Project description:Shwachman-Diamond syndrome (SDS) is a bone marrow failure (BMF) syndrome associated with an increased risk of myelodysplasia and leukemia. The molecular mechanisms of SDS are not fully understood. We report that primitive hematopoietic cells from SDS patients present with a reduced activity of the small Rho GTPase Cdc42 and concomitantly a reduced frequency of HSCs polar for polarity proteins. The level of apolarity of SDS HSCs correlated with the magnitude of HSC depletion in SDS patients. Importantly, exogenously provided Wnt5a or GDF11 that elevates the activity of Cdc42 restored polarity in SDS HSCs and increased the number of HSCs in SDS patient samples in surrogate ex vivo assays. Single cell level RNA-Seq analyses of SDS HSCs and daughter cells demonstrated that SDS-HSC treated with GDF11 are transcriptionally more similar to control than to SDS-HSCs. Treatment with GDF11 reverted pathways in SDS HSCs associated with rRNA processing and ribosome function, but also viral infection and immune function, p53-dependent DNA damage, spindle checkpoints, and metabolism, further implying a role of these pathways in HSC failure in SDS. Our data suggest that HSC failure in SDS is driven at least in part by low Cdc42 activity in SDS HSCs. Our data thus identify novel rationale approaches to attenuate HSCs failure in SDS.
Project description:We have developed a new conditional transgenic mouse showing that MLL-ENL, at an endogenous-like expression level, induces leukemic transformation selectively in LT-HSCs. To investigate the molecular mechanism of leukemic transformation in LT-HSCs conditionally expressing MLL-ENL, we preliminarily performed comprehensive gene expression profiling of CreER-transduced LT-HSCs and ST-HSCs using cDNA microarray analysis. For initial screening of candidate genes invloved in the leukemic transformation, total RNA was extracted from colony-forming cells derived from LT-HSCs and ST-HSCs transduced with CreER or mock. Four samples were analyzed, and CreER-transduced LT/ST-HSC-derived cells were compared with mock-transduced LT/ST-HSC-derived cells, while CreER/mock-transduced LT-HSC-derived cells were compared with CreER/mock-transduced ST-HSC-derived cells.
Project description:We have used a conditional mouse model to investigate the role of Zbtb11 specifically in hematopoiesis. When Zbtb11 was deleted in the hematopoietic compartment, embryos died at embryonic day E18.5 with hematopoietic failure. Zbtb11 hematopoietic knockout (Zbtb11hKO) hematopoietic stem cells (HSCs) were overabundantly specified at E14.5 through E17.5 compared to controls. Overspecification was accompanied by loss of stemness, inability to differentiate into committed progenitors and mature lineages in fetal liver, failure to seed fetal bone marrow and total hematopoietic failure. Zbtb11hKO HSCs did not proliferate in vitro and were constrained in cell cycle progression, demonstrating a cell-intrinsic role for Zbtb11 in proliferation and cell cycle regulation in mammalian HSCs. scRNAseq analysis identified Zbtb11-deficient HSCs were underrepresented in an erythroid-primed subpopulation and showed downregulation of oxidative phosphorylation (OXPHOS) pathways and dysregulation of genes associated with the hematopoietic niche. We have identified a cell-intrinsic requirement for Zbtb11-mediated gene regulatory networks in sustaining a pool of maturation-capable hematopoietic stem and progenitor cells.
Project description:During adult bone marrow hematopoiesis, extremely rare and dormant hematopoietic stem cells (HSCs) harbor the highest self-renewal activity within all blood cells. They give rise to active HSCs, which generate multipotent progenitors (MPPs) which differentiate into lineage-committed progenitors and subsequently mature cells. While HSCs are characterized by long-term self-renewal capacity, quiescence and multipotency, MPPs show steadily decreasing self-renewal activity, are cycling but are thought to maintain multipotency. To establish a comprehensive genome-wide landscape of expressed transcripts, we performed a quantitative transcriptome analysis by next-generation sequencing (RNA-seq) of seven ex vivo FACS-sorted mouse HSC/progenitor populations. Eleven-fold coverage of the genome was achieved, revealing quantification of > 27,000 mRNA species of which 589 long non-coding RNAs (lncRNAs) were quantified. A profile of 79 differentially expressed lncRNAs in HSC-MPPs was identified suggesting a role for these RNA species in HSC/progenitor biology. Expression clusters of transcription factors and cell adhesion molecules are identified between the different cell populations. Dormant HSCs, as identified by label-retaining assays, showed a highly differential expression profile compared to active HSCs. In addition to >200 differentially expressed cell surface receptors and lncRNAs, processes including metabolism, development, immune response, signaling (TGFb, Kit, senescence/autophagy) are distinct between the two types of HSCs. In addition, using whole cell proteome analysis of FACS-sorted HSCs and MPP1, >6,000 proteins were identified by quantitative tandem mass spectrometry. Quantification of these proteins confirmed the close relationship between these cell types also seen in their transcript profile and revealed processes such as energy metabolism, immune response and cell cycle to be modulated along early lineage progression. While MPP1/2 still show multilineage potential in reconstitution experiments, a strong lineage bias and low self-renewal potential is observed in mice reconstituted with MPP3/4. These functional differences are accompanied by complex changes in their transcriptome and is also revealed by principal component analysis. In summary, the global mRNA, lncRNA and proteome signatures uncovered here and which are complemented by functional assays, provide a comprehensive and searchable resource of the molecular make-up of the entire HSC/progenitor population present in the bone marrow. These data will provide the basis for a global understanding of stem cell biology in the adult blood system. The uploaded dataset corresponds to the quantitative proteomic comparison of HSC and MPP1, which was done in three biological replicates. Data analysis: MS raw data files were processed with MaxQuant (version 1.3.0.5) (Cox and Mann 2008). Enzyme specificity was set to trypsin/P and a maximum of two missed cleavages were allowed. Cysteine carbamidomethylation and methionine oxidation were selected as fixed and variable modifications, respectively. The derived peak list was searched using the built-in Andromeda search engine (version 1.3.0.5) in MaxQuant against the Uniprot mouse database (2013.02.20) containing 75,721 proteins to which 247 frequently observed contaminants as well as reversed sequences of all entries had been added. Initial maximal allowed mass tolerance was set to 20 ppm for peptide masses, followed by 6 ppm in the main search, and 0.5 Dalton for fragment ion masses. The minimum peptide length was set to six amino acid residues and three labeled amino acid residues were allowed. A 1% false discovery rate (FDR) was required at both the protein level and the peptide level. In addition to the FDR threshold, proteins were considered identified if they had at least one unique peptide. The protein identification was reported as an indistinguishable “protein group” if no unique peptide sequence to a single database entry was identified. The ‘match between runs’ was enabled for consecutive peptide fractions with a 2 minutes time window. The iBAQ algorithm was used for estimation of the abundance of different proteins within a single sample (proteome) (Schwanhausser 2011). For evaluation of differential protein expression between HSC and MPP1, statistical analysis was performed for the proteins quantified in all three replicates using the Limma package in R/Bioconductor (Gentleman 2004, Smyth 2004). After fitting a linear model to the data, an empirical Bayes moderated t-test was used for the protein ratios, which were weighted on log10(summed peptide intensities) in order to capture the effect that the statistical spread of unregulated proteins is much more focused for highly abundant proteins than for low abundance ones (Cox 2008). P-values were then adjusted for multiple testing with Benjamini and Hochberg's method and proteins with an adjusted p-value lower than 0.1 were considered to be differentially expressed between HSC and MPP1. Associated transcriptomics data has been deposited at ArrayExpress with accession E-MTAB-2262.
Project description:In oroder to understand the maturation process of pre-HSCs to HSC, we conducted scRNA-seq using E11.5pre-HSCs and E12.5&E14.5 LT_HSC populations. Pseudotime analysis and velocity analysis show the progression of pre-HSC to mature HSCs and also divergent point of lineage trajectory.
Project description:Under conditions of the liver exposed to chronic insults such as viral infection, excess deposition of fat, regurgitation of bile acids etc., hepatic stellate cells (HSCs) change from quiescent to activated states and proliferate. During this process, HSCs secrete collagen and metalloproteinases. Involvement of collagen in sustaining activated HSC (aHSC) survival was postulated, although the precise mechanisms underlying the survival and apoptosis of aHSCs is still controversial. In this study, we compared the expression profiles between quiescent and activated HSCs to clarify the mechanisms of apoptosis for exploration of novel anti-fibrosis modalities.
Project description:Bone marrow Hdc-GFPhi and Hdc-GFPlo HSPC (SLAM-LSK, Lin-c-kit+Sca-1+CD150+CD48-) HSCs were isolated from mouse femur and tibia from histidine decarboxylase (Hdc) green fluorescent protein (Hdc-GFP) mice. Hdc-GFPhi HSC and Hdc-GFPlo HSC cells were sorted by combinations of GFP and the cell surface markers of HSC. total RNA was isolated from sorted 2,500 HSPCs using ARCTURUS PicoPure RNA isolation kit (Life Technologies). cDNA was amplified and libraries were constructed by using SMARTer Ultra Low Input RNA kit (Clontech Laboratories) and Nextera XT DNA Library Preparation kit (Illumina) according to manufacturer’s instructions respectively. Sequencing was performed on the Illumina HiSeq2000 platform.
Project description:With ageing, intrinsic hematopoietic stem cell (HSC) activity decreases, resulting in impaired tissue homeostasis, reduced engraftment following transplantation and increased susceptibility to diseases. However, whether ageing affects also the HSC niche impairing the capacity to support HSC function is still largely unknown. Here, by using in-vivo long-term label retention assays we demonstrate that aged labelling retaining (LR) HSCs, which are in the old mice the most quiescent HSC subpopulation with the highest regenerative capacity and cellular polarity, reside predominantly in perisinusoidal niches. Furthermore, we demonstrate that sinusoidal niches and perisinusoidal Nes-GFPlow cells are uniquely preserved in shape, morphology and number upon ageing. Finally, we show that myeloablative chemotherapy can selectively disrupt aged sinusoidal niches, which is linked to hematopoietic failure and decreased survival of aged mice. Overall, our data characterize for the first time the functional alterations of the aged HSC niche and unveil that perisinusoidal niches are uniquely preserved and protect HSCs from ageing.
Project description:The hematopoietic stem cell (HSC) compartment is heterogeneous, yet our understanding of the identities of different HSC subtypes is limited. Here we show that platelet integrin CD41 (M-NM-1IIb), currently thought to only transiently mark fetal HSCs, is expressed on an adult HSC subtype that accumulates with age. CD41+ HSCs were largely quiescent and exhibited myeloerythroid and megakaryocyte gene priming, governed by Gata1, whereas CD41- HSCs were more proliferative and exhibited lymphoid gene priming. When isolated without the use of blocking antibodies, CD41+ HSCs possessed long-term repopulation capacity upon serial transplantations and showed a marked myeloid-bias compared to CD41-HSCs, which yielded a more lymphoid-biased progeny. CD41-knockout mice displayed multilineage hematopoietic defects coupled with decreased quiescence and survival of HSCs, suggesting that CD41 is functionally relevant for HSC maintenance and hematopoietic homeostasis. Transplantation experiments indicated that CD41-KO associated defects are long-term transplantable and HSC-derived, and in part mediated through the loss of platelet mass leading to decreases in HSC exposure to important platelet released cytokines, such as TGFM-NM-21. In summary, our data provide a novel marker to identify a myeloid-biased HSC subtype that becomes prevalent with age, and highlights the dogma of HSC regulation by their progeny. For microarray analysis, 1000 HSCs were FACS sorted from pools of 4-5 mice directly into lysis buffer, RNA extracted and whole transcript amplification was performed as previously described (Gonzalez-Roca E, Garcia-Albeniz X, Rodriguez-Mulero S, Gomis RR, Kornacker K, Auer H. Accurate expression profiling of very small cell populations. PLoS One. 2010;5:e14418.)