Genetics and Cell Biology Special Seminar : Encoding memory in 3D: How polycomb-mediated genome folding facilitates epigenetic memory through dynamic chromatin architecture

I utilized chromatin tracing imaging across cell types and tissues to assay the 3D folding of the polycomb-repressed Hoxa locus. Contrary to prior repression models where compaction or phase separation of chromatin drives transcriptional silencing, I found that the polycomb system produces a dynamic and cell-type specific organization that is often decompact or mixed with other chromatin states. This dynamic folding moves the chromatin architecture field beyond a binary model of “open is active and closed is repressed” and provides a mechanism for cells to tune epigenetic memory via spatial feedback of chromatin folding.