Expression and activity of poly(ADP-ribose) glycohydrolase in cultured astrocytes, neurons, and C6 glioma cells

Poly(ADP-ribose) metabolism plays a major role in DNA repair, transcription, replication, and recombination. Poly(ADP-ribose) polymerases are localized primarily to the nucleus, whereas significant levels of poly(ADP-ribose) glycohydrolase (PARG) are believed to be located in the cytoplasm. Only one PARG gene has been identified, but prior studies have reported multiple products of this gene. Here we studied PARG activity and PARG gene expression in several CNS cell types that span the cell growth spectrum: rapidly dividing C6 glioma tumor cells, dividing astrocytes, non-dividing astrocytes (due to contact inhibition), and post-mitotic neurons. Activity assays showed no overall differences between these cell types, but the nuclear to cytoplasmic ratio of PARG activity was highest in C6 glioma cells and lowest in neurons. Western blotting revealed full-length PARG as well as lower molecular weight PARG species in all four cell types.