Snai2 maintains bone marrow niche cells by repressing osteopontin expression
Ontology highlight
ABSTRACT: Bone marrow (BM) mesenchymal stem and progenitor cells (MSPCs) are a critical constituent of the hematopoietic stem cell (HSC) niche. Previous studies have suggested that the zinc-finger epithelial-mesenchymal transition transcription factor Snai2 (also known as Slug) regulated HSCs autonomously. Here, we show that Snai2 expression in the BM is restricted to the BM stromal compartment where it regulates the HSC niche. Germline or MSPC-selective Snai2 deletion reduces the functional MSPC pool, their mesenchymal lineage output, and impairs HSC niche function during homeostasis and after stress. RNA-sequencing analysis revealed that Spp1 (osteopontin) expression is markedly upregulated in Snai2-deficient MSPCs. Genetic deletion of Spp1 in Snai2-deficient mice, rescues MSPCs’ functions. Thus, SNAI2 is a critical regulator of the transcriptional network maintaining MSPCs by the suppression of osteopontin expression.
Project description:Transcriptional profiling of mouse mesenchymal stem/progenitor cells (MSPC) comparing control Ptpn11+/+ MSPC with Ptpn11E76K/+ MSPC. By obtaining 20 million reads of sequence from two pair, we confirmed our cytokine/chemokine array data and quantitative ELISA data from both mouse and patient-derived specimens. CCL3, CCL12, CCL4, and CXCL12 (SDF-1) were aberrantly produced by Ptpn11 mutated MSPCs
Project description:Cellular competition for limiting hematopoietic factors is a physiologically regulated but poorly understood process. Here, we studied this phenomenon by hampering hematopoietic progenitor access to Leptin receptor+ mesenchymal stem/progenitor cells (MSPCs) and endothelial cells (ECs). We showed that HSC numbers increased by 2-fold when multipotent and lineage-restricted progenitors fail to respond to CXCL12 produced by MSPCs and ECs. HSCs were qualitatively normal, and HSC expansion only occurred when early hematopoietic progenitors but not differentiated hematopoietic cells lacked CXCR4. Furthermore, the MSPC and EC transcriptomic heterogeneity was remarkably stable, suggesting that it is impervious to dramatic changes in hematopoietic progenitor interactions. Instead, HSC expansion was caused by increased availability of membrane-bound stem cell factor (mSCF) on MSPCs and ECs due to reduced consumption by cKit-expressing hematopoietic progenitors. These studies revealed an intricate homeostatic balance between HSCs and proximal hematopoietic progenitors regulated by cell competition for limiting amounts of mSCF.
Project description:Cellular competition for limiting hematopoietic factors is a physiologically regulated but poorly understood process. Here, we studied this phenomenon by hampering hematopoietic progenitor access to Leptin receptor+ mesenchymal stem/progenitor cells (MSPCs) and endothelial cells (ECs). We showed that HSC numbers increased by 2-fold when multipotent and lineage-restricted progenitors fail to respond to CXCL12 produced by MSPCs and ECs. HSCs were qualitatively normal, and HSC expansion only occurred when early hematopoietic progenitors but not differentiated hematopoietic cells lacked CXCR4. Furthermore, the MSPC and EC transcriptomic heterogeneity was remarkably stable, suggesting that it is impervious to dramatic changes in hematopoietic progenitor interactions. Instead, HSC expansion was caused by increased availability of membrane-bound stem cell factor (mSCF) on MSPCs and ECs due to reduced consumption by cKit-expressing hematopoietic progenitors. These studies revealed an intricate homeostatic balance between HSCs and proximal hematopoietic progenitors regulated by cell competition for limiting amounts of mSCF.
Project description:Hematopoietic stem cells (HSCs) primarily reside in the bone marrow, where they receive external cues from their local microenvironment. The complex milieu of biophysical cues, cellular components, and cell-secreted factors regulates the process by which HSC produce the blood and immune system. We previously showed direct co-culture of primary murine hematopoietic stem and progenitor cells with a population of marrow-derived mesenchymal stromal and progenitor cells (MSPCs) in a methacrylamide-functionalized gelatin (GelMA) hydrogel improves hematopoietic progenitor maintenance. However, the mechanism by which MSPCs influenced HSC fate decisions remained unknown. Herein, we report the use of proteomic analysis to correlate HSC phenotype to a broad candidate pool of 200 soluble factors produced by combined mesenchymal and hematopoietic progeny. Partial Least Squares Regression (PLSR), along with an iterative filter method, identified TGFβ-1, MMP-3, c-RP, and TROY as positively correlated with HSC maintenance. Experimentally, we then observe exogenous stimulation of HSC monocultures in GelMA hydrogels with these combined cytokines increases the ratio of hematopoietic progenitors to committed progeny after a 7-day culture 7.52 ± 3.65 fold compared to non-stimulated monocultures. Findings suggest a cocktail of the downselected cytokines amplify hematopoietic maintenance potential of HSCs beyond that of MSPC-secreted factors alone. This work integrates empirical and computation methods to identify cytokine combinations to improve HSC maintenance within an engineered HSC niche, suggesting a route towards identifying feeder-free culture platforms for HSC expansion.
Project description:SNAI2 is a transcription factor involved in multiple processes in both physiology and pathology, including apoptosis, epithelial-mesenchymal transition and tumorigenesis. The effects of SNAI2 on the epithelial compartment have been interpreted as an effect of its expression and action in that compartment. In this work, we demonstrated that the absence of Snai2 in other compartments has repercussions in different aspects of the behavior of the epithelial cells of luminal breast tumors, developed by MMTV-ErbB2/Neu transgenic mice that do not express SNAI2 in the epithelial component. The absent of SNAI2 in the stroma of these tumors is accompanied by different characteristics at histopathological and molecular levels than those having functional SNAI2. These results indicate that the expression of SNAI2 in the tumor niche contributes to the luminal tumor development and behavior.
Project description:De novo ASXL1 mutations are found in patients with Bohring-Opitz syndrome, a disease with severe developmental defects and early childhood fatality. The underlying pathologic mechanisms remain largely unknown. Using Asxl1-targeted murine models,we found that Asxl1 global loss or conditional deletion in osteoblasts and their progenitors in mice leads to significant bone loss and markedly decreased numbers of marrow mesenchymal stem/progenitor cells (MSPCs) compared with wild-type (WT) littermates. Asxl1-/- MSPCs displayed impaired self-renewal and skewed differentiation-away from osteoblasts and favoring adipocytes. RNA-seq analysis reveals the altered expression of genes involved in cell proliferation, skeletal development and morphogenesis. Furthermore, gene set enrichment analysis showed a decreased gene expression of stem cell self-renewal signature,suggesting the role of Asxl1 in regulating the stemness of MSPCs. Importantly, introducing Asxl1 normalized NANOG and OCT4 expression and restored the self-renewal capacity of Asxl1-/- MSPCs. Our study unveils a pivotal role of ASXL1 in maintenance of MSPC functions and skeletal development. Examination of mRNA profiles in wild type and Asxl1-/- MSPCs by deep sequencing
Project description:Myelodysplastic syndromes (MDS) are a heterogenous group of diseases affecting the hematopoietic stem cell that are curable only by stem cell transplantation. Both hematopoietic cell intrinsic changes and extrinsic signals from the bone marrow niche seem to ultimately lead to MDS. Animal models of MDS indicate that alterations in specific mesenchymal progenitor subsets in the bone marrow microenvironment can induce or select for abnormal hematopoietic cells. Here we identify a subset of human bone marrow (BM) mesenchymal cells marked by the expression of CD271, CD146 and CD106. This subset of human mesenchymal cells is equivalent to those in mice that, when perturbed, results in an MDS-like syndrome. Transcriptional analysis identified epithelial to mesenchymal transition as the most enriched gene set and Osteopontin (SPP1) as the most overexpressed gene. The loss of expression of Spp1 in the microenvironment resulted in an accelerated progression of the transplanted Vav-driven Nup98-HoxD13 MDS model as demonstrated by increased chimerism, increased contribution of mutant cells to the myeloid lineage and a more pronounced anemia when compared to animals with a wild type microenvironment. These data indicate that molecular perturbations can occur in specific bone marrow mesenchymal subsets of MDS patients. However, the niche adaptations to dysplastic clones include Spp1 overexpression that can constrain disease progression. Therefore, niche changes with malignant disease can also serve to protect the host.
Project description:Myelodysplastic syndromes (MDS) are a heterogenous group of diseases affecting the hematopoietic stem cell that are curable only by stem cell transplantation. Both hematopoietic cell intrinsic changes and extrinsic signals from the bone marrow niche seem to ultimately lead to MDS. Animal models of MDS indicate that alterations in specific mesenchymal progenitor subsets in the bone marrow microenvironment can induce or select for abnormal hematopoietic cells. Here we identify a subset of human bone marrow (BM) mesenchymal cells marked by the expression of CD271, CD146 and CD106. This subset of human mesenchymal cells is equivalent to those in mice that, when perturbed, results in an MDS-like syndrome. Transcriptional analysis identified epithelial to mesenchymal transition as the most enriched gene set and Osteopontin (SPP1) as the most overexpressed gene. The loss of expression of Spp1 in the microenvironment resulted in an accelerated progression of the transplanted Vav-driven Nup98-HoxD13 MDS model as demonstrated by increased chimerism, increased contribution of mutant cells to the myeloid lineage and a more pronounced anemia when compared to animals with a wild type microenvironment. These data indicate that molecular perturbations can occur in specific bone marrow mesenchymal subsets of MDS patients. However, the niche adaptations to dysplastic clones include Spp1 overexpression that can constrain disease progression. Therefore, niche changes with malignant disease can also serve to protect the host.
Project description:Myelodysplastic syndromes (MDS) are a heterogenous group of diseases affecting the hematopoietic stem cell that are curable only by stem cell transplantation. Both hematopoietic cell intrinsic changes and extrinsic signals from the bone marrow niche seem to ultimately lead to MDS. Animal models of MDS indicate that alterations in specific mesenchymal progenitor subsets in the bone marrow microenvironment can induce or select for abnormal hematopoietic cells. Here we identify a subset of human bone marrow (BM) mesenchymal cells marked by the expression of CD271, CD146 and CD106. This subset of human mesenchymal cells is equivalent to those in mice that, when perturbed, results in an MDS-like syndrome. Transcriptional analysis identified epithelial to mesenchymal transition as the most enriched gene set and Osteopontin (SPP1) as the most overexpressed gene. The loss of expression of Spp1 in the microenvironment resulted in an accelerated progression of the transplanted Vav-driven Nup98-HoxD13 MDS model as demonstrated by increased chimerism, increased contribution of mutant cells to the myeloid lineage and a more pronounced anemia when compared to animals with a wild type microenvironment. These data indicate that molecular perturbations can occur in specific bone marrow mesenchymal subsets of MDS patients. However, the niche adaptations to dysplastic clones include Spp1 overexpression that can constrain disease progression. Therefore, niche changes with malignant disease can also serve to protect the host.