Project description:IL-23 negatively regulates St2 and Gata3 expression in intestinal CD4+ T cells Colitis was induced by co-transfer of WT and Il23r-/- naïve CD4 T cells into Rag1-/- recipients. Upon development of clinical signs of inflammation WT and Il23r-/- CD4+ T cells were sort-purified from the colon lamina propria on the basis of congenic markers. Total RNA was extracted immediately after the sort without further manipulation.
Project description:Induced Treg (iTreg) cells are essential for tolerance and can be used therapeutically, yet their stability in vivo and mechanisms of suppression are unresolved. Here, we used a treatment model of colitis to examine the role of autologous IL-10 in iTreg cell function. Mice treated with IL-10+/+ iTreg cells in combination with IL-10–/– natural Treg (nTreg) cells survived and gained weight, even though iTreg cells were numerically disadvantaged and comprised just ~20% of all Treg cells in treated mice. Notably, ~85% of the transferred iTreg cells lost Foxp3 expression (ex-iTreg) but retained a portion of the iTreg transcriptome which failed to limit their pathogenic potential. The TCR repertoires of iTreg and ex-iTreg cells exhibited almost no overlap, which indicates that the two populations are clonally unrelated and maintained by different selective pressures. These data demonstrate a potent and critical role for iTreg cell produced IL-10 that can supplant the IL-10 produced by nTreg cells and compensate for the inherent instability of the iTreg population. BALB/c Rag1-/- mice were treated with 500,00 WT nTreg cells plus 500,000 WT in-vitro-derived iTreg cells. After 125 days cells were sorted by flow cytometry from spleens and mesenteric lymph nodes from 14 treated mice. EGFP+ Thy1.1+ iTreg cells, EGFP+ Thy1.1– nTreg cells, and EGFP–Thy1.1+ ex-iTreg cells were pooled and used to generate total RNA for each iTreg, nTreg, and ex-iTreg array set, which was labeled and hybridized to Affymetrix 430 2.0 GeneChips in accordance to the manufacturer’s protocol. Two sets of arrays were performed, and the results were averaged. Both iTreg and nTreg array sets were compared to a) naïve CD4+EGFP– Tconv cells from Foxp3EGFP. The subset of probe sets whose expression increased or decreased by twofold or more relative to Tconv cells as a common standard was identified and used for further analysis.
Project description:Background: Microorganisms are the major cause of food spoilage during storage, processing and distribution. Pseudomonas fluorescens is a typical spoilage bacterium that contributes to a large extent to the spoilage process of proteinaceous food. RpoS is considered an important global regulator involved in stress survival and virulence in many pathogens. Our previous work revealed that RpoS contributed to the spoilage activities of P. fluorescens by regulating resistance to different stress conditions, extracellular acylated homoserine lactone (AHL) levels, extracellular protease and total volatile basic nitrogen (TVB-N) production. However, RpoS-dependent genes in P. fluorescens remained undefined. Results: RNA-seq transcriptomics analysis combined with quantitative proteomics analysis basing on multiplexed isobaric tandem mass tag (TMT) labeling was performed for the P. fluorescens wild-type strain UK4 and its derivative carrying a rpoS mutation. A total of 375 differentially expressed genes (DEGs) and 212 differentially expressed proteins (DEPs) were identified in these two backgrounds. The DGEs were further verified by qRT-PCR tests, and the genes directly regulated by RpoS were confirmed by 5’-RACE-PCR sequencing. The combining transcriptome and proteome analysis revealed a role of this regulator in several cellular processes, including polysaccharide metabolism, intracellular secretion and extracellular structures, cell well biogenesis, stress responses, ammonia and biogenic amine production, which may contribute to biofilm formation, stress resistance and spoilage activities of P. fluorescens. Moreover, in this work we indeed observed that RpoS contributed to the production of the macrocolony biofilm’s matrix.
Project description:Mouse B cell precursors from fetal liver and adult bone marrow generate distinctive B cell progeny when transplanted into immunodeficient recipients, supporting a two-pathway model for B lymphopoiesis, fetal “B-1” and adult “B-2”. Recently Lin28b was shown to be important for the switch between fetal and adult pathways; however, neither the mechanism of Lin28b action nor the importance of BCR signaling in this process was addressed. Here we report important advances in our understanding of the regulation of B 1/B-2 development. First, modulation of Let-7 in fetal Pro-B cells is sufficient to alter fetal B-1 development to produce B cells resembling the progeny of adult B-2 development. Second, intact BCR signaling is required for generation of B1a B cells from Lin28b-transduced bone marrow progenitors, supporting a requirement for ligand-dependent selection, as is the case for normal B1a B cells. Third, the VH repertore of Lin28b-induced bone marrow B1a B cells differs from that of normal B1a. Finally we identify the Arid3a transcription factor as a key target of Let-7, whose ectopic expression is sufficient to induce B-1 development in adult Pro-B cells and whose knockdown blocks B-1 development in fetal Pro-B cells. 2 individual sorts of bone marrow Pro-B cells 4 days after Lin28b retroviral transduction (and 2 sorts of empty vector control) and 2 individual sorts of fetal liver Pro-B cells 4 days after Let-7b retroviral transduction (and 2 sorts of empty vector controls).
Project description:In vertebrates, pluripotent pharyngeal mesoderm progenitors produce the cardiac precursors of the second heart field as well as the branchiomeric head muscles and associated stem cells. However, the cellular and molecular mechanisms underlying the transition from multipotent progenitors to distinct heart and muscle precursors remain obscured by the complexity of vertebrate embryos. Here, using the ascidian Ciona intestinalis as a simple chordate model for cardiopharyngeal development, we show that bipotent progenitors are transcriptionally primed to activate both heart and pharyngeal muscle regulatory programs, which become restricted to the corresponding precursors following a conserved pattern of asymmetric divisions. Localized expression of COE (Collier/OLF1/EBF) then orchestrates the transition to a pharyngeal muscle fate both by promoting an MRF (Myogenic Regulatory Factor)-associated core myogenic program in myoblasts and by maintaining an undifferentiated state in their sister precursors through Notch-mediated lateral inhibition. Using single cell lineage tracing, we show that the latter are stem-like muscle precursors, which form most of the juvenile body wall muscles following proliferation, self-renewal, re-activation of MRF, and migration. We discuss the implications of our findings for the development and evolution of the cardiopharyngeal mesoderm in chordates. We combined fluorescence-activated cell sorting (FACS) and whole genome transcription profiling following perturbations of COE function to characterize the transcriptional dynamics underlying the specification of heart and ASM precursors in the ascidian cardiopharyngeal lineage. We used whole genome transcription profiling of FACS-purified cell populations isolated from 21 hpf larvae expressing FoxF>COE, FoxF>COE::WRPW or the FoxF>NLS::lacZ control. To gain insights into the transcriptional dynamics underlying fate specification in the cardiopharyngeal lineage, we also purified B7.5-lineage cells from control embryos and larvae collected every two hours from 8 to 28 hpf. This time window encompasses all developmental transitions from early TVC specification till ASM ring formation and initial differentiation.
Project description:To identify mechanisms that regulate V(D)J recombination, we used proximity-dependent biotin identification to analyze the interactomes of full length and truncated forms of RAG1 in pre-B cells. This revealed an association of RAG1 with numerous nucleolar proteins in a manner dependent on amino acids 216-383 and allowed identification of a motif required for nucleolar localization. Experiments in transformed pre-B cell lines and cultured primary pre-B cells reveal a strong correlation between disruption of nucleoli, reduced association of RAG1 with a nucleolar marker, and increases in V(D)J recombination activity. Mutation of the RAG1 nucleolar localization motif boosts recombination while removal of the first 215 amino acids of RAG1, which are required for efficient egress from nucleoli, reduces recombination activity. Our findings indicate that nucleolar sequestration of RAG1 is a negative regulatory mechanism in V(D)J recombination and identify regions of the RAG1 N-terminal region that control nucleolar association and egress.
Project description:The generation of naM-CM-/ve T lymphocytes is critical for immune function yet the mechanisms governing their maturation remain incompletely understood. We have identified a mouse mutant, bloto, that harbors a hypomorphic mutation in the zinc finger protein Zfp335. Mutant blt/blt mice exhibit a naM-CM-/ve T cell deficiency due to an intrinsic developmental defect that begins to manifest in the thymus and continues into the periphery, affecting T cells that have recently undergone thymic egress. Zfp335 binds to promoter regions via a consensus motif, and its target genes are enriched in categories related to protein metabolism, mitochondrial function and transcriptional regulation. Restoring the expression of one target, Ankle2, partially rescues T cell maturation. Our findings identify Zfp335 as a transcription factor and essential regulator of late-stage intrathymic and post-thymic T cell maturation. WT and blt/blt CD4+ RTEs were sorted from mixed hematopoietic chimeras for RNA extraction and gene expression analysis on Affymetrix arrays. 6 samples were analyzed in total, with 3 biological replicates per genotype.