Increased KV2.1 Channel Clustering Underlies the Reduction of Delayed Rectifier K+ Currents in Hippocampal Neurons of the Tg2576 Alzheimer's Disease Mouse

KCNG4 Genetic Variant Linked to Migraine Prevents Expression of KCNB1

Migraines are a common type of headache affecting around 15% of the population. The signalling pathways leading to migraines have not been fully understood, but neuronal voltage-gated ion channels, such as KCNG4, have been linked to this pathology. KCNG4 (Kv6.4) is a silent member of the superfamily of voltage-gated potassium (Kv) channels, which expresses in heterotetramers with members of the KCNB (Kv2) family. The genetic variant Kv6.4-L360P has previously been linked to migraines, but their mode of action remains unknown. Here, we characterized the molecular characteristics of Kv6.4-L360P when co-expressed with Kv2.1. We found that Kv6.4-L360P almost completely abolishes Kv2 currents, and we propose that this mechanism in the trigeminal system, linked to the initiation of migraine, leads to the pathology.

Region-specific changes in gene expression are associated with cognitive deficits in the alpha-synuclein-induced model of Parkinson's disease: A transcriptomic profiling study

Mild cognitive impairment (MCI) is a common trait of Parkinson's disease (PD), often associated with early motor deficits, eventually evolving to PD with dementia in later disease stages. The neuropathological substrate of MCI is poorly understood, which weakens the development and administration of proper therapies. In an α-synuclein (αSyn)-based model of PD featuring early motor and cognitive impairments, we investigated the transcriptome profile of brain regions involved in PD with cognitive deficits, via a transcriptomic analysis based on RNA sequencing (RNA-seq) technology. Rats infused in the substantia nigra with human α-synuclein oligomers (H-SynOs) developed mild cognitive deficits after three months, as measured by the two-trial recognition test in a Y-maze and the novel object recognition test. RNA-seq analysis showed that 17,436 genes were expressed in the anterior cingulate cortex (ACC) and 17,216 genes in the hippocampus (HC). In the ACC, 51 genes were differentially expressed between vehicle and H-αSynOs treated samples, which showed N= 21 upregulated and N = 30 downregulated genes. In the HC, 104 genes were differentially expressed, the majority of them not overlapping with DEGs in the ACC, with N = 41 upregulated and N = 63 downregulated in H-αSynOs-treated samples. The Gene Ontology (GO) and the Kyoto Encyclopedia of Gene and Genomes (KEGG) analysis, followed by the protein-protein interaction (PPI) network inspection of DEGs, revealed that in the ACC most enriched terms were related with immune functions, specifically with antigen processing/presentation via the major histocompatibility complex (MHC) class II and phagocytosis via CD68, supporting a role for dysregulated immune responses in early PD cognitive dysfunction. Immunofluorescence analysis confirmed the decreased expression of CD68 within microglial cells. In contrast, the most significantly enriched terms in the HC were mainly involved in mitochondrial homeostasis, potassium voltage-gated channel, cytoskeleton and fiber organisation, suggesting that the gene expression in the neuronal population was mostly affected in this region in early disease stages. Altogether results show that H-αSynOs trigger a region-specific dysregulation of gene expression in ACC and HC, providing a pathological substrate for MCI associated with early PD.

ALPK1 Expressed in IB4-Positive Neurons of Mice Trigeminal Ganglions Promotes MIA-Induced TMJ pain

Pain is one of the main reasons for patients with temporomandibular joint (TMJ) disorders seeking medical care. However, there is no effective treatment yet as its mechanism remains unclear. Herein, we found that the injection of monoiodoacetate (MIA) into mice TMJs can induce typical joint pain as early as 3 days, accompanied by an increased percentage of calcitonin gene-related peptide positive (CGRP+) neurons and isolectin B4 positive (IB4+) in the trigeminal ganglions (TGs). Our previous study has discovered that alpha-kinase 1 (ALPK1) may be involved in joint pain. Here, we detected the expression of ALPK1 in neurons of TGs in wild-type (WT) mice, and it was upregulated after intra-TMJ injection of MIA. Meanwhile, the increased percentage of neurons in TGs expressing ALPK1 and CGRP or ALPK1 and IB4 was also demonstrated by the immunofluorescent double staining. Furthermore, after the MIA injection, ALPK1-/- mice exhibited attenuated pain behavior, as well as a remarkably decreased percentage of IB4+ neurons and an unchanged percentage of CGRP+ neurons, as compared with WT mice. In vitro assay showed that the value of calcium intensity was weakened in Dil+ neurons from ALPK1-/- mice of TMJ pain induced by the MIA injection, in relation to those from WT mice, while it was significantly enhanced with the incubation of recombinant human ALPK1 (rhA). Taken together, these results suggest that ALPK1 promotes mice TMJ pain induced by MIA through upregulation of the sensitization of IB4+ neurons in TGs. This study will provide a new potential therapeutic target for the treatment of TMJ pain.