Mechanisms of Repression

While PcG proteins are known and well characterized, their mechanisms of action leading to stable repression remain elusive. Silencing of gene expression might involve multiple non-exclusive mechanisms. PREs might interfere with activators by competing for binding to overlapping DNA sequences. PRE silencing might also be achieved by altering chromatin architecture (for instance by changing specific positions or the packing density of nucleo-somes) in order to prevent access of specific regulatory elements to transcription factors. Another mechanism may be to interfere with the RNA poly-merase II machinery. This can be achieved at any of the multiple steps involved in the processes of transcription initiation and elongation. Finally, a way to prevent transcription may be to segregate target genes in nuclear compartments that are depleted from RNA polymerases.

0 0

Post a comment