Project description:BLNK (BASH/SLP-65) encodes an adaptor protein within the B-cell receptor signaling. Loss-of-function mutations of BLNK are observed in human preB-ALL, and a subset of Blnk knock-out mice develop preB-ALL. To understand the molecular mechanism of preB-ALL development associated with the Blnk mutation, retroviral tagging was applied on Blnk KO mice using Moloney murine leukemia virus (MoMLV). The Blnk mutation significantly accelerated the disease onset of MoMLV-induced leukemia and increased the incidence of preB-ALL. Cebpb was identified as the most frequent common retroviral integration site, suggesting that Cebpb upregulation cooperates with Blnk mutation. Transgenic expression of the LAP (liver-enriched activator protein) isoform of C/EBP-beta significantly accelerated preB-ALL development of Blnk ko mice. We used microarrays to detail the global program of gene expression in mouse preB-ALL
Project description:BLNK (BASH/SLP-65) encodes an adaptor protein within the B-cell receptor signaling. Loss-of-function mutations of BLNK are observed in human preB-ALL, and a subset of Blnk knock-out mice develop preB-ALL. To understand the molecular mechanism of preB-ALL development associated with the Blnk mutation, retroviral tagging was applied on Blnk KO mice using Moloney murine leukemia virus (MoMLV). The Blnk mutation significantly accelerated the disease onset of MoMLV-induced leukemia and increased the incidence of preB-ALL. Cebpb was identified as the most frequent common retroviral integration site, suggesting that Cebpb upregulation cooperates with Blnk mutation. Transgenic expression of the LAP (liver-enriched activator protein) isoform of C/EBP-beta significantly accelerated preB-ALL development of Blnk ko mice. We used microarrays to detail the global program of gene expression in mouse preB-ALL
Project description:Additional sex comb-like 1 (ASXL1) is frequently mutated in a spectrum of myeloid malignancies and is associated with poor prognosis. Cancer genome sequencing found that AXL1 mutations frequently co-occur with splicing factors’ mutations (SRSF2, U2AF1, ZRZR2 and SF3B1) in myeloid malignancies. Several studies have reported that Patients with both ASXL1 and splicing mutations have a significantly worse prognosis than those with a single type of mutation, but the mechanisms largely remain to be elucidated. Here we constructed an ASXL1 and SRSF2 co-mutated mouse model and found that Srsf2P95H/+ mutation exacerbated Asxl1Y588XTg-induced leukemogenesis. Mechanistically, the co-existence of ASXL1 mutation and SRSF2 mutation altered the function of hematopoietic stem and progenitor cells and resulted in skewed myeloid differentiation.
Project description:CCAAT/enhancer binding protein beta (C/EBPb) is a member of a family of highly conserved transcription factors that regulates numerous genes involved in proliferation and differentiation in a variety of tissues. C/EBPb is deregulated in human breast cancer and germline deletion of this gene results in multiple defects in mammary gland development. We hypothesized that C/EBPb regulates mammary stem cell self-renewal, maintenance and/or differentiation through the regulation of multiple target genes that coordinate mammary gland development. Utilizing both a germline knockout mouse model and a conditional knockout strategy, we demonstrated that mammosphere formation was significantly decreased in C/EBPb-deficient mammary epithelial cells (MECs). The ability of C/EBPb-deleted MECs to regenerate the mammary gland in vivo was severely impaired when transplanted at limiting dilution. Furthermore, serial transplantation of C/EBPb-null mammary tissue resulted in decreased outgrowth potential when compared to wildtype, and an early senescence phenotype. Flow cytometric analysis revealed that C/EBPb-null MECs contain a lower frequency of repopulating stem cells accompanied by an increase in committed, differentiated luminal cells as compared to wildtype. Microarray analysis of stem/progenitor cell populations was performed and revealed an alteration in cell fate specification in C/EBPb-null glands, exemplified by the aberrant expression of basal markers in the luminal cell compartment. Collectively, our studies demonstrate that C/EBPb is a critical regulator of mammary stem cell differentiation, and an important determinant of luminal cell fate specification. Experiment Overall Design: To identify potential signaling pathways regulated by C/EBPb in stem/progenitor cells, microarray analysis was performed on two stem/progenitor cell subpopulations. For this analysis, subpopulations defined by LIN-CD24+CD29hi and LIN-CD24hiCD29lo were FACS sorted from wildtype and germline C/EBPb-/- glands, and RNA was isolated from each group.
Project description:CCAAT/enhancer binding protein beta (C/EBPb) is a member of a family of highly conserved transcription factors that regulates numerous genes involved in proliferation and differentiation in a variety of tissues. C/EBPb is deregulated in human breast cancer and germline deletion of this gene results in multiple defects in mammary gland development. We hypothesized that C/EBPb regulates mammary stem cell self-renewal, maintenance and/or differentiation through the regulation of multiple target genes that coordinate mammary gland development. Utilizing both a germline knockout mouse model and a conditional knockout strategy, we demonstrated that mammosphere formation was significantly decreased in C/EBPb-deficient mammary epithelial cells (MECs). The ability of C/EBPb-deleted MECs to regenerate the mammary gland in vivo was severely impaired when transplanted at limiting dilution. Furthermore, serial transplantation of C/EBPb-null mammary tissue resulted in decreased outgrowth potential when compared to wildtype, and an early senescence phenotype. Flow cytometric analysis revealed that C/EBPb-null MECs contain a lower frequency of repopulating stem cells accompanied by an increase in committed, differentiated luminal cells as compared to wildtype. Microarray analysis of stem/progenitor cell populations was performed and revealed an alteration in cell fate specification in C/EBPb-null glands, exemplified by the aberrant expression of basal markers in the luminal cell compartment. Collectively, our studies demonstrate that C/EBPb is a critical regulator of mammary stem cell differentiation, and an important determinant of luminal cell fate specification. Keywords: multiple group comparison
Project description:Genetic studies have identified recurrent somatic mutations in Acute Myeloid Leukemia (AML) patients, including in WT1 (Wilms’ tumor gene 1). The molecular mechanisms by which WT1 mutations contribute to leukemogenesis have not yet been fully elucidated. We investigated the role of Wt1 gene dosage in steady state and pathologic hematopoiesis. Wt1 heterozygous loss enhanced stem cell self-renewal in an age-dependent manner, with increased stem cell function over time and age-dependent leukemic transformation. Wt1-haploinsufficient leukemias were characterized by progressive genetic and epigenetic alterations, including in known leukemia disease alleles, demonstrating a requirement for additional events to promote hematopoietic transformation. Consistent with this observation, we found that Wt1 haploinsufficiency cooperates with Flt3-ITD mutation to induce fully penetrant AML. Our studies provide insight into mechanisms of Wt1-loss in leukemogenesis and into the evolutionary events required to induce transformation of Wt1-haploinsufficient stem/progenitor cells.