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Voltage-gated sodium channels (VGSCs) play a crucial role in epilepsy. The expressions of different VGSCs subtypes are varied in diverse animal models of epilepsy that may reflect their multiple phenotypes or the complexity of the mechanisms of epilepsy. In a previous study, we reported that NaV1.1 and NaV1.3 were up-regulated in the hippocampus of the spontaneously epileptic rat (SER). In this study, we further analyzed both the expression and distribution of the typical VGSC subtypes NaV1.1, NaV1.2, NaV1.3 and NaV1.6 in the hippocampus and in the cortex of the temporal lobe of two genetic epileptic animal models: the SER and the tremor rat (TRM). The expressions of calmodulin (CaM) and calmodulin-dependent protein kinase II (CaMKII) were also analyzed with the purpose of assessing the effect of the CaM/CaMKII pathway in these two models of epilepsy. Increased expression of the four VGSC subtypes and CaM, accompanied by a decrease in CaMKII was observed in the hippocampus of both the SERs and the TRM rats. However, the changes observed in the expression of VGSC subtypes and CaM were decreased with an elevated CaMKII in the cortex of their temporal lobes. Double-labeled immunofluorescence data suggested that in SERs and TRM rats, the four subtypes of the VGSC proteins were present throughout the CA1, CA3 and dentate gyrus regions of the hippocampus and temporal lobe cortex and these were co-localized in neurons with CaM. These data represent the first evidence of abnormal changes in expression of four VGSC subtypes (NaV1.1, NaV1.2, NaV1.3 and NaV1.6) and CaM/CaMKII in the hippocampus and temporal lobe cortex of SERs and TRM rats. These changes may be involved in the generation of epileptiform activity and underlie the observed seizure phenotype in these rat models of genetic epilepsy., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Voltage-gated sodium channels (VGSC) have been linked to inherited forms of epilepsy. The expression and biophysical properties of VGSC in the hippocampal neuronal culture model have not been clarified. In order to evaluate mechanisms of epileptogenesis that are related to VGSC, we examined the expression and function of VGSC in the hippocampal neuronal culture model in vitro and spontaneously epileptic rats (SER) in vivo. Our data showed that the peak amplitude of transient, rapidly-inactivating Na(+) current (I(Na,T)) in model neurons was significantly increased compared with control neurons, and the activation curve was shifted to the negative potentials in model neurons in whole cell recording by patch-clamp. In addition, channel activity of persistent, non-inactivating Na(+) current (I(Na,P)) was obviously increased in the hippocampal neuronal culture model as judged by single-channel patch-clamp recording. Furthermore, VGSC subtypes Na(V)1.1, Na(V)1.2 and Na(V)1.3 were up-regulated at the protein expression level in model neurons and SER as assessed by Western blotting. Four subtypes of VGSC proteins in SER were clearly present throughout the hippocampus, including CA1, CA3 and dentate gyrus regions, and neurons expressing VGSC immunoreactivity were also detected in hippocampal neuronal culture model by immunofluorescence. These findings suggested that the up-regulation of voltage-gated sodium channels subtypes in neurons coincided with an increased sodium current in the hippocampal neuronal culture model, providing a possible explanation for the observed seizure discharge and enhanced excitability in epilepsy., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Na V 1.5 channel is an integral membrane protein involved in the initiation and conduction of action potentials. IQ motif is located in the C-terminal domain of Na V 1.5 sodium channel, which is highly conserved in human sodium channel subtypes. IQ motif is involved in the Ca2+-dependent regulation through interaction with the regulatory proteins such as calpastatin domain L (CS L). Mutations in SCN5A, the gene encoding Na V 1.5 channel, have been linked to many cardiac arrhythmias, such as Long QT syndrome type 3 (LQT3) and Brugada syndrome (BRS). LQT3-associated mutations in Na V 1.5 IQ motif, IQ Q1909R and IQ R1913H , have been reported to affect the late I Na. A BRS-associated mutation in Na V 1.5 IQ motif, IQ A1924T, has been reported to affect the peak I Na. But the detailed pathogenic mechanisms of LQT3 and BRS remains unclear. To explore the binding properties of CS L to IQ motif and its muants associated with LQT3/BRS, molecular docking and GST pull down assay were performed in this study. As a result, S58 and E59 in CS L activating channel effect region L54-64 were involved in the conformation of the CS L /IQ WT complex by protein-protein docking. IQ motif could bind to CS L in a [CS L ]-dependent and [Ca2+]-dependent manner by pull down assay. However, the binding affinities of IQ Q1909R and IQ R1913H to CS L were decreased and its reaction rates with CS L were slower. The binding characteristics of IQ A1924T to CS L was opposite in a [Ca2+]-dependent manner and its binding efficacy became smaller. The changes of the binding characteristics of IQ mutants to CS L would affect the regulation of Na V 1.5 channel, which may be related to LQT3 and BRS. • CS L could bind to Na V 1.5 channel IQ motif in a [CS L ]-dependent and [Ca2+]-dependent manner. • The binding sites of CS L to IQ motif were within the region of CS L that reprime the activity of Ca V 1.2 channel, L54-64. • LQTs-associated mutants, IQ Q1909R and IQ R1913H weakened the binding activity to CS L and the reaction rates were slower. • The binding characteristics of BRS-associated mutant, IQ A1924T , to CS L was reversed in the [Ca2+]-dependent manner. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is a progressive inflammatory injury, and mesenchymal stem cells (MSCs) can be used to treat ALI. MSC-conditioned medium (MSC-CM) contains many cytokines, in which keratinocyte growth factor (KGF) is a soluble factor that plays a role in lung development. We aim to explore the protective effects of MSCs secreted KGF on ALI, and investigate the involvement of epithelial sodium channel (ENaC), which are important in alveolar fluid reabsorption. Both lipopolysaccharides (LPS)-induced mouse and alveolar organoid ALI models were established to confirm the potential therapeutic effect of MSCs secreted KGF. Meanwhile, the expression and regulation of ENaC were determined in alveolar type II epithelial (ATII) cells. The results demonstrated that MSC-CM and KGF could alleviate the extent of inflammation-related pulmonary edema in ALI mice, which was abrogated by a KGF neutralizing antibody. In an alveolar organoid ALI model, KGF in MSC-CM could improve the proliferation and decrease the differentiation of ATII cells. At the cellular level, the LPS-inhibited protein expression of ENaC could be reversed by KGF in MSC-CM. In addition, bioinformatics analysis and our experimental data provided the evidence that the NF-κB signaling pathway may be involved in the regulation of ENaC. Our research confirmed that the therapeutic effect of MSC-CM on edematous ALI was closely related to KGF, which may be involved in the proliferation and differentiation of ATII cells, as well as the upregulation of ENaC expression by the inhibition of NF-κB signaling pathway. [Display omitted] • MSC-CM and KGF had therapeutic effects on LPS-induced ALI model in mice. • KGF in MSC-CM could recover LPS-induced 3D alveolar organoid damage. • NF-κB signaling pathway may participate in the therapeutic effect of KGF in MSC-CM on ALI and the regulation of ENaC. [ABSTRACT FROM AUTHOR]

Highlights: [•] Increased VGSCs and CaM but decreased CaMKII were found in hippocampus. [•] Decreased VGSCs and CaM but increased CaMKII were observed in temporal lobe cortex. [•] VGSC proteins appeared in CA1, CA3 and DG of hippocampus and temporal lobe cortex. [•] Co-localizations of VGSCs and CaM were found in hippocampus and temporal lobe cortex. [Copyright &y& Elsevier]