Dataset Information

The Role of Crowding Forces in Juxtaposing ?-Globin Gene Domain Remote Regulatory Elements in Mouse Erythroid Cells.

ABSTRACT: The extremely high concentration of macromolecules in a eukaryotic cell nucleus indicates that the nucleoplasm is a crowded macromolecular solution in which large objects tend to gather together due to crowding forces. It has been shown experimentally that crowding forces support the integrity of various nuclear compartments. However, little is known about their role in control of chromatin dynamics in vivo. Here, we experimentally addressed the possible role of crowding forces in spatial organization of the eukaryotic genome. Using the mouse ?-globin domain as a model, we demonstrated that spatial juxtaposition of the remote regulatory elements of this domain in globin-expressing cells may be lost and restored by manipulation of the level of macromolecular crowding. In addition to proving the role of crowding forces in shaping interphase chromatin, our results suggest that the folding of the chromatin fiber is a major determinant in juxtaposing remote genomic elements.

SUBMITTER: Golov AK

PROVIDER: S-EPMC4593578 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Publications

The Role of Crowding Forces in Juxtaposing β-Globin Gene Domain Remote Regulatory Elements in Mouse Erythroid Cells.

Golov Arkadiy K AK Gavrilov Alexey A AA Razin Sergey V SV

PloS one 20151005 10

The extremely high concentration of macromolecules in a eukaryotic cell nucleus indicates that the nucleoplasm is a crowded macromolecular solution in which large objects tend to gather together due to crowding forces. It has been shown experimentally that crowding forces support the integrity of various nuclear compartments. However, little is known about their role in control of chromatin dynamics in vivo. Here, we experimentally addressed the possible role of crowding forces in spatial organi ...[more]

PMID: 26436546

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Project description:The Lim domain only 2 (Lmo2) gene encodes a transcriptional cofactor critical for the development of hematopoietic stem cells. Several distal regulatory elements have been identified upstream of the Lmo2 gene in the human and mouse genomes that are capable of enhancing reporter gene expression in erythroid cells and may be responsible for the high level transcription of Lmo2 in the erythroid lineage. In this study we investigate how these elements regulate transcription of Lmo2 and whether or not they function cooperatively in the endogenous context. Chromosome conformation capture (3C) experiments show that chromatin-chromatin interactions exist between upstream regulatory elements and the Lmo2 promoter in erythroid cells but that these interactions are absent from kidney where Lmo2 is transcribed at twelve fold lower levels. Specifically, long range chromatin-chromatin interactions occur between the Lmo2 proximal promoter and two broad regions, 3-31 and 66-105 kb upstream of Lmo2, which we term the proximal and distal control regions for Lmo2 (pCR and dCR respectively). Each of these regions is bound by several transcription factors suggesting that multiple regulatory elements cooperate in regulating high level transcription of Lmo2 in erythroid cells. Binding of CTCF and cohesin which support chromatin loops at other loci were also found within the dCR and at the Lmo2 proximal promoter. Intergenic transcription occurs throughout the dCR in erythroid cells but not in kidney suggesting a role for these intergenic transcripts in regulating Lmo2, similar to the broad domain of intergenic transcription observed at the human β-globin locus control region. Our data supports a model in which the dCR functions through a chromatin looping mechanism to contact and enhance Lmo2 transcription specifically in erythroid cells. Furthermore, these chromatin loops are supported by the cohesin complex recruited to both CTCF and transcription factor bound regions.

Project description:UNLABELLED: BACKGROUND: The ?-globin gene domains of vertebrate animals constitute popular models for studying the regulation of eukaryotic gene transcription. It has previously been shown that in the mouse the developmental switching of globin gene expression correlates with the reconfiguration of an active chromatin hub (ACH), a complex of promoters of transcribed genes with distant regulatory elements. Although it is likely that observations made in the mouse ?-globin gene domain are also relevant for this locus in other species, the validity of this supposition still lacks direct experimental evidence. Here, we have studied the spatial organization of the chicken ?-globin gene domain. This domain is of particular interest because it represents the perfect example of the so-called 'strong' tissue-specific gene domain flanked by insulators, which delimit the area of preferential sensitivity to DNase I in erythroid cells. RESULTS: Using chromosome conformation capture (3C), we have compared the spatial configuration of the ?-globin gene domain in chicken red blood cells (RBCs) expressing embryonic (3-day-old RBCs) and adult (9-day-old RBCs) ?-globin genes. In contrast to observations made in the mouse model, we found that in the chicken, the early embryonic ?-globin gene, ?, did not interact with the locus control region in RBCs of embryonic lineage (3-day RBCs), where this gene is actively transcribed. In contrast to the mouse model, a strong interaction of the promoter of another embryonic ?-globin gene, ?, with the promoter of the adult ?-globin gene, ?A, was observed in RBCs from both 3-day and 9-day chicken embryos. Finally, we have demonstrated that insulators flanking the chicken ?-globin gene domain from the upstream and from the downstream interact with each other, which places the area characterized by lineage-specific sensitivity to DNase I in a separate chromatin loop. CONCLUSIONS: Taken together, our results strongly support the ACH model but show that within a domain of tissue-specific genes, the active status of a promoter does not necessarily correlate with the recruitment of this promoter to the ACH.

Dataset Information

The Role of Crowding Forces in Juxtaposing ?-Globin Gene Domain Remote Regulatory Elements in Mouse Erythroid Cells.

Publications

The Role of Crowding Forces in Juxtaposing β-Globin Gene Domain Remote Regulatory Elements in Mouse Erythroid Cells.

Similar Datasets

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