Frontiers in Molecular Neuroscience最新文献

Introduction: The neuron-specific K-Cl cotransporter KCC2 maintains low intracellular chloride levels, which are crucial for fast GABAergic and glycinergic neurotransmission. KCC2 also plays a pivotal role in the development of excitatory glutamatergic neurotransmission by promoting dendritic spine maturation. The cytoplasmic C-terminal domain (KCC2-CTD) plays a critical regulatory role in the molecular mechanisms controlling the cotransporter activity through dimerization, phosphorylation, and protein interaction.

Methods: To identify novel CTD regulatory motifs, we used the Mu transposon-based mutagenesis system to generate a library of KCC2 mutants with 5 amino acid insertions randomly distributed within the KCC2-CTD. We determined the insertion positions in 288 mutants by restriction analysis and selected clones with a single insertion site outside known KCC2 regulatory motifs. We analyzed the subcellular distribution of KCC2-CTD mutants in cultured cortical neurons using immunocytochemistry and selected ten mutants with ectopic expression patterns for detailed characterization.

Results: A fluorescent Cl^--transport assay in HEK293 cells revealed mutants with both reduced and enhanced Cl^--extrusion activity, which overall correlated with their glycosylation patterns. Live-cell immunostaining analysis of plasma membrane expression of KCC2-CTD mutants in cultured cortical neurons corroborated the glycosylation data. Furthermore, the somatodendritic chloride gradient in neurons transfected with the KCC2-CTD mutants correlated with their Cl^--extrusion activity in HEK293 cells. Gain- and loss-of-function mutant positions were analyzed using available KCC2 cryo-EM structures.

Discussion: Two groups of mutants were identified based on 3D structural analysis. The first group, located near the interface of transmembrane and cytoplasmic domains, may affect interactions with the N-terminal inhibitory peptide regulating KCC2 activity. The second group, situated on the external surface of the cytoplasmic domain, may disrupt interactions with regulatory proteins. Analyzing CTD mutations that modulate KCC2 activity enhances our understanding of its function and is essential for developing novel anti-seizure therapies.

Mitochondria and lysosomes are critical for neuronal homeostasis, as highlighted by their dysfunction in various neurological diseases. Recent studies have identified dynamic membrane contact sites between mitochondria and lysosomes, independent of mitophagy and the lysosomal degradation of mitochondrial-derived vesicles (MDVs), allowing bidirectional crosstalk between these cell compartments, the dynamic regulation of organelle networks, and substance exchanges. Emerging evidence suggests that abnormalities in mitochondria-lysosome contact sites (MLCSs) contribute to neurological diseases, including Parkinson's disease, Charcot-Marie-Tooth (CMT) disease, lysosomal storage diseases, and epilepsy. This article reviews recent research advances regarding the tethering processes, regulation, and function of MLCSs and their role in neurological diseases.

Multiple sclerosis (MS) is a chronic central nervous system (CNS) disease with demyelinating inflammatory characteristics. It is the most common nontraumatic and disabling disease affecting young adults. The incidence and prevalence of MS have been increasing. However, its exact cause remains unclear. The main tests used to support the diagnosis are magnetic resonance imaging (MRI) examination and cerebrospinal fluid (CSF) analysis. Nonetheless, to date, no sensitive or specific marker has been identified for the detection of the disease at its initial stage. In recent years, researchers have focused on the fact that the number of natural killer cell group 2 member D (NKG2D) family of C-type lectin-like receptor + (NKG2D+) T cells in the peripheral blood, CSF, and brain tissue has been shown to be higher in patients with MS than in controls. The activating receptor belonging to the NKG2D is stimulated by specific ligands: in humans these are major histocompatibility complex (MHC) class I polypeptide-related sequence A (MICA) and MHC class I polypeptide-related sequence B (MICB) proteins and UL16 binding 1-6 proteins (ULBP1-6). Under physiological conditions, the aforementioned ligands are expressed at low or undetectable levels but can be induced in response to stress factors. NKG2D ligands (NKG2DLs) are involved in epigenetic regulation of their expression. To date, studies in cell cultures, animal models, and brain tissues have revealed elevated expression of MICA/B, ULPB4, and its mouse homolog murine UL16 binding protein-like transcript (MULT1), in oligodendrocytes and astrocytes from patients with MS. Furthermore, soluble forms of NKG2DLs were elevated in the plasma and CSF of patients with MS compared to controls. In this review, we aim to describe the role of NKG2D and NKG2DLs, and their interactions in the pathogenesis of MS, as well as in other autoimmune diseases such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE), and celiac disease (CeD). We also assess the potential of these proteins as diagnostic markers and consider future perspectives for targeting NKG2D ligands and their pathways as therapeutic targets in MS.

Multiple sclerosis (MS) affects 2.8 million people worldwide. Although the cause is unknown, various risk factors might be involved. MS involves the immune system attacking the central nervous system's myelin sheath, leading to neuron damage. This study used a cuprizone (CPZ)-intoxicated mouse model to simulate MS's demyelination/remyelination process. It evaluated the molecular, histological, and behavioral effects of vanillic acid (VA), a natural phenolic acid, alone and with Ibudilast (IBD), a clinically tested MS medication. Mice were divided into a control group (regular chow) and a CPZ group (0.3% cuprizone chow for 5 consecutive weeks). During remyelination, the CPZ group was split into four groups: no therapy, 10 mg/kg of IBD, 30 mg/kg of VA, and combined, each treated for 4 weeks. Behavioral, biochemical, molecular, and histopathological tests occurred in the 5^th week (demyelination), 7^th (early remyelination), and 9^th (late remyelination). Cognitive assessments were at weeks 5 and 9. VA enhanced motor, coordination, and cognitive impairments in CPZ-intoxicated mice and improved histopathological, molecular, and biochemical features during early remyelination. IBD improved behavioral abnormalities across all tests, but combined therapy showed no significant difference from single therapies. Further investigations are necessary to understand VA's mechanisms and potential as an MS treatment.

Introduction: To further advance our understanding of Muscular Dystrophies (MDs) and Spinocerebellar Ataxias (SCAs), it is necessary to identify the biological patterns associated with disease pathology. Although progress has been made in the fields of genetics and transcriptomics, there is a need for proteomics and metabolomics studies. The present study aimed to be the first to document serum metabolic signatures of MDs (DMD, BMD, and LGMD 2A) SCAs (SCA 1-3), from a South Asian perspective.

Methods: A total of 28 patients (SCA 1-10, SCA 2-2, SCA 3-2, DMD-10, BMD-2, LGMD-2) and eight controls (aged 8-65 years) were included. Metabolomic analysis was performed by Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS), with support from the Houston Omics Collaborative.

Results and discussion: Amino acid metabolism was the primary altered super pathway in DMD followed by carbohydrate metabolism and lipid metabolism. In contrast, BMD and LGMD 2A exhibited a more prominent alteration in lipid metabolism followed by amino acid metabolism. In SCAs, primarily lipid, amino acid, peptide, nucleotide, and xenobiotics pathways are affected. Our findings offer new insights into the variance of metabolite levels in MD and SCA, with substantial implications for pathology, drug development, therapeutic targets and clinical management. Intriguingly, this study identified two novel metabolites associated with SCA. This pilot cross-sectional study warrants further research involving larger groups of participants, to validate our findings.

PANoptosis is a novelly defined mode of programmed cell death that involves the activation of multiple cellular death pathways, including pyroptosis, apoptosis, and necroptosis, triggering robust inflammatory reactions. Autophagy is a crucial cellular process that maintains cellular homeostasis and protects cells from various stresses. PANoptosis and autophagy, both vital players in the intricate pathological progression of ischemic stroke (IS), a brain ailment governed by intricate cell death cascades, have garnered attention in recent years for their potential interplay. While mounting evidence hints at a crosstalk between these two processes in IS, the underlying mechanisms remain elusive. Therefore, this review delves into and dissects the intricate mechanisms that underpin the intersection of PANoptosis and autophagy in this devastating condition. In conclusion, the crosstalk between PANoptosis and autophagy in IS presents a promising target for the development of novel stroke therapies. Understanding the interplay between these two pathways offers a much-needed insight into the underlying mechanisms of IS and opens the possibility for new therapeutic strategies.

Hirschsprung's disease (HSCR) is characterized by congenital absence of ganglion cells in the gastrointestinal tract, which leads to impaired defecation, constipation and intestinal obstruction. The current diagnosis of HSCR is based on Rectal Suction Biopsies (RSBs), which could be complex in newborns. Occasionally, there is a delay in diagnosis that can increase the risk of clinical complications. Consequently, there is room for new non-invasive diagnostic methods that are objective, more logistically feasible and also deliver a far earlier base for a potential surgical intervention. In recent years, microRNA (miRNA) has come into the focus as a relevant early marker that could provide more insights into the etiology and progression of diseases. Therefore, in the search of a non-invasive HSCR biomarker, we analyzed miRNA expression in urine samples of HSCR patients. Results from 5 HSCR patients using microarrays, revealed hsa-miR-378 h, hsa-miR-210-5p, hsa-miR-6876-3p, hsa-miR-634 and hsa-miR-6883-3p as the most upregulated miRNAs; while hsa-miR-4443, hsa-miR-22-3p, hsa-miR-4732-5p, hsa-miR-3187-5p, and hsa-miR-371b-5p where the most downregulated miRNAs. Further search in miRNAwalk and miRDB databases showed that certainly most of these dysregulated miRNAs identified target HSCR associated genes, such as RET, GDNF, BDNF, EDN3, EDNRB, ERBB, NRG1, SOX10; and other genes implied in neuronal migration and neurogenesis. Finally, we could also validate some of these miRNA changes in HSCR urine by RT-qPCR. Altogether, our analyzed HSCR cohort presents a dysregulated miRNA expression presents that can be detected in urine. Our findings open the possibility of using specific urine miRNA signatures as non-invasive HSCR diagnosis method in the future.

Hydrocephalus is a neurological condition caused by aberrant circulation and/or obstructed cerebrospinal fluid (CSF) flow after cerebral ventricle abnormal dilatation. In the past 50 years, the diagnosis and treatment of hydrocephalus have remained understudied and underreported, and little progress has been made with respect to prevention or treatment. Further research on the pathogenesis of hydrocephalus is essential for developing new diagnostic, preventive, and therapeutic strategies. Various genetic and molecular abnormalities contribute to the mechanisms of hydrocephalus, including gene deletions or mutations, the activation of cellular inflammatory signaling pathways, alterations in water channel proteins, and disruptions in iron metabolism. Several studies have demonstrated that modulating the expression of key proteins, including TGF-β, VEGF, Wnt, AQP, NF-κB, and NKCC, can significantly influence the onset and progression of hydrocephalus. This review summarizes and discusses key mechanisms that may be involved in the pathogenesis of hydrocephalus at both the genetic and molecular levels. While obstructive hydrocephalus can often be addressed by removing the obstruction, most cases require treatment strategies that involve merely slowing disease progression by correcting CSF circulation patterns. There have been few new research breakthroughs in the prevention and treatment of hydrocephalus.

Auditory neuropathy spectrum disorder (ANSD) is an auditory dysfunction disorder characterized by impaired speech comprehension. Its etiology is complex and can be broadly categorized into genetic and non-genetic factors. TMEM43 mutation is identified as a causative factor in ANSD. While some studies have been conducted using animal models, its pathogenic mechanisms in humans remain unclear. TMEM43 is predominantly expressed in cochlear glia-like support cells (GLSs) and plays a vital role in gap junction intercellular communication. In this work, we utilized induced pluripotent stem cells from an ANSD patient carrying the TMEM43 gene mutation c.1114C>T (p.Arg372Ter) and directed their differentiation toward GLSs to investigate the effect of TMEM43 mutation on the function of gap junctions in cochlear GLSs in vitro. Reduced expression of genes associated with GLSs characteristics and reduced gap junction intercellular communication in TMEM43 mutant cell lines were observed compared to controls. Transcriptome analysis revealed that differentially expressed genes were significantly enriched in pathways related to cell proliferation, differentiation, extracellular space and adhesion. Furthermore, significant alterations were noted in the PI3K-Akt signaling pathway and the calcium signaling pathway, which could potentially influence gap junction function and contribute to hearing loss. In summary, our study based on patient-derived iPSCs sheds new light on the molecular mechanisms by which TMEM43 mutations may lead to ANSD. These mutations could result in developmental defects in GLSs and a diminished capacity for gap junction function, which may be implicated in the auditory deficits observed in ANSD patients. Our study explored the pathological effects of the TMEM43 mutation and its causal relationship with ANSD using a patient-derived iPSC-based GLSs model, providing a foundation for future mechanistic studies and potential drug screening efforts.