Exploring chromosomal structural heterogeneity across multiple cell lines
Abstract
Using computer simulations, we generate cell-specific 3D chromosomal structures and compare them to recently published chromatin structures obtained through microscopy. We demonstrate using machine learning and polymer physics simulations that epigenetic information can be used to predict the structural ensembles of multiple human cell lines. Theory predicts that chromosome structures are fluid and can only be described by an ensemble, which is consistent with the observation that chromosomes exhibit no unique fold. Nevertheless, our analysis of both structures from simulation and microscopy reveals that short segments of chromatin make two-state transitions between closed conformations and open dumbbell conformations. Finally, we study the conformational changes associated with the switching of genomic compartments observed in human cell lines. The formation of genomic compartments resembles hydrophobic collapse in protein folding, with the aggregation of denser and predominantly inactive chromatin driving the positioning of active chromatin toward the surface of individual chromosomal territories.
Data availability
All of the simulated chromosome structures have been deposited in the Nucleome Data Bank (https://ndb.rice.edu/Data).
-
Cheng_etal_H1-hESC_2020Nucleome Data Bank, Cheng_etal_H1-hESC_2020.
-
Cheng_etal_HUVEC_2020Nucleome Data Bank, Cheng_etal_HUVEC_2020.
-
Cheng_etal_HMEC_2020Nucleome Data Bank, Cheng_etal_HMEC_2020.
-
Cheng_etal_Hela-S3_2020Nucleome Data Bank, Cheng_etal_Hela-S3_2020.
-
Cheng_etal_IMR90_2020Nucleome Data Bank, Cheng_etal_IMR90_2020.
-
Cheng_etal_K562_2020Nucleome Data Bank, Cheng_etal_K562_2020.
-
IMR90_chr21-18-20Mb.csvIMR90_chr21-18-20Mb.csv.
-
IMR90_chr21-28-30Mb.csvIMR90_chr21-28-30Mb.csv.
-
K562_chr21-28-30Mb.csvK562_chr21-28-30Mb.csv.
Article and author information
Author details
Funding
National Science Foundation (PHY-1427654)
- Ryan R Cheng
- Vinicius Contessoto
- Erez Lieberman-Aiden
- Peter G Wolynes
- Michele Di Pierro
- Jose N Onuchic
NHGRI Center for Excellence for Genomic Sciences (HG006193)
- Erez Lieberman-Aiden
Welch Foundation (Q-1866)
- Erez Lieberman-Aiden
Cancer Prevention and Research Institute of Texas (R1304)
- Erez Lieberman-Aiden
NIH Office of the Director (U01HL130010)
- Erez Lieberman-Aiden
NIH Office of the Director (UM1HG009375)
- Erez Lieberman-Aiden
NVIDIA Research Center Award
- Erez Lieberman-Aiden
IBM University Challenge Award
- Erez Lieberman-Aiden
Google Research Award
- Erez Lieberman-Aiden
McNair Medical Institute Scholar
- Erez Lieberman-Aiden
President's Early Career in Science and Engineering
- Erez Lieberman-Aiden
National Science Foundation (CHE-1614101)
- Jose N Onuchic
Welch Foundation (C-1792)
- Jose N Onuchic
Cancer Prevention and Research Institute of Texas
- Jose N Onuchic
Welch Foundation
- Vinicius Contessoto
Sao Paulo Research Foundation and Higher Education Personnel (2016/13998-8)
- Vinicius Contessoto
Higher Education Personnel Improvement Coordination (2017/09662-7)
- Vinicius Contessoto
D. R. Bullard-Welch Chair at Rice University (Grant C-0016)
- Peter G Wolynes
NIH Office of the Director (1DP2OD008540-01)
- Erez Lieberman-Aiden
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Cheng et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,297
- views
-
- 369
- downloads
-
- 50
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Further reading
-
- Chromosomes and Gene Expression
Specialized magnetic beads that bind target proteins to a cryogenic electron microscopy grid make it possible to study the structure of protein complexes from dilute samples.
-
- Chromosomes and Gene Expression
- Structural Biology and Molecular Biophysics
Type II nuclear receptors (T2NRs) require heterodimerization with a common partner, the retinoid X receptor (RXR), to bind cognate DNA recognition sites in chromatin. Based on previous biochemical and overexpression studies, binding of T2NRs to chromatin is proposed to be regulated by competition for a limiting pool of the core RXR subunit. However, this mechanism has not yet been tested for endogenous proteins in live cells. Using single-molecule tracking (SMT) and proximity-assisted photoactivation (PAPA), we monitored interactions between endogenously tagged RXR and retinoic acid receptor (RAR) in live cells. Unexpectedly, we find that higher expression of RAR, but not RXR, increases heterodimerization and chromatin binding in U2OS cells. This surprising finding indicates the limiting factor is not RXR but likely its cadre of obligate dimer binding partners. SMT and PAPA thus provide a direct way to probe which components are functionally limiting within a complex TF interaction network providing new insights into mechanisms of gene regulation in vivo with implications for drug development targeting nuclear receptors.