RNA-based strategies to rescue inhibition as potential treatment for GABRA1-dependent epilepsy

Newly discovered group of natural antisense long non-coding RNAs, known as SINEUPs, exhibits the ability to ameliorate defective gene expression by enhancing mRNA translation. A subgroup of severe and drug resistant forms of epileptic encephalopathies (EEs) have been associated to the haploinsufficiency of the GABRA1 gene that, by coding for the α1 subunit of the main inhibitory synaptic receptor, leads to impaired GABAergic inhibition. By taking advantage of a heterozygous α1 knock-out mouse model of epilepsy (het-α1 KO), we exploit SINEUP approach to restore GABAergic inhibitory deficits. Compared to wild-type animals, the het-α1 KO mice altered the kinetics of inhibitory synaptic currents (IPSCs) in principal cells of the layer 4 (L4PC) somatosensory cortex (S1). Additional investigation of the thalamocortical circuit revealed reduced feedforward inhibition in L4PC of het-α1 KO mice, resulting in a frequency-dependent increase in E/I conductance ratio. Given the crucial role of fast-spiking PV interneurons in maintaining E/I balance, we examined synaptic plasticity at PV-L4PC synapses, uncovering diminished inhibitory synaptic potentiation in het-α1 KO mice with respect to WT. Remarkably, administration of GABRA1-SINEUP rescued all the above mentioned deficits in the KO mice, thus identifying this molecular tool as an excellent candidate for the treatment of epilepsy-associated cellular and circuit abnormalities linked to GABRA1 haploinsufficiency.