Decreased Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel 2 Activity in a Rat Model of Absence Epilepsy and the Effect of ZD7288, an Ih Inhibitor, on the Spike-and-Wave Discharges

<b><i>Introduction:</i></b> Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel currents of <i>Ih</i> and absence epilepsy seizures are associated, but studies reveal differential results. <b><i>Objective:</i></b> In our study, we aimed to investigate the role of the HCN channels on the expression of spike-and-wave discharges (SWDs) using the Genetic Absence Epilepsy Rats from Strasbourg (GAERS) model. <b><i>Methods:</i></b> HCN isoform levels from isolated brains of both naïve nonepileptic Wistar and GAERS groups were evaluated by enzyme-linked immunosorbent assay. ZD7288, an <i>Ih</i> inhibitor as well as an HCN channel antagonist, was administered intracerebroventricularly to the adult GAERS groups, and to evaluate their SWD activities, electroencephalography was recorded. The effect of ZD7288 on the cumulative total duration and number of SWDs and the mean duration of each SWD complex was evaluated. <b><i>Results:</i></b> The HCN2 levels in the cortex and hippocampus of the GAERS group were lower compared to the naïve nonepileptic Wistar group (<i>p</i> &#x3c; 0.05). ZD7288 increased the number of SWDs at the 20th and 120th min with the highest administered dose of 7 μg (<i>p</i> &#x3c; 0.05). <b><i>Conclusion:</i></b> The <i>Ih</i> inhibitor ZD7288 increased the number of SWDs in a genetic absence epilepsy rat model, although this increase may not be significant due to the inconsistent time-dependent effects. In GAERS, the cortical and hippocampal HCN2 channel levels were significantly lower compared to the control group. Further studies are needed with higher doses of ZD7288 to determine if the effects will increase drastically.

miR-190a-5p Partially Represses the Abnormal Electrical Activity of SCN3B in Cardiac Arrhythmias by Downregulation of IL-2

Cardiac arrhythmias (CAs) are generally caused by disruption of the cardiac conduction system; interleukin-2 (IL-2) is a key player in the pathological process of CAs. This study aimed to investigate the molecular mechanism underlying the regulation of IL-2 and the sodium channel current of sodium voltage-gated channel beta subunit 3 (SCN3B) by miR-190a-5p in the progression of CAs. ELISA results suggested the concentration of peripheral blood serum IL-2 in patients with atrial fibrillation (AF) to be increased compared to that in normal controls; fluorescence in situ hybridization indicated that the expression of IL-2 in the cardiac tissues of patients with AF to be upregulated and that miR-190a-5p to be downregulated. Luciferase reporter assay, quantitative real-time-PCR, and whole-cell patch-clamp experiments confirmed the downregulation of IL-2 by miR-190a-5p and influence of the latter on the sodium current of SCN3B. Overall, miR-190a-5p suppressed the increase in SCN3B sodium current caused by endogenous IL-2, whereas miR-190a-5p inhibitor significantly reversed this effect. IL-2 was demonstrated to be directly regulated by miR-190a-5p. We, therefore, concluded that the miR-190a-5p/IL-2/SCN3B pathway could be involved in the pathogenesis of CAs and miR-190a-5p might acts as a potential protective factor in pathogenesis of CAs.

Comparative Analysis on Transcriptomics of Ivermectin Resistant and Sensitive Strains of Haemonchus Contortus

Background: Ivermectin (IVM) is one of the most important and widely used anthelmintics in veterinary medicine. However, its efficacy is increasingly compromised by widespread resistance, and the exact mechanism of IVM resistance remains unclear for most parasitic nematodes including Haemonchus contortus, a blood-sucking parasitic nematode of small ruminants.Methods: In this study, we isolated and assessed an IVM resistant strain from Zhaosu, Xinjiang, China. Subsequently, the comparative analyses on transcriptomics of IVM susceptible and resistant H. contortus adult worms were carried out using RNA sequencing and bioinformatics.Results: In total, 543 and 359 differentially expressed genes (DEGs) were identified in male and female adult worms of the resistant strain compared with the susceptible strain, respectively. The DEGs encode molecules involved in receptor activities, transport, detoxification, lipid metabolism and cuticle collagen formation. In addition, Gene Ontology (GO) analysis revealed that transcriptional changes were dominant in genes associated with ligand-gated channel activity, oxidation-reduction process, lipid metabolic process, and structural constituent of cuticle. The results support previous proposal that the IVM resistant mechanism of H. contortus involved in both neuromuscular and non-neuromuscular pathways. Finally, the quantitative RT-PCR results confirmed that the transcriptional profiles of selected DEGs (male: 8 genes, female: 10 genes) were consistent with those obtained by the RNA-Seq.Conclusions: The findings from this work provided valuable information for further studies on the IVM resistance in H. contortus.

A deep dive into VDAC1 conformational diversity using all-atom simulations provides new insights into the structural origin of the closed states

The voltage-dependent anion channel 1 (VDAC1) is a crucial mitochondrial transporter which controls the flow of ions and respiratory metabolites entering or exiting mitochondria. As a voltage-gated channel, VDAC1 can switch between a high conducting "open" state and low conducting "closed" states emerging at high transmembrane potential. Although cell homeostasis depends on channel gating to regulate the transport of ions and metabolites, structural hallmarks characterizing the closed states remain unknown. Here we performed microsecond accelerated molecular dynamics to highlight a vast region of VDAC1 conformational landscape accessible at typical voltage known to promote closure. Conformers exhibiting stable subconducting properties inherent to closed states were identified. In all cases, the low conductance was due to the particular positioning of an unfolded part of the N-terminus which obstructed the channel pore. While the N-terminal tail was found to be sensitive to voltage orientation, our low-conducting models suggest that closed states predominantly take place from disordered events and do not result from the displacement of a voltage sensor or a significant change in the pore. In addition, our results were consistent with conductance jumps observed in experiments and corroborates a recent study describing entropy as a key factor for VDAC gating.

The Role of Prostaglandin E1 as a Pain Mediator through Facilitation of Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel 2 via the EP2 Receptor in Trigeminal Ganglion Neurons of Mice

Cyclooxygenase metabolizes dihomo-γ-linolenic acid and arachidonic acid to form prostaglandin (PG) E, including PGE1 and PGE2, respectively. Although PGE2 is well known to play an important role in the development and maintenance of hyperalgesia and allodynia, the role of PGE1 in pain is unknown. We confirm whether PGE1 induced pain using orofacial pain behavioral test in mice and determine the target molecule of PGE1 in TG neurons with whole-cell patch-clamp and immunohistochemistry. Intradermal injection of PGE1 to the whisker pads of mice induced a reduced threshold, enhancing the excitability of HCN channel-expressing trigeminal ganglion (TG) neurons. The HCN channel-generated inward current (Ih) was increased by 135.3 ± 4.8% at 100 nM of PGE1 in small- or medium-sized TG, and the action of PGE1 on Ih showed a concentration-dependent effect, with a median effective dose (ED50) of 29.3 nM. Adenylyl cyclase inhibitor (MDL12330A), 8-bromo-cAMP, and the EP2 receptor antagonist AH6809 inhibited PGE1-induced Ih. Additionally, PGE1-induced mechanical allodynia was blocked by CsCl and AH6809. PGE1 plays a role in mechanical allodynia through HCN2 channel facilitation via the EP2 receptor in nociceptive neurons, suggesting a potential therapeutic target in that PGE1 could be involved in pain as endogenous substances under inflammatory conditions.

KCNH2 Regulates the Growth and Metastasis of Pancreatic Cancer

The mortality rate of pancreatic cancer (PC) remains high due to late diagnosis, early metastasis, and difficulty of complete resection. The online databases showed that potassium voltage-gated channel subfamily H member 2 (KCNH2) was highly expressed in pancreatic tumor tissues and was closely related to the poor survival of patients with PC. However, the mechanism of action of KCNH2 in PC is still unclear. In the present study, for the first time, we explored the regulatory effect of KCNH2 in PC. The results showed that KCNH2 was upregulated in PC compared with normal pancreatic tissues. High KCNH2 expression was associated with low tissue differentiation, high malignancy, and poor prognosis of PC. Moreover, knockdown of KCNH2 inhibited the proliferation and apoptosis of PC cells, as well as the epithelial-mesenchymal transition process, thereby promoting PC cell migration and invasion. In addition, KCNH2 knockdown inhibited the progression and metastasis of PC in a mouse xenograft model. In conclusion, these findings highlighted the potential of KCNH2 as a targeted molecule in the treatment of PC.

Novel SCN5A and GPD1L Variants Identified in Two Unrelated Han-Chinese Patients With Clinically Suspected Brugada Syndrome

Brugada syndrome (BrS) is a complexly genetically patterned, rare, malignant, life-threatening arrhythmia disorder. It is autosomal dominant in most cases and characterized by identifiable electrocardiographic patterns, recurrent syncope, nocturnal agonal respiration, and other symptoms, including sudden cardiac death. Over the last 2 decades, a great number of variants have been identified in more than 36 pathogenic or susceptibility genes associated with BrS. The present study used the combined method of whole exome sequencing and Sanger sequencing to identify pathogenic variants in two unrelated Han-Chinese patients with clinically suspected BrS. Minigene splicing assay was used to evaluate the effects of the splicing variant. A novel heterozygous splicing variant c.2437-2A&gt;C in the sodium voltage-gated channel alpha subunit 5 gene (SCN5A) and a novel heterozygous missense variant c.161A&gt;T [p.(Asp54Val)] in the glycerol-3-phosphate dehydrogenase 1 like gene (GPD1L) were identified in these two patients with BrS-1 and possible BrS-2, respectively. Minigene splicing assay indicated the deletion of 15 and 141 nucleotides in exon 16, resulting in critical amino acid deletions. These findings expand the variant spectrum of SCN5A and GPD1L, which can be beneficial to genetic counseling and prenatal diagnosis.