Project description:The global gene expression profiles of human umbilical cord blood and adult bone marrow CD34+CD33-CD38-Rho(lo)c-kit+ cells, enriched for hematopoietic stem/progenitor cells (HSC) with CD34+CD33-CD38-Rho(hi) cells, enriched in committed hematopoietic progenitor cells (HPC), were compared to identify candidate regulators of HSC self-renewal versus differentiation fate decisions.
Project description:The fate options of hematopoietic stem cells (HSCs) include self-renewal, differentiation, migration and apoptosis, but the interaction between intracellular Ca2+ and cytoplasmic chaperon protein in regulating fate options of long term-HSCs (LT-HSC) is unknown. We created a S100A6 conditional knockout mouse model in the hematopoietic system and our studies showed that in S100A6KO, the number of LT-HSCs was significantly reduced and HSCs engrafted poorly. After 5FU challenge, the frequency of S100A6KO HSCs remained significantly low. Our data showed that S100A6 failed to self-renew through Akt pathway in an intracellular calcium (Cai2+)-dependent manner. Expression profiling of S100A6KO obtained from gene signatures revealed that cytosolic calcium level and proteins translocation to mitochondria were decreased. Mitochondrial oxidative phosphorylation was impaired in S100A6KO. Proteomic data indicated Hsp90 protein and chaperonin family were reduced. Our findings demonstrated that S100A6 regulates fate options of HSCs self-renewal through integrating Akt signaling, specifically governing mitochondria metabolic function and protein quality.
Project description:Hematopoietic cell fate decisions such as self-renewal and differentiation are highly regulated through multiple molecular pathways. One pathway, the ubiquitin proteasome system (UPS), controls protein levels by tagging them with polyubiquitin chains and promoting their degradation through the proteasome. Ubiquitin E3 ligases serve as the substrate-recognition component of the UPS. Through investigating the FBOX family of E3 ligases, we discovered that Fbxo21 was highly expressed in the hematopoietic stem and progenitor cell (HSPC) population, and showed low to no expression in mature myeloid populations. To determine the role of FBXO21 on HSPC maintenance, self-renewal, and differentiation, we generated shRNAs against FBXO21 and a hematopoietic specific Fbxo21 conditional knockout (cKO) mouse model. We found that silencing FBXO21 in HSPCs led to a loss in colony formation and an increase in cell differentiation in vitro. Additionally, stressing the HSPC populations in our Fbxo21 cKO mouse with 5-FU injections resulted in a decrease in survival, despite these populations showing minimal alterations during steady-state hematopoiesis. Although FBXO21 has previously been proposed to regulate cytokine signaling via ASK and p38, our results show that depletion of FBXO21 led to altered ERK signaling in vitro. Together, these findings suggest ubiquitin E3 ligase FBXO21 regulates HSPCs through cytokine mediated pathways.
Project description:The Notch pathway regulates cell-fate decisions in a wide variety of cell types, often inhibiting particular differentiation programs and permitting either self-renewal or differentiation along alternate pathways. Notch receptors and Notch ligands have been found on hematopoietic stem cells (HSC) or marrow stromal cells. In the present study, through a microarray approach, we analyzed the gene expression variations from cultured murine HSC with or without a Notch ligand Delta4 at 6 hours, 12 hours and 24 hours after the induction of the Notch pathway. 13 samples against a common reference. two dye swap for each condition.
Project description:Increasing evidence links metabolic activity and cell growth to decline in hematopoietic stem cell (HSC) function during aging. The Lin28b/Hmga2 pathway controls tissue development and in the hematopoietic system the postnatal downregulation of this pathway causes a decrease in self renewal of adult HSCs compared to fetal HSCs. Igf2bp2 is an RNA binding protein and a mediator of the Lin28b/Hmga2 pathway, which regulates metabolism and growth signaling by influencing RNA stability and translation of its target genes. It is currently unknown whether Lin28/Hmga2/Igf2bp2 signaling impacts on aging-associated impairments in HSC function and hematopoiesis. Here, we analyzed homozygous Igf2bp2 germline knockout mice and wildtype control animals to address this question. The study shows that Igf2bp2 deletion rescues aging phenotypes of the hematopoietic system, such as the expansion of HSC numbers in bone marrow and the biased increase of myeloid cells in peripheral blood. This rescue of hematopoietic aging coincides with reduced mitochondrial metabolism and glycolysis in Igf2bp2-/- HSCs compared to Igf2bp2+/+ HSCs. Conversely, Igf2bp2 overexpression activates protein synthesis pathways in HSCs and leads to a rapid loss of self renewal by enhancing myeloid skewed differentiation in an mTOR/PI3K-dependent manner. Together, these results show that Igf2bp2 regulates energy metabolism and growth signaling in HSCs and that the activity of this pathways influences self renewal, differentiation, and aging of HSCs.
Project description:The global gene expression profiles of human umbilical cord blood and adult bone marrow CD34+CD33-CD38-Rho(lo)c-kit+ cells, enriched for hematopoietic stem/progenitor cells (HSC) with CD34+CD33-CD38-Rho(hi) cells, enriched in committed hematopoietic progenitor cells (HPC), were compared to identify candidate regulators of HSC self-renewal versus differentiation fate decisions. Keywords: parallel sample
Project description:The Notch pathway regulates cell-fate decisions in a wide variety of cell types, often inhibiting particular differentiation programs and permitting either self-renewal or differentiation along alternate pathways. Notch receptors and Notch ligands have been found on hematopoietic stem cells (HSC) or marrow stromal cells. In the present study, through a microarray approach, we analyzed the gene expression variations from cultured murine HSC with or without a Notch ligand Delta4 at 6 hours, 12 hours and 24 hours after the induction of the Notch pathway. Keywords: time course
Project description:We have used mouse embryonic stem cells (ESCs) as a model to study the signaling mechanisms that regulate self-renewal and commitment to differentiation. We hypothesized that genes critical to stem cell fate would be dynamically regulated at the initiation of commitment. Time course microarray analysis following initiation of commitment led us to propose a model of ESC maintenance in which highly regulated transcription factors and chromatin remodeling genes (down-regulated in our time course) maintain repression of genes responsible for cell differentiation, morphogenesis and development (up-regulated in our time course). Microarrays of Oct4, Nanog and Sox2 shRNA knockdown cell lines confirmed predicted regulation of target genes. shRNA knockdowns of candidate genes were tested in a novel high throughput screen of self-renewal, confirming their role in ESC pluripotency. We have identified genes that are critical for self-renewal and those that initiate commitment and developed draft transcriptional networks that control self-renewal and early development. Keywords: genetic modification Gene expression in Oct4 knockdown, Sox2 knockdown and their empty vector contol ES cells was analyzed.
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic mechanisms balance normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic regulators are considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in human LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly prognostic for patient survival. Gain- and loss-of-function analyses demonstrated that miR-126 restrained cell cycle progression, prevented differentiation, and increased self-renewal of human LSC. By targeting the G0 to G1 gatekeeper CDK3, miR-126 preserved LSC quiescence and promoted chemotherapy resistance. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC.
Project description:Nodal and Activin are morphogens of the TGFbeta superfamily of signaling molecules that direct differential cell fate decisions in a dose- and distance-dependent manner. During early embryonic development the Nodal/Activin pathway is responsible for the specification of mesoderm, endoderm, node and mesendoderm. In contradiction to this drive towards cellular differentiation, the pathway also plays important roles in the maintenance of self-renewal and pluripotency in embryonic and epiblast stem cells. The molecular basis behind stem cell interpretation of Nodal/Activin signaling gradients and the undertaking of disparate cell fate decisions remains poorly understood. Here, we show that any perturbation of endogenous signaling levels in mouse ES cells leads to their exit from self renewal towards divergent differentiation programs. Increasing Nodal signals above basal levels by direct stimulation with Activin promotes differentiation towards the mesendodermal lineages while repression of signaling with the specific Nodal/Activin receptor inhibitor SB431542 induces trophectodermal differentiation. To address how quantitative Nodal/Activin signals are translated qualitatively into distinct cell fates decisions, we performed chromatin immunoprecipitation of phospho-Smad2 the primary downstream transcriptional factor of the Nodal/Activin pathway followed by massively parallel sequencing and show that phospho-Smad2 binds to and regulates distinct subsets of target genes in a dose-dependent manner. Crucially, Nodal/Activin signaling directly controls the Oct4 master regulator of pluripotency by graded phospho-Smad2 binding in the promoter region. Hence stem cells interpret and carry out differential Nodal/Activin signaling instructions via a corresponding gradient of Smad2 phosphorylation that selectively titrates self-renewal against alternative differentiation programs by direct regulation of distinct target gene subsets and Oct4 expression. Four biological replicates consisting of 4 different passages of E14TG2a ES cells at P20, P21, P23 and P24