Epigenetics Podcast

Development of Site-Specific ChIP Technologies (Hodaka Fujii)

In this episode of the Epigenetics Podcast, we caught up with Dr. Hodaka Fujii, Professor of Biochemistry and Genome Biology at Hirosaki University Graduate School of Medicine and School of Medicine, to talk about his work on the development of locus-specific ChIP technologies.
The goal of conventional chromatin immunoprecipitation (ChIP) assays is to find genomic locations of transcription factor binding or genome-wide profiles of histone tail modifications.  In contrast to that, the guest of this episode, Dr. Fujii, has developed methods such as insertional chromatin immunoprecipitation (iChIP) and engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) to identify the factors that are binding to specific sites on the genome.
In iChIP, LexA binding sites are inserted into the genomic region of interest. In parallel, the DNA-binding domain of LexA, fused with FLAG epitope tags and a nuclear localization signal, is expressed in the same cells. After crosslinking and chromatin preparation, the resulting chromatin is immunoprecipitated with an antibody against the tag. This allows proteins or RNA interacting with the region of interest to be analyzed with the appropriate downstream application. The enChIP takes a similar approach, but does not require insertion of the LexA binding sites. Instead, a FLAG-tagged dCas9 protein together with the respective guide RNA are used to target the region of the genome of interest. After the IP and the purification DNA, RNA, or proteins can be analyzed accordingly. The lack of the requirement of to insert the LexA binding sites into the genome makes enChIP much more straightforward than iChIP.
In this interview, we discuss the story behind how Dr. Fujii got into the field of epigenetics, how he developed iChIP, and how the method was improved over the years. Furthermore, we discuss the development of enChIP and how this can be used as an alternate method to Hi-C.
 
References
 
Akemi Hoshino, Satoko Matsumura, … Hodaka Fujii (2004) Inducible Translocation Trap (Molecular Cell) DOI: 10.1016/j.molcel.2004.06.017
Akemi Hoshino, Hodaka Fujii (2009) Insertional chromatin immunoprecipitation: a method for isolating specific genomic regions (Journal of Bioscience and Bioengineering) DOI: 10.1016/j.jbiosc.2009.05.005
Toshitsugu Fujita, Hodaka Fujii (2013) Efficient isolation of specific genomic regions and identification of associated proteins by engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) using CRISPR (Biochemical and Biophysical Research Communications) DOI: 10.1016/j.bbrc.2013.08.013
Toshitsugu Fujita, Miyuki Yuno, … Hodaka Fujii (2015) Identification of Non-Coding RNAs Associated with Telomeres Using a Combination of enChIP and RNA Sequencing (PLOS ONE) DOI: 10.1371/journal.pone.0123387
Toshitsugu Fujita, Miyuki Yuno, Hodaka Fujii (2016) Efficient sequence-specific isolation of DNA fragments and chromatin by in vitro enChIP technology using recombinant CRISPR ribonucleoproteins (Genes to Cells) DOI: 10.1111/gtc.12341
Toshitsugu Fujita, Miyuki Yuno, … Hodaka Fujii (2017) Identification of physical interactions between genomic regions by enChIP-Seq (Genes to Cells) DOI: 10.1111/gtc.12492
Toshitsugu Fujita, Fusako Kitaura, … Hodaka Fujii (2017) Locus-specific ChIP combined with NGS analysis reveals genomic regulatory regions that physically interact with the Pax5 promoter in a chicken B cell line (DNA Research) DOI: 10.1093/dnares/dsx023
 
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Regulation of Chromatin Organization by Histone Chaperones (Geneviève Almouzni)

In this episode of the Epigenetics Podcast, we caught up with Geneviève Almouzni, Ph.D., Research Director at the CNRS at Institut Curie in Paris, to talk about her work on the regulation of chromatin organization by histone chaperones.
Geneviève Almouzni got her Ph.D. from Université Pierre-et-Marie-Curie in 1988 under the supervision of Marcel Méchali. She then moved to the United States to work as a postdoc in the National Institutes of Health in the laboratory of Professor Alan Wolffe. In 1994, she returned to Paris and became a Junior Group Leader at Institut Curie and became a Group Leader there in 2000. In 2013, she took over the direction of research at the Institut Curie and became the third woman to hold this position, after Marie Curie and Irène Joliot-Curie.
Geneviève Almouzni’s research focuses on the assembly of chromatin and the identification of histone chaperones. Histone chaperones are necessary for the establishment and maintenance of chromatin, as they help to assemble the nucleosomes out of the core histones and DNA. This occurs both when the polymerase transcribes through a nucleosome and after DNA replication and repair.
The Almouzni group has identified and characterized multiple histone chaperones, including CAF-1, HirA, and HJURP. Furthermore, they investigated how post-translational modifications on soluble histones influence the final epigenetic state of the nucleosome and the reassembly of chromatin after DNA replication. In the last couple of years, the group has focused on the unraveling the link between the structure of chromatin at centromeres and cancer.
In this interview, we discuss the focus of the Almouzni lab on histone chaperones, how the lab was able to identify its first one with CAF-1, how histone PTMs on soluble histones influence the deposition on the DNA, and how the chromatin on centromeres is involved in cancer.
 
References
 
Dominique Ray-Gallet, Jean-Pierre Quivy, … Geneviève Almouzni (2002) HIRA Is Critical for a Nucleosome Assembly Pathway Independent of DNA Synthesis (Molecular Cell) DOI: 10.1016/S1097-2765(02)00526-9
Pierre-Henri L. Gaillard, Emmanuelle M.-D. Martini, … Geneviève Almouzni (1996) Chromatin Assembly Coupled to DNA Repair: A New Role for Chromatin Assembly Factor I (Cell) DOI: 10.1016/S0092-8674(00)80164-6
Jean-Pierre Quivy, Danièle Roche, … Geneviève Almouzni (2004) A CAF-1 dependent pool of HP1 during heterochromatin duplication (The EMBO Journal) DOI: 10.1038/sj.emboj.7600362
 
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How the "Fragile Nucleosome" Science Community Came to Life (Christine Cucinotta, Melvin Noe Gonzalez)

In this episode of the Epigenetics Podcast, we caught up with Dr. Christine Cucinotta and Dr. Melvin Noe Gonzalez to talk about how they brought the #fragilenucleosome seminar series and Discord channel to life.
 
Christine Cucinotta and Melvin Noe Gonzales are part of the organizing committee of the independent scientific community "Fragile Nucleosome." This community consists of a Discord channel with more than 1,000 members, a biweekly seminar series, a mentoring program, and a journal club series. The Fragile Nucleosome is organized exclusively by early-career scientists, without external sponsors or under the roof of a single graduate program or university.
 
In this interview, Christine and Melvin share the story on how the Fragile Nucleosome community got started, what has happened so far, and what the future plans are for the #fragilenucleosome.
 
 
References
#fragilenucleosome on Twitter
Fragile Nucleosome Discord Channel
Fragile Nucleosome on generegulation.org
Christine Cucinotta on Twitter
Melvin Noe Gonzalez on Twitter
 
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Epigenetic Influence on Memory Formation and Inheritance (Isabelle Mansuy)

In this episode of the Epigenetics Podcast, we caught up with Professor Isabelle Mansuy, Ph.D., from the University of Zürich and the ETH Zürich, to talk about her work on epigenetic influences on memory formation and inheritance.
 
Dr. Mansuy received her Ph.D. from the Friedrich Miescher Institute, Basel, Switzerland in 1994. After doing a postdoc at the Center for Neurobiology and Behavior at the Howard Hughes Medical Institute at the Columbia University in New York, she moved to Zürich and became Assistant Professor in Neurobiology at the Department of Biology at the Swiss Federal Institute of Technology in 1998. In 2004 Dr. Mansuy became Professor at the Brain Research Institute of the University Zurich, where, in 2007, she became Managing Director. Since 2013 she has been a full Professor in Neuroepigenetics at the University of Zürich and at the ETH in Zürich.
 
Dr. Isabelle Mansuy's work centers around the formation of memories and how those memories are inherited. She started to work on memory formation in the beginning of her research career, where she investigated the influence of calcineurin and Zif268 in this process. In the early 2010s she pivoted and transitioned to work on transgenerational epigenetic inheritance. To investigate this field of research she created an unbiased experiment that allowed her to study the transgenerational influence of early life stress, which she was able to observe for across up to 4 generations through the germline.
 
If you want to learn more about the challenges and obstacles that needed to be overcome to create this novel experimental approach to tackle the questions of and which epigenetic factors might influence transgenerational epigenetic inheritance, don't miss out on this episode.
 
 
References
Karsten Baumgärtel, David Genoux, … Isabelle M. Mansuy (2008) Control of the establishment of aversive memory by calcineurin and Zif268 (Nature Neuroscience) DOI: 10.1038/nn.2113
Tamara B. Franklin, Holger Russig, … Isabelle M. Mansuy (2010) Epigenetic Transmission of the Impact of Early Stress Across Generations (Biological Psychiatry) DOI: 10.1016/j.biopsych.2010.05.036
Johannes Gräff, Bisrat T. Woldemichael, … Isabelle M. Mansuy (2012) Dynamic histone marks in the hippocampus and cortex facilitate memory consolidation (Nature Communications) DOI: 10.1038/ncomms1997
Eloïse A. Kremer, Niharika Gaur, … Isabelle M. Mansuy (2018) Interplay between TETs and microRNAs in the adult brain for memory formation (Scientific Reports) DOI: 10.1038/s41598-018-19806-z
Katharina Gapp, Ali Jawaid, … Isabelle M. Mansuy (2014) Implication of sperm RNAs in transgenerational inheritance of the effects of early trauma in mice (Nature Neuroscience) DOI: 10.1038/nn.3695
Katharina Gapp, Saray Soldado-Magraner, … Isabelle M. Mansuy (2014) Early life stress in fathers improves behavioural flexibility in their offspring (Nature Communications) DOI: 10.1038/ncomms6466
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Influence of Dynamic RNA Methylation on Gene Expression (Chuan He)

In this episode of the Epigenetics Podcast, we caught up with Dr. Chuan He, John T. Wilson Distinguished Service Professor at University of Chicago, to talk about his work on the influence of dynamic RNA methylation on gene expression. RNA methylation is an important biological process, and cellular RNA methylation levels can have profound impacts on normal cellular differentiation and cancer cell proliferation.
Dr. He received his Ph.D. from MIT in 2000 and went on to do his postdoctoral work at Harvard University. He then became Assistant Professor at the University of Chicago in 2002, was promoted to Associate Professor in 2008, and in 2014 he became the John T. Wilson Distinguished Service Professor at the University of Chicago.  From 2012 to 2017 he was Director of the Institute for Biophysical Dynamics at the University of Chicago.
Chuan He's current research focuses on understanding the reversible RNA modification m6A. This modification was discovered in the 1980s, but work from Dr. He's laboratory showing that m6A was indeed a transient epigenetic modification by the discovery of the first m6A demethylase FTO in 2011 rekindled the interest in this modification. In the following years Dr. He and his team identified and characterized additional m6A enzymes, including the m6A eraser ALKBH5, the m6A readers YTH and HNRNP, and the m6A writer complex METTL3/14. 
METTL3/14 is a core complex in this regulatory network, and it requires an accessory factor WTAP, which mediates cellular m6A RNA methylation. The current work in the He lab focuses on how the methylation selectivity of this complex is achieved.
In this interview, we discuss the story of how the He lab discovered the members of the family of proteins that read, write, and erase RNA modifications and how those RNA modifications act in the field of epigenetics.
 
References
 
Guifang Jia, Cai-Guang Yang, … Chuan He (2008) Oxidative demethylation of 3-methylthymine and 3-methyluracil in single-stranded DNA and RNA by mouse and human FTO (FEBS letters) DOI: 10.1016/j.febslet.2008.08.019
Guifang Jia, Ye Fu, … Chuan He (2011) N6-methyladenosine in nuclear RNA is a major substrate of the obesity-associated FTO (Nature Chemical Biology) DOI: 10.1038/nchembio.687
Guanqun Zheng, John Arne Dahl, … Chuan He (2013) ALKBH5 is a mammalian RNA demethylase that impacts RNA metabolism and mouse fertility (Molecular Cell) DOI: 10.1016/j.molcel.2012.10.015
Jianzhao Liu, Yanan Yue, … Chuan He (2014) A METTL3-METTL14 complex mediates mammalian nuclear RNA N6-adenosine methylation (Nature Chemical Biology) DOI: 10.1038/nchembio.1432
 
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How to Publish in Nature: Lessons from the ENCODE Consortium (Michelle Trenkmann, Senior Editor at Nature)

In this episode of the Epigenetics Podcast, we caught up with Dr. Michelle Trenkmann, Senior Editor at Nature. We discussed her work as an editor at Nature and how she contributed to the ENCODE 3 publications, which are the results of the third phase of the ENCODE project. Dr. Trenkmann also talked about how to get your research published in Nature and what it’s like to review high profile scientific articles.
 
ENCODE References
 
Immersive ENCODE Website
Perspectives on ENCODE
 
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The Role of Non-Histone Proteins in Chromosome Structure and Function During Mitosis (Bill Earnshaw)

In this episode of the Epigenetics Podcast, we caught up with Professor Bill Earnshaw, Wellcome Trust Principal Research Fellow at the University of Edinburgh, to talk about his work on the role of non-histone proteins in chromosome structure and function during mitosis.
 
In the beginning of Bill Earnshaw's research career little was known about the structure that holds the two individual sister chromatids together. This led to Bill pioneering in the use of autoantibodies for the identification and cloning of key chromosomal proteins. He used serum from a scleroderma patient to identify and clone human centromeric proteins, which paved the way for the molecular characterization of the metazoan kinetochore.
 
Later the chromosomal passenger complex (CPC) was identifies in his lab using biochemical studies. This complex contains Aurora B kinase plus its targeting and regulatory subunits INCENP, Survivin, and Borealin/Dasra B. 
 
More recently, he teamed up with the laboratories of Job Dekker and Leonid Mirny. In this collaboration they used a system for synchronous mitotic entry developed by Kumiko Samejima.These studies used a combination of chemical biology, gene targeting, Hi-C genomics, and polymer modeling to explore the roles of condensin I and condensin II in mitotic chromosome formation. The results revealed that during prophase interphase higher-order chromatin organization breaks down and subsequently condensin II and condensin I work together to form hierarchical loops that give chromosomes their compact morphology.
 
In this interview, we discuss the story on how centromeric proteins were first identified using sera from human scleroderma patients, how the chromosomal passenger complex was discovered, and how condensin I and II work together in chromatin loop formation.
 
 
References
 
Johan H. Gibcus, Kumiko Samejima, … Job Dekker (2018) A pathway for mitotic chromosome formation (Science (New York, N.Y.)) DOI: 10.1126/science.aao6135
A. F. Pluta, A. M. Mackay, … W. C. Earnshaw (1995) The Centromere: Hub of Chromosomal Activities (Science) DOI: 10.1126/science.270.5242.1591
Nuno M. C. Martins, Jan H. Bergmann, … William C. Earnshaw (2016) Epigenetic engineering shows that a human centromere resists silencing mediated by H3K27me3/K9me3 (Molecular Biology of the Cell) DOI: 10.1091/mbc.E15-08-0605
Oscar Molina, Giulia Vargiu, … William C. Earnshaw (2016) Epigenetic engineering reveals a balance between histone modifications and transcription in kinetochore maintenance (Nature Communications) DOI: 10.1038/ncomms13334
Jan G Ruppert, Kumiko Samejima, … William C Earnshaw (2018) HP 1α targets the chromosomal passenger complex for activation at heterochromatin before mitotic entry (The EMBO Journal) DOI: 10.15252/embj.201797677
 
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Effects of DNA Methylation on Chromatin Structure and Transcription (Dirk Schübeler)

In this episode of the Epigenetics Podcast, we caught up with Dr. Dirk Schübeler, Director of the Friedrich Miescher Institute (FMI) in Basel, Switzerland, to talk about his work on the effects of DNA methylation on chromatin structure and transcription.
 
Dirk Schübeler was born in Germany and started his scientific career in Braunschweig, Germany. After his postdoc at the Fred Hutchinson Cancer Research Center in Seattle, he joined the FMI in 2003 and never left. He was recently appointed as the Director of the FMI in March 2020.
 
Dirk Schübeler’s research focuses on DNA methylation and its effects on chromatin and transcription. It is widely known that DNA methylation leads to gene silencing, but many of the mechanisms and regulatory factors involved in this process remain understudied. Therefore, Dirk Schübeler and his team set out to characterize the DNA methylation profiles in normal human somatic cells and compare them with the methylation profiles in transformed human cells. More recent work in his lab led by postdoc Tuncay Baubec focused on factors that bind to methylated DNA regions and modify chromatin structure. The factors they studied include the MBD protein family and also proteins like DNMT3B.
 
In this interview, we discuss the impact of DNA methylation on chromatin states, how CpG-binding factors influence those processes, and we also talk about his new role as Director of the Friedrich Miescher Institute.
 
References
Tuncay Baubec, Daniele F. Colombo, … Dirk Schübeler (2015) Genomic profiling of DNA methyltransferases reveals a role for DNMT3B in genic methylation (Nature) DOI: 10.1038/nature14176 
Paul Adrian Ginno, Lukas Burger, … Dirk Schübeler (2018) Cell cycle-resolved chromatin proteomics reveals the extent of mitotic preservation of the genomic regulatory landscape (Nature Communications) DOI: 10.1038/s41467-018-06007-5 
Michael B. Stadler, Rabih Murr, … Dirk Schübeler (2011) DNA-binding factors shape the mouse methylome at distal regulatory regions (Nature) DOI: 10.1038/nature10716 
Silvia Domcke, Anaïs Flore Bardet, … Dirk Schübeler (2015) Competition between DNA methylation and transcription factors determines binding of NRF1 (Nature) DOI: 10.1038/nature16462 
Florian Lienert, Christiane Wirbelauer, … Dirk Schübeler (2011) Identification of genetic elements that autonomously determine DNA methylation states (Nature Genetics) DOI: 10.1038/ng.946
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