Epigenetics Podcast

The Nucleosome (Ada and Don Olins)

The Nucleosome is the basic building unit of chromatin. It consists out of 147 base pairs of double stranded DNA wrapped around the Histone core octamer that consists out of 2 copies of each dimer of H2A/H2B, and H3/H4. Nucleosomes are organized like "beads on a string" to form a modifiable regulatory basis for higher order structures of chromatin. The first images of the nucleosome as a particle was published by our guests Ada and Don Olins from the University of New England in 1974 (Olins, A. L. & Olins, D. E. Spheroid Chromatin Units (ν Bodies). Science 183, 330–332 (1974).). This observation lead the way to numerous discoveries around chromatin which ultimately culminated in the discovery of the 2.8 Angstrom high-resolution crystal structure 20 years ago in the year 1997 (Luger, K., Mäder, A. W., Richmond, R. K., Sargent, D. F. & Richmond, T. J. Crystal structure of the nucleosome core particle at 2.8 Å resolution. Nature 389, 251–260 (1997).)
References for this episode
Ada L. Olins, Donald E. Olins. Spheroid Chromatin Units (ν Bodies). Science. 25 Jan 1974: Vol. 183, Issue 4122, pp. 330-332. DOI: 10.1126/science.183.4122.330
Ada L. Olins, Donald E. Olins, et al. An epichromatin epitope. Nucleus. 2011 Jan-Feb; 2(1): 47–60. DOI: 10.4161/nucl.2.1.13271
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Multiple Challenges in ChIP (Adam Blattler)

Chromatin Immunoprecipitation (ChIP) was first developed in Drosophila, where interactions of RNA Pol II with genes were investigated (Mol. Cell. Biol. August 1985 vol. 5 no. 8 2009-2018). Then, in a 1993 publication, (Genes & Dev. 1993 7:592-604), the group of James Broach described the association of histone acetylation state with transcriptional gene silencing in yeast. The technique was first used successfully in mammalian cells by Richard Treisman's group, published in 1998 (Cell (1998) 92:475-87).Chromatin Immunoprecipitation is used to link specific states of chromatin to individual loci in a cell, to understand how genes are regulated, and to decipher the Histone Code. In this Episode, we discuss the multiple challenges of ChIP experiments and the difficulties that can arise during different steps of the process.
References for this episode
Epigenetics News:
Chung-Chau Hon, Jordan A. Ramilowski, … Alistair R. R. Forrest. An atlas of human long non-coding RNAs with accurate 5′ ends. Nature. March 2017. doi:10.1038/nature21374
Jennifer L. Guerriero, Alaba Sotayo, … Anthony Letai. Class IIa HDAC inhibition reduces breast tumours and metastases through anti-tumour macrophages. Nature. March 2017. doi:10.1038/nature21409
Nitika Taneja, Martin Zofall, … Shiv I. S. Grewal. SNF2 Family Protein Fft3 Suppresses Nucleosome Turnover to Promote Epigenetic Inheritance and Proper Replication. Molecular Cell. April 2017. DOI:10.1016/j.molcel.2017.02.006
Multiple Challenges in ChIP
D. S. Gilmour, J. T. Lis. In vivo interactions of RNA polymerase II with genes of Drosophila melanogaster. Molecular and Cellular Biology. August 1985. doi:10.1128/MCB.5.8.2009
M. Braunstein, A. B. Rose, … J. R. Broach. Transcriptional silencing in yeast is associated with reduced nucleosome acetylation. Genes & Development. 1993. doi:10.1101/gad.7.4.592
Arthur S. Alberts, Olivier Geneste, Richard Treisman. Activation of SRF-Regulated Chromosomal Templates by Rho-Family GTPases Requires a Signal that Also Induces H4 Hyperacetylation. Cell. February 1986. doi:10.1016/S0092-8674(00)80941-1
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