Expansion of CAG triplet repeats by human DNA polymerases λ and β in vitro, is regulated by flap endonuclease 1 and DNA ligase 1

Copyright © 2015 Elsevier B.V. All rights reserved..

Huntington's disease (HD) is a neurological genetic disorder caused by the expansion of the CAG trinucleotide repeats (TNR) in the N-terminal region of coding sequence of the Huntingtin's (HTT) gene. This results in the addition of a poly-glutamine tract within the Huntingtin protein, resulting in its pathological form. The mechanism by which TRN expansion takes place is not yet fully understood. We have recently shown that DNA polymerase (Pol) β can promote the microhomology-mediated end joining and triplet expansion of a substrate mimicking a double strand break in the TNR region of the HTT gene. Here we show that TNR expansion is dependent on the structure of the DNA substrate, as well as on the two essential Pol β co-factors: flap endonuclease 1 (Fen1) and DNA ligase 1 (Lig1). We found that Fen1 significantly stimulated TNR expansion by Pol β, but not by the related enzyme Pol λ, and subsequent ligation of the DNA products by Lig1. Interestingly, the deletion of N-terminal domains of Pol λ, resulted in an enzyme which displayed properties more similar to Pol β, suggesting a possible evolutionary mechanism. These results may suggest a novel mechanism for somatic TNR expansion in HD.

Medienart:

E-Artikel

Erscheinungsjahr:

2015

Erschienen:

2015

Enthalten in:

Zur Gesamtaufnahme - volume:29

Enthalten in:

DNA repair - 29(2015) vom: 28. Mai, Seite 101-11

Sprache:

Englisch

Beteiligte Personen:

Crespan, Emmanuele [VerfasserIn]
Hübscher, Ulrich [VerfasserIn]
Maga, Giovanni [VerfasserIn]

Links:

Volltext

Themen:

9007-49-2
DNA
DNA Ligase ATP
DNA Ligases
DNA Polymerase beta
DNA polymerase β
DNA polymerase λ
DNA polymerase beta2
Double strand breaks repair
EC 2.7.7.-
EC 2.7.7.7
EC 3.1.-
EC 3.1.11.-
EC 6.5.1.-
EC 6.5.1.1
FEN1 protein, human
Flap Endonucleases
Flap endonuclease 1
Journal Article
LIG1 protein, human
Research Support, Non-U.S. Gov't
Trinucleotide repeat expansion

Anmerkungen:

Date Completed 08.02.2016

Date Revised 09.12.2020

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.dnarep.2015.01.005

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM246290080