Fig. 9: Models of how Msc1 and ESCRT-III may influence DSB repair in late-M.
From: Continuous nuclear envelope surveillance is required for DNA double strand break repair
a In late-M, the nucleus assumes an extended dumbbell shape with already segregated sister chromatids (a single pair of sisters is depicted for simplicity). (1) After a DSB occurs in one of the sisters, the extended nucleus becomes shorter and the bridge becomes thicker. The sisters also move closer and can coalesce for HR repair of the DSB. The broken ends can also get attached to the NE to facilitate retrograde events, and NPCs may participate in this attachment. (2) If segregated sisters are physically partitioned, as it occurs in Δmsc1, there are late-M cells in which sister chromatid approximation is challenged. A similar scenario may happen in NE invaginations in ESCRT-III mutants. (3) Alternatively, or in addition to partitions, NPC maldistribution and aggregation, which are observed in both mutants, could challenge DSB processing and template search. b A dynamic model for the role of Msc1 in preventing late-M nuclear partitions. Msc1 would remove NE blebs before they segment nuclear areas.
