Project description:Specialized niche environments specify and maintain stem and progenitor cells, but little is known about the identities and functional interactions of niche components in vivo. Here, we describe a modular system for the generation of artificial hematopoietic niches in the mouse embryo. A circumscribed tissue that lacks niche function but is physiologically accessible for hematopoietic progenitor cells is functionalized by individual and combinatorial expression of four factors, the chemokines Ccl25 and Cxcl12, the cytokine Scf and the Notch ligand DLL4. The distinct phenotypes and variable numbers of hematopoietic cells in the resulting niches reveal synergistic, context-dependent and hierarchical interactions among niche effector molecules. The surprisingly simple rules determining niche outcomes enable the in vivo engineering of artificial niches conducive to the presence of distinct myeloid or T or B lymphoid lineage precursors. The dataset comprises 24 samples divided into eight sample groups each representing a different lymphoid progenitor cell type isolated from wild-type (+/-) or transgenic (-/-) thymic niches. -/-, Foxn1-deficient genotype; +/-, Foxn1 heterozygous phenotype; DP, CD4/CD8 double-poisztive thymocytes; DN3, CD4/CD8-negative stage 3 thymocytes; SP4, CD4 single-positive thymocytes; SP8, CD8 single-positive thymocytes; B IgM-, IgM surface negative B cells; B IgM+, IgM surface positive B cells; B IgM- -/-, IgM surface negative B cells from Foxn1-deficient genotype.
Project description:This experiment looks at the dissection of the microenvironment in the lung metastatic niche in a model of murine triple-negative breast cancer as disease progresses. Mice received an orthotopic inoculation of 4T1 cells and disease was allowed to progress for 7, 14, or 21 days correlating to the pre-metastatic, micro-metastatic, and metastatic niche, respectively. Healthy controls were obtained along with each time point.
Project description:Stem cell functions require activation of stem cell-intrinsic transcriptional programs as well as intimate extracellular interactions with a niche microenvironment. How the core pluripotency transcriptional machinery controls residency of stem cells in the niche microenvironment is unknown. Here we show that the helix loop helix transcriptional regulators Id (Inhibitors of DNA binding) are the master regulators that coordinate stem cell activities with anchorage of neural stem cells (NSCs) to the embryonic and postnatal niche. Conditional inactivation of Id genes (Id1, Id2 and Id3) in the mouse NSC compartment triggered detachment of embryonic and post-natal NSCs from the ventricular and vascular niche respectively, followed by premature differentiation. Through an unbiased interrogation of the gene modules directly targeted by deletion of Id genes in NSCs, we discovered that Id proteins repress the bHLH-mediated activation of Rap1GAP, thus serving to maintain the GTPase activity of RAP1, a key mediator of cell adhesion. Preventing the elevation of Rap1GAP efficiently countered the consequences of Id loss on NSC-niche interaction and stem cell identity. Thus, by preserving anchorage to the extracellular environment of NSCs, Id activity synchronizes NSC functions to residency in the specialized niche. We generated Id-cTKO mice carrying a Cre-recombinase-oestrogen-receptor-T2 (Cre-ER) allele targeted to the ubiquitously expressed ROSA26 locus (Id-cTKO-Rosa-Cre-ER). In this system, 4-hydroxytamoxifen (4-OHT) releases the Cre recombinase inhibition and allows recombination of genomic loxP sites. Indeed, efficient deletion of Id1 and Id2 with complete loss of Id protein expression was detectable after treatment of NSCs with 4-OHT for 72 h. Total RNA was extracted from triplicate samples of Id-cTKO-Rosa-Cre-ER NSCs treated for different times (6 h, 12 h, 18 h, 24 h, 48 h, 96 h, 144 h) with 4-OHT or control vehicle and used for analysis on Illumina MouseWG-6 expression BeadChip. The raw array data was normalized using the Bioconductor package Lumi using quantile normalization.
Project description:Specialized niche environments specify and maintain stem and progenitor cells, but little is known about the identities and functional interactions of niche components in vivo. Here, we describe a modular system for the generation of artificial hematopoietic niches in the mouse embryo. A circumscribed tissue that lacks niche function but is physiologically accessible for hematopoietic progenitor cells is functionalized by individual and combinatorial expression of four factors, the chemokines Ccl25 and Cxcl12, the cytokine Scf and the Notch ligand DLL4. The distinct phenotypes and variable numbers of hematopoietic cells in the resulting niches reveal synergistic, context-dependent and hierarchical interactions among niche effector molecules. The surprisingly simple rules determining niche outcomes enable the in vivo engineering of artificial niches conducive to the presence of distinct myeloid or T or B lymphoid lineage precursors.
Project description:B-cell acute lymphoblastic leukemia (B-ALL) blasts hijack the bone marrow (BM) microenvironment to form chemo-protective leukemic BM ‘niches’, facilitating chemo-resistance and, ultimately, disease relapse. However, the ability to dissect these evolving, complex interactions among distinct B-ALL subtypes and their varying BM niches is limited with current in vivo methods. Herein, we reconstituted an in vitro three-dimensional (3D) organotypic leukemic BM niche model using a ‘Leukemia-on-a-Chip’ platform and comparatively studied the spatial and genetic heterogeneity of the BM niche in regulating B-ALL chemotherapy resistance. By emulating the leukemia BM anatomy in vitro, we determined that the perivascular and endosteal niches, through providing cytokine (e.g. CXCL12) and adhesive (e.g. VCAM-1/OPN) signals, differentially enhance downstream leukemia-intrinsic NF-κB signaling to support B-ALL survival and regulate cell cycle-related signaling to promote dormancy, which following demonstrated the pre-clinical utility of this microphysiological system to screen concomitant niche-directed therapies. Furthermore, we revealed the heterogeneity across different B-ALL subtypes by mapping subtype-specific leukemia and niche signals with application of single-cell RNA sequencing and analysis, which may contribute to chemotherapy resistance and disease relapse. Together, these results validate that our Leukemia-on-a-Chip allows for real-time and controllable dissection of the dynamic and heterotypic interactions between leukemia blasts and their BM microenvironment, which may translate to personalized therapeutics screening and disease management.
Project description:To further identify gene expression signatures in the niche cells (CD45 negative) during proliferation of Hematopoietic stem cells (LSK), we employed mice whole genome (60K) microarray expression profiling as a discovery platform to identify the up-regulated and down-regulated genes of the niche.
Project description:Mice were intravenously injected with extracellular vesicles (EVs) isolated from B16V wt (n=3) or BAG6KO (n=3) cells or with PBS (n=3) as a control for 4 weeks on a weekly basis. Since B-16V melanoma cells colonise the lung upon intravenous injection and referring to current literature, we hypothesise that melanoma EVs alter the (immune-) microenvironment of the lung to prepare a pre-metastatic niche. Based on current literature and own previous experiments identifying BAG6 as an immunoregulatory protein that is also involved in the biogenesis of EVs, we are particularly interested in differences between the immune signature upon wt EV treatment compared to BAG6KO EV treatment.
Project description:Stem cell functions require activation of stem cell-intrinsic transcriptional programs as well as intimate extracellular interactions with a niche microenvironment. How the core pluripotency transcriptional machinery controls residency of stem cells in the niche microenvironment is unknown. Here we show that the helix loop helix transcriptional regulators Id (Inhibitors of DNA binding) are the master regulators that coordinate stem cell activities with anchorage of neural stem cells (NSCs) to the embryonic and postnatal niche. Conditional inactivation of Id genes (Id1, Id2 and Id3) in the mouse NSC compartment triggered detachment of embryonic and post-natal NSCs from the ventricular and vascular niche respectively, followed by premature differentiation. Through an unbiased interrogation of the gene modules directly targeted by deletion of Id genes in NSCs, we discovered that Id proteins repress the bHLH-mediated activation of Rap1GAP, thus serving to maintain the GTPase activity of RAP1, a key mediator of cell adhesion. Preventing the elevation of Rap1GAP efficiently countered the consequences of Id loss on NSC-niche interaction and stem cell identity. Thus, by preserving anchorage to the extracellular environment of NSCs, Id activity synchronizes NSC functions to residency in the specialized niche.
Project description:With the recent advancements in genome editing, next generation sequencing (NGS), and scalable cloning techniques, scientists can now conduct genetic screens at unprecedented levels of scale and precision. With such a multitude of technologies, there is a need for a simple yet comprehensive pipeline to enable systematic mammalian genetic screening. In this study, we develop novel algorithms for target identi fication and a toxin-less Gateway cloning tool, termed MegaGate, for library cloning which, when combined with existing genetic perturbation methods and NGS-coupled readouts, enable versatile engineering of relevant mammalian cell lines. Our integrated pipeline for Sequencing-based Target Ascertainment and Modular Perturbation Screening (STAMPScreen) can thus be utilized for a host of cell state engineering applications.