ABSTRACT: Expression of one out of > 1000 olfactory receptor (OR) genes is stochastic, yet organized into anatomic "zones" along the dorsoventral axis of the olfactory epithelium. Here we profile the gene expression, chromatin state and nuclear architecture of olfactory sensory neurons and olfactory progenitors of different zones. We discovered that zonal OR expression is specified by two processes: low-level polygenic transcription of OR genes in olfactory progenitors, as wells as the chromatin structure and nuclear architecture during olfactory differentiation. Specifically, in cells of any zonal segment, polygenic transcription in olfactory progenitors defines the OR repertoire eligible for OR choice as the cells mature, while an increased level of heterochromatin and chromatin compaction represses ectopic more dorsally expressed ORs. We find that this process is regulated by the NFI family of transcription factors that are expressed in a graded fashion in the olfactory epithelium. Conditional deletion of NFI A, B, and X results in a transformation of the chromatin state and nucellar architecture and an accompanying shift in the preferred OR repertoire.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:The genome is partitioned into topologically associated domains and genomic compartments with shared chromatin valence. This architecture is constrained by the DNA polymer, which precludes interactions between genes on different chromosomes. Here we report a marked divergence from this pattern of nuclear organization that occurs in mouse olfactory sensory neurons. Chromatin conformation capture using in situ Hi-C on fluorescence-activated cell-sorted olfactory sensory neurons and their progenitors shows that olfactory receptor gene clusters from 18 chromosomes make specific and robust interchromosomal contacts that increase with differentiation of the cells. These contacts are orchestrated by intergenic olfactory receptor enhancers, the 'Greek islands', which first contribute to the formation of olfactory receptor compartments and then form a multi-chromosomal super-enhancer that associates with the single active olfactory receptor gene. The Greek-island-bound transcription factor LHX2 and adaptor protein LDB1 regulate the assembly and maintenance of olfactory receptor compartments, Greek island hubs and olfactory receptor transcription, providing mechanistic insights into and functional support for the role of trans interactions in gene expression.
Project description:Dendrite and synapse development are critical for establishing appropriate neuronal circuits, and disrupted timing of these events can alter connectivity leading to disordered neural function. In early postnatal development of cerebellar granule neurons (CGNs), the expression of many genes is temporally regulated. Further, NFI (Nuclear Factor I) proteins have been shown to play important roles in the regulation of gene expression in developing CGNs. To identify NFI-regulated genome-wide targets involved in late maturation of mouse CGNs, we performed two groups of microarray expression analysis: (1) temporal expression arrays using 1.5 and 6 day cultures of mouse CGNs representing immature and more mature CGNs, respectively, which identified 844 Temporal-Up or Down genes; and (2) NFI-regulated genes in 6 day CGN cultures that were infected at the time of plating with lentiviral vectors expressing either NFI dominant repressor (NFI-EnR) or EnR control protein. This identified 686 NFI-Up (NFI-EnR down-regulated) or NFI-Down (NFI-EnR up-regulated) genes. Overlap analysis identified 212 temporal genes that were regulated by NFI. These results indicated that NFI plays a pivotal role in the regulation of late CGN maturation. For temporal arrays, mouse CGN progenitors were purified from P6 mouse cerebellum and cultured for either 1.5 or 6 days. Three biological replicates were analyzed for each time point. For NFI arrays, CGN progenitors from P6 mice were transduced upon plating with either NFI-EnR or EnR control lentivirus and cultured 6 days. Four pairs of biological replicates were performed.
Project description:Using Affymetrix HG-U133-Plus 2.0 array and Laser Capture Microdissection techniques, we determined whether growth in different zones of the same tumor affected expression of genes by human pancreatic cancer cells. Human L3.6pl pancreatic cancer cells were implanted into the pancreas of nude mice. Gene expression patterns in tumor cells within the central and peripheral zones were compared and statistical differences were determined for 1222 genes. Bioinformatic functional prediction analysis revealed that 346 upregulated genes in the peripheral zone were related to cytoskeleton organization and biogenesis, cell cycle, cell adhesion, cell motility, DNA replication, localization, integrin-mediated signaling pathway, development, morphogenesis, and IkB kinase/NF-kB cascade; and 876 upregulated genes in the central zone were related with regulation of cell proliferation, regulation of transcription, transmembrane receptor protein tyrosine kinase signaling pathway, response to stress, small GTPase mediated signal transduction, hexose metabolism, cell death, response to external stimulus, carbohydrate metabolism, and response to wounding. Results from the microarray were confirmed for reliability by in situ hybridization analysis. Collectively, these data demonstrate zonal heterogeneity for gene expression profiles in tumors and suggest that characterization of zonal gene expression profiles are essential to obtain reproducible data, to predict disease prognosis, and to design specific therapeutics. Experiment Overall Design: Three paired samples