Regulation of meiotic chromatin loop size by chromosomal position.

Heng, Henry H.Q.; Chamberlain, John W.; Shi, Xiaomei; Spyropoulos, Barbara; Tsui, Lap‐Chee; Møens, Peter B.

doi:10.1073/pnas.93.7.2795

Cited by 89 publications

(60 citation statements)

References 21 publications

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“…The presence of the glucocorticoid enhances the interaction by about threefold (compare lanes 3 and 4). These results are similar to those observed for interactions between several nuclear receptors and their partners (9,22). It should be pointed out that GR contains both ligand-dependent and ligand-independent activation domains.…”

Section: Baf250 Is An Integral Component Of Human Bafsupporting

confidence: 78%

A Specificity and Targeting Subunit of a Human SWI/SNF Family-Related Chromatin-Remodeling Complex

Nie

Xue

Yang

et al. 2000

Molecular and Cellular Biology

276

254

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The SWI/SNF family of chromatin-remodeling complexes facilitates gene activation by assisting transcription machinery to gain access to targets in chromatin. This family includes BAF (also called hSWI/SNF-A) and PBAF (hSWI/SNF-B) from humans and SWI/SNF and Rsc from Saccharomyces cerevisiae. However, the relationship between the human and yeast complexes is unclear because all human subunits published to date are similar to those of both yeast SWI/SNF and Rsc. Also, the two human complexes have many identical subunits, making it difficult to distinguish their structures or functions. Here we describe the cloning and characterization of BAF250, a subunit present in human BAF but not PBAF. BAF250 contains structural motifs conserved in yeast SWI1 but not in any Rsc components, suggesting that BAF is related to SWI/SNF. BAF250 is also a homolog of the Drosophila melanogaster Osa protein, which has been shown to interact with a SWI/SNFlike complex in flies. BAF250 possesses at least two conserved domains that could be important for its function. First, it has an AT-rich DNA interaction-type DNA-binding domain, which can specifically bind a DNA sequence known to be recognized by a SWI/SNF family-related complex at the ␤-globin locus. Second, BAF250 stimulates glucocorticoid receptor-dependent transcriptional activation, and the stimulation is sharply reduced when the C-terminal region of BAF250 is deleted. This region of BAF250 is capable of interacting directly with the glucocorticoid receptor in vitro. Our data suggest that BAF250 confers specificity to the human BAF complex and may recruit the complex to its targets through either protein-DNA or protein-protein interactions.

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Section: Baf250 Is An Integral Component Of Human Bafsupporting

confidence: 78%

A Specificity and Targeting Subunit of a Human SWI/SNF Family-Related Chromatin-Remodeling Complex

Nie

Xue

Yang

et al. 2000

Molecular and Cellular Biology

276

254

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“…We have previously shown that loop size is constrained according to the chromosomal region (Heng et al, 1996). When the same DNA fragments were integrated into different regions of the chromosome, the loop size was significantly different.…”

Section: Resultsmentioning

confidence: 99%

Chromatin loops are selectively anchored using scaffold/matrix-attachment regions

Heng

Goetze

Ye³

et al. 2004

Journal of Cell Science

182

140

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The biological significance of nuclear scaffold/matrix-attachment regions (S/MARs) remains a topic of long-standing interest. The key to understanding S/MAR behavior relies on determining the physical attributes of in vivo S/MARs and whether they serve as rigid or flexible chromatin loop anchors. To analyze S/MAR behavior, single and multiple copies of the S/MAR-containing constructs were introduced into various host genomes of transgenic mice and transfected cell lines. These in vivo integration events provided a system to study the association and integration patterns of each introduced S/MAR. By utilizing FISH to visualize directly the localization of S/MARs on the nuclear matrix or chromatin loop, we were able to assign specific attributes to the S/MAR. Surprisingly, when multiple-copy S/MARs were introduced they were selected and used as nuclear matrix anchors in a discriminatory manner, even though they all contained identical primary sequences. This selection process was probably mediated by S/MAR availability including binding strength and copy number, as reflected by the expression profiles and association of multi-copy tandem inserted constructs. Whereas S/MARs functioned as the mediators of loop attachment, they were used in a selective and dynamic fashion. Consequently, S/MAR anchors were necessary but not sufficient for chromatin loops to form. These observations reconcile many seemingly contradictory attributes previously associated with S/MARs.

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“…Meiotic prophase in the mouse has become a model system for studying principles of chromosome organization. There are antibodies available to several of the SC proteins (Dobson et al, 1994), and the determinants of loop size have been the subject of several investigations (Heng et al, 1994(Heng et al, , 1996. The haploid genome size is 2.5 ϫ 10 9 bp.…”

Section: Resultsmentioning

confidence: 99%

Polymer Models of Meiotic and Mitotic Chromosomes

Marko

Siggia

1997

MBoC

124

125

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Polymers tied together by constraints exhibit an internal pressure; this idea is used to analyze physical properties of the bottle-brush-like chromosomes of meiotic prophase that consist of polymer-like flexible chromatin loops, attached to a central axis. Using a minimal number of experimental parameters, semiquantitative predictions are made for the bending rigidity, radius, and axial tension of such brushes, and the repulsion acting between brushes whose bristles are forced to overlap. The retraction of lampbrush loops when the nascent transcripts are stripped away, the oval shape of diplotene bivalents between chiasmata, and the rigidity of pachytene chromosomes are all manifestations of chromatin pressure. This two-phase (chromatin plus buffer) picture that suffices for meiotic chromosomes has to be supplemented by a third constituent, a chromatin glue to understand mitotic chromosomes, and explain how condensation can drive the resolution of entanglements. This process resembles a thermal annealing in that a parameter (the affinity of the glue for chromatin and/or the affinity of the chromatin for buffer) has to be tuned to achieve optimal results. Mechanical measurements to characterize this protein-chromatin matrix are proposed. Finally, the propensity for even slightly chemically dissimilar polymers to phase separate (cluster like with like) can explain the apparent segregation of the chromatin into AϩT-and GϩC-rich regions revealed by chromosome banding.

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Regulation of meiotic chromatin loop size by chromosomal position.

Cited by 89 publications

References 21 publications

A Specificity and Targeting Subunit of a Human SWI/SNF Family-Related Chromatin-Remodeling Complex

A Specificity and Targeting Subunit of a Human SWI/SNF Family-Related Chromatin-Remodeling Complex

Chromatin loops are selectively anchored using scaffold/matrix-attachment regions

Polymer Models of Meiotic and Mitotic Chromosomes

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