Polycomb group mediated target gene repression

How does transcriptional memory work in plants? This is the key question we are currently focussing on. Key players in keeping the cellular memory are Polycomb group (PcG) proteins. PcG genes have been originally identified in Drosophila as part of a cellular memory system that maintains transcription patterns set in the first stages of embryonic live, throughout development and adult live. Some PcG proteins form complexes that insert histone methylation marks into chromatin causing transcriptional repression. Disturbances in the ratio of active and repressive histone methylation marks result in the development of cancer in animals and causes dedifferentiation of plant cells.

By which mechanisms PcG proteins locate to their targets and which mechanisms prevent PcG protein function are question that are currently intensively investigated in the lab.

Related Publications:

Roszak P, Köhler C (2011) Polycomb group proteins are required to couple seed coat initiation to fertilization (2011) Proceedings of the National Academy of Sciences of the USA  108:20826-31 (Medline)

The CHD3 Chromatin Remodeler PICKLE and Polycomb Group Proteins Antagonistically Regulate Meristem Activity in the Arabidopsis Root. (2011) Ernst Aichinger, Corina B.R. Villar, Riccardo Di Mambro, Sabrina Sabatini, Claudia Köhler
Plant Cell 23: 1047-1060

Aichinger, E., Villar, C.B.R., Farrona, S., Reyes, J.C., Hennig, L., Köhler, C. (2009) CHD3 proteins and Polycomb group proteins antagonistically determine cell identity in Arabidopsis. PLoS Genet. (8):e1000605. (Medline)

Köhler, C., Villar, C.B.R. (2008) Programming of gene expression by Polycomb group proteins Trends Cell Biol. 18:236-243. (Medline)

Leroy, O, Hennig, L, Breuninger, H, Laux, T, Köhler, C (2007) Polycomb group proteins function in the female gametophyte to determine seed development in plants. Development 134:3639-3648. (Medline)

Makarevich, G., Leroy, O., Akinci, U., Schubert, D., Clarenz, O., Goodrich, J., Grossniklaus, U., Köhler, C. (2006) Different Polycomb group complexes regulate common target genes in Arabidopsis. EMBO Rep. 7:947-952. (Medline)

Schönrock N, Bouveret R, Leroy O, Borghi L, Kohler C, Gruissem W, Hennig L. (2006) Polycomb-group proteins repressthe floral activator AGL19 in the FLC-independent vernalization pathway. Genes Dev. 20:1667-78. (Medline)

Köhler, C., Hennig, L., Spillane, C., Pien, S., Gruissem, W., Grossniklaus, U. (2003). The Polycomb group protein MEDEA regulates seed development by controlling expression of the MADS-box gene PHERES1. Genes Dev., 17, 1540-1553. (Medline)