RNA oxidation: Role of polynucleotide phosphorylase in the quality control of oxidized RNA

Reactive oxygen species is one of the most common cellular RNA damaging agents in living organisms. A growing number of studies show a strong correlation between oxidatively damaged RNA and human diseases, predominantly age-related neurodegenerative disorders. Oxidized RNAs impair the fundamental cellular processes including gene regulatory activities and protein synthesis. Molecular characterization of oxidized RNA such as understanding the sources of RNA oxidation, their mechanism of action, and cellular consequences may help to unravel their involvement in the pathogenesis of human diseases. Several proteins and factors with potential function to control RNA oxidation have been identified. Here, we will discuss the role of oxidized RNA binding protein polynucleotide phosphorylase (PNPase) in the quality control of oxidized RNA. PNPase is an evolutionarily conserved 3’-5’ exoribonuclease having multifaceted RNA regulatory roles. Apart from binding to oxidized RNA, PNPase reduces the level of RNA oxidation and protects cells during oxidative stress. In this review, we discuss RNA oxidation and its quality control process with a specific focus on PNPase in regulating oxidized RNA.