From Placeholder Nucleosomes to Zygotic Genome Activation (Patrick Murphy)

In this episode of the Epigenetics Podcast, we talked with Patrick Murphy from Cornell University about his work on gene regulation and cellular identity.

Dr. Murphy's research focuses on the molecular mechanisms that govern gene expression through transcriptional and chromatin-based regulatory networks. At the start of the Interview Dr. Murphy describes an innovative single-molecule analytical approach he developed during his early research. This method enables the simultaneous detection of multiple epigenetic marks and contributes to his foundational studies on chromatin biology. Focusing on chromatin states, he introduces the concept of placeholder nucleosomes which are specialised nucleosomes that play key roles in maintaining a permissive chromatin state and facilitating gene activation during embryonic development.

The discussion further explores Dr. Murphy's transition from studying Drosophila to working with zebrafish, highlighting his focus on chromatin reprogramming during zygotic genome activation. He presents data from his collaborations that reveal intriguing roles for specific chromatin marks, emphasising how these discoveries hold potential for understanding gene expression regulation in both zebrafish and mammalian models.

Dr. Murphy also shares insights into a project investigating the impacts of paternal cigarette smoke on offspring health, which led to an exploration of systemic inflammation responses and their lasting effects on gene expression in the brain. This unique intersection of basic and translational research underlines the wide-ranging implications of his findings.

References

• Murphy, P. J., Cipriany, B. R., Wallin, C. B., Ju, C. Y., Szeto, K., Hagarman, J. A., Benitez, J. J., Craighead, H. G., & Soloway, P. D. (2013). Single-molecule analysis of combinatorial epigenomic states in normal and tumor cells. Proceedings of the National Academy of Sciences of the United States of America, 110(19), 7772–7777. https://doi.org/10.1073/pnas.1218495110
• Murphy, P. J., Wu, S. F., James, C. R., Wike, C. L., & Cairns, B. R. (2018). Placeholder Nucleosomes Underlie Germline-to-Embryo DNA Methylation Reprogramming. Cell, 172(5), 993–1006.e13. https://doi.org/10.1016/j.cell.2018.01.022
• Park, B. J., Hua, S., Casler, K. D., Cefaloni, E., Ayers, M. C., Lake, R. F., Murphy, K. E., Vertino, P. M., O'Connell, M. R., & Murphy, P. J. (2025). CUT&Tag overcomes biases of ChIP and establishes chromatin patterns for repetitive genomic loci. iScience, 28(11), 113757. https://doi.org/10.1016/j.isci.2025.113757

Related Episodes

• Pioneer Transcription Factors and Their Influence on Chromatin Structure (Ken Zaret)
• In Vivo Nucleosome Structure and Dynamics (Srinivas Ramachandran)
• Nucleosome Positioning in Cancer Diagnostics (Vladimir Teif)

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