Project description:Found PAR bZip target genes. The loss of circadian PAR bZip transcription factors results in epilepsy, DBP (albumin D-site-binding protein), HLF (hepatic leukemia factor), and TEF (thyrotroph embryonic factor) are the three members of the PAR bZip (proline and acidic amino acid-rich basic leucine zipper) transcription factor family. All three of these transcriptional regulatory proteins accumulate with robust circadian rhythms in tissues with high amplitudes of clock gene expression, such as the suprachiasmatic nucleus (SCN) and the liver. However, they are expressed at nearly invariable levels in most brain regions, in which clock gene expression only cycles with low amplitude. Here we show that mice deficient for all three PAR bZip proteins are highly susceptible to generalized spontaneous and audiogenic epilepsies that frequently are lethal. Transcriptome profiling revealed pyridoxal kinase (Pdxk) as a target gene of PAR bZip proteins in both liver and brain. Pyridoxal kinase converts vitamin B6 derivatives into pyridoxal phosphate (PLP), the coenzyme of many enzymes involved in amino acid and neurotransmitter metabolism. PAR bZip-deficient mice show decreased brain levels of PLP, serotonin, and dopamine, and such changes have previously been reported to cause epilepsies in other systems. Hence, the expression of some clock-controlled genes, such as Pdxk, may have to remain within narrow limits in the brain. This could explain why the circadian oscillator has evolved to generate only low-amplitude cycles in most brain regions.; find REV-ERB ALPHA target genes
Project description:Blood cell formation is a tightly regulated process initiated from a rare population of multipotent hematopoietic stem cells. Subsequent differentiation proceeds in a hierarchical manner with the generation of intermediate progenitor cells, in which alternative lineage potentials become gradually restricted. A deeper understanding of these events is crucial not only to understand normal blood cell formation, but also for leukemia, where a defining feature is inappropriate differentiation. Here, we identified Hepatic Leukemia Factor (Hlf) as being highly and selectively expressed in primitive multipotent hematopoietic stem and progenitors. We demonstrate that Hlf is a strong negative regulator of B-, NK- and T cell development and instructs multipotent progenitors to adopt a myeloid fate in a cell autonomous manner; phenotypes underwritten by the induction of myeloid affiliated transcriptional programs, the concomitant ablation of lymphoid gene programs and a genome-wide binding spectra that involved active enhancers of myeloid-competent cells. Collectively, our studies establish Hlf as a key regulator of the earliest lineage-commitment events at the transition from multipotency to lineage-restricted progeny, with implications for both normal and malignant hematopoiesis. Gene expression profiling of control or Hlf/Hlf lentivirus infected GMLPs (2 replicates per group) and Hlf inducible GMLPs maintained for 4 days on OP9 stroma in the presence or absence of doxycycline (2 replicates per group)
Project description:ZNF384-rearranged fusion oncoproteins (FO) define a subset of lineage ambiguous leukemias, but the mechanistic role of ZNF384 FO in leukemogenesis and lineage ambiguity is poorly understood. Here, using viral expression in mouse and human hematopoietic stem and progenitor cells (HSPCs) and a Ep300-Zfp384 mouse model we show that ZNF384 FO promote hematopoietic expansion, myeloid lineage skewing, and self-renewal. In mouse HSPCs, concomitant lesions such as NRASG12D, were required for fully penetrant leukemia, whereas expression of ZNF384 FO drove development of B/myeloid leukemia in human HSPCs, with sensitivity of human ZNF384r leukemia to FLT3 inhibition in vivo. Mechanistically, ZNF384 FO occupy a subset of predominantly intragenic/enhancer regions with increased histone 3 lysine acetylation suggesting enhancer function. These data define a paradigm for FO-driven lineage ambiguous leukemia, in which expression in HSPCs results in deregulation of lineage-specific genes and hematopoietic skewing, progressing to full leukemic transformation in the presence of proliferative stress.
Project description:The defining characteristics of leukemia, such as lineage and genetics, are associated with a typical age of onset. Understanding mechanisms of leukemia age specificity could improve disease models to develop new therapies. We used heterochronic transplantation of murine leukemia driven by MLL-AF9 to investigate the relative contribution of the age of the cell-of-origin or the hematopoietic microenvironment to the lineage fate of leukemia initiating cells (LICs). We show that the neonatal hematopoietic niche supports the development of infant-like mixed lineage B-cell/myeloid leukemia, while a mature niche promotes adult-like pure acute myeloid leukemia (AML) from identical cells of origin. We attribute this to inhibition of B-lymphoid fate in multipotent progenitor-like LICs by Ccl5 from adult bone marrow (BM) stroma, and implicate glycogen synthase kinase-3 (GSK-3) signaling in the myeloid fate specification in mouse and human MLL-driven leukemia. These findings connect maturation and aging of the hematopoietic system to leukemia age specificity.
Project description:The defining characteristics of leukemia, such as lineage and genetics, are associated with a typical age of onset. Understanding mechanisms of leukemia age specificity could improve disease models to develop new therapies. We used heterochronic transplantation of murine leukemia driven by MLL-AF9 to investigate the relative contribution of the age of the cell-of-origin or the hematopoietic microenvironment to the lineage fate of leukemia initiating cells (LICs). We show that the neonatal hematopoietic niche supports the development of infant-like mixed lineage B-cell/myeloid leukemia, while a mature niche promotes adult-like pure acute myeloid leukemia (AML) from identical cells of origin. We attribute this to inhibition of B-lymphoid fate in multipotent progenitor-like LICs by Ccl5 from adult bone marrow (BM) stroma, and implicate glycogen synthase kinase-3 (GSK-3) signaling in the myeloid fate specification in mouse and human MLL-driven leukemia. These findings connect maturation and aging of the hematopoietic system to leukemia age specificity.
Project description:The defining characteristics of leukemia, such as lineage and genetics, are associated with a typical age of onset. Understanding mechanisms of leukemia age specificity could improve disease models to develop new therapies. We used heterochronic transplantation of murine leukemia driven by MLL-AF9 to investigate the relative contribution of the age of the cell-of-origin or the hematopoietic microenvironment to the lineage fate of leukemia initiating cells (LICs). We show that the neonatal hematopoietic niche supports the development of infant-like mixed lineage B-cell/myeloid leukemia, while a mature niche promotes adult-like pure acute myeloid leukemia (AML) from identical cells of origin. We attribute this to inhibition of B-lymphoid fate in multipotent progenitor-like LICs by Ccl5 from adult bone marrow (BM) stroma, and implicate glycogen synthase kinase-3 (GSK-3) signaling in the myeloid fate specification in mouse and human MLL-driven leukemia. These findings connect maturation and aging of the hematopoietic system to leukemia age specificity.
Project description:The PAR-domain basic leucine zipper (PAR bZip) transcription factors DBP, TEF, and HLF accumulate in a highly circadian manner in several peripheral tissues, including liver and kidney. Mice devoid of all three of these proteins are born at expected Mendelian ratios, but are epilepsy-prone, age at an accelerated rate and die prematurely. In the hope of identifying PAR bZip target genes whose altered expression might contribute to the high morbidity and mortality of PAR bZip triple knockout mice, we compared the liver and kidney transcriptomes of these animals to those of wild-type or heterozygous mutant mice. These experiments revealed that PAR bZip proteins control the expression of many enzymes and regulators involved in detoxification and drug metabolism, such as cytochrome P450 enzymes, carboxylesterases, and constitutive androstane receptor (CAR). Indeed, PAR bZip triple knockout mice are hypersensitive to xenobiotic compounds, and the deficiency in detoxification may contribute to their early ageing.
Project description:Blood cell formation is a tightly regulated process initiated from a rare population of multipotent hematopoietic stem cells. Subsequent differentiation proceeds in a hierarchical manner with the generation of intermediate progenitor cells, in which alternative lineage potentials become gradually restricted. A deeper understanding of these events is crucial not only to understand normal blood cell formation, but also for leukemia, where a defining feature is inappropriate differentiation. Here, we identified Hepatic Leukemia Factor (Hlf) as being highly and selectively expressed in primitive multipotent hematopoietic stem and progenitors. We demonstrate that Hlf is a strong negative regulator of B-, NK- and T cell development and instructs multipotent progenitors to adopt a myeloid fate in a cell autonomous manner; phenotypes underwritten by the induction of myeloid affiliated transcriptional programs, the concomitant ablation of lymphoid gene programs and genome-wide binding spectra that involved active enhancers of myeloid-competent cells. Collectively, our studies establish Hlf as a key regulator of the earliest lineage-commitment events at the transition from multipotency to lineage-restricted progeny, with implications for both normal and malignant hematopoiesis.