Loss-of-function variants in the KCNQ5 gene are implicated in genetic generalized epilepsies

The competing endogenous RNA lnc94641-miR957-3p mediates male fertility in Zeugodacus cucurbitae Coquillett

BACKGROUND

Insect spermatogenesis is a complex process. Numerous genes are involved in sperm motility, which is crucial for male fertility. Few long non-coding RNAs (lncRNAs) in the testis regulate insect spermatogenesis. We previously identified 364 testis-enriched lncRNAs in the globally invasive pest Zeugodacus cucurbitae Coquillett. One of these lncRNAs, lnc94641, is abundantly expressed in the testis; however, its role in spermatogenesis remains unknown.

RESULTS

Suppression of lnc94641 expression led to a 60% decrease in spermatozoa count and a 29% decrease in offspring hatchability. A microRNA (miRNA), miR-957-3p, was experimentally demonstrated to bind to lnc94641 competitively. miR-957-3p overexpression recapitulated reproductive defect phenotypes similar to those caused by lnc94641 knockdown. Furthermore, target gene predictions combined with quantitative reverse transcription PCR, RNA pull-down, and dual luciferase reporter assays confirmed that miR-957-3p targets voltage-gated potassium channel 5 (VGKC5) and odorant receptor 85c (OR85c), elucidating a functional lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) regulatory axis. Fluorescence in situ hybridization (FISH) assays demonstrated the co-localization of lnc94641, miR-957-3p, and VGKC5/OR85c in the mature and transformed regions of the testes. Suppression of VGKC5/OR85c expression resulted in a 68% and 50% decrease in spermatozoa number and an 18% and 21% decrease in offspring hatchability, mirroring the phenotype observed with lnc94641-silencing, thereby reinforcing the mechanistic coherence of this regulatory network.

CONCLUSION

These results revealed a ceRNA axis mediated by 'lnc94641-miR957-3p-VGKC5/OR85c' involved in spermatogenesis that impairs male fertility in the melon fly. Molecular perturbations (lncRNA knockdown or miRNA overexpression) consistently impair sperm production and offspring viability by dysregulating ion channels and chemosensory genes. This mechanistically resolved pathway, centered on the core components VGKC5 and OR85c, revealed conserved reproductive vulnerabilities that could enable the targeted genetic control of this agricultural pest. © 2025 Society of Chemical Industry.

Chronic hypoxia induces alternative splicing of transcripts in the goldfish brain

Several species evolved mechanisms to tolerate periods of severe environmental hypoxia and anoxia. Among them, goldfish are unique as they do not enter a comatose state under such conditions. Taking advantage of the recently published and annotated goldfish genome, we had previously profiled the transcriptomic response of the goldfish brain under normoxic (21 kPa oxygen saturation, N) and hypoxic conditions (2.1 kPa oxygen saturation) after 1 and 4 weeks (1WH, 4WH). Using the RNA-Seq data, we report the occurrence of alternative mRNA splicing (skipped exon, retained intron, alternative 3' or 5' splice sites, and mutually exclusive exons). At 1WH/N, 1004 significant alternative splicing events on 769 gene loci were identified, increasing to 1187 on 963 loci at 4WH/N. There were 305 loci with alternatively spliced transcripts common to both 1WH/N and 4WH/N, 221 of which exhibited the same precise location and splicing mechanism. Specific gene transcripts affected by alternative splicing events were almost entirely different from previously identified differentially expressed genes under chronic hypoxia. GO-term enrichment analyses of gene loci of alternatively spliced transcripts, however, did include similar pathways as previously identified for DEGs. These include epigenetic machinery, ion channel activity (1WH/N), glutamate signaling (4WH/N), endothelial cell function, and ATP hydrolyzation pathways (1WH/N + 4WH/N). We describe selected examples of alternatively spliced transcripts to discuss possible functional relevance in the goldfish brain response to chronic hypoxia. Together, our data identified an additional layer of regulation in brain pathways relevant to hypoxia tolerance in goldfish, which complement previously reported gene expression changes.

Phosphatidylinositol 4,5-bisphosphate activation mechanism of human KCNQ5

The human voltage-gated potassium channels KCNQ2, KCNQ3, and KCNQ5 can form homo- and heterotetrameric channels that are responsible for generating the neuronal M current and maintaining the membrane potential stable. Activation of KCNQ channels requires both the depolarization of membrane potential and phosphatidylinositol 4,5-bisphosphate (PIP2). Here, we report cryoelectron microscopy structures of the human KCNQ5-calmodulin (CaM) complex in the apo, PIP2-bound, and both PIP2- and the activator HN37-bound states in either a closed or an open conformation. In the closed conformation, a PIP2 molecule binds in the middle of the groove between two adjacent voltage-sensing domains (VSDs), whereas in the open conformation, one additional PIP2 binds to the interface of VSD and the pore domain, accompanying structural rearrangement of the cytosolic domain of KCNQ and CaM. The structures, along with electrophysiology analyses, reveal the two different binding modes of PIP2 and elucidate the PIP2 activation mechanism of KCNQ5.

Advances in the design and development of chemical modulators of the voltage-gated potassium channels KV7.4 and KV7.5

INTRODUCTION

Hypertension remains a major public health concern, with significant morbidity and mortality worldwide. Despite the availability of various antihypertensive medications, blood pressure control remains suboptimal in many individuals. During the last decades, KV7.4 and KV7.5, which were already known from the view of neuronal regulation, emerged as possible important players in the regulation of vascular tone and blood pressure.

AREAS COVERED

This review covers physiological functions and current advancements in the development of KV7.4 and KV7.5 channel modulators. The authors highlight the structural elements likely to be important for the future design of KV7 subtype-selective modulators, underscoring their potential as an innovative hypertension treatment.

EXPERT OPINION

Extensive research has been focused on targeting neuronal KV7.2 and KV7.3 channels, while KV7.4 and KV7.5 attracted less attention. Many of the developed compounds represent derivatives of flupirtine or retigabine, whereby subtype channel selectivity has only been demonstrated for a handful of individual compounds. Novel substances address additional sites within the binding pocket by incorporating new functional groups. A comprehensive and systematic evaluation of a compound set with significant subtype selectivity should be performed. The discovery of new highly active, less toxic, and selective compounds, therefore, remains the goal of further research in the coming years.

Investigation of epilepsy-related genes in a Drosophila model

ABSTRACT

Complex genetic architecture is the major cause of heterogeneity in epilepsy, which poses challenges for accurate diagnosis and precise treatment. A large number of epilepsy candidate genes have been identified from clinical studies, particularly with the widespread use of next-generation sequencing. Validating these candidate genes is emerging as a valuable yet challenging task. Drosophila serves as an ideal animal model for validating candidate genes associated with neurogenetic disorders such as epilepsy, due to its rapid reproduction rate, powerful genetic tools, and efficient use of ethological and electrophysiological assays. Here, we systematically summarize the advantageous techniques of the Drosophila model used to investigate epilepsy genes, including genetic tools for manipulating target gene expression, ethological assays for seizure-like behaviors, electrophysiological techniques, and functional imaging for recording neural activity. We then introduce several typical strategies for identifying epilepsy genes and provide new insights into gene-gene interactions in epilepsy with polygenic causes. We summarize well- established precision medicine strategies for epilepsy and discuss prospective treatment options, including drug therapy and gene therapy for genetic epilepsy based on the Drosophila model. Finally, we also address genetic counseling and assisted reproductive technology as potential approaches for the prevention of genetic epilepsy.

Potential Therapeutic Targets for Hypotension in Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is marked by genetic mutations occurring in the DMD gene, which is widely expressed in the cardiovascular system. In addition to developing cardiomyopathy, patients with DMD have been reported to be susceptible to the development of symptomatic hypotension, although the mechanisms are unclear. Analysis of single-cell RNA sequencing data has identified potassium voltage-gated channel subfamily Q member 5 (KCNQ5) and possibly ryanodine receptor 2 (RyR2) as potential candidate hypotension genes whose expression is significantly upregulated in the vascular smooth muscle cells of DMD mutant mice. We hypothesize that heightened KCNQ5 and RyR2 expression contributes to decreased arterial blood pressure in patients with DMD. Exploring pharmacological approaches to inhibit the KCNQ5 and RyR2 channels holds promise in managing the systemic hypotension observed in individuals with DMD. This avenue of investigation presents new prospects for improving clinical outcomes for these patients.

What voltage-sensing phosphatases can reveal about the mechanisms of ion channel regulation by phosphoinositides

Many membrane proteins including ion channels and ion transporters are regulated by membrane phospholipids such as phosphoinositides in cell membranes and organelles. Voltage-sensing phosphatase, VSP, is a voltage-sensitive phosphoinositide phosphatase which dephosphorylates PI(4,5)P2 into PI(4)P. VSP rapidly reduces the level of PI(4,5)P2 upon membrane depolarization, thus serving as a useful tool to quantitatively study phosphoinositide-regulation of ion channels and ion transporters using a cellular electrophysiology system. In this review, we focus on the application of VSPs to Kv7 family potassium channels, which have been important research targets in biophysics, pharmacology and medicine.

Identification of Novel Gene Regulatory Networks for Dystrophin Protein in Vascular Smooth Muscle Cells by Single-Nuclear Transcriptome Analysis

Duchenne muscular dystrophy is an X-linked recessive disease caused by mutations in dystrophin proteins that lead to heart failure and respiratory failure. Dystrophin (DMD) is not only expressed in cardiomyocytes and skeletal muscle cells, but also in vascular smooth muscle cells (VSMCs). Patients with DMD have been reported to have hypotension. Single nuclear RNA sequencing (snRNA-seq) is a state-of-the-art technology capable of identifying niche-specific gene programs of tissue-specific cell subpopulations. To determine whether DMD mutation alters blood pressure, we compared systolic, diastolic, and mean blood pressure levels in mdx mice (a mouse model of DMD carrying a nonsense mutation in DMD gene) and the wide-type control mice. We found that mdx mice showed significantly lower systolic, diastolic, and mean blood pressure than control mice. To understand how DMD mutation changes gene expression profiles from VSMCs, we analyzed an snRNA-seq dataset from the muscle nucleus of DMD mutant (DMDmut) mice and control (Ctrl) mice. Gene Ontology (GO) enrichment analysis revealed that the most significantly activated pathways in DMDmut-VSMCs are involved in ion channel function (potassium channel activity, cation channel complex, and cation channel activity). Notably, we discovered that the DMDmut-VSMCs showed significantly upregulated expression of KCNQ5 and RYR2, whereas the most suppressed pathways were transmembrane transporter activity (such as anion transmembrane transporter activity, inorganic anion transmembrane transporter activity, import into cell, and import across plasma membrane). Moreover, we analyzed metabolic pathways from the Kyoto Encyclopedia of Genes and Genomes (KEGG) using "scMetabolism" R package. DMDmut-VSMCs exhibited dysregulation of pyruvate metabolism and nuclear acid metabolism. In conclusion, via the application of snRNA-seq, we (for the first time) identify the potential molecular regulation by DMD in the upregulation of the expression of KCNQ5 genes in VSMCs, which helps us to understand the mechanism of hypotension in DMD patients. Our study potentially offers new possibilities for therapeutic interventions in systemic hypotension in DMD patients with pharmacological inhibition of KCNQ5.

Potassium channelopathies associated with epilepsy-related syndromes and directions for therapeutic intervention

A number of mutations to members of several CNS potassium (K) channel families have been identified which result in rare forms of neonatal onset epilepsy, or syndromes of which one prominent characteristic is a form of epilepsy. Benign Familial Neonatal Convulsions or Seizures (BFNC or BFNS), also referred to as Self-Limited Familial Neonatal Epilepsy (SeLNE), results from mutations in 2 members of the K_V7 family (KCNQ) of K channels; while generally self-resolving by about 15 weeks of age, these mutations significantly increase the probability of generalized seizure disorders in the adult, in some cases they result in more severe developmental syndromes. Epilepsy of Infancy with Migrating Focal Seizures (EIMSF), or Migrating Partial Seizures of Infancy (MMPSI), is a rare severe form of epilepsy linked primarily to gain of function mutations in a member of the sodium-dependent K channel family, KCNT1 or SLACK. Finally, KCNMA1 channelopathies, including Liang-Wang syndrome (LIWAS), are rare combinations of neurological symptoms including seizure, movement abnormalities, delayed development and intellectual disabilities, with Liang-Wang syndrome an extremely serious polymalformative syndrome with a number of neurological sequelae including epilepsy. These are caused by mutations in the pore-forming subunit of the large-conductance calcium-activated K channel (BK channel) KCNMA1. The identification of these rare but significant channelopathies has resulted in a resurgence of interest in their treatment by direct pharmacological or genetic modulation. We will briefly review the genetics, biophysics and pharmacology of these K channels, their linkage with the 3 syndromes described above, and efforts to more effectively target these syndromes.