Epigenetics Podcast

The Role of SMCHD1 in Development and Disease (Marnie Blewitt)

In this episode of the Epigenetics Podcast, we caught up with Marnie Blewitt from the Walter and Eliza Hall Institute of Medical Research to talk about her work on the role of SMCHD1 in Development and Disease.
The Laboratory of Marnie Blewitt focuses finding inhibitors or activators for the epigenetic regulator SMCHD1. Marnie Blewitt identified and characterized this protein during her PhD and the findings were published in 2008 in Nature Genetics. Since then, she and her team were able to investigate the function of this protein further. By doing so, they showed the involvement of SMCHD1 in cancer and several other diseases. Currently the lab is screening for small molecules that can act as inhibitors or activators of SMCHD1 the former as potential treatments for facioscapulohumeral muscular dystrophy, the latter for Prader Willi and Schaaf-Yang syndromes, both of which have no current targeted treatments.
 
References
Blewitt, M. E., Gendrel, A.-V., Pang, Z., Sparrow, D. B., Whitelaw, N., Craig, J. M., Apedaile, A., Hilton, D. J., Dunwoodie, S. L., Brockdorff, N., Kay, G. F., & Whitelaw, E. (2008). SmcHD1, containing a structural-maintenance-of-chromosomes hinge domain, has a critical role in X inactivation. Nature Genetics, 40(5), 663–669. https://doi.org/10.1038/ng.142
Leong, H. S., Chen, K., Hu, Y., Lee, S., Corbin, J., Pakusch, M., Murphy, J. M., Majewski, I. J., Smyth, G. K., Alexander, W. S., Hilton, D. J., & Blewitt, M. E. (2013). Epigenetic Regulator Smchd1 Functions as a Tumor Suppressor. Cancer Research, 73(5), 1591–1599. https://doi.org/10.1158/0008-5472.CAN-12-3019
Gordon, C. T., Xue, S., Yigit, G., Filali, H., Chen, K., Rosin, N., Yoshiura, K., Oufadem, M., Beck, T. J., McGowan, R., Magee, A. C., Altmüller, J., Dion, C., Thiele, H., Gurzau, A. D., Nürnberg, P., Meschede, D., Mühlbauer, W., Okamoto, N., … Reversade, B. (2017). De novo mutations in SMCHD1 cause Bosma arhinia microphthalmia syndrome and abrogate nasal development. Nature Genetics, 49(2), 249–255. https://doi.org/10.1038/ng.3765
 
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Epigenetics and X-Inactivation (Edith Heard)
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Single-Molecule Imaging of the Epigenome (Efrat Shema)

In this episode of the Epigenetics Podcast, we caught up with Efrat Shema from the Weizmann Institute of Science to talk about her work on Single Molecule Imaging of chromatin, and the analysis of nucleosomes circulating in plasma.
In ChIP-Seq experiments the peak you get as a read out represents an average over, most often, millions of cells. Furthermore, one often does not know if that peak represents one or more than one nucleosome. If you then want to study multiple marks at the same time, the question remains: do those modifications occur at the same time, in the same cell?
The Laboratory of Efrat Shema works on answering those questions by developing methods to study the modification patterns on single nucleosomes with single molecule imaging. With that it is possible to study single nucleosomes in a high throughout manner to identify the modifications they are decorated with. A subsequent sequencing step makes it possible to identify the genomic location of that nucleosome.
 
References
Shema, E., Bernstein, B. E., & Buenrostro, J. D. (2019). Single-cell and single-molecule epigenomics to uncover genome regulation at unprecedented resolution. Nature Genetics, 51(1), 19–25. https://doi.org/10.1038/s41588-018-0290-x
Shema, E., Jones, D., Shoresh, N., Donohue, L., Ram, O., & Bernstein, B. E. (2016). Single-molecule decoding of combinatorially modified nucleosomes. Science, 352(6286), 717–721. https://doi.org/10.1126/science.aad7701
Shema, E., Kim, J., Roeder, R. G., & Oren, M. (2011). RNF20 Inhibits TFIIS-Facilitated Transcriptional Elongation to Suppress Pro-oncogenic Gene Expression. Molecular Cell, 42(4), 477–488. https://doi.org/10.1016/j.molcel.2011.03.011
Shema, E., Tirosh, I., Aylon, Y., Huang, J., Ye, C., Moskovits, N., Raver-Shapira, N., Minsky, N., Pirngruber, J., Tarcic, G., Hublarova, P., Moyal, L., Gana-Weisz, M., Shiloh, Y., Yarden, Y., Johnsen, S. A., Vojtesek, B., Berger, S. L., & Oren, M. (2008). The histone H2B-specific ubiquitin ligase RNF20/hBRE1 acts as a putative tumor suppressor through selective regulation of gene expression. Genes & Development, 22(19), 2664–2676. https://doi.org/10.1101/gad.1703008
 
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ATAC-Seq, scATAC-Seq and Chromatin Dynamics in Single-Cells (Jason Buenrostro)
Investigating the Dynamics of Epigenetic Plasticity in Cancer with Single Cell Technologies (Céline Vallot)
The Past, Present, and Future of Epigenetics (Joe Fernandez, founder of Active Motif)
 
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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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