The DNA-binding protein, Ikaros, functions as a potent tumor suppressor and hematopoietic regulator. However, the mechanisms by which Ikaros functions in the nucleus remain largely undefined, due in part to its atypical DNA-binding properties and partnership with the poorly understood Mi-2/NuRD complex. In this study, we extended our analysis of thymocyte development and lymphomagenesis in a mouse strain containing a specific deletion of Ikaros zinc finger 4, which exhibits a select subset of abnormalities observed in Ikaros null mice. By examining thymopoiesis in vivo and in vitro, numerous abnormalities were observed. RNA-sequencing revealed that each developmental stage is characterized by mis-regulation of a limited number of genes, with a strong preference for genes modulated in a stage-specific manner. Strikingly, individual genes and pathways rarely exhibited Ikaros-dependence at all developmental stages. Instead, the most consistent feature of aberrantly expressed genes was a reduced magnitude of expression level change during a developmental transition. These results and others suggest that Ikaros may not be a dedicated and consistent activator or repressor of a defined set of genes. Instead, its primary function may be to support the dynamic range of gene expression changes during developmental transitions via atypical molecular mechanisms that remain undefined. Overall design: RNA-Seq of T cells at varying developmental stages and T cells expressing activated Notch in WT and Ikzf1-dF4/dF4 mutant backgrounds
Regulation of gene expression dynamics during developmental transitions by the Ikaros transcription factor.
No sample metadata fields
View SamplesThe development, homeostasis and function of B lymphocytes involve multiple rounds of B cell receptor (BCR)-controlled proliferation and prolonged maintenance. We analyzed the role of transcription factor Zfx, a recently identified regulator of stem cell maintenance, in B cell development and homeostasis. Conditional Zfx deletion in the bone marrow blocked B cell development at the pre-BCR selection checkpoint. Zfx deficiency in peripheral B cells caused impaired generation of the B-1 cell lineage, accelerated B cell turnover, depletion of mature recirculating cells, and delayed T-dependent antibody responses. Zfx-deficient B cells showed normal proximal BCR signaling, but impaired BCR-induced proliferation and survival. This was accompanied by aberrantly enhanced and prolonged integrated stress response, and delayed induction of Cyclin D2 and Bcl-xL proteins. Thus, Zfx restrains the stress response and couples antigen receptor signaling to B cell expansion and maintenance during development and peripheral homeostasis.
Transcription factor Zfx controls BCR-induced proliferation and survival of B lymphocytes.
No sample metadata fields
View SamplesStem cells (SC) exhibit a unique capacity for self-renewal in an undifferentiated state. It is unclear whether the self-renewal of pluripotent embryonic SC (ESC) and of tissue-specific adult SC such as hematopoietic SC (HSC) is controlled by common mechanisms. The deletion of transcription factor Zfx impaired the self-renewal but not the differentiation capacity of murine ESC; conversely, Zfx overexpression facilitated ESC self-renewal by opposing differentiation. Furthermore, Zfx deletion abolished the maintenance of adult bone marrow HSC, but did not affect erythromyeloid progenitors or fetal HSC. In both ESC and HSC, Zfx activated a common set of direct target genes. In addition, the loss of Zfx resulted in the induction of immediate-early and/or stress-inducible genes in both SC types but not in their differentiated progeny. These studies identify the first shared transcriptional regulator of ESC and HSC, suggesting a common molecular basis of self-renewal in embryonic and adult SC.
Zfx controls the self-renewal of embryonic and hematopoietic stem cells.
No sample metadata fields
View SamplesThe C2H2 zinc finger is the most prevalent DNA-binding motif in the mammalian proteome, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros, a critical regulator of lymphopoiesis and leukemogenesis. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling (this GEO submission: RNA-Seg of whole thymus from wt and the two ZnF mutants), reveal that different subsets of fingers within multi-finger transcription factors can regulate distinct target genes and biological functions, and they demonstrate that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors. Overall design: Ikaros RNA-Seq from double positive thymocytes comparing wt (n=2), Ikaros-ZnF1-/- mutant (n=2) and Ikaros-ZnF4-/- mutant (n=2)
Selective regulation of lymphopoiesis and leukemogenesis by individual zinc fingers of Ikaros.
Sex, Age, Specimen part, Cell line, Subject
View SamplesThe C2H2 zinc finger is the most prevalent DNA-binding motif in the mammalian proteome, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros, a critical regulator of lymphopoiesis and leukemogenesis. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling (this GEO submission: RNA-Seg of whole thymus from wt and the two ZnF mutants), reveal that different subsets of fingers within multi-finger transcription factors can regulate distinct target genes and biological functions, and they demonstrate that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors. Overall design: RNA-Seq from sorted primary proB cell Hardy Fractions B and C+C'', comparing wt, Ikaros-ZnF1-/- mutant and Ikaros-ZnF4-/- mutant.
Selective regulation of lymphopoiesis and leukemogenesis by individual zinc fingers of Ikaros.
Specimen part, Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
ZFX controls propagation and prevents differentiation of acute T-lymphoblastic and myeloid leukemia.
Specimen part, Cell line, Treatment
View SamplesAcute myeloid leukemia (AML) propagates as a cellular hierarchy which is maintained by a rare subpopulation of self-renewing leukemia-initiating cells (LICs). These LICs phenotypically resemble HSCs and early myeloid progenitors, and they are functionally defined by their ability to reconstitute AML in xenografted mice.
ZFX controls propagation and prevents differentiation of acute T-lymphoblastic and myeloid leukemia.
Cell line, Treatment
View SamplesAcute myeloid leukemia (AML) and acute T-lymphoblastic leukemia (T-ALL) maintain the undifferentiated phenotype and proliferative capacity of their respective cells of origin, hematopoietic stem/progenitor cells and immature thymocytes. The mechanisms that maintain these progenitor-like characteristics are poorly understood. We report that the transcription factor Zfx is required for the development and propagation of experimental AML caused by MLL-AF9 fusion, and of T-ALL caused by Notch1 activation. In both leukemia types, Zfx activated progenitor-associated gene expression programs and prevented differentiation. Key Zfx target genes included mitochondrial enzymes Ptpmt1 and Idh2, whose overexpression partially rescued the propagation of Zfx-deficient AML. These studies identify a common mechanism that controls the cell-of-origin characteristics of acute leukemias derived from disparate lineages and transformation mechanisms.
ZFX controls propagation and prevents differentiation of acute T-lymphoblastic and myeloid leukemia.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Temporal clustering of gene expression links the metabolic transcription factor HNF4α to the ER stress-dependent gene regulatory network.
Specimen part
View SamplesProtein misfolding stress in the endoplasmic reticulum (ER) leads to dysregulation of lipid metabolism in the liver, and ER stress is associated with human diseases that are accompanied by hepatic lipid accumulation, including obesity, alcoholism, and viral hepatitis; yet the pathways leading from ER stress to the regulation of lipid metabolism are poorly understood. Working exclusively in vivo, we used a bottom-up approach to infer pathways in the genetic regulation of lipid metabolism by the UPR.
Temporal clustering of gene expression links the metabolic transcription factor HNF4α to the ER stress-dependent gene regulatory network.
Specimen part
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