Project description:A greater understanding of the molecular pathways that underpin the unique human hematopoietic stem and progenitor cell (HSPC) self-renewal program will improve strategies to expand these critical cell types for regenerative therapies. The post-transcriptional mechanisms guiding HSPC fate during ex vivo expansion have not been closely investigated. Using shRNA-mediated knockdown, we show that the RNA-binding protein (RBP) Musashi-2 (MSI2) is required for human HSPC self-renewal. Conversely, when overexpressed, MSI2 induces multiple pro-self-renewal phenotypes, including significant ex vivo expansion of short- and long-term repopulating cells through direct attenuation of aryl hydrocarbon receptor (AHR) signaling. Using a global analysis of MSI2-RNA interactions, we determined that MSI2 post-transcriptionally downregulates canonical AHR pathway components in cord blood HSPCs. Our study provides new mechanistic insight into RBP-controlled RNA networks that underlie the self-renewal process and provides evidence that manipulating such networks can provide a novel means to enhance the regenerative potential of human HSPCs expanded ex vivo.
Project description:A greater understanding of the molecular pathways that underpin the unique human hematopoietic stem and progenitor cell (HSPC) self-renewal program will improve strategies to expand these critical cell types for regenerative therapies. The post-transcriptional mechanisms guiding HSPC fate during ex vivo expansion have not been closely investigated. Using shRNA-mediated knockdown, we show that the RNA-binding protein (RBP) Musashi-2 (MSI2) is required for human HSPC self-renewal. Conversely, when overexpressed, MSI2 induces multiple pro-self-renewal phenotypes, including significant ex vivo expansion of short- and long-term repopulating cells through direct attenuation of aryl hydrocarbon receptor (AHR) signaling. Using a global analysis of MSI2-RNA interactions, we determined that MSI2 post-transcriptionally downregulates canonical AHR pathway components in cord blood HSPCs. Our study provides new mechanistic insight into RBP-controlled RNA networks that underlie the self-renewal process and provides evidence that manipulating such networks can provide a novel means to enhance the regenerative potential of human HSPCs expanded ex vivo.
Project description:Targeting the estrogen signaling pathway has proved to be of great value in the treatment of human breast cancer. Tamoxifen, a selective estrogen receptor modulator (SERM), is the most widely used antiestrogen. However, only 40-50% of patients with estrogen receptor (ER) positive breast cancer benefit from tamoxifen treatment and 30-50% acquire resistance and the disease progresses. Continuous treatment with conventional therapy may contribute to cancer progression in recurring cancers through the accumulation of drug resistant cancer progenitors. We found that MCF7 tamoxifen-resistant (TAM-R) cells possess a significantly higher proportion of cancer progenitor cells than tamoxifen-sensitive MCF7 cells. Our results indicate that the chemokine receptor CXCR4 plays an important role in the maintenance of cancer progenitors in a tamoxifen-resistant cell line and downregulation of CXCR4 signaling by small molecule antagonists specifically inhibits growth of a stem-like cell population in tamoxifen-resistant tumors both in vitro and in vivo. Whole genome gene expression analysis revealed aryl hydrocarbon receptor (AhR) signaling as one of the top networks that is differentially regulated in MCF7(TAM-R) xenograft tumors treated with the CXCR4 antagonist AMD3100 as compared to MCF7 tumors. Further, small molecule antagonists of AhR signaling specifically inhibit the progenitor population in MCF7(TAM-R) cells suggesting that the aryl hydrocarbon receptor could be a putative target for the treatment of tamoxifen-resistant breast cancers. Introduction transplants remains limited by the ability to expand these cells ex vivo. An unbiased screen with primary human HSCs identified a purine derivative, StemRegenin 1 (SR1), that promotes the ex vivo expansion of CD34+ cells. Culture of HSCs with SR1 led to a 50-fold increase in cells expressing CD34 and a 17-fold increase in cells that retain the ability to engraft immunodeficient mice. Mechanistic studies show that SR1 acts by antagonizing the aryl hydrocarbon receptor (AHR). The identification of SR1 and AHR modulation as a means to induce ex vivo HSC expansion should facilitate the clinical use of HSC therapy. Tamoxifen resistant or sensitive xenografts; mice treated with estrogen and/or CXCR4 modulators
Project description:Hematopoietic progenitors from AML patients express the aryl hydrocarbon receptor signaling pathway. Independent of in vivo engraftability to detect leukemic stem cells, AHR antagonism allows in vitro survival and expansion of AML progenitors, while retaining patient-to-patient heterogeneity. Based on AML expression data, we show that AHR antagonism disrupts the AHR signaling pathway but it doesn't affect the overall genomic profile of the samples
Project description:This SuperSeries is composed of the following subset Series: GSE15857: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Kidney GSE15858: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Liver Refer to individual Series
Project description:An in vitro model of human hematopoietic stem cell differentiation is found to allow development of multiple immune lineages through use of single-cell methods. Using this model, we demonstrate that activation of aryl hydrocarbon receptor (AHR) signaling drives human hematopoietic stem and progenitor cells (HSPCs) to differentiate towards myeloid lineages at the expense of lymphoid lineages. Gene perturbations in progenitor cells and lineage-specified immune cells by AHR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are identified.
Project description:Although practiced clinically for more than 40 years, the use of hematopoietic stem cell (HSC) transplants remains limited by the ability to expand these cells ex vivo. An unbiased screen with primary human HSCs identified a purine derivative, StemRegenin 1 (SR1), that promotes the ex vivo expansion of CD34+ cells. Culture of HSCs with SR1 led to a 50-fold increase in cells expressing CD34 and a 17-fold increase in cells that retain the ability to engraft immunodeficient mice. Mechanistic studies show that SR1 acts by antagonizing the aryl hydrocarbon receptor (AHR). The identification of SR1 and AHR modulation as a means to induce ex vivo HSC expansion should facilitate the clinical use of HSC therapy. LGC006, a less potent SR1 analog, was also examined. KEYWORDS: two compounds, multiple doses, one time point two compounds, multiple doses, one time point
Project description:Emerging studies revealed an immunomodulatory role of the Aryl hydrocarbon receptor (AhR), a receptor sensing environmental contaminants, and involved in their detoxification. Besides its function as a transcription factor, AhR can participate in non-genomic signaling through ubiquitination and phosphorylation-dependent processes. In this study, a multi-PTM-omics approach, including proteome, ubiquitome, and phosphoproteome, was utilized to examine mechanisms of non-genomic AhR-signaling in endotoxin-activated monocyte-derived macrophages. This dataset entails proteome and phosphoproteome data.