Project description:The ligand for the c-Kit receptor, KitL, exists as a membrane-associated (mKitL) and a soluble form (sKitL). KitL functions outside c-Kit activation have not been identified. We show that co-culture of c-Kit– and mKitL–expressing NIH3T3 cells results in signaling through mKitL: c-Kit–bound mKitL recruits calcium-modulating cyclophilin ligand (CAML) to selectively activate Akt, leading to CREB phosphorylation, mTOR pathway activation, and increased cell proliferation. Activation of mKitL in thymic vascular endothelial cells (VECs) induces mKitL- and Akt-dependent proliferation, and genetic ablation of mKitL in thymic VECs blocks their c-Kit responsiveness and proliferation during neonatal thymic expansion. Therefore, mKitL–c-Kit form a bi-directional signaling complex that acts in the developing thymus to coordinate thymic VEC and early thymic progenitor (ETP) expansion by simultaneously promoting ETP survival and VEC proliferation. This mechanism may be relevant to both normal tissues and malignant tumors that depend on KitL–c-Kit signaling for their proliferation.
Project description:To examine the transcriptome of various mimetic thymic epithelial cell populations (CilTEC, MyoTEC, Hetero-post TEC, microfold TEC, endocrine TEC and corneoTEC) we sorted these populations from young WT mice and performed bulk RNAseq
Project description:We report the identification of immature thymic CD4(-),CD8(-) double-negative (DN)1e cells with the NKT cell lineage potential. We also analyzed the gene expression profiles of DN1e thymocytes compared with those of mature thymic NKT cell developmental stages termed NKT stage-1, 2, and -3, which are characterized by differential expression levels of NK1.1 and CD44 antigens in C57BL/6 mouse strain. Next generation sequencing of total transcriptomes using total RNA isolated from FACS sorted ex vivo thymic DN1eP (Lin-/CD44+/CD25-/CD24low/CD5+/CD27+/Ly108-/CXCR3+) fraction, and mature thymic alphaGalCer-loaded CD1d dimer+TCRbeta+ NKT cell developmental stage-1 (CD44-/NK1.1-), stage-2 (CD44+/NK1.1-), and stage-3 (CD44+/NK1.1+) cells.
Project description:We report the identification of immature thymic CD4(-),CD8(-) double-negative (DN)1e cells with the NKT cell lineage potential. We also analyzed the gene expression profiles of DN1e thymocytes compared with those of mature thymic NKT cell developmental stages termed NKT stage-1, 2, and -3, which are characterized by differential expression levels of NK1.1 and CD44 antigens in C57BL/6J mouse strain.
Project description:The thymus is the site of T lymphocyte development and T cell education to recognize foreign, but not self, antigens. B cells also reside and develop in the thymus, although their function(s) are less clear. During ‘thymic involution,’ a process of lymphoid atrophy and adipose replacement linked to sexual maturation, thymic cells decline. However, thymic B cells decrease far less than T cells, such that B cells comprise ~1% of neonatal thymocytes, but up to ~10% in adulthood in humans. All jawed vertebrates possess a thymus, and we and others have shown that zebrafish (Danio rerio) also have thymic B cells. Here, we investigated the precise identities of zebrafish thymic T and B cells and how they change with involution. We assessed the timing and specific details of zebrafish thymic involution using multiple lymphocyte-specific, fluorophore-labeled transgenic lines, quantifying changes in thymic lymphocytes pre- vs. post-involution. Our results prove that, as in humans, zebrafish thymic B cells increase relative to T cells post-involution. We also performed RNA sequencing (RNA-seq) on D. rerio thymic and marrow lymphocytes of four novel double-transgenic lines, identifying distinct populations of immature T and B cells. Collectively, this is the first comprehensive analysis of zebrafish thymic involution, demonstrating its similarity to human involution, and establishing the highly genetically-manipulatable zebrafish model as a template for involution studies.
Project description:Thymic lymphomas develop spontaneously in LN3 mice. As for T-ALL in general, ex vivo LN3 lymphoma cells require stromal support to remain viable in culture. We found that primary stromal cells from thymic lymphomas, but not from wild-type thymi, support ex vivo lymphoma survival. By FACS sorting stromal populations, we identified dendritic cells in the tumor microenvironment as the cells capable of supporting lymphoma survival. We used microarrays to analyze the gene expression profiles of T-ALL cells and tumor-associated versus wild-type thymic dendritic cell subsets.