DNA-PKCS IN SYNAPTIC PLASTICITY: A CROSSROADS BETWEEN NEURONAL ACTIVITY, DNA DAMAGE AND CELLULAR METABOLISM

DNA double-strand breaks (DSBs), caused by normal brain activity, play a physiological role in gene expression involved in learning and memory. DNA-PKcs, a DSB repair protein, is essential for Long Term Potentiation (LTP). Emerging evidence links DNA-PKcs also to energy metabolism by regulating glycolytic enzymes. Aims of the present study are to: (i) determine whether neuronal activity-induced DSBs and LTP require a rapid glycolytic switch to meet the energy demands of chromatin remodeling and gene expression; 2) explore the role of DNA-PKcs in coordinating DSBs and metabolic responses during LTP.
We used primary neurons isolated from E15.5 embryos from WT and DNA-PKcs -/- (KO) mice. Synaptic activity was induced by different types of stimuli (NMDA, KCl, forskolin/rolipram) and DSB formation was assessed via immunofluorescence, by monitoring gamma-H2AX foci. Immediately-early gene (IEG) expression was assessed via Real-TimePCR. Neuronal metabolism was analyzed through Seahorse extracellular flux analysis.
Here we show that in WT cultures LTP strongly induces a metabolic switch, resembling a Warburg-like effect. LTP parallels gamma-H2AX foci formation that are normally repaired within hours. On the contrary, we found that KO neurons show a reduced glycolytic switch along with a delay of DSB repair kinetics and an altered expression of LTP IEGs.
Here we put in evidence that DNA-PKcs could represent a crucial hub in the regulation of multiple synaptic plasticity processes, coordinating the interplay between DNA repair, energy metabolism and IEG expression. Overall, our data identify DNA-PKcs as a putative effector of glycolytic regulation associated with neuronal activity.