UPF 1069

UPF 1069, a derivative of isoquinolinone, is a potent and selective inhibitor of poly-(ADP-ribose) polymerase 2 (PARP-2), with the value of 50% inhibition concentration IC₅₀ of 0.3 μmol/L, that is capable of reducing PAR formation both in recombinant enzyme preparations and in nuclear extracts from PARP^-1-/- fibroblasts. Although its inhibition towards PARP-2 is most selective among other PARP-2 inhibitors, UPF 1069 also inhibits PARP-1 with a lesser potency (the value of IC₅₀ of 8 μmol/L). Having been used to investigate the role of PARP-1 and PARP-2 in post-ischaemic brain damage, UPF 1069 enhances oxygen-glucose deprivation (OGD) injury in hippocampal slices.

Reference

Moroni F, Formentini L, Gerace E, Camaioni E, Pellegrini-Giampietro DE, Chiarugi A, Pellicciari R. Selective PARP-2 inhibitors increase apoptosis in hippocampal slices but protect cortical cells in models of post-ischaemic brain damage. Br J Pharmacol. 2009;157(5):854-862

Selective PARP-2 inhibitors increase apoptosis in hippocampal slices but protect cortical cells in models of post-ischaemic brain damage.[Pubmed:19422384]

Br J Pharmacol. 2009 Jul;157(5):854-62.

BACKGROUND AND PURPOSE: Poly(ADP-ribose) polymerases (PARP)-1 and PARP-2 play complementary tasks in the maintenance of genomic integrity, but their role in cell death or survival processes is rather different. A recently described series of selective PARP-2 inhibitors (UPF-1035, UPF-1069) were used to study the role of PARP-1 and PARP-2 in post-ischaemic brain damage. EXPERIMENTAL APPROACH: We evaluated post-ischaemic brain damage in two different in vitro models: rat organotypic hippocampal slices exposed to oxygen-glucose deprivation (OGD) for 20-30 min, a model characterized by apoptosis-like cell death and mouse mixed cortical cell cultures exposed to 60 min OGD, a model in which cells die with mostly necrosis-like features. KEY RESULTS: In organotypic hippocampal slices, PARP-2 inhibition with UPF-1069 (0.01-1 micromolxL(-1)) caused a concentration-dependent exacerbation (up to 155%) of OGD-induced CA1 pyramidal cell death. Higher concentrations, acting on both PARP-1 and PARP-2, had no effect on OGD injury. In mouse mixed cortical cells exposed to OGD, on the contrary, UPF-1069 (1-10 micromolxL(-1)) significantly reduced post-ischaemic damage. CONCLUSION AND IMPLICATIONS: Selective PARP-2 inhibitors increased post-OGD cell death in a model characterized by loss of neurons through a caspase-dependent, apoptosis-like process (hippocampal slice cultures), but they reduced post-OGD damage and increased cell survival in a model characterized by a necrosis-like process (cortical neurons). UPF-1069 may be a valuable tool to explore the function of PARP-2 in biological systems and to examine the different roles of PARP isoenzymes in the mechanisms of cell death and survival.

Mild activation of poly(ADP-ribose) polymerase (PARP) is neuroprotective in rat hippocampal slice models of ischemic tolerance.[Pubmed:22639866]

Eur J Neurosci. 2012 Jul;36(1):1993-2005.

Ischemic tolerance is a phenomenon in which exposure to a mild preconditioning stress results in resistance to a subsequent lethal ischemic insult. Here we investigated the role of poly(ADP-ribose) polymerase (PARP) in the development of ischemic tolerance by using organotypic rat hippocampal slices exposed to 30 min oxygen-glucose deprivation (OGD), which leads to selective injury of the CA1 subregion 24 h later. We developed models of pharmacological preconditioning by exposing slices to subtoxic concentrations of either N-methyl-D-aspartate (NMDA) or (S)-3,5-dihydroxyphenylglycine (DHPG) and then, 24 h later, to 30 min OGD. Under these conditions, we observed a significant reduction in OGD-induced CA1 damage. Exposure of slices to the PARP-1 and -2 inhibitors TIQ-A, PJ-34 and UPF 1069 during preconditioning prevented the development of OGD tolerance in a concentration-dependent manner. NMDA and DHPG preconditioning increased the activity of PARP, as detected by immunoblots using antibodies against the poly(ADP-ribose) polymer product, but was not associated with consumption of cellular NAD(+) or ATP. Neuroprotection induced by preconditioning was also prevented by the caspase inhibitor Z-VAD-FMK. The modest but significant increase in caspase-3/7 induced by preconditioning, however, was not associated with PARP-1 cleavage, as occurred with staurosporine. Finally, TIQ-A prevented the activation of ERK1/2 and Akt induced by NMDA preconditioning, suggesting that the protective mechanism evoked by PARP requires activation of these prosurvival mediators. Our results suggest that preconditioning with appropriate pharmacological stimuli may promote neuroprotective mechanisms triggered by the sublethal activation of two otherwise deleterious executioners such as PARP and caspase-3/7.