Journal of Neurochemistry最新文献

Astrocytes, the most abundant glial cells in the CNS, play a crucial role in supporting neurons and respond to injury or disease through astrogliosis, a process marked by cellular hypertrophy and increased glial fibrillary acidic protein (GFAP) expression. Interleukin-33 (IL-33) was originally identified as an alarmin and is known to be produced by astrocytes and oligodendrocytes in the CNS. Recently, we reported its role in regulating oligodendrocyte differentiation. However, its role in astrocytes remains less defined. In a demyelinating mouse model induced by gliotoxin cuprizone (CPZ), IL-33 was previously shown to be reduced in oligodendrocytes within the corpus callosum. In this study, we found that lipopolysaccharide (LPS) stimulation enhanced nuclear IL-33 expression and GFAP production in cortical astrocytes. Using lentiviral-mediated IL-33 knockdown (IL33KD) and overexpression (IL33oe), we demonstrated that IL-33 positively regulates GFAP expression. Interestingly, we observed an increase in nuclear IL-33-expressing GFAP⁺ cortical astrocytes in CPZ-treated mice. In contrast, CPZ-induced GFAP upregulation in cortical astrocytes was abolished in IL-33 knockout (il33^KO) mice. Furthermore, chronic CPZ feeding in il33^KO mice led to increased microgliosis and neuronal damage within the frontal cortex, as well as abnormal anxiety-like behaviors. Collectively, these results indicate that elevated nuclear IL-33 in astrocytes under inflammatory conditions is critical for GFAP upregulation and astrogliosis. Loss of IL-33 disrupts astrocyte neuroprotective functions and glial reactivity in the frontal cortex, contributing to behavioral abnormalities under a demyelinating insult.

Temporal lobe epilepsy (TLE) is a prevalent form of drug-resistant epilepsy characterized by profound biochemical alterations. Emerging evidence suggests that metabolic dysregulation plays a crucial role in the development of TLE. In this study, we employed a kainic acid-induced mouse model of TLE to investigate metabolic remodeling and key regulatory pathways at Day 14 post–status epilepticus, a time point within early epilepsy, corresponding to the early phase of spontaneous seizure emergence during epileptogenic progression. Liquid chromatography–mass spectrometry-based proteomics and metabolomics analyses were conducted on hippocampal and serum samples to identify and quantify differentially expressed metabolites and proteins. Joint pathway analysis revealed substantial metabolic reprogramming, with consistent upregulation of the hexosamine biosynthetic pathway (HBP), converging on amino sugar and nucleotide sugar metabolism. Western blotting, immunohistochemistry, and targeted metabolite quantification further validated the elevation of key HBP components in the hippocampus, supporting HBP activation as a hallmark of metabolic remodeling during early seizure emergence. These findings provide novel insight into the metabolic landscape of epileptogenesis and highlight HBP-related alterations as potential contributors to seizure development and promising therapeutic targets.

Brain capillary endothelial cells (BCECs) express transferrin receptor 1 (TfR1) to ensure sufficient iron transport into the brain. Our main objective was to examine adult mice subjected to dietary iron deficiency (ID) for possible changes in the content of TfR1 in BCECs and the influence thereof on the uptake and possible transport across the blood–brain barrier (BBB) of high-affinity, rat anti-mouse transferrin receptor IgG2a antibody (clone RI7217) targeting the TfR1. We subjected adult, female mice to dietary ID for 8 weeks. Iron and copper were measured using inductively coupled plasma mass spectrometry (ICP-MS) in various tissues, including total brain, and fractions of brain tissue separated to contain a capillary enriched fraction (“capillary fraction”) and a post-capillary, non-endothelial-containing brain parenchymal fraction (“brain fraction”). Possible effects of ID on the cerebral angioarchitecture were estimated using 3D confocal microscopy of optically cleared brain samples labeled using intravenous injection of wheat germ agglutinin with subsequent machine learning-based segmentation and vascular tracing. TfR1 was quantified using ELISA. RI7217 antibodies were conjugated with 1.4 nm nanogold and brain uptake quantified using ICP-MS. ID significantly reduced the iron content in the capillary fraction, liver, spleen, kidney, heart, and skeletal muscles. ID increased the copper content in the brain. Analysis of cerebral cortical angioarchitecture revealed no changes following dietary ID, except for a minor increase in tortuosity of small-caliber vessels. Following ID, the concentration of TfR1 protein remained unchanged in total brain, and the isolated capillaries and brain fraction. In contrast, the uptake of nanogold-conjugated RI7217 was increased in total brain, the brain fraction, liver, spleen, and isolated retinae. The targeting to TfR1 in ID hence suggested increased brain uptake of RI7217. Hypothetically, elevated transport of RI7217 could occur due to increased trafficking of TfR1-containing vesicles through BCECs in ID.

Multielemental analysis of cerebrospinal fluid (CSF) yields critical insights into the pathophysiology of neurological disorders and holds potential as a diagnostic and predictive tool for Alzheimer's disease (AD). The present work presents the development and validation of an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) based method for multielemental determination in CSF, including metals and metalloids as analytes. As a proof of concept, the importance of the CSF element determination was evaluated in a cohort of patients with AD (n = 20) and non-AD controls (n = 19) who displayed typical levels of core CSF biomarkers (Aβ42, P-tau, and total-tau). Discrete sample introduction ICP-MS/MS procedure was effective for accurate and precise CSF analysis. The methodology provided better sensitivities and limits of detection than a conventional one based on sample dilution and analysis in continuous sample introduction mode, while only requiring a 20 μL CSF sample volume. A total of 24 elements were encountered and quantified in CSF, with reduced levels of Mn, Cr, Se, Fe, and Zn in the CSF from AD patients and increased levels of Ag and Bi, compared with non-AD patients. Particularly, Mn fully discriminated AD from non-AD subjects, with binary regression analysis indicating that Mn was the most effective element to distinguish between AD and non-AD groups. Furthermore, distinctive correlation profiles were found between AD and non-AD controls for elements with AD core biomarkers and the alternative amyloidogenic sAPPβ fragment. Quantitative determination of metals, metalloids and non-metals displays differences associated with pathological status, serving as additional biomarkers for neurological diseases.

Spinocerebellar ataxia type 14 (SCA14) is an autosomal-dominant disorder caused by more than 80 PRKCG missense variants encoding protein kinase Cγ (PKCγ), a serine/threonine kinase highly enriched in Purkinje cells (PCs). Despite typically late onset and slow progression, the molecular basis of age-related decline remains unclear. We used a somatic in vivo approach to express wild-type (WT) PKCγ–GFP or the prototypical G128D PKCγ–GFP selectively in PCs of neonatal mice via an adeno-associated virus (AAV) under a PC-specific promoter. G128D PKCγ–GFP formed cytoplasmic aggregates, mislocalized PCs during development, and produced gait deficits by 4 weeks that worsened with age, despite preserved PC counts and overall cerebellar volume at 1.5 years. Immunohistochemistry revealed a selective vulnerability of climbing-fiber (CF) input: vesicular glutamate transporter 2 (VGLUT2), a marker of CF synapses, declined significantly from 12 to 60 weeks in G128D mice, and the VGLUT2-positive innervation field was narrower than age-matched WT at both time points. By contrast, the glutamate/aspartate transporter GLAST in Bergmann-glial radial processes was reduced predominantly at 12 weeks in G128D mice. The δ2 glutamate receptor (GluD2) at parallel fibers and glial fibrillary acidic protein (GFAP) decreased with age but were comparable between expression conditions. Notably, aggregated mutant PKCγ accumulated within the axon initial segment (AIS), whose architecture progressively deteriorated; the altered AIS excluded PKCγ–GFP from distal axons and, by 60 weeks, was associated with reduced delivery of the vesicular GABA transporter (VGAT) to deep cerebellar nuclei (DCN), consistent with impaired anterograde transport. Hence, rather than overt neuronal loss, the cumulative burden of G128D-specific CF/axonal deficits and age-accentuated circuit and glial changes—reduced GLAST function and decreased GluD2—accounts for the worsening motor phenotype. This AAV-based system provides a practical platform to dissect late-onset pathogenic mechanisms and evaluate therapeutic strategies in vivo.