RNA processing meets DNA stability: RNaseH2, helicase DDX3X, DNA polymerases ², » and · responding to genotoxic stress (DSB.AD006.200)

Area tematica

Scienze biomediche

Area progettuale

Struttura responsabile del progetto di ricerca

Istituto di genetica molecolare "Luigi Luca Cavalli Sforza" (IGM)

Responsabile di progetto

GIOVANNI MAGA
Telefono: 0382/5061
E-mail: maga@igm.cnr.it

Abstract

The presence in the genome of ribonucleotides (rNMPs) erroneously incorporated by DNA polymerases (Pols) causes replication stress and DNA strand breaks. During previous AIRC projects, we have shown that Pols ², » and · can incorporate rNMPs also opposite DNA lesions, affecting both lesion removal and ribonucleotide excision repair (RER) by RNaseH2 and Pols ´/µ. RNaseH2 is the only known human enzyme able to excise a single rNMP within a DNA strand. We have found that the human RNA helicase DDX3X, a regulator of stress-induced gene expression and DNA damage response pathways, has RNaseH2-type activity. This would be the first example of an alternative RNaseH2-type enzyme in human cells.

Obiettivi

1) Due to the inability of Pols ´/µ to bypass lesions, our hypothesis is that specialized Pols ², » and · can substitute for Pols ´/µ in RER of damaged DNA.
2) Cleavage of a rNMP can proceed through RNaseH2 or the highly mutagenic topoisomerase 1 pathway. We hypothesize that DDX3X may also participate in alternative RER pathways whose specificity has to be investigated.
3) Overexpressed RNaseH2, Pols ², », · and DDX3X are found in many tumors and promote mutagenicity and genetic instability. We hypothesize a coordination among these proteins at the functional and expression levels, whose alteration leads to increased mutagenicity.
Expected Results
1) Uncovering novel RER pathways acting on damaged DNA.
2) Clarifying the role(s) of DDX3X as an alternative RNaseH2-type enzyme in human cells.
3) Investigating the mutual interactions among repair Pols, RNaseH2 and DDX3X in tolerance towards DNA damage, including rNMPs accumulation, and the mechanistic consequences of perturbation of their relative levels.

Data inizio attività

01/01/2018

Parole chiave

DNA repair, DNA polymerases, cancer

Ultimo aggiornamento: 04/12/2024