Abstract
BackgroundThe formation of ADP-ribose polymers on target proteins by poly(ADP-ribose) polymerases serves a variety of cell signaling functions. In addition, extensive activation of poly(ADP-ribose) polymerase-1 (PARP-1) is a dominant cause of cell death in ischemia-reperfusion, trauma, and other conditions. Poly(ADP-ribose) glycohydrolase (PARG) degrades the ADP-ribose polymers formed on acceptor proteins by PARP-1 and other PARP family members. PARG exists as multiple isoforms with differing subcellular localizations, but the functional significance of these isoforms is uncertain.Methods / Principal FindingsPrimary mouse astrocytes were treated with an antisense phosphorodiamidate morpholino oligonucleotide (PMO) targeted to exon 1 of full-length PARG to suppress expression of this nuclear-specific PARG isoform. The antisense-treated cells showed down-regulation of both nuclear PARG immunoreactivity and nuclear PARG enzymatic activity, without significant alteration in cytoplasmic PARG activity. When treated with the genotoxic agent MNNG to induced PARP-1 activation, the antisense-treated cells showed a delayed rate of nuclear PAR degradation, reduced nuclear condensation, and reduced cell death.Conclusions/SignificanceThese results support a preferentially nuclear localization for full-length PARG, and suggest a key role for this isoform in the PARP-1 cell death pathway.
Highlights
Poly(ADP-ribose) polymerases consume NAD+ to form poly(ADP-ribose) on acceptor proteins
In the present study we aimed to examine the specific role of nuclear Poly(ADP-ribose) glycohydrolase (PARG) activity in poly(ADP-ribose) polymerase-1 (PARP-1) – mediated cell death by selectively blocking translation of the 111 kDa, nuclear-targeted isoform using an antisense phosphorodiamidate morpholino oligonucleotide (PMO) targeted to the 59 start of exon 1 (Fig. 1A)
Immunostaining for PARG in mouse astrocyte cultures treated with antisense PARG PMO showed a marked and selective loss of immunoreactivity from the nuclei of the antisense PMO-treated cells, as compared to sister cultures treated with control PMO or no PMO (Fig. 1B)
Summary
Poly(ADP-ribose) polymerases consume NAD+ to form poly(ADP-ribose) (abbreviated as PAR) on acceptor proteins. This post-translational modification influences protein-protein interactions and serves a variety of cell signaling functions [1]. Extensive activation of PARP-1 occurs after ischemia-reperfusion, trauma, and other conditions that cause DNA damage. In these settings, PARP-1 activation leads to NAD+ depletion, mitochondrial release of apoptosisinducing factor, and cell death [3,4,5]. Extensive activation of poly(ADP-ribose) polymerase-1 (PARP-1) is a dominant cause of cell death in ischemia-reperfusion, trauma, and other conditions. Poly(ADP-ribose) glycohydrolase (PARG) degrades the ADP-ribose polymers formed on acceptor proteins by PARP-1 and other PARP family members. PARG exists as multiple isoforms with differing subcellular localizations, but the functional significance of these isoforms is uncertain
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
