Restriction of AID activity and somatic hypermutation by PARP-1.

Authors :: Tepper S
Mortusewicz O
Członka E
Bello A
Schmidt A
Jeschke J
Fischbach A
Pfeil I
Petersen-Mahrt SK
Mangerich A
Helleday T
Leonhardt H
Jungnickel B
Source :: Nucleic acids research [Nucleic Acids Res] 2019 Aug 22; Vol. 47 (14), pp. 7418-7429.
Publication Year :: 2019
Abstract: Affinity maturation of the humoral immune response depends on somatic hypermutation (SHM) of immunoglobulin (Ig) genes, which is initiated by targeted lesion introduction by activation-induced deaminase (AID), followed by error-prone DNA repair. Stringent regulation of this process is essential to prevent genetic instability, but no negative feedback control has been identified to date. Here we show that poly(ADP-ribose) polymerase-1 (PARP-1) is a key factor restricting AID activity during somatic hypermutation. Poly(ADP-ribose) (PAR) chains formed at DNA breaks trigger AID-PAR association, thus preventing excessive DNA damage induction at sites of AID action. Accordingly, AID activity and somatic hypermutation at the Ig variable region is decreased by PARP-1 activity. In addition, PARP-1 regulates DNA lesion processing by affecting strand biased A:T mutagenesis. Our study establishes a novel function of the ancestral genome maintenance factor PARP-1 as a critical local feedback regulator of both AID activity and DNA repair during Ig gene diversification.<br /> (© The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.)