Join Us! CSB Cutting Lecture Series, Irene Chiolo, PhD, Friday, April 10, 2026, LK130
The Department of Chemical and Systems Biology Presents
Cutting Lecture Series
Irene Chiolo, PhD
Professor of Biological Sciences
University of Southern California
Friday, April 10, 2026
12:30 PM – 1:30 PM (Pacific Time)
LKSC – LK130
Talk Title: “Compartmentalizing Repair: multiphase condensates and non-coding RNAs in heterochromatin repair”
Abstract: Pericentromeric heterochromatin occupies 10-30% of the genome and is mostly composed of repeated sequences that are epigenetically silenced and prone to aberrant recombination. Faithful homologous recombination (HR) repair of these sequences relies on the relocalization of repair sites to the nuclear periphery. This likely prevents aberrant recombination by isolating DSBs and their repair templates from ectopic sequences before strand invasion. Relocalization occurs in two steps. First, repair sites diffuse from the center to the periphery of the heterochromatin domain through capillary forces generated between Nup98 condensates that are immiscible with the heterochromatin condensates and exclude the Rad51 recombinase. Next, nuclear actin filaments (F-actin) and myosins drive the directed motion of repair sites to the nuclear periphery. We discovered that, contrary to the expectation, silencing contributes to repair initiation. Transcription also occurs at heterochromatic repair sites, but the role of silencing and transcription in repair dynamics was poorly understood. We will discuss our progress on these studies, including the interplay between silencing, transcription, and bimolecular condensates in heterochromatin repair. These studies are establishing new links between nuclear architecture and dynamics, phase separation, repair progression, and the stability of repeated DNA sequences, identifying new mechanisms for genome integrity.
CSB Faculty Host: Karlene Cimprich, PhD