title: Insights into interphase large-scale chromatin structure from analysis of engineered chromosome regions.
abstract: How chromatin folds into mitotic and interphase chromosomes has remained a difficult question for many years. We have used three generations of engineered chromosome regions as a means of visualizing specific chromosome regions in live cells and cells fixed under conditions that preserve large-scale chromatin structure. Our results confirm the existence of large-scale chromatin domains and fibers formed by the folding of 10-nm and 30-nm chromatin fibers into larger, spatially distinct domains. Transcription at levels within severalfold of the levels measured for endogenous loci occur within these large-scale chromatin structures on a condensed template linearly compacted several hundred fold to 1000-fold relative to B-form DNA. However, transcriptional induction is accompanied by a severalfold decondensation of this large-scale chromatin structure that propagates hundreds of kilobases beyond the induced gene. Examination of engineered chromosome regions in mouse embryonic stem cells (ESCs) and differentiated cells suggests a surprising degree of plasticity in this large-scale chromatin structure, allowing long-range DNA interactions within the context of large-scale chromatin fibers. Recapitulation of gene-specific differences in large-scale chromatin conformation and nuclear positioning using these engineered chromosome regions will facilitate identification of cis and trans determinants of interphase chromosome architecture.
authors.affiliation: Department of Cell and Developmental Biology and Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA. asbel@illinois.edu
authors.forename: A S
authors.initials: AS
authors.lastname: Belmont
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: P B
authors.initials: PB
authors.lastname: Sinclair
authors.forename: W
authors.initials: W
authors.lastname: Wu
authors.forename: Q
authors.initials: Q
authors.lastname: Bian
authors.forename: I
authors.initials: I
authors.lastname: Kireev
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002843:Chromatin / Q000737:chemistry* / Q000648:ultrastructure; D033481:Chromosomes, Mammalian / Q000235:genetics* / Q000648:ultrastructure; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D005818:Genetic Engineering; D015894:Genome, Human / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D051379:Mice; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D002843:Chromatin