent on Notch signaling, and a separate amplitude-control function dependent on Runx1, a factor already present in multipotent progenitors. Despite their necessity for Bcl11b activation, these inputs act in a stage specific manner, providing a multitiered mechanism for developmental gene regulation. Overall design: Two sets of samples were generated from DN T-cell sub-populations derived from culture of bone marrow progenitors from mice containing a knock-in Bcl11b-YFP reporter
Asynchronous combinatorial action of four regulatory factors activates Bcl11b for T cell commitment.
Specimen part, Subject
View SamplesPolarization of macrophages to M1 or M2 cells is important for mounting responses against bacterial and helminth infection respectively. Jumonji domain containing 3 (JMJD3), a histone 3 K27 demethylase, has been implicated in the activation of macrophages. Here we show that JMJD3 is essential for M2 macrophage polarization to helminth infection and chitin, though JMJD3 is dispensable for M1 responses. Furthermore, Jmjd3 is critical for proper bone marrow macrophage differentiation in a demethylase activity-dependent manner. Jmjd3 deficiency affected trimethylation of H3K27 in only a limited numbers of genes. Among them, we identified Irf4 as the target transcription factor critical for controlling M2 macrophage polarization. Collectively, these results show that JMJD3-mediated H3K27 demethylation is critical for regulating M2 macrophage development leading to anti-helminth host responses.
The Jmjd3-Irf4 axis regulates M2 macrophage polarization and host responses against helminth infection.
Specimen part, Treatment
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