The competing mini-dumbbell mechanism: new insights into CCTG repeat expansion.

ABSTRACT: CCTG repeat expansions in intron 1 of the cellular nucleic acid-binding protein gene are associated with myotonic dystrophy type 2. Recently, we have reported a novel mini-dumbbell (MDB) structure formed by two CCTG or TTTA repeats, which potentially has a critical role in repeat expansions. Here we present a mechanism, called the competing MDB mechanism, to explain how the formation of MDB can lead to efficient mismatch repair (MMR) escape and thus CCTG repeat expansions during DNA replication. In a long tract of CCTG repeats, two competing MDBs can be formed in any segment of three repeats. Fast exchange between these MDBs will make the commonly occupied repeat behave like a mini-loop. Further participations of the 5'- or 3'-flanking repeat in forming competing MDBs will make the mini-lo

SUBMITTER: Guo P 

PROVIDER: S-EPMC5661647 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature