Project description:Motor neuron (MN), together with interneuron, are the two major neuronal types in spinal cord. MNs control muscle movement and are essential for breathing, walking and fine motor skills. Malfunction of MNs is frequently associated with neuronal diseases such as spinal muscular atrophy and amyotrophic lateral sclerosis. To establish normal function, MNs need to be differentiated properly from neural progenitor cells. Thus, it is of great importance to study the mechanism for MN specification. This study focuses on Mnx1 - a conserved homeobox transcription factor gets expressed during MN specification. Mnx1 is also the most widely used MN marker. Previous studies reported that Mnx1 mutation in mouse causes early lethality - probably by affecting the controlling over respiratory system. However, the exact role of Mnx1 for MN identity remains poorly understood. Taking advantage of a recently developed in vitro model for efficient MN induction from mouse ES cells, we combined experimental and OMICs techniques to systematically investigate the molecular function of Mnx1. We identified thousands of Mnx1 binding sites - many are co-bound by core MN factor Lhx3 and Isl1 and lack active histone marks. Disruption of Mnx1 causes increased expression of 85 genes - while only 14 genes get down-regulated. Up-regulated genes are enriched with neuronal functions, usually get expressed during MN differentiation, and tend to have higher expression in motor neurons and brain compared with other tissues – indicating Mnx1 may fine tune neuronal genes to desired level. However, only a dozen of regions with increased H3K27ac marks are bound by Mnx1, and only two up-regulated genes (Pbx3 and Pou6f2) are identified as putative direct targets of Mnx1 - both are core neuronal factors with the potential to regulate other differential neuronal genes. These results suggest that Mnx1 may contribute to MN identity by fine-tuning the expression of many neuronal genes through direct regulation of a few core neuronal transcription factors. In summary, this study represents the first systematic investigation about the molecular function of the core MN factor Mnx1. It clarifies the mechanism of Mnx1 for MN identity, and also improves the understanding about the regulation mode of homeobox transcription factors.
Project description:The leukemic cell line GDM-1 was established from a patient with acute myelomonoblastic leukemia [4]. GDM-1 cells carry a reciprocal translocation t(6;7)(q23;q36) juxtaposing the transcription factor (TF) gene motor neuron and pancreas homeobox 1 (MNX1, also designated HLXB9 or HB9) on chromosome 7 (chr7) to the locus of the transcriptional activator MYB on chr6. The translocation does not result in a fusion transcript but leads to aberrant activation of MNX1, suspected to be due to altered topologically associating domains, nuclear positioning or ectopic mechanisms. GDM-1 represents the only AML cell line overexpressing MNX1. Here we demonstrate that the interaction between the MNX1 promoter with a ‘hijacked’ enhancer from the MYB/AHI1 locus leads to ectopic activation of MNX1.
Project description:The leukemic cell line GDM-1 was established from a patient with acute myelomonoblastic leukemia [4]. GDM-1 cells carry a reciprocal translocation t(6;7)(q23;q36) juxtaposing the transcription factor (TF) gene motor neuron and pancreas homeobox 1 (MNX1, also designated HLXB9 or HB9) on chromosome 7 (chr7) to the locus of the transcriptional activator MYB on chr6. The translocation does not result in a fusion transcript but leads to aberrant activation of MNX1, suspected to be due to altered topologically associating domains, nuclear positioning or ectopic mechanisms. GDM-1 represents the only AML cell line overexpressing MNX1. Here we demonstrate that the interaction between the MNX1 promoter with a ‘hijacked’ enhancer from the MYB/AHI1 locus leads to ectopic activation of MNX1.
Project description:The leukemic cell line GDM-1 was established from a patient with acute myelomonoblastic leukemia [4]. GDM-1 cells carry a reciprocal translocation t(6;7)(q23;q36) juxtaposing the transcription factor (TF) gene motor neuron and pancreas homeobox 1 (MNX1, also designated HLXB9 or HB9) on chromosome 7 (chr7) to the locus of the transcriptional activator MYB on chr6. The translocation does not result in a fusion transcript but leads to aberrant activation of MNX1, suspected to be due to altered topologically associating domains, nuclear positioning or ectopic mechanisms. GDM-1 represents the only AML cell line overexpressing MNX1. Here we demonstrate that the interaction between the MNX1 promoter with a ‘hijacked’ enhancer from the MYB/AHI1 locus leads to ectopic activation of MNX1.
Project description:The leukemic cell line GDM-1 was established from a patient with acute myelomonoblastic leukemia [4]. GDM-1 cells carry a reciprocal translocation t(6;7)(q23;q36) juxtaposing the transcription factor (TF) gene motor neuron and pancreas homeobox 1 (MNX1, also designated HLXB9 or HB9) on chromosome 7 (chr7) to the locus of the transcriptional activator MYB on chr6. The translocation does not result in a fusion transcript but leads to aberrant activation of MNX1, suspected to be due to altered topologically associating domains, nuclear positioning or ectopic mechanisms. GDM-1 represents the only AML cell line overexpressing MNX1. Here we demonstrate that the interaction between the MNX1 promoter with a ‘hijacked’ enhancer from the MYB/AHI1 locus leads to ectopic activation of MNX1.
Project description:In mammals, fine motor control is essential for skilled behavior, and is subserved by specialized subdivisions of the primary motor cortex (M1) and other components of the brain’s motor circuitry. We profiled the epigenomic state of several components of the Rhesus macaque motor system, including subdivisions of M1 corresponding to hand and orofacial control. We compared this to open chromatin data from M1 in rat, mouse, and human. We found broad similarities as well as unique specializations in open chromatin regions (OCRs) between M1 subdivisions and other brain regions, as well as species- and lineage-specific differences reflecting their evolutionary histories. By distinguishing shared mammalian M1 OCRs from primate- and human-specific specializations, we highlight gene regulatory programs that could subserve the evolution of skilled motor behaviors such as speech and tool use. Further, in order to predict candidate enhancers in additional species for which primary data was not available, we developed machine learning models trained on genome sequence across species.
Project description:The leukemic cell line GDM-1 was established from a patient with acute myelomonoblastic leukemia [4]. GDM-1 cells carry a reciprocal translocation t(6;7)(q23;q36) juxtaposing the transcription factor (TF) gene motor neuron and pancreas homeobox 1 (MNX1, also designated HLXB9 or HB9) on chromosome 7 (chr7) to the locus of the transcriptional activator MYB on chr6. The translocation does not result in a fusion transcript but leads to aberrant activation of MNX1, suspected to be due to altered topologically associating domains, nuclear positioning or ectopic mechanisms. GDM-1 represents the only AML cell line overexpressing MNX1. Here we demonstrate that the interaction between the MNX1 promoter with a ‘hijacked’ enhancer from the MYB/AHI1 locus leads to ectopic activation of MNX1.
Project description:Acute myeloid leukemia (AML) results from aberrant hematopoietic processes and these changes are frequently initiated by chromosomal translocations. One particular subtype, AML with translocation t(7;12)(q36;p13), is found in children diagnosed before two years of age. The chromosomal breakage points of the t(7;12) have consistently been found to be located after exon 1 in the Motor neuron and pancreas homeobox 1 (MNX1) gene in chromosome 7, and after exon 2 in the ETV6 gene in chromosome 12. The aim of this study is the investigation of the leukomogenic potenial of MNX1 overexpression and MNX1-ETV6 fusion using mouse models, in addition to the molecular pathway through which MNX1 is inducing leukemia.