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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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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