ARTD2 activity is stimulated by RNA.

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• ADP-ribosyltransferases (ARTs) are crucial enzymes involved in DNA repair and maintaining genome stability.
• ARTD1 (PARP1) and ARTD2 (PARP2) are homologous enzymes that catalyze ADP-ribosylation, a key post-translational modification.
• Both ARTD1 and ARTD2 play roles in the cellular response to genotoxic stress.

Purpose of the Study:

• To investigate the role of ARTD1 and ARTD2 in cellular ADP-ribosylation under genotoxic stress.
• To characterize the effect of Actinomycin D (ActD) on ADP-ribosylation induced by hydrogen peroxide (H2O2) or N-methyl-N'-methyl-nitro-N-nitrosoguanidine (MNNG).
• To identify novel activators of ARTD2-mediated ADP-ribosylation.

Main Methods:

• Cellular assays measuring poly-ADP-ribose (PAR) formation under various stress conditions.
• Treatment with H2O2, MNNG, and Actinomycin D (ActD).
• In vitro experiments to assess ARTD2 activation by RNA and the role of its SAP domain.

Main Results:

• Co-treatment with ActD significantly enhanced H2O2- or MNNG-induced PAR formation.
• This enhancement was primarily mediated by ARTD2, not ARTD1.
• In vitro studies demonstrated that RNA strongly activates ARTD2, with the SAP domain being critical for RNA binding.

Conclusions:

• RNA acts as a novel activator of ARTD2-dependent ADP-ribosylation.
• ARTD2 plays a significant role in the cellular response to genotoxic stress, particularly when RNA polymerase I-dependent transcripts accumulate.
• These findings provide new insights into the regulation of ARTD2 and its function in the nucleus.