Project description:We used microarrays to investigate gene expression changes in tumor-bearing Sca1-TOMATO-Lmo2 Nu/Nu mice Tumor-bearing bone marrows of three Sca1-TOMATO-Lmo2 Nu/Nu mice compared with bone marrow cells from four Control Nude mice and with thymus leukemic cells from ten Sca1-TOMATO-Lmo2 mice. GSM2209767 - GSM2209776 are re-analyses of GSE83570 (GSM2209749 - GSM220975 and GSM2209757 - GSM2209759).
Project description:WT bone marrow (BM) was transplanted into WT or CMO recipient mice. For 12 weeks the WT cells (including WT hematopoietic stem cells; HSCs) were exposed to WT or CMO BM niche. After 12 weeks, the BM was isolated, the WT donor HSCs were sorted, RNA isolated and RNA sequencing was performed. This experiment allowed us to investigate the effect of the WT or CMO BM niche on WT HSCs.
Project description:Lmo2 is an oncogenic transcription factor that is a frequent target of chromosomal abnormalities in this T-cell acute lymphoblastic leukemia (T-ALL). In transgenic mouse models, overexpression of Lmo2 causes thymocyte self-renewal leading to T-cell leukemia with long latency. However, the requirement of Lmo2 for maintenance of overt leukemia is poorly understood. We found that Lyl1, a critical cofactor for Lmo2-induced leukemia, is frequently lost in cell lines derived from Lmo2-transgenic mice, raising the possibility that Lmo2 function is dispensable at this stage. To study this, we developed a Tetracycline-repressible knock-in mouse model (Vav-TRE-Lmo2), which expresses Lmo2 throughout the haematopoietic system. This led to specific effects on T-cell development and the development of T-cell leukemia with long latency, preceded by the presence of self-renewing T-cells in the thymus. Repression of Lmo2 overcame the Lmo2-induced thymocyte developmental block at the preleukemic stage and led to elimination of Lmo2-induced thymocyte self-renewal in vivo. In contrast, Lmo2 function was dispensable for the majority of overt Lmo2-induced T-cell leukemias as well as leukemia-derived cell lines, implying an evolution of oncogene addiction in the majority of T-cell leukemias. Lmo2-dependence in T-ALL was associated with an immature gene expression profile, but could not be predicted by immunophenotype or assessment of Notch pathway activation. Thus, Lmo2 can give rise to both Lmo2-depenent and –independent T-cell leukemias. The Vav-TRE-Lmo2 model should be useful to determine the molecular features associated with Lmo2-dependence, as well as the critical components of the Lmo2-induced self-renewal pathways in T-ALL.
Project description:The bone marrow niche plays a critical role in controlling the fate of hematopoietic stem cells (HSCs) by integrating intrinsic and extrinsic signals. However, the molecular events in the HSC niche remain to be investigated. Here, we report that intercellular adhesion molecule-1 (ICAM-1) maintains HSC quiescence and repopulation capacity in the niche. ICAM-1-deficient mice (ICAM-1-/-) displayed significant expansion of phenotypic long-term HSCs with impaired quiescence, as well as favors myeloid cell expansion. ICAM-1-deficient HSCs presented normal reconstitution capacity during serial transplantation; however, reciprocal transplantation experiments showed that ICAM-1 deficiency in the niche impaired HSCs quiescence and repopulation capacity. In addition, ICAM-1 deletion caused failure to retain HSCs in the bone marrow and changed the expression profile of stroma cell-derived factors, possibly representing the mechanism for defective HSCs in ICAM-1-/- mice. Collectively, these observations identify ICAM-1 as a regulator in the bone marrow niche.
Project description:The bone marrow (BM) niche comprised of BM endothelial cells (BMECs) and LepR+ mesenchymal stromal cells (MSCs), plays a critical role in preserving the fitness of hematopoietic stem cells (HSCs). Aging is associated with defects in the BM niche that impair their ability to support HSC activity. However, mechanisms underlying age-related defects in the BM niche remain poorly understood. In this study, we identify BM niche derived Netrin-1 (NTN1) as a critical regulator of BM niche cell fitness during aging. Conditional deletion of NTN-1 specifically within BM MSCs or BMECs of young mice resulted in premature aging phenotypes within the BM niche including increased vascular leakiness, hypoxia, DNA damage and adiposity. On the other hand, supplementation of aged mice with NTN1 resulted in restoration of these hallmark niche defects and a rejuvenation of HSC activity. Mechanistically, we identify NTN1 as a critical regulator of DNA Damage Response (DDR) within BM niche cells and HSCs. In this experiment, RNA Seq analysis was performed on HSCs derived from young mice (3 month old), PBS treated aged mice (18 month old), and NTN1 treated aged mice (18 month old), to characterize transcriptional alterations within HSCs during aging, and following NTN1 treatment of aged mice.
Project description:It was reported that Ebf1-deficient hematopoietic progenitor cells were expandable on OP9 stromal cells in the presence of SCF, Flt3L and IL7, and maintained with the potential for the differentiation into other hematopoietic lineages including T cells with Notch signaling. In contrast, we found that those on thymic stromal cells were similarly expanded but gradually lost their potential to T cell lineage. To know the molecular machinery to retain their potential, we compared their profiles of the transcripts by microarray analysis. Expression of three genes (Meis1, Hmga2 and Lmo2) from this signature was quantified in the same RNA samples by real-time PCR, confirming their difference in the stemness-related genes. It was revealed that Lmo2 is responsible for the maintenance of T-cell differentiation potential among them. Thereafter, the expression profiles were also compared between Ebf1-deficient pro-B cell lines without the potential and their enforced transfectants of Lmo2, showing the downstream targets of Lmo2 in early lymphoid progenitor cells.
Project description:Purpose: Compare the transcriptome of hematopoietic stem cells (HSCs) that were aged in old and young niches Methods: barcoded GFP+ HSCs were FACS-sorted from a) three recipient mice 15 months post transplantation, and b) six serial transplantation recipient mice 5 months after the 8th transplantation, then subjected to processed using the Chromium Single-cell 3′ v2 Library Kit (10× Genomics, Pleasanton, CA) following the manufacturer’s instructions Results: we obtained transcriptomes of about 12k HSCs aged in young niche, and about 10k HSCs aged in old niche, with the average sequencing depth at close to 50k reads per cell Conclusions: we identified striking differences in gene expression profiles 1) between HSCs aged in young niches from mice with early aging and from mice with delayed aging, and 2) between HSCs aged in old niches and young niches when mice exhibited hematopoietic aging phenotype