SOX11 identified by target gene evaluation of miRNAs differentially expressed in focal and non-focal brain tissue of therapy-resistant epilepsy patients

Abstract

MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally control the expression of their target genes via RNA interference. There is increasing evidence that expression of miRNAs is dysregulated in neuronal disorders, including epilepsy, a chronic neurological disorder characterized by spontaneous recurrent seizures. Mesial temporal lobe epilepsy (MTLE) is a common type of focal epilepsy in which disease-induced abnormalities of hippocampal neurogenesis in the subgranular zone as well as gliosis and neuronal cell loss in the cornu ammonis area are reported. We hypothesized that in MTLE altered miRNA-mediated regulation of target genes could be involved in hippocampal cell remodeling. A miRNA screen was performed in hippocampal focal and non-focal brain tissue samples obtained from the temporal neocortex (both n=8) of MTLE patients. Out of 215 detected miRNAs, two were differentially expressed (hsa-miR-34c-5p: mean increase of 5.7 fold (p=0.014), hsa-miR-212-3p: mean decrease of 76.9% (p=0.0014)). After in-silico target gene analysis and filtering, reporter gene assays confirmed RNA interference for hsa-miR-34c-5p with 3′-UTR sequences of GABRA3, GRM7 and GABBR2 and for hsa-miR-212-3p with 3′-UTR sequences of SOX11, MECP2, ADCY1 and ABCG2. Reporter gene assays with mutated 3′-UTR sequences of the transcription factor SOX11 identified two different binding sites for hsa-miR-212-3p and its primary transcript partner hsa-miR-132-3p. Additionally, there was an inverse time-dependent expression of Sox11 and miR-212-3p as well as miR-132-3p in rat neonatal cortical neurons. Transfection of neurons with anti-miRs for miR-212-3p and miR-132-3p suggest that both miRNAs work synergistically to control Sox11 expression. Taken together, these results suggest that differential miRNA expression in neurons could contribute to an altered function of the transcription factor SOX11 and other genes in the setting of epilepsy, resulting not only in impaired neural differentiation, but also in imbalanced neuronal excitability and accelerated drug export.

Practical Strategies and Concepts in GPCR Allosteric Modulator Discovery: Recent Advances with Metabotropic Glutamate Receptors

“…mGlu 7 is thought to be a therapeutic target for various CNS disorders; polymorphisms in the GRM7 gene have been linked to autism, depression, bipolar disorder, attention deficit hyperactivity disorder (ADHD), and schizophrenia. 315–329 The first reported allosteric agonist of mGlu 7 , AMN082 ( 87 ), demonstrates agonist activity in vitro and was reported to be active in models of stress-related CNS disorders (Figure 25). 330 However, more recent reports suggest that the in vivo activity might involve mechanisms in addition to mGlu 7 .…”

Involvement of microRNAs in epileptogenesis

“…The first genome‐wide profiling study of miRNA expression in human TLE patients compared several epilepsy‐associated cellular processes and found that the immune response was predicted to be the most prominently targeted process by deregulated miRNAs . In particular, miR‐221 and miR‐222 were shown in several reports to be down‐regulated and seem to correlate with endogenous intercellular adhesion molecule 1 (ICAM1) expression in astrocytes from TLE patients . Because ICAM1 is a protein that favors immune and inflammatory responses, these miRNAs might be proinflammatory during epileptogenesis.…”

“…Because it has also been reported to be a tumor suppressor when down‐regulated in various types of cancer, loss of miR‐137 might also have effects on cell death during epileptogenesis. Similarly, let‐7 is an miRNA family thought to be involved in cell cycle regulation by promoting differentiation, and multiple let‐7 members have been found deregulated during epileptogenesis by different groups . However, the direction of deregulation is highly variable, depending on the let‐7 isoform considered.…”

MicroRNA profiling in the dentate gyrus in epileptic rats

“…[7] There is increasing evidence to support that miRNA changes are involved in the pathophysiology of epilepsy. [8] Using either rodent epilepsy models or human tissue from patients with epilepsy, a number of previous studies have demonstrated that miRNA expression is altered in epilepsy.…”