Reduction of Kcnt1 is therapeutic in mouse models of SCN1A and SCN8A epilepsy

Comprehensive genetic diagnosis and therapeutic perspectives in 155 children with developmental and epileptic encephalopathy

We studied a retrospective cohort of children with developmental and epileptic encephalopathy (DEE), a group of neurological conditions characterized by early onset epilepsy and severe developmental delay. Cases were recruited from three university hospitals based on clinical criteria, after a blinded cross-validation process, and most were subject to both array-CGH and exome-based gene panel analyses. 155 subjects were included. A genetic diagnosis was identified in 105 (68 %). A majority of patients (71 %) had onset of symptoms before the age of one year. In this age group a disease-causing variant was identified in 73 % of children, the highest proportion of cases reported so far. Genetic heterogeneity was high, involving 40 different genes. The most prevalent gene was SCN1A. Eight genes were identified in multiple patients and accounted for 50 % of all diagnoses. The remaining genes represented ultra-rare disorders. In many cases, molecular diagnosis leads to treatment adaptation and allows for genetic counseling. Those results highlight the growing importance of genetic investigations especially in children with symptoms onset before the age of 1. Finally, we evaluated the disease-causing variants in an intention-to-treat approach and found that almost half would theoretically be amenable to personalized therapy using antisense oligonucleotides (ASOs).

Merritt-Putnam Symposium | Developmental and Epileptic Encephalopathies-Current Concepts and Novel Approaches

Developmental and epileptic encephalopathies (DEEs) are among the most severe and difficult to treat epilepsies. Two broad strategies for understanding the etiology and impacts of DEEs include genetic and complex adaptive systems approaches. This review, inspired by the 2024 Merritt-Putnam Symposium, describes current perspectives of DEE, identifies limitations of current views, and discusses potential novel ways forward. First, we discuss the rationale for a reevaluation of the role of seizures in the pathogenesis of cognitive and behavioral impairments in DEE. Second, we discuss newly emerging methods employing neural organoids to study brain development and DEE in vitro. Third, we present recent precision therapy approaches for the clinical treatment of DEE. Lastly, we discuss computational systems approaches to understanding the genetic landscape of DEE. The severe and multifaceted impacts of DEE and associated comorbidities underscore the necessity of novel interdisciplinary approaches to produce an improved understanding of etiology and more effective treatment strategies.

Structure-Activity Relationship Studies in a Series of 2-Aryloxy-N-(pyrimidin-5-yl)acetamide Inhibitors of SLACK Potassium Channels

Epilepsy of infancy with migrating focal seizures (EIMFS) is a rare, serious, and pharmacoresistant epileptic disorder often linked to gain-of-function mutations in the KCNT1 gene. KCNT1 encodes the sodium-activated potassium channel known as SLACK, making small molecule inhibitors of SLACK channels a compelling approach to the treatment of EIMFS and other epilepsies associated with KCNT1 mutations. In this manuscript, we describe a hit optimization effort executed within a series of 2-aryloxy-N-(pyrimidin-5-yl)acetamides that were identified via a high-throughput screen. We systematically prepared analogs in four distinct regions of the scaffold and evaluated their functional activity in a whole-cell, automated patch clamp (APC) assay to establish structure-activity relationships for wild-type (WT) SLACK inhibition. Two selected analogs were also profiled for selectivity versus other members of the Slo family of potassium channels, of which SLACK is a member, and versus a panel of structurally diverse ion channels. The same two analogs were evaluated for activity versus the WT mouse channel as well as two clinically relevant mutant human channels.

Voltage-Gated Ion Channel Compensatory Effect in DEE: Implications for Future Therapies

Developmental and Epileptic Encephalopathies (DEEs) represent a clinically and genetically heterogeneous group of rare and severe epilepsies. DEEs commonly begin early in infancy with frequent seizures of various types associated with intellectual disability and leading to a neurodevelopmental delay or regression. Disease-causing genomic variants have been identified in numerous genes and are implicated in over 100 types of DEEs. In this context, genes encoding voltage-gated ion channels (VGCs) play a significant role, and part of the large phenotypic variability observed in DEE patients carrying VGC mutations could be explained by the presence of genetic modifier alleles that can compensate for these mutations. This review will focus on the current knowledge of the compensatory effect of DEE-associated voltage-gated ion channels and their therapeutic implications in DEE. We will enter into detailed considerations regarding the sodium channels SCN1A, SCN2A, and SCN8A; the potassium channels KCNA1, KCNQ2, and KCNT1; and the calcium channels CACNA1A and CACNA1G.

Whole transcriptome sequencing reveals key genes and ceRNA regulatory networks associated with pimpled eggs in hens

Eggshell is one of the most important indicators of egg quality, and due to low shell strength, pimple eggs (PE) are more susceptible to breakage, thus causing huge economic losses to the egg industry. At the current time, the molecular mechanisms that regulate the formation of pimple eggs are poorly understood. In this study, uterine tissues of PE-laying hens (n = 8) and normal egg (NE) -laying hens (n = 8) were analyzed by whole transcriptome sequencing, and a total of 619 differentially expressed mRNAs (DE mRNAs), 122 differentially expressed lncRNAs (DE lncRNAs) and 21 differentially expressed miRNAs (DE miRNAs) were obtained. Based on the targeting relationship among DE mRNAs, DE lncRNAs and DE miRNAs, we constructed a competitive endogenous RNA (ceRNA) network including 12 DE miRNAs, 19 DE lncRNAs, and 128 DE mRNAs. Considering the large amount of information contained in the network, we constructed a smaller ceRNA network to better understand the complex mechanisms of pimple egg formation. The smaller ceRNA network network contains 7 DE lncRNAs (LOC107056551, LOC121109367, LOC121108909, LOC121108862, LOC112530033, LOC121113165, LOC107054145), 5 DE miRNAs (gga-miR-6568-3p, gga-miR-31-5p, gga-miR-18b-3p, gga-miR-1759-3p, gga-miR-12240-3p) and 7 DE mRNAs (CABP1, DNAJC5, HCN3, HPCA, IBSP, KCNT1, OTOP3), and these differentially expressed genes may play key regulatory roles in the formation of pimpled eggs in hens. This study provides the overall expression profiles of mRNAs, lncRNAs and miRNAs in the uterine tissues of hens, which provides a theoretical basis for further research on the molecular mechanisms of pimpled egg formation, and has potential applications in improving eggshell quality.

Structure-Activity Relationship Studies in a Series of Xanthine Inhibitors of SLACK Potassium Channels

Gain-of-function mutations in the KCNT1 gene, which encodes the sodium-activated potassium channel known as SLACK, are associated with the rare but devastating developmental and epileptic encephalopathy known as epilepsy of infancy with migrating focal seizures (EIMFS). The design of small molecule inhibitors of SLACK channels represents a potential therapeutic approach to the treatment of EIMFS, other childhood epilepsies, and developmental disorders. Herein, we describe a hit optimization effort centered on a xanthine SLACK inhibitor (8) discovered via a high-throughput screen. Across three distinct regions of the chemotype, we synthesized 58 new analogs and tested each one in a whole-cell automated patch-clamp assay to develop structure-activity relationships for inhibition of SLACK channels. We further evaluated selected analogs for their selectivity versus a variety of other ion channels and for their activity versus clinically relevant SLACK mutants. Selectivity within the series was quite good, including versus hERG. Analog 80 (VU0948578) was a potent inhibitor of WT, A934T, and G288S SLACK, with IC50 values between 0.59 and 0.71 µM across these variants. VU0948578 represents a useful in vitro tool compound from a chemotype that is distinct from previously reported small molecule inhibitors of SLACK channels.

Disease-causing Slack potassium channel mutations produce opposite effects on excitability of excitatory and inhibitory neurons

The KCNT1 gene encodes the sodium-activated potassium channel Slack (KCNT1, KNa1.1), a regulator of neuronal excitability. Gain-of-function mutations in humans cause cortical network hyperexcitability, seizures, and severe intellectual disability. Using a mouse model expressing the Slack-R455H mutation, we find that Na+-dependent K+ (KNa) and voltage-dependent sodium (NaV) currents are increased in both excitatory and inhibitory cortical neurons. These increased currents, however, enhance the firing of excitability neurons but suppress that of inhibitory neurons. We further show that the expression of NaV channel subunits, particularly that of NaV1.6, is upregulated and that the length of the axon initial segment and of axonal NaV immunostaining is increased in both neuron types. Our study on the coordinate regulation of KNa currents and the expression of NaV channels may provide an avenue for understanding and treating epilepsies and other neurological disorders.