Biology Reference
In-Depth Information
CHAPTER EIGHT
H3K9/HP1 and Polycomb: Two Key
Epigenetic Silencing Pathways for
Gene Regulation and Embryo
Development
,†,1 , Mathieu Tardat *
,1 , Antoine H.F.M. Peters *
,†,2
Peter Nestorov *
* Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
Faculty of Sciences, University of Basel, Basel, Switzerland
1 Equal contribution.
2 Corresponding author: e-mail address: antoine.peters@fmi.ch
Contents
1.
Introduction and Evolutionary Perspective
244
2. The H3K9/HP1 Pathway and Its Role in Development
245
2.1 Developmental role through regulation of gene expression
245
2.2 Function in the germline
255
2.3 New insights into the function of H3K9/HP1 pathway?
257
3. Polycomb Repressive Pathways
259
3.1 Composition and developmental role of PcG proteins
259
3.2 Polycomb regulation
268
4. Conclusion
272
Acknowledgments
274
References
274
Abstract
Proper development of an embryo requires tightly controlled expression of specific sets
of genes. In order to generate all the lineages of the adult, populations of pluripotent
embryonic stem cells differentiate and activate specific transcriptional programs
whereas others are shutdown. The role of transcription factors is obvious in promoting
expression of such developmental genes; however maintenance of specific states
throughout cell division needs additional mechanisms. Indeed, the nucleoprotein com-
plex of DNA and histones, the chromatin, can act as a facilitator or barrier to transcription
depending on its configuration. Chromatin-modifying enzymes regulate accessibility of
DNA by establishing specific sets of chromatin, which will be either permissive or repres-
sive to transcription. In this review, we will describe the H3K9/HP1 and Polycomb path-
ways, which mediate transcriptional repression by modifying chromatin. We discuss
how these two major epigenetic silencing modes are dynamically regulated and
how they contribute to the early steps of embryo development.
 
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