Peter Rugg-Gunn

Research Summary

We are interested in understanding how the epigenome is established during human development and stem cell differentiation, and how epigenetic information changes over the life course of a person.

To research these topics, we use different types of stem cell (primarily human pluripotent stem cells) in combination with a variety of molecular and genetic approaches to characterise and perturb their epigenomes. The stem cell models are sometimes complemented with the characterisation of mouse and human embryos at very early stages in their development.

This research is important because establishing our epigenomes correctly during development has long lasting consequences on our health, and we need to know more about how it happens and why it sometimes goes wrong. Our work also provides new avenues for improving the epigenetic stability of human pluripotent stem cells, and our abilitiy to drive their specialisation towards useful cell types, which are essential requirements to fulfill their promise in regenerative medicine. 

Latest Publications

Widespread reorganisation of pluripotent factor binding and gene regulatory interactions between human pluripotent states.
Chovanec P, Collier AJ, Krueger C, Várnai C, Semprich CI, Schoenfelder S, Corcoran AE, Rugg-Gunn PJ

The transition from naive to primed pluripotency is accompanied by an extensive reorganisation of transcriptional and epigenetic programmes. However, the role of transcriptional enhancers and three-dimensional chromatin organisation in coordinating these developmental programmes remains incompletely understood. Here, we generate a high-resolution atlas of gene regulatory interactions, chromatin profiles and transcription factor occupancy in naive and primed human pluripotent stem cells, and develop a network-graph approach to examine the atlas at multiple spatial scales. We uncover highly connected promoter hubs that change substantially in interaction frequency and in transcriptional co-regulation between pluripotent states. Small hubs frequently merge to form larger networks in primed cells, often linked by newly-formed Polycomb-associated interactions. We identify widespread state-specific differences in enhancer activity and interactivity that correspond with an extensive reconfiguration of OCT4, SOX2 and NANOG binding and target gene expression. These findings provide multilayered insights into the chromatin-based gene regulatory control of human pluripotent states.

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Nature communications, 12, 1, 07 04 2021

PMID: 33828098

Genome-wide analysis of DNA replication and DNA double-strand breaks using TrAEL-seq.
Kara N, Krueger F, Rugg-Gunn P, Houseley J

Faithful replication of the entire genome requires replication forks to copy large contiguous tracts of DNA, and sites of persistent replication fork stalling present a major threat to genome stability. Understanding the distribution of sites at which replication forks stall, and the ensuing fork processing events, requires genome-wide methods that profile replication fork position and the formation of recombinogenic DNA ends. Here, we describe Transferase-Activated End Ligation sequencing (TrAEL-seq), a method that captures single-stranded DNA 3' ends genome-wide and with base pair resolution. TrAEL-seq labels both DNA breaks and replication forks, providing genome-wide maps of replication fork progression and fork stalling sites in yeast and mammalian cells. Replication maps are similar to those obtained by Okazaki fragment sequencing; however, TrAEL-seq is performed on asynchronous populations of wild-type cells without incorporation of labels, cell sorting, or biochemical purification of replication intermediates, rendering TrAEL-seq far simpler and more widely applicable than existing replication fork direction profiling methods. The specificity of TrAEL-seq for DNA 3' ends also allows accurate detection of double-strand break sites after the initiation of DNA end resection, which we demonstrate by genome-wide mapping of meiotic double-strand break hotspots in a dmc1Δ mutant that is competent for end resection but not strand invasion. Overall, TrAEL-seq provides a flexible and robust methodology with high sensitivity and resolution for studying DNA replication and repair, which will be of significant use in determining mechanisms of genome instability.

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PLoS biology, 19, 3, 24 Mar 2021

PMID: 33760805

Naive Pluripotent Stem Cells Exhibit Phenotypic Variability that Is Driven by Genetic Variation.
Ortmann D, Brown S, Czechanski A, Aydin S, Muraro D, Huang Y, Tomaz RA, Osnato A, Canu G, Wesley BT, Skelly DA, Stegle O, Choi T, Churchill GA, Baker CL, Rugg-Gunn PJ, Munger SC, Reinholdt LG, Vallier L

Variability among pluripotent stem cell (PSC) lines is a prevailing issue that hampers not only experimental reproducibility but also large-scale applications and personalized cell-based therapy. This variability could result from epigenetic and genetic factors that influence stem cell behavior. Naive culture conditions minimize epigenetic fluctuation, potentially overcoming differences in PSC line differentiation potential. Here we derived PSCs from distinct mouse strains under naive conditions and show that lines from distinct genetic backgrounds have divergent differentiation capacity, confirming a major role for genetics in PSC phenotypic variability. This is explained in part through inconsistent activity of extra-cellular signaling, including the Wnt pathway, which is modulated by specific genetic variants. Overall, this study shows that genetic background plays a dominant role in driving phenotypic variability of PSCs.

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Cell stem cell, 1, 1, 11 Aug 2020

PMID: 32795399