Objective: Pathogenic variants in SCN8A, encoding the voltage‐gated sodium (Na+) channel α subunit Nav1.6, is a known cause of epilepsy. Here, we describe clinical and genetic features of all patients with SCN8A epilepsy evaluated at a single‐tertiary care center, with biophysical data on identified Nav1.6 variants and pharmacological response to selected Na+ channel blockers.Methods: SCN8A variants were identified via an exome‐based panel of epilepsy‐associated genes for next generation sequencing (NGS), or via exome sequencing. Biophysical characterization was performed using voltage‐clamp recordings of ionic currents in heterologous cells.Results: We observed a range in age of onset and severity of epilepsy and associated developmental delay/intellectual disability. Na+ channel blockers were highly or partially effective in most patients. Nav1.6 variants exhibited one or more biophysical defects largely consistent with gain of channel function. We found that clinical severity was correlated with the presence of multiple observed biophysical defects and the extent to which pathological Na+ channel activity could be normalized pharmacologically. For variants not previously reported, functional studies enhanced the evidence of pathogenicity.Interpretation: We present a comprehensive single‐center dataset for SCN8A epilepsy that includes clinical, genetic, electrophysiologic, and pharmacologic data. We confirm a spectrum of severity and a variety of biophysical defects of Nav1.6 variants consistent with gain of channel function. Na+ channel blockers in the treatment of SCN8A epilepsy may correlate with the effect of such agents on pathological Na+ current observed in heterologous systems.

Habituation is a basic form of implicit learning and represents a sensory filter that is disrupted in autism, schizophrenia, and several other mental disorders. Despite extensive research in the past decades on habituation of startle and other escape responses, the underlying neural mechanisms are still not fully understood. There is evidence from previous studies indicating that BK channels might play a critical role in habituation. We here used a wide array of approaches to test this hypothesis. We show that BK channel activation and subsequent phosphorylation of these channels are essential for synaptic depression presumably underlying startle habituation in rats, using patch-clamp recordings and voltage-sensitive dye imaging in slices. Furthermore, positive modulation of BK channelsin vivocan enhance short-term habituation. Although results using different approaches do not always perfectly align, together they provide convincing evidence for a crucial role of BK channel phosphorylation in synaptic depression underlying short-term habituation of startle. We also show that this mechanism can be targeted to enhance short-term habituation and therefore to potentially ameliorate sensory filtering deficits associated with psychiatric disorders.SIGNIFICANCE STATEMENTShort-term habituation is the most fundamental form of implicit learning. Habituation also represents a filter for inundating sensory information, which is disrupted in autism, schizophrenia, and other psychiatric disorders. Habituation has been studied in different organisms and behavioral models and is thought to be caused by synaptic depression in respective pathways. The underlying molecular mechanisms, however, are poorly understood. We here identify, for the first time, a BK channel-dependent molecular synaptic mechanism leading to synaptic depression that is crucial for habituation, and we discuss the significance of our findings for potential treatments enhancing habituation.

Background: Streptococcus mutans is a leading causative agent of dental caries and exerts pathogenicity by forming biofilms. Dental caries continues to be a significant public health issue worldwide, affecting an estimated 2.5 billion people, showing a 14.6% increase over the past decade. Herein, the antibacterial potential of Chlorophyllin extracted from Spinacia oleracea was evaluated against biofilm-forming S. mutans via in vitro and in silico studies. Methodology: The antimicrobial activity of chlorophyllin extract against S. mutans isolates was tested using the agar well diffusion method. Chlorophyllin extract was also tested against biofilm-forming isolates of S. mutans. Chlorophyllin was docked with the antigen I/II (AgI/II) protein of S. mutans to evaluate its antimicrobial mechanism. The chemical structure and canonical SMILES format of Chlorophyllin were obtained from PubChem. Additionally, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses of Chlorophyllin were performed using ADMETlab 2.0 to assess its pharmacokinetic properties. Results: An agar well diffusion assay revealed that all S. mutans isolates were susceptible to Chlorophyllin extract and showed a variety of inhibition zones ranging from 32 to 41 mm. Chlorophyllin reduces the biofilm strength of four isolates from strong to moderate and six from strong to weak. The antibiofilm potential of Chlorophyllin was measured by a reduction in the number of functional groups observed in the Fourier Transform Infrared Spectrometer (FTIR) spectra of the extracellular polymeric substance (EPS) samples. Chlorophyllin showed binding with AgI/II proteins of S. mutans, which are involved in adherence to the tooth surface and initiating biofilm formation. The ADMET analysis revealed that the safety of Chlorophyllin exhibited favorable pharmacokinetic properties. Conclusions: Chlorophyllin stands out as a promising antibacterial and antibiofilm agent against biofilm-forming S. mutans, and its safety profile highlights its potential suitability for further investigation as a therapeutic agent.

RAS/MAPK gene dysfunction underlies various cancers and neurocognitive disorders. Although the roles of RAS/MAPK genes have been well studied in cancer, less is known about their function during neurodevelopment. There are many genes that work in concert to regulate RAS/MAPK signaling, suggesting that if common brain phenotypes could be discovered they could have a broad impact on the many other disorders caused by distinct RAS/MAPK genes. We assessed the cellular and molecular consequences of hyperactivating the RAS/MAPK pathway using two distinct genes in a cell type previously implicated in RAS/MAPK-mediated cognitive changes, cortical GABAergic interneurons. We uncovered some GABAergic core programs that are commonly altered in each of the mutants. Notably, hyperactive RAS/MAPK mutants bias developing cortical interneurons towards those that are somatostatin positive. The increase in somatostatin-positive interneurons could also be prevented by pharmacological inhibition of the core RAS/MAPK signaling pathway. Overall, these findings present new insights into how different RAS/MAPK mutations can converge on GABAergic interneurons, which may be important for other RAS/MAPK genes and related disorders.

The cell-type-specific expression of ligand/receptor and cell-adhesion molecules is a fundamental mechanism through which neurons regulate connectivity. Here, we determine a functional relevance of the long-established mutually exclusive expression of the receptor tyrosine kinase Kit and the trans-membrane protein Kit Ligand by discrete populations of neurons in the mammalian brain. Kit is enriched in molecular layer interneurons (MLIs) of the cerebellar cortex (i.e., stellate and basket cells), while cerebellar Kit Ligand is selectively expressed by a target of their inhibition, Purkinje cells (PCs). By in vivo genetic manipulation spanning embryonic development through adulthood, we demonstrate that PC Kit Ligand and MLI Kit are required for, and capable of driving changes in, the inhibition of PCs. Collectively, these works in mice demonstrate that the Kit Ligand/Kit receptor dyad sustains mammalian central synapse function and suggest a rationale for the affiliation of Kit mutation with neurodevelopmental disorders.