Extended Data Fig. 9: TOP2A’s catalytic activity and its guiding function to localize to the chromosome axis are critical to reduce condensin II abundance at centromeres.
From: Condensin dysfunction is a reproductive isolating barrier in mice
a, Hybrid oocytes expressing MinSat or MinSat-TOP2A were fixed at prometaphase I and stained for TOP2A. TOP2A levels recruited to spretus centromeres by this targeting strategy was equivalent to that on major satellites. This experiment was repeated independently two times with similar results. b,c, Hybrid oocytes expressing MinSat-TOP2AY804F, MinSat-TOP2A∆CTD or MinSat-TOP2ACTD were fixed either at metaphase I and stained for NCAPD3 (b) or fixed at prometaphase I and counterstained with DAPI (c). These experiments were repeated independently two to four times with similar results. MinSat-TOP2AY804F, MinSat-TOP2A∆CTD and MinSat-TOP2ACTD were less efficient in reducing condensin II abundance and inducing centromere stretching compared to MinSat-TOP2A (wild-type), indicating that both TOP2A’s catalytic activity and its guiding function to localize to the chromosome axis are important to reduce condensin II abundance at centromeres62. “D” and “S” indicate domesticus and spretus centromeres, respectively. Images are maximum intensity z projections to show all chromosomes (left) or optical slices magnified to show individual chromosomes (right). Scale bar: 5 µm. d, Schematic showing two pathways that regulate condensin II levels. Nuclear NCAPG2 levels dictate the condensin II abundance on the overall chromosome, while major satellites locally reduce condensin II abundance via TOP2A. spretus pericentromeres have very little major satellites, maintaining their centromeres compact despite they have lower basal condensin II levels on the chromosome.
