Antagonizing Increased miR-135a Levels at the Chronic Stage of Experimental TLE Reduces Spontaneous Recurrent Seizures

Abstract

Mesial temporal lobe epilepsy (mTLE) is a chronic neurological disease characterized by recurrent seizures. The antiepileptic drugs currently available to treat mTLE are ineffective in one-third of patients and lack disease-modifying effects. miRNAs, a class of small noncoding RNAs which control gene expression at the post-transcriptional level, play a key role in the pathogenesis of mTLE and other epilepsies. Although manipulationofmiRNAsatacutestageshasbeenreportedtoreducesubsequentspontaneousseizures,itisuncertainwhethertargetingmiRNAs at chronic stages of mTLE can also reduce seizures. Furthermore, the functional role and downstream targets of most epilepsy-associated miRNAs remain poorly understood. Here, we show that miR-135a is selectively upregulated within neurons in epileptic brain and report that targeting miR-135a in vivo using antagomirs after onset of spontaneous recurrent seizures can reduce seizure activity at the chronic stage of experimental mTLE in male mice. Further, by using an unbiased approach combining immunoprecipitation and RNA sequencing, we identify several novel neuronal targets of miR-135a, including Mef2a. Mef2 proteins are key regulators of excitatory synapse density. Mef2a and miR-135a show reciprocal expression regulation in human (of both sexes) and experimental TLE, and miR-135a regulates dendritic spine number and type through Mef2. Together, our data show that miR-135a is target for reducing seizure activity in chronic epilepsy, and that deregulation of miR-135a in epilepsy may alter Mef2a expression and thereby affect synaptic function and plasticity.

A systems approach delivers a functional microRNA catalog and expanded targets for seizure suppression in temporal lobe epilepsy

“…S1 A and B). Next, additional mice were subjected to IAKA and then monitored over the next 2 wk for spontaneous recurrent seizures (SRSs) (29,31). After establishing equivalent baseline rates of SRSs (SI Appendix, Fig.…”

MicroRNAs and target genes in epileptogenesis

“…In TLE patients, miR‐135a expression is upregulated 14,40 . Furthermore, mechanistic studies in the kainic acid–induced mouse epilepsy model showed that miR‐135a downregulation using antagomirs after the onset of spontaneous seizures reduced the number of spontaneous seizures per day and the seizure count and duration by targeting hippocampal myocyte enhancer factor 2A (mef2a), 41 suggesting that miR‐135a has the potential to modify epileptogenesis. MEF2A, as a transcription factor that is highly expressed in hippocampal CA1 neurons, 42 suppresses excitatory synapse number in hippocampal neurons 43 ; however, the effects of miR‐135a on epileptogenesis require further clarification 5 .…”

Ago2-seq identifies new microRNA targets for seizure control

“…Non-radioactive in situ hybridization (ISH) was performed as described previously 64 . Except, hybridization was performed with 10 nM of double-DIG (3’ and 5’) - labelled locked nucleic acid (LNA) probes for miR-10a-5p, miR-142a-5p, miR-21a-5p and LNA-DIG Scramble probe (Exiqon) overnight at 50 °C followed by stringency washes at 55 °C.…”