Herzog N, Hartkamp JD, Verheugd P, Treude F, Forst AH, Feijs KL, Lippok B, Kremmer E, Kleine H, Lüscher B
ADP-ribosylation is a posttranslational modification regulating various physiological processes, including DNA damage repair, gene transcription, and signal transduction. Intracellular ADP-ribosyltransferases (ARTDs or PARPs) modify their substrates either by poly- or mono-ADP-ribosylation. Previously we identified ARTD10 (formerly PARP10) as a mono-ADP-ribosyltransferase and observed that exogenous ARTD10 but not ARTD10-G888W, a catalytically inactive mutant, interferes with cell proliferation. To expand on this observation we established cell lines with inducible ARTD10 or ARTD10-G888W. Consistent with our previous findings, induction of the wild-type protein but not the mutant inhibited cell proliferation, primarily by inducing apoptosis. During apoptosis, ARTD10 itself was targeted by caspases. We mapped the major cleavage site at EIAMD406↓S, a sequence that was preferentially recognized by caspase-6. Caspase-dependent cleavage inhibited the pro-apoptotic activity of ARTD10, as ARTD10-(1-406) and ARTD10-(407-1025), either alone or together, were unable to induce apoptosis, despite catalytic activity of the latter. Deletion of the N-terminal RNA recognition motif (RRM) in ARTD10-(257-1025) also resulted in loss of pro-apoptotic activity. Thus our findings indicate that the RRM contributes to the pro-apoptotic effect together with the catalytic domain. We suggest that these two domains must be physically linked to stimulate apoptosis, possibly to target ARTD10 through the RRM to specific substrates that control cell death. Moreover we established that knockdown of ARTD10 reduced apoptosis in response to DNA damaging agents. Together these findings indicate that ARTD10 is involved in the regulation of apoptosis and that once apoptosis is activated ARTD10 is cleaved as part of a negative feedback regulation. © 2013 The Authors Journal compilation © 2013 FEBS.