Poster abstracts
Poster number 90 submitted by Thulasi Mahendran
Selective mRNA oxidation of the electron transport chain complex subunits in human neuronal cells dysregulate energy production in Multiple Sclerosis
Thulasi Mahendran (Department of Chemistry and Biochemistry, Kent State University), Soumitra Basu (Department of Chemistry and Biochemistry, Kent State University)
Abstract:
Mitochondria is the site of major cellular energy production. Any disruption in mitochondrial functions has deleterious effect on the cells, since it curtails energy supply essential for cell survival. Multiple Sclerosis (MS) is one of the neurodegenerative diseases associated with dysfunctional mitochondria. In addition to energy production, mitochondria serve as the primary source of reactive oxygen species (ROS) generation in cells. Decrease in complex I, III and IV activities in the neurons were observed in MS patients. Marked rise in ROS leading to oxidation damage to mitochondria and biomolecules, such as, DNA, proteins and lipids were widely studied, while very little is known about oxidation induced damage RNA. Subunits of the ETC complexes are encoded by both mitochondrial and nuclear genomes. Any potential oxidative damage to the mRNAs of these subunits will most likely have detrimental effects on subunit synthesis leading to mitochondrial dysfunction. Subjecting differentiated human neuroblastoma SH-SY5Y cells to 100 µM H2O2 treatment resulted in four mRNAs from the mitochondrial genome that are selectively oxidized leading to nearly 30-40% reduction in protein levels with concomitant decrease in complex I activity. We also performed RNA deep sequencing using nuclear encoded RNAs from oxidized SH-SY5Y and identified several nuclear encoded ETC subunit mRNAs particularly from complexes I, III, IV and V as oxidized with a fold change of ≥ 2. The KEGG network interaction analysis revealed that these targets are associated with many of neurodegenerative diseases including MS. We also determined that there is nearly 50% loss in the mitochondrial membrane potential after 12 hrs following a 30 min H2O2 treatment. Taken together we hypothesize that deficiency of the ETC complex subunits due to mRNA oxidation can create a vicious cycle of ROS generation in the mitochondria, leading to enhanced mitochondrial dysfunction and neurodegeneration in MS and potentially other neurological disorders. We validated our results in post-mortem MS patient brain samples, where we observed the oxidation of the same set of mRNAs as was observed in SH-SY5Y cells. Therefore, RNA oxidation may play a role in mitochondrial dysfunction via affecting the energy synthesis (ETC) pathway causing neurodegeneration.
Keywords: RNA oxidation, Mitochondrial dysfunction, Multiple Sclerosis