Epigenetics Podcast

Heterochromatin Protein 1 and its Influence on the Structure of Chromatin (Serena Sanulli)

In this episode of the Epigenetics Podcast, we caught up with Serena Sanulli from Stanford University to talk about her work on Heterochromatin Protein 1 (HP1), the structure of chromatin on the atomic-scale and the meso-scale, and phase separation.
The Laboratory of Serena Sanulli is interested in finding connections between changes that happen on the nucleosomal level and the resulting impact on chromatin conformation on the meso-scale. They combine methods like NMR and Hydrogen-Deuterium Exchange-MS with Cell Biology and Genetics. This enables them to dissect how cells use the diverse biophysical properties of chromatin to regulate gene expression across length and time scales.
A second focus of the lab is HP1, which interacts with the nucleosome and changes its conformation, enabling the compaction of the genome into heterochromatin, effectively silencing genes in that region. A high concentration of HP1 leads to the phenomenon of phase separation in the nucleus, which the Sanulli lab is now investigating.
 
References
Sanulli, S., Justin, N., Teissandier, A., Ancelin, K., Portoso, M., Caron, M., Michaud, A., Lombard, B., da Rocha, S. T., Offer, J., Loew, D., Servant, N., Wassef, M., Burlina, F., Gamblin, S. J., Heard, E., & Margueron, R. (2015). Jarid2 Methylation via the PRC2 Complex Regulates H3K27me3 Deposition during Cell Differentiation. Molecular Cell, 57(5), 769–783. https://doi.org/10.1016/j.molcel.2014.12.020
Sanulli, S., Trnka, M. J., Dharmarajan, V., Tibble, R. W., Pascal, B. D., Burlingame, A. L., Griffin, P. R., Gross, J. D., & Narlikar, G. J. (2019). HP1 reshapes nucleosome core to promote phase separation of heterochromatin. Nature, 575(7782), 390–394. https://doi.org/10.1038/s41586-019-1669-2
Sanulli, S., & Narlikar, G. J. (2021). Generation and Biochemical Characterization of Phase‐Separated Droplets Formed by Nucleic Acid Binding Proteins: Using HP1 as a Model System. Current Protocols, 1(5). https://doi.org/10.1002/cpz1.109
 
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Transcription and Polycomb in Inheritance and Disease (Danny Reinberg)
Heterochromatin and Phase Separation (Gary Karpen)
 
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The Effects of Early Life Stress on Mammalian Development (Catherine J. Peña)

In this episode of the Epigenetics Podcast, we caught up with Catherine Jensen Peña from Princeton University to talk about her work on early life stress and its effects on behavior.
The Laboratory of Catherine Peña focuses on how early life experiences are encoded and maintained into adulthood, with a long-lasting impact on behavior. Recent work showed, that child maltreatment and other forms of early life stress increase the lifetime risk of depression and other mood, anxiety, and drug disorders by 2-4 fold. The Peña Lab uses genome wide approaches to investigate key brain regions with a two-hit stress model.
Using RNA-Seq, the Peña Lab has shown that depression-like gene expression patterns are programmed by early life stress, similar to observations in mice exhibiting depression-like behavior after adult stress and are visible even before behavioral changes. Furthermore, latent and unique transcriptional responses to adult stress among a subset of genes is programmed by early life stress. The role of chromatin modifications in regulating these processes are investigated using state of the art technologies like Mod-Spec or ATAC-Seq.
 
References
Kronman, H., Torres-Berrío, A., Sidoli, S., Issler, O., Godino, A., Ramakrishnan, A., Mews, P., Lardner, C. K., Parise, E. M., Walker, D. M., van der Zee, Y. Y., Browne, C. J., Boyce, B. F., Neve, R., Garcia, B. A., Shen, L., Peña, C. J., & Nestler, E. J. (2021). Long-term behavioral and cell-type-specific molecular effects of early life stress are mediated by H3K79me2 dynamics in medium spiny neurons. Nature Neuroscience, 24(5), 667–676. https://doi.org/10.1038/s41593-021-00814-8
Peña, C. J., Smith, M., Ramakrishnan, A., Cates, H. M., Bagot, R. C., Kronman, H. G., Patel, B., Chang, A. B., Purushothaman, I., Dudley, J., Morishita, H., Shen, L., & Nestler, E. J. (2019). Early life stress alters transcriptomic patterning across reward circuitry in male and female mice. Nature Communications, 10(1), 5098. https://doi.org/10.1038/s41467-019-13085-6
Peña, C. J., Kronman, H. G., Walker, D. M., Cates, H. M., Bagot, R. C., Purushothaman, I., Issler, O., Loh, Y.-H. E., Leong, T., Kiraly, D. D., Goodman, E., Neve, R. L., Shen, L., & Nestler, E. J. (2017). Early life stress confers lifelong stress susceptibility in mice via ventral tegmental area OTX2. Science, 356(6343), 1185–1188. https://doi.org/10.1126/science.aan4491
 
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Targeting COMPASS to Cure Childhood Leukemia (Ali Shilatifard)

In this episode of the Epigenetics Podcast, we caught up with Ali Shilatifard from Northwestern University to talk about his work on targeting COMPASS to cure childhood leukemia.
The Shilatifard Lab studies childhood leukemia and how it can potentially be treated using epigenetic targets. The team focuses on is SET1/COMPASS, a histone H3 lysine4 methylase. Ali Shilatifard was able to purify and identify its activity, with results published in 2001 in PNAS. This protein complex is conserved from yeast to drosophila to humans.
Surprisingly, the Shilatifard Team could show that the catalytic activity of COMPASS is not necessary for viability of drosophila. Furthermore, they found that catalytic activity was not the decisive feature of the complex, but rather its role in the context of chromatin structure, in particular a protein domain that only spans 80 amino acids within the 4000 amino acid protein.
 
References
Miller, T., Krogan, N. J., Dover, J., Erdjument-Bromage, H., Tempst, P., Johnston, M., Greenblatt, J. F., & Shilatifard, A. (2001). COMPASS: A complex of proteins associated with a trithorax-related SET domain protein. Proceedings of the National Academy of Sciences, 98(23), 12902–12907. https://doi.org/10.1073/pnas.231473398
Lin, C., Garruss, A. S., Luo, Z., Guo, F., & Shilatifard, A. (2013). The RNA Pol II Elongation Factor Ell3 Marks Enhancers in ES Cells and Primes Future Gene Activation. Cell, 152(1–2), 144–156. https://doi.org/10.1016/j.cell.2012.12.015
Wang, L., Zhao, Z., Ozark, P. A., Fantini, D., Marshall, S. A., Rendleman, E. J., Cozzolino, K. A., Louis, N., He, X., Morgan, M. A., Takahashi, Y., Collings, C. K., Smith, E. R., Ntziachristos, P., Savas, J. N., Zou, L., Hashizume, R., Meeks, J. J., & Shilatifard, A. (2018). Resetting the epigenetic balance of Polycomb and COMPASS function at enhancers for cancer therapy. Nature Medicine, 24(6), 758–769. https://doi.org/10.1038/s41591-018-0034-6
Morgan, M. A. J., & Shilatifard, A. (2020). Reevaluating the roles of histone-modifying enzymes and their associated chromatin modifications in transcriptional regulation. Nature Genetics, 52(12), 1271–1281. https://doi.org/10.1038/s41588-020-00736-4
 
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Effects of Non-Enzymatic Covalent Histone Modifications on Chromatin (Yael David)

In this episode of the Epigenetics Podcast, we caught up with Yael David from Memorial Sloan Kettering Cancer Center in New York to talk about her work on Effects of Non-Enzymatic Covalent Histone Modifications on Chromatin. 
The David lab studies on non-enzymatic covalent modifications of Histones, including Histone glycation and citrullination. These modifications recognize metabolites that are produced in the cell and aid as a sensor for chromatin to quickly adapt to cellular changes. These unique modifications do not have a so-called erasing enzyme, which makes them terminal, rendering these sites inaccessible for further modifications such as methylation or acetylation.  
A second area of research in the David lab is Histone H1. The lab has developed a new method to purify Histone H1, superior to the commonly used method of acid extraction which leads to degradation of Histone H1. This purification method enabled the lab to purify and characterize the functional properties of all Histone H1 variants. 
 
References
David, Y., Vila-Perelló, M., Verma, S., & Muir, T. W. (2015). Chemical tagging and customizing of cellular chromatin states using ultrafast trans -splicing inteins. Nature Chemistry, 7(5), 394–402. https://doi.org/10.1038/nchem.2224
David, Y., & Muir, T. W. (2017). Emerging Chemistry Strategies for Engineering Native Chromatin. Journal of the American Chemical Society, 139(27), 9090–9096. https://doi.org/10.1021/jacs.7b03430
Osunsade, A., Prescott, N. A., Hebert, J. M., Ray, D. M., Jmeian, Y., Lorenz, I. C., & David, Y. (2019). A Robust Method for the Purification and Characterization of Recombinant Human Histone H1 Variants. Biochemistry, 58(3), 171–176. https://doi.org/10.1021/acs.biochem.8b01060
Zheng, Q., Omans, N. D., Leicher, R., Osunsade, A., Agustinus, A. S., Finkin-Groner, E., D’Ambrosio, H., Liu, B., Chandarlapaty, S., Liu, S., & David, Y. (2019). Reversible histone glycation is associated with disease-related changes in chromatin architecture. Nature Communications, 10(1), 1289. https://doi.org/10.1038/s41467-019-09192-z
Zheng, Q., Osunsade, A., & David, Y. (2020). Protein arginine deiminase 4 antagonizes methylglyoxal-induced histone glycation. Nature Communications, 11(1), 3241. https://doi.org/10.1038/s41467-020-17066-y
 
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ATAC-Seq, scATAC-Seq and Chromatin Dynamics in Single-Cells (Jason Buenrostro)

In this episode of the Epigenetics Podcast, we caught up with Jason Buenrostro from Harvard University to talk about his work on developing biological tools to measure chromatin dynamics in single-cells. He explains how his lab uses these tools to study chromatin alterations in different cell types and disease states to uncover new mechanisms of gene regulation and their contribution to those diseases.
In his first years of his research career Jason Buenrostro took a risk and just added an enzyme called Transposase to cells in a cell culture. What he saw on a subsequent agarose gel astonished him. He was able to recreate a nucleosomal ladder that he knew from experiments using MNase or DNase-Seq, however, without the tedious steps of optimization. In the following years he optimized that method and data analyzation into a method known today as ATAC-Seq. In recent years he was also able to bring ATAC-Seq to the next level and developed single cell ATAC-Seq (scATAC-Seq), and combining it with RNA-Seq in a multi-omics approach.
In this Episode we discuss how Jason Buenrostro developed ATAC-Seq in William Greenleaf's lab, how a lack of equipment shaped the ATAC-Seq protocol, and how scATAC-Seq has enabled a whole different way of looking at biological samples.
 
References
Buenrostro, J. D., Giresi, P. G., Zaba, L. C., Chang, H. Y., & Greenleaf, W. J. (2013). Transposition of native chromatin for fast and sensitive epigenomic profiling of open chromatin, DNA-binding proteins and nucleosome position. Nature Methods, 10(12), 1213–1218. https://doi.org/10.1038/nmeth.2688
Buenrostro, J. D., Wu, B., Litzenburger, U. M., Ruff, D., Gonzales, M. L., Snyder, M. P., Chang, H. Y., & Greenleaf, W. J. (2015). Single-cell chromatin accessibility reveals principles of regulatory variation. Nature, 523(7561), 486–490. https://doi.org/10.1038/nature14590
Buenrostro, J. D., Corces, M. R., Lareau, C. A., Wu, B., Schep, A. N., Aryee, M. J., Majeti, R., Chang, H. Y., & Greenleaf, W. J. (2018). Integrated Single-Cell Analysis Maps the Continuous Regulatory Landscape of Human Hematopoietic Differentiation. Cell, 173(6), 1535-1548.e16. https://doi.org/10.1016/j.cell.2018.03.074
Lareau, C. A., Duarte, F. M., Chew, J. G., Kartha, V. K., Burkett, Z. D., Kohlway, A. S., Pokholok, D., Aryee, M. J., Steemers, F. J., Lebofsky, R., & Buenrostro, J. D. (2019). Droplet-based combinatorial indexing for massive-scale single-cell chromatin accessibility. Nature Biotechnology, 37(8), 916–924. https://doi.org/10.1038/s41587-019-0147-6
 
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Synthetic Chromatin Epigenetics (Karmella Haynes)

In this episode of the Epigenetics Podcast, we caught up with Karmella Haynes from Emory University to talk about her work on synthetic chromatin epigenetics.
The Haynes lab focuses on the design of synthetic chromatin sensor proteins. The first one of this kind, the Polycomb Transcription Factor (PcTF), was published in 2011. It senses H3K27me3 and recruits effector proteins to the sites of this modification. This sensor can be brought into cancer cells to activate hundreds of silenced genes. The lab now focuses on characterizing the effects of these sensor proteins genome wide, and seeks to find a way to deliver those sensor into cancer cells, without affecting healthy cells.
In this Episode we discuss how Karmella Haynes got into the field of Epigenetics, how she designed the PcTF sensor proteins, and the way she came to learn how important the right control experiments are. In the end we also discuss her activities to promote diversity and inclusion in science.
 
References
Haynes, K. A., & Silver, P. A. (2011). Synthetic Reversal of Epigenetic Silencing. Journal of Biological Chemistry, 286(31), 27176–27182. https://doi.org/10.1074/jbc.C111.229567
Haynes, K. A., Ceroni, F., Flicker, D., Younger, A., & Silver, P. A. (2012). A Sensitive Switch for Visualizing Natural Gene Silencing in Single Cells. ACS Synthetic Biology, 1(3), 99–106. https://doi.org/10.1021/sb3000035
Daer, R. M., Cutts, J. P., Brafman, D. A., & Haynes, K. A. (2017). The Impact of Chromatin Dynamics on Cas9-Mediated Genome Editing in Human Cells. ACS Synthetic Biology, 6(3), 428–438. https://doi.org/10.1021/acssynbio.5b00299
Tekel, S. J., & Haynes, K. A. (2017). Molecular structures guide the engineering of chromatin. Nucleic Acids Research, 45(13), 7555–7570. https://doi.org/10.1093/nar/gkx531
Tekel, S. J., Vargas, D. A., Song, L., LaBaer, J., Caplan, M. R., & Haynes, K. A. (2018). Tandem Histone-Binding Domains Enhance the Activity of a Synthetic Chromatin Effector. ACS Synthetic Biology, 7(3), 842–852. https://doi.org/10.1021/acssynbio.7b00281
 
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Development of Integrative Machine Learning Tools for Neurodegenerative Diseases (Enrico Glaab)

In this episode of the Epigenetics Podcast, we caught up with Enrico Glaab from the University of Luxemburg to talk about his work on the development of integrative machine learning tools for neurodegenerative diseases.
The work of Dr. Enrico Glaab focuses on neurodegenerative disorders like Parkinson’s and Alzheimer’s disease. In his group his team works on the development of software tools to analyze molecular, clinical and neuroimaging data for those diseases that can be used and applied easily by scientists and deliver publication ready figures. More recently, Enrico Glaab's group got interested in the influence of Epigenetics in Parkinson's and Alzheimer's disease.
In this Episode we discuss how Enrico Glaab made the switch from wet-lab to becoming a bioinformatician and how he uses integrative machine learning tools to find approaches to not only cure but also be able to detect neurodegenerative diseases like Alzheimer's or Parkinson's early on.
 
References
Enrico Glaab, Reinhard Schneider (2015) RepExplore: addressing technical replicate variance in proteomics and metabolomics data analysis (Bioinformatics) DOI: 10.1093/bioinformatics/btv127
Enrico Glaab, Reinhard Schneider (2015) Comparative pathway and network analysis of brain transcriptome changes during adult aging and in Parkinson’s disease (Neurobiology of Disease) DOI: 10.1016/j.nbd.2014.11.002
Sandra Köglsberger, Maria Lorena Cordero-Maldonado, … Enrico Glaab (2017) Gender-Specific Expression of Ubiquitin-Specific Peptidase 9 Modulates Tau Expression and Phosphorylation: Possible Implications for Tauopathies (Molecular Neurobiology) DOI: 10.1007/s12035-016-0299-z
Enrico Glaab, Paul Antony, … Manuel Buttini (2019) Transcriptome profiling data reveals ubiquitin-specific peptidase 9 knockdown effects (Data in Brief) DOI: 10.1016/j.dib.2019.104130
 
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Ultraconserved Enhancers and Enhancer Redundancy (Diane Dickel)

In this episode of the Epigenetics Podcast, we caught up with Diane Dickel from Lawrence Berkeley National Laboratory to talk about her work on ultraconserved enhancers and enhancer redundancy.
Diane Dickel and her co-workers study non-coding regions of the genome that harbor distant-acting transcriptional regulatory regions, called enhancers. Enhancers have been shown to be critical for normal embryonic development, implying evolutional conservation. Diane Dickel and her team try to identify and characterize enhancers at a genomic scale. Their efforts include the use of CRISPR/CAS9 to mutate enhancer sequences in order to understand sequence dependent functional relevance.
In this episode we discuss the function of ultraconserved enhancers, what ultraconservation actually means, how enhancer redundancy works and how Diane Dickel dealt with a failed PhD project.
 
References
Dickel, D. E., Ypsilanti, A. R., Pla, R., Zhu, Y., Barozzi, I., Mannion, B. J., Khin, Y. S., Fukuda-Yuzawa, Y., Plajzer-Frick, I., Pickle, C. S., Lee, E. A., Harrington, A. N., Pham, Q. T., Garvin, T. H., Kato, M., Osterwalder, M., Akiyama, J. A., Afzal, V., Rubenstein, J. L. R., … Visel, A. (2018). Ultraconserved Enhancers Are Required for Normal Development. Cell, 172(3), 491-499.e15. https://doi.org/10.1016/j.cell.2017.12.017
Gorkin, D. U., Barozzi, I., Zhao, Y., Zhang, Y., Huang, H., Lee, A. Y., Li, B., Chiou, J., Wildberg, A., Ding, B., Zhang, B., Wang, M., Strattan, J. S., Davidson, J. M., Qiu, Y., Afzal, V., Akiyama, J. A., Plajzer-Frick, I., Novak, C. S., … Ren, B. (2020). An atlas of dynamic chromatin landscapes in mouse fetal development. Nature, 583(7818), 744–751. https://doi.org/10.1038/s41586-020-2093-3
Snetkova, V., Ypsilanti, A. R., Akiyama, J. A., Mannion, B. J., Plajzer-Frick, I., Novak, C. S., Harrington, A. N., Pham, Q. T., Kato, M., Zhu, Y., Godoy, J., Meky, E., Hunter, R. D., Shi, M., Kvon, E. Z., Afzal, V., Tran, S., Rubenstein, J. L. R., Visel, A., … Dickel, D. E. (2021). Ultraconserved enhancer function does not require perfect sequence conservation. Nature Genetics, 53(4), 521–528. https://doi.org/10.1038/s41588-021-00812-3
 
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