Laufer Center Seminar - Stefan Niekamp
Stefan Niekamp, Ph.D.
Damon Runyon and K99 Postdoctoral Fellow Massachusetts General Hospital & Harvard Medical School
February 9, 2026 at 1:00 PM
Laufer Center Lecture Hall 101
Title: How the Material Properties of Chromatin Shape Gene Regulation
Gene expression is controlled by opposing chromatin-associated protein complexes that either silence or activate genes. How these antagonistic complexes physically compete for chromatin to establish distinct gene expression states remains poorly understood. Using the Polycomb Repressive Complex 1 (PRC1) and the activating chromatin remodeler SWI/SNF as a model system, we combine single-molecule reconstitution, super-resolution microscopy, and genomic approaches to show that PRC1 assembles into chromatin-dependent condensates. These are dense, droplet-like assemblies whose material properties depend on PRC1 complex composition. By assembling distinct PRC1 variants, cells can tune condensate properties to physically exclude SWI/SNF from chromatin. Conversely, SWI/SNF-bound chromatin suppresses PRC1 condensation through an ATP-independent mechanism. Strikingly, altering condensate material properties directly changes gene expression levels. Together, these findings reveal that gene regulatory outcomes can be encoded by the combinatorial assembly and physical properties of chromatin regulatory complexes themselves, providing a mechanistic framework for understanding how gene expression is shaped in development and disease.
