Project description:The importance of extrinsic regulation of hematopoietic stem cell activity is increasingly acknowledged. Here we report the generation of a new niche system, which supports expansion of mouse hematopoietic stem cells in vitro. Characterization of this niche revealed a transcriptional regulatory network including four critical factors, namely FOS, SPI1, KLF10 and TFEC. Interestingly, these factors are essential for osteoclastogenesis, thus revealing an osteoclastic network that supports hematopoietic stem cell self-renewal. Lentiviral vectors containing putative transcription factors regulating HSC expansion were transfected into GPE cells and gene expression values were compared to empty vector controls.
Project description:The importance of extrinsic regulation of hematopoietic stem cell activity is increasingly acknowledged. Here we report the generation of a new niche system, which supports expansion of mouse hematopoietic stem cells in vitro. Characterization of this niche revealed a transcriptional regulatory network including four critical factors, namely FOS, SPI1, KLF10 and TFEC. Interestingly, these factors are essential for osteoclastogenesis, thus revealing an osteoclastic network that supports hematopoietic stem cell self-renewal.
Project description:Maintenance of hematopoietic stem cell (HSC) function in the niche is an orchestrated event. Osteomacs (OM), are key cellular components of the niche. Previously, we documented that osteoblasts, OM, and megakaryocytes interact to promote hematopoiesis. Here, we further characterize OM and identify megakaryocyte-induced mediators that augment the role of OM in the niche. Single cell mRNAseq, mass spectrometry, and CyTOF examination of megakaryocyte-stimulated OM suggested that upregulation of CD166 and Embigin on OM augment their hematopoiesis maintenance function. CD166 knockout OM or shRNA-Embigin knockdown OM, confirmed that loss of these molecules significantly reduced OM ability to augment the osteoblast-mediated hematopoietic enhancing activity. Recombinant CD166 and Embigin partially substituted for OM function, characterizing both proteins as critical mediators of OM hematopoietic function. Our data identify Embigin and CD166 as OM-regulated critical components of HSC function in the niche and potential participants in various in vitro manipulations of stem cells.
Project description:During embryonic development the placental vasculature acts as a major hematopoietic niche, where endolthelial to hematopoietic transition ensures emergence of hematopoietic stem cells (HSCs). However, the molecular mechanisms that regulate the placental hematoendothelial niche are poorly understood. Using a parietal trophoblast giant cell (TGC)-specific knockout mouse model and single-cell RNA-sequencing, we show that the paracrine factors secreted by this single layer of TGCs are critical in the development of this niche. Disruptions in the TGC specific paracrine signaling leads to the loss of HSC population and the concomitant expansion of a KDR+/DLL4+/PROM1+ hematoendothelial cell-population in the placenta. Combining single-cell transcriptomics and receptor-ligand pair analyses, we also define the parietal TGC-dependent paracrine signaling network and identify Integrin signaling as a fundamental regulator of this process. Our study elucidates novel mechanisms by which non autonomous signaling from the primary parietal TGCs maintains the delicate placental hematopoietic-angiogenic balance and ensures embryonic and extraembryonic development.
Project description:Jak3 is the only non-promiscuous member of the Jak family of secondary messengers. Jak3–/– mice display defective T and NK cell development, which results in a SCID phenotype. As a result, studies to date have focused on understanding and targeting the cell-autonomous role of Jak3 in immunity, while functional Jak3 expression outside the hematopoietic system remains largely unreported. We show that Jak3 is expressed in endothelial cells across hematopoietic and non-hematopoietic organs, with heightened expression in the bone marrow. The bone marrow niche is understood as a network of different cell types that regulate hematopoietic function. We show that the Jak3–/– bone marrow niche is deleterious for the maintenance of long-term repopulating hematopoietic stem cells (LT-HSCs) and that JAK3-overexpressing endothelial cells have increased potential to expand LT-HSCs in vitro. Increased arterial zonation in the bone marrow of Jak3–/– mice further situates Jak3 as a marker of sinusoidal endothelium. This work may serve to identify a novel function for a highly specific tyrosine kinase in the bone marrow vascular niche and to further characterize the LT-HSC function of sinusoidal endothelium.
Project description:Crosstalk between mesenchymal stromal cells (MSCs) and hematopoietic stem and cells (HSCs) is essential for hematopoietic homeostasis and lineage output. Ebf1-deficient MSCs have reduced mesenchymal lineage potential. Ebf1 deletion in Cxcl12-abundant reticular (CAR) cells and PDGFRα+Sca1+CD45-CD31-Lin- (PαS) cells in the bone marrow decreased the numbers of HSPCs and myeloid cells. EBF1 in the bone marrow niche regulates a transcriptional program that determines the functional interactions with HSCs and the long-term balance between the myeloid and lymphoid cell fates.
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes. Mouse hematopoietic stem cells were purified from bone marrow cells using negative and positive selection with a Magnetic-Activated Cell Sorter (MACS). total RNA and mRNA were purified from the purified cells using Trizol reagent and magnetic oligo dT beads. Double strand cDNAs were synthesized using a cDNA synthesis kit and anchored oligo dT primers. After NlaIII digestion, 3’ cDNAs were isolated and amplified through 16-cycle PCR. SAGE tags were released from the 3’ cDNA after linker ligation. Ditags were formed, concatemerized and cloned into a pZERO vector. Sequencing reactions were performed with the ET sequencing terminator kit. Sequences were collected using a Megabase 1000 sequencer. SAGE tag sequences were extracted using SAGE 2000 software.
Project description:Recent studies have demonstrated that mitochondria can be transferred between different cell types to control metabolic homeostasis. However, whether the mitochondria transfer network occurred in the skeletal system or regulate skeletal metabolic homeostasis in vivo is not fully elucidated. Herein, we found that osteolineage cells transfer mitochondria to CD11b+ myeloid, B220+ lymphoid and hematopoietic stem and progenitor cells (HSPCs), of which monocytes/macrophages received the most transferred mitochondria. This process was inhibited by GC treatment contributing to the progression of glucocorticoid-induced osteoporosis (GIOP). Further analysis demonstrated that osteolineage cells transfer mitochondria to osteoclastic lineage cells via Miro1 mediated direct contact, and altered the glutathione metabolism, leading to the ferroptosis of osteoclastic lineage cells, thus inhibiting osteoclast activities. These findings revealed an unappreciated mechanism of mitochondrial regulation of skeletal metabolic homeostasis via mitochondria transfer and provide new insights of the mechanism of GIOP progression.