Failure to confirm association of a polymorphism in KCNMB4 gene with mesial temporal lobe epilepsy

Potassium Channels and Human Epileptic Phenotypes: An Updated Overview

Potassium (K⁺) channels are expressed in almost every cells and are ubiquitous in neuronal and glial cell membranes. These channels have been implicated in different disorders, in particular in epilepsy. K⁺ channel diversity depends on the presence in the human genome of a large number of genes either encoding pore-forming or accessory subunits. More than 80 genes encoding the K⁺ channels were cloned and they represent the largest group of ion channels regulating the electrical activity of cells in different tissues, including the brain. It is therefore not surprising that mutations in these genes lead to K⁺ channels dysfunctions linked to inherited epilepsy in humans and non-human model animals. This article reviews genetic and molecular progresses in exploring the pathogenesis of different human epilepsies, with special emphasis on the role of K⁺ channels in monogenic forms.

Microarray data analysis of neuroblastoma: Expression of SOX2 downregulates the expression of MYCN

The present study aimed to identify the genes directly or indirectly correlated with the amplification of MYCN in neuroblastoma (NB). Microarray data (GSE53371) were downloaded from Gene Expression Omnibus, and included 10 NB cell lines with MYCN amplification and 10 NB cell lines with normal MYCN copy numbers. Differentially expressed genes (DEGs) were identified using the Linear Models for Microarray Data package, and a false discovery rate of <0.05 and |log2FC (fold change)|>1 were selected as cut‑off criteria. Hierarchical clustering analysis and Gene Ontology analysis were respectively performed for the DEGs using the Pheatmap package in R language and The Database for Annotation, Visualization and Integrated Discovery. A protein‑protein interaction network (PPI) was constructed for the DEGs using the Search Tool for the Retrieval of Interacting Genes database. Pathway analysis was performed for the DEGs in the PPI network using the WEB‑based GEne SeT AnaLysis Toolkit. The correlation between MYCN and the key gene associated with MYCN was determined using Pearson's correlation coefficient. In total, 137 downregulated and 35 upregulated DEGs were identified. Functional enrichment analysis indicated that KCNMB4 was involved in the regulation of action potential in neuron term, and the FOS, GLI3 and GLI1 genes were involved in the extracellular matrix‑receptor interaction pathway. The PPI network and correlation analysis revealed that the expression of SOX2 was directly correlated with the expression of MYCN, and the correlation coefficient of SOX2 and MYCN was ‑0.83. Therefore, SOX2, KCNMB4, FOS, GLI3 and GLI1 may be involved in the pathogenesis of NB, with the expression of SOX2 downregulating the expression of MYCN.

K(+) channelepsy: progress in the neurobiology of potassium channels and epilepsy

K(+) channels are important determinants of seizure susceptibility. These membrane proteins, encoded by more than 70 genes, make the largest group of ion channels that fine-tune the electrical activity of neuronal and non-neuronal cells in the brain. Their ubiquity and extremely high genetic and functional diversity, unmatched by any other ion channel type, place K(+) channels as primary targets of genetic variations or perturbations in K(+)-dependent homeostasis, even in the absence of a primary channel defect. It is therefore not surprising that numerous inherited or acquired K(+) channels dysfunctions have been associated with several neurologic syndromes, including epilepsy, which often generate confusion in the classification of the associated diseases. Therefore, we propose to name the K(+) channels defects underlying distinct epilepsies as "K(+) channelepsies," and introduce a new nomenclature (e.g., Kx.y-channelepsy), following the widely used K(+) channel classification, which could be also adopted to easily identify other channelopathies involving Na(+) (e.g., Nav x.y-phenotype), Ca(2+) (e.g., Cav x.y-phenotype), and Cl(-) channels. Furthermore, we discuss novel genetic defects in K(+) channels and associated proteins that underlie distinct epileptic phenotypes in humans, and analyze critically the recent progress in the neurobiology of this disease that has also been provided by investigations on valuable animal models of epilepsy. The abundant and varied lines of evidence discussed here strongly foster assessments for variations in genes encoding for K(+) channels and associated proteins in patients with idiopathic epilepsy, provide new avenues for future investigations, and highlight these proteins as critical pharmacological targets.