Fig.6.

Possible roles of FAN1 in processing repeat-containing DNA, protecting against repeat instability. (a) Replication-associated repeat instability; FAN1 may process slip-outs formed on a template or nascent strand during replication and may stabilize repeat length or induce contraction. (b) A slip-out formed by repeat-containing DNA can be processed by a non-mitotic DNA repair associated mechanism. FAN1 may act as one of the critical nucleases to process repeat slip-outs to stabilize the repeat tract against length variations. (c) In non-replicating cells, repeat instability is associated with active transcription across the expanded repeat. FAN1 may process the slip-outs formed following unidirectional or bidirectional transcription across the expanded repeat, to stabilize repeat tract against length variations.