Interdisciplinary Graduate Program
Program in Systems Biology
First Thesis Advisor
chromatin, Hi-C, transcription, RNA, telophase, kinetics, cell cycle, mitosis, interphase, chromosome conformation capture, CTCF, condensin, cohesin, TAD, topologically associated domain, loop extrusion, microphase separation, NCAPH, Rad21, NCAPH2, synchronization, G1 entry, triptolide, DRB, RNase A
Following the discovery of the one-dimensional sequence of human DNA, much focus has been directed on microscopy and molecular techniques to learn about the spatial organization of chromatin in a 3D cell. The development of these powerful tools has enabled high-resolution, genome-wide analysis of chromosome structure under many different conditions. In this thesis, I focus on how the organization of interphase chromatin is established and maintained following mitosis. Mitotic chromosomes are folded into helical loop arrays creating short and condensed chromosomes, while interphase chromosomes are decondensed and folded into a number of structures at different length scales ranging from loops between CTCF sites, enhancers and promoters to topologically associating domains (TADs), and larger compartments. While the chromatin organization at these two very different states is well defined, the transition from a mitotic to interphase chromatin state is not well understood.
The aim of this thesis is to determine how interphase chromatin is organized following mitotic chromosome decondensation and to interrogate factors potentially responsible for driving the transition. First, I determine the temporal order with which CTCF-loops, TADs, and compartments reform as cells exit mitosis, revealing a unique structure at the anaphase-telophase transition never observed before. Second, I test the role of transcription in reformation of 3D chromosome structure and show that active transcription is not required for the formation of most interphase chromatin features; instead, I propose that transcription relies on the proper formation of these structures. Finally, I show that RNA in the interphase nucleus can be degraded with only slight consequences on the overall chromatin organization, suggesting that once interphase chromatin structures are achieved, the structures are stable and RNA is only required to reduce the mixing of active and inactive compartments. Together, these studies further our understanding of how interphase structures form, how these structures relate to functional activities of the interphase cell, and the stability of chromatin structures over time.
Abramo KN. (2020). Building the Interphase Nucleus: A study on the kinetics of 3D chromosome formation, temporal relation to active transcription, and the role of nuclear RNAs. GSBS Dissertations and Theses. https://doi.org/10.13028/a9gd-gw44. Retrieved from https://escholarship.umassmed.edu/gsbs_diss/1099
Rights and Permissions
Licensed under a Creative Commons license
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Bioinformatics Commons, Cell Biology Commons, Computational Biology Commons, Genomics Commons, Laboratory and Basic Science Research Commons, Molecular Biology Commons, Molecular Genetics Commons, Systems Biology Commons