This study identified genetic mutations linked to resistance to pyrethroid insecticides in the plant pest Lygus pratensis. The voltage-gated sodium channel (VGSC) gene was cloned, revealing two mutations (Met918Thr and Leu1014Phe) in laboratory strains and field populations from Inner Mongolia, resulting in variable pyrethroid resistance. A 3D model of LpVGSC was created using homology modeling, and pyrethroid binding patterns were analyzed via molecular docking. Molecular dynamics simulations confirmed structural stability changes and binding stability of pyrethroids to VGSC sites. Mutation frequencies of homozygous and heterozygous genotypes did not exceed 40 and 20%, respectively. Toxicity tests showed high resistance to λ-cyhalothrin (LC50:401.31 ng/cm2). The kdr (L1014F) and superkdr (M918T) mutations weakened interaction forces, reducing pyrethroid binding. M918T and L1014F mutations are predicted to reduce Type I pyrethroid affinity, suggesting Type II pyrethroids may be more effective against resistant strains. These findings aid in resistance management and insecticide design.

Voltage-gated sodium (Nav) channels sense membrane potential and drive cellular electrical activity. The deathstalker scorpion α-toxin LqhαIT exerts a strong action potential prolonging effect on Nav channels. To elucidate the mechanism of action of LqhαIT, we determined a 3.9 Å cryoelectron microscopy (cryo-EM) structure of LqhαIT in complex with the Nav channel from Periplaneta americana (NavPas). We found that LqhαIT binds to voltage sensor domain 4 and traps it in an \"S4 down\" conformation. The functionally essential C-terminal epitope of LqhαIT forms an extensive interface with the glycan scaffold linked to Asn330 of NavPas that augments a small protein-protein interface between NavPas and LqhαIT. A combination of molecular dynamics simulations, structural comparisons, and prior mutagenesis experiments demonstrates the functional importance of this toxin-glycan interaction. These findings establish a structural basis for the specificity achieved by scorpion α-toxins and reveal the conserved glycan as an essential component of the toxin-binding epitope.

Spodoptera frugiperda is a long-distance migratory pest with strong dispersal ability, fast reproduction speed and destructive feeding, so it is difficult to prevent and control. Pyrethroid insecticides are commonly used in pest insects control, And since the voltage-gated sodium channel (VGSC) serves as a major target of pyrethroids, it is important to study this gene for pest control. VGSC is an integral transmembrane protein consisting of approximately 2,000 amino acid residues found in neurons, myocytes, endocrine cells, and ovarian cells and involved in the initiation and propagation of excitable cellular action potentials. In this study, the cDNA sequence of the VGSC was identified from S. frugiperda by rapid amplification of cDNA ends (RACE) which contained an open reading frame of 6,261 bp encoding a protein of 2,086 amino acids. The molecular weight of this protein was predicted to be 236 kDa, and the theoretical isoelectric point was 5.21. A phylogenetic tree constructed based on lepidopteran insects showed that the VGSC of S. frugiperda was most closely relative to that of Spodoptera litura. VGSC is a highly conserved protein with Ion channel conserved structural domains of transmembrane proteins. qPCR showed that the VGSC gene was highly expressed in the epidermis of 2nd instar larvae, and its expression level was low in other tissues, such as the foregut and Malpighian tubules. In addition, VGSC was also detected in the prepupal stage, then gradually increased in abundance after entering the adult stage, peaked at the adult males on the 4th day of pupal stage, and decreased afterwards. The recombinant plasmid of pSumo-mut-VGSC was constructed and induced to express a His tag fused VGSC protein. Polyclonal antibodies were prepared from purified recombinant VGSC protein. The antibody was ELISA-titered, and the western blotting results showed that it specifically recognized VGSC, whether it was recombinant or endogenous protein. These results have laid the foundation for future studies on the physiological function of this gene in the growth and development of S. frugiperda.

In sensory neurons that transmit pain signals, whether acute or chronic, voltage-gated sodium channels (VGSCs) are crucial for regulating excitability. NaV1.1, NaV1.3, NaV1.6, NaV1.7, NaV1.8, and NaV1.9 have been demonstrated and defined their functional roles in pain signaling based on their biophysical properties and distinct patterns of expression in each subtype of sensory neurons. Scorpions and spiders are traditional Chinese medicinal materials, belonging to the arachnid class. Most of the studied species of them have evolved venom peptides that exhibit a wide variety of knottins specifically targeting VGSCs with subtype selectivity and conformational specificity. This review provides an overview on the exquisite knottins from scorpion and spider venoms targeting pain-related NaV channels, describing the sequences and the structural features as well as molecular determinants that influence their selectivity on special subtype and at particular conformation, with an aim for the development of novel research tools on NaV channels and analgesics with minimal adverse effects.

Pyrethroids are widely used against agricultural pests and human disease vectors due to their broad insecticidal spectrum, fast action, and low mammalian toxicity. Unfortunately, overuse of pyrethroids has led to knockdown resistance (kdr) caused by mutations in voltage-gated sodium channels. Mutation I1011M was repeatedly detected in numerous pyrethroid-resistant Aedes aegypti populations from Latin American and Brazil. In addition, mutation G923V was first reported to coexist with I1011M in permethrin/DDT-resistant Ae. aegypti, whether G923V enhances the I1011M-mediated pyrethroid resistance in sodium channels remains unclear. In this study, we introduced mutations G923V and I1011M alone or in combination into the pyrethroid-sensitive sodium channel AaNav1-1 and examined the effects of these mutations on gating properties and pyrethroid sensitivity. We found mutations I1011M and G923V + I1011M shifted the voltage dependence of activation in the depolarizing direction, and none of mutations affect the voltage-dependence of inactivation. G923V and G923V + I1011M mutations reduced the channel sensitivity to both Type I and Type II pyrethroids. However, I1011M alone conferred resistance to Type I pyrethroids, not to Type II pyrethroids. Interestingly, significant synergism effects on Type I pyrethroids were observed between mutations G923V and I1011M. The effects of all mutations on channel sensitivity to DDT were identical with those to Type I pyrethroids. Our results confirm the molecular basis of resistance mediated by mutations G923V and I1011M and may contribute to develop molecular markers for monitoring pest resistance to pyrethroids.

This review focuses on the expression and function of voltage-gated sodium channel subtype NaV1.7 in various cancers and explores its impact on the metastasis driving cell functions such as proliferation, migration, and invasiveness. An overview of its structural characteristics, drug binding sites, inhibitors and their likely mechanisms of action are presented. Despite the lack of clarity on the precise mechanism by which NaV1.7 contributes to cancer progression and metastasis; many studies have suggested a connection between NaV1.7 and proteins involved in multiple signaling pathways such as PKA and EGF/EGFR-ERK1/2. Moreover, the functional activity of NaV1.7 appears to elevate the expression levels of MACC1 and NHE-1, which are controlled by p38 MAPK activity, HGF/c-MET signaling and c-Jun activity. This cascade potentially enhances the secretion of extracellular matrix proteases, such as MMPs which play critical roles in cell migration and invasion activities. Furthermore, the NaV1.7 activity may indirectly upregulate Rho GTPases Rac activity, which is critical for cytoskeleton reorganization, cell adhesion, and actin polymerization. The relationship between NaV1.7 and cancer progression has prompted researchers to investigate the therapeutic potential of targeting NaV1.7 using inhibitors. The positive outcome of such studies resulted in the discovery of several inhibitors with the ability to reduce cancer cell migration, invasion, and tumor growth underscoring the significance of NaV1.7 as a promising pharmacological target for attenuating cancer cell proliferation and metastasis. The research findings summarized in this review suggest that the regulation of NaV1.7 expression and function by small molecules and/or by genetic engineering is a viable approach to discover novel therapeutics for the prevention and treatment of metastasis of cancers with elevated NaV1.7 expression.

Voltage-gated sodium channels (VGSCs) are transmembrane protein complexes that are vital to the generation and propagation of action potentials in nerve and muscle fibers. The canonical VGSC is generally conceived as a heterotrimeric complex formed by 2 classes of membrane-spanning subunit: an α-subunit (pore forming) and 2 β-subunits (non-pore forming). NaV1.5 is the main sodium channel α-subunit of mammalian ventricle, with lower amounts of other α-subunits, including NaV1.6, being present. There are 4 β-subunits (β1-β4) encoded by 4 genes (SCN1B-SCN4B), each of which is expressed in cardiac tissues. Recent studies suggest that in addition to assignments in channel gating and trafficking, products of Scn1b may have novel roles in conduction of action potential in the heart and intracellular signaling. This includes evidence that the β-subunit extracellular amino-terminal domain facilitates adhesive interactions in intercalated discs and that its carboxyl-terminal region is a substrate for a regulated intramembrane proteolysis (RIP) signaling pathway, with a carboxyl-terminal peptide generated by β1 RIP trafficked to the nucleus and altering transcription of various genes, including NaV1.5. In addition to β1, the Scn1b gene encodes for an alternative splice variant, β1B, which contains an identical extracellular adhesion domain to β1 but has a unique carboxyl-terminus. Although β1B is generally understood to be a secreted variant, evidence indicates that when co-expressed with NaV1.5, it is maintained at the cell membrane, suggesting potential unique roles for this understudied protein. In this review, we focus on what is known of the 2 β-subunit variants encoded by Scn1b in heart, with particular focus on recent findings and the questions raised by this new information. We also explore data that indicate β1 and β1B may be attractive targets for novel antiarrhythmic therapeutics.

Pain is a major issue in healthcare throughout the world. It remains one of the major clinical issues of our time because it is a common sequela of numerous conditions, has a tremendous impact on individual quality of life, and is one of the top drivers of cost in medicine, due to its influence on healthcare expenditures and lost productivity in those affected by it. Patients and healthcare providers remain desperate to find new, safer and more effective analgesics. Growing evidence indicates that the voltage-gated sodium channel Nav1.8 plays a critical role in transmission of pain-related signals throughout the body. For that reason, this channel appears to have strong potential to help develop novel, more selective, safer, and efficacious analgesics. However, many questions related to the physiology, function, and clinical utility of Nav1.8 remain to be answered. In this article, we discuss the latest studies evaluating the role of Nav1.8 in pain, with a particular focus on visceral pain, as well as the steps taken thus far to evaluate its potential as an analgesic target. We also review the limitations of currently available studies related to this topic, and describe the next scientific steps that have already been undertaken, or that will need to be pursued, to fully unlock the capabilities of this potential therapeutic target.

(1) Background: In Cambodia, Aedes albopictus is an important vector of the dengue virus. Vector control using insecticides is a major strategy implemented in managing mosquito-borne diseases. Resistance, however, threatens to undermine the use of insecticides. In this study, we present the levels of insecticide resistance of Ae. albopictus in Cambodia and the mechanisms involved. (2) Methods: Two Ae. albopictus populations were collected from the capital, Phnom Penh city, and from rural Pailin province. Adults were tested with diagnostic doses of malathion (0.8%), deltamethrin (0.03%), permethrin (0.25%), and DDT (4%) using WHO tube assays. Synergist assays using piperonyl butoxide (PBO) were implemented before the pyrethroid assays to detect the potential involvement of metabolic resistance mechanisms. Adult female mosquitoes collected from Phnom Penh and Pailin were tested for voltage-gated sodium channel (VGSC) kdr (knockdown resistance) mutations commonly found in Aedes sp.-resistant populations throughout Asia (S989P, V1016G, and F1534C), as well as for other mutations (V410L, L982W, A1007G, I1011M, T1520I, and D1763Y). (3) Results: The two populations showed resistance against all the insecticides tested (<90% mortality). The use of PBO (an inhibitor of P450s) strongly restored the efficacy of deltamethrin and permethrin against the two resistant populations. Sequences of regions of the vgsc gene showed a lack of kdr mutations known to be associated with pyrethroid resistance. However, four novel non-synonymous mutations (L412P/S, C983S, Q1554STOP, and R1718L) and twenty-nine synonymous mutations were detected. It remains to be determined whether these mutations contribute to pyrethroid resistance. (4) Conclusions: Pyrethroid resistance is occurring in two Ae. albopictus populations originating from urban and rural areas of Cambodia. The resistance is likely due to metabolic resistance specifically involving P450s monooxygenases. The levels of resistance against different insecticide classes are a cause for concern in Cambodia. Alternative tools and insecticides for controlling dengue vectors should be used to minimize disease prevalence in the country.

Dravet syndrome is a developmental and epileptic encephalopathy (DEE) characterized by intractable seizures, comorbidities related to developmental, cognitive, and motor delays, and a high mortality burden due to sudden unexpected death in epilepsy (SUDEP). Most Dravet syndrome cases are attributed to SCN1A haploinsufficiency, with genetic modifiers and environmental factors influencing disease severity. Mouse models with heterozygous deletion of Scn1a recapitulate key features of Dravet syndrome, including seizures and premature mortality; however, severity varies depending on genetic background. Here, we refined two Dravet survival modifier (Dsm) loci, Dsm2 on chromosome 7 and Dsm3 on chromosome 8, using interval-specific congenic (ISC) mapping. Dsm2 was complex and encompassed at least two separate loci, while Dsm3 was refined to a single locus. Candidate modifier genes within these refined loci were prioritized based on brain expression, strain-dependent differences, and biological relevance to seizures or epilepsy. High priority candidate genes for Dsm2 include Nav2, Ptpn5, Ldha, Dbx1, Prmt3 and Slc6a5, while Dsm3 has a single high priority candidate, Psd3. This study underscores the complex genetic architecture underlying Dravet syndrome and provides insights into potential modifier genes that could influence disease severity and serve as novel therapeutic targets.