Loss of Na+ channel β2 subunits is neuroprotective in a mouse model of multiple sclerosis

Multiple sclerosis (MS) is a CNS disease that includes demyelination and axonal degeneration. Voltage-gated Na⁺ channels are abnormally expressed and distributed in MS and its animal model, Experimental Allergic Encephalomyelitis (EAE). Up-regulation of Na⁺ channels along demyelinated axons is proposed to lead to axonal loss in MS/EAE. We hypothesized that Na⁺ channel β2 subunits (encoded by Scn2b) are involved in MS/EAE pathogenesis, as β2 is responsible for regulating levels of channel cell surface expression in neurons. We induced non-relapsing EAE in Scn2b^+/+ and Scn2b^?/? mice on the C57BL/6 background. Scn2b^?/? mice display a dramatic reduction in EAE symptom severity and lethality as compared to wildtype, with significant decreases in axonal degeneration and axonal loss. Scn2b^?/? mice show normal peripheral immune cell populations, T cell proliferation, cytokine release, and immune cell infiltration into the CNS in response to EAE, suggesting that Scn2b inactivation does not compromise immune function. Our data suggest that loss of β2 is neuroprotective in EAE by prevention of Na⁺ channel up-regulation in response to demyelination.     

Physical and functional cooperation of neural cell adhesion molecule and ��1-integrin in neurite outgrowth induction

Neural cell adhesion molecule (NCAM) and ??1-integrin are both involved in cell differentiation, with changes in the expression of these two molecules correlating with changes in the malignancy of tumor cells. There is a known functional correlation between NCAM and ??1-integrin in adhesion and also neurite outgrowth in tumor cells. In the present study, we used immunostaining and immunoprecipitation studies to demonstrate that isoform 120 of NCAM associates physically as well as functionally with ??1-integrin in the induction of neurite outgrowth in SH-SY5Y-human neuroblastoma cells. The interaction between these two molecules is mandatory for neurite outgrowth. NCAM blockage completely inhibits the effects of ??1-integrin on neurite outgrowth. These findings further our understanding of the interactions between NCAMs and integrins in malignancy.     

Expression and regulation of voltage-gated sodium channel β1 subunit protein in human gliosis-associated pathologies

Auxiliary beta1 subunits of voltage-gated sodium channels (NaChs) critically regulate channel activity and may also act as cell adhesion molecules (CAMs). In a recent study we have shown that the expression of beta1 NaCh protein is increased in reactive astrocytes in a rat epilepsy model of mesial temporal lobe epilepsy. The present study was undertaken to examine whether changes of NaCh beta1 subunit protein expression are also associated with structural changes occurring in human reactive astrocytes under different pathological conditions in vivo, as well as in response to changing environmental conditions in vitro. Strong beta1 astroglial immunoreactivity was present in human brain tissue from patients with astrogliosis. The over-expression of beta1 protein in reactive glia was observed in both epilepsy-associated brain pathologies (temporal lobe epilepsy, cortical dysplasia), as well as non-epileptic (cerebral infarction, multiple sclerosis, amyotrophic lateral sclerosis, meningo-encephalitis) disorders. The up-regulation of beta1 subunit protein in astrocytes can be reproduced in vitro. beta1 protein is highly expressed in human astrocytes cultured in the presence of trophic factors, under conditions in which they show morphology similar to the morphology of cells undergoing reactive gliosis. The growth factor-induced overexpression of beta1 protein was abrogated by PD98059, which inhibits the mitogen-activated protein kinase pathway. These findings demonstrate that the expression of NaCh beta1 subunit protein in astrocytes is plastic, and indicate a novel mechanism for modulation of glial function in gliosis-associated pathologies.     

Acid-sensing ion channel 1a:a novel target in Alzheimer's disease?

Alzheimer's disease(AD)represents the most common form of dementia and is characterized by a progressive decline of cognitive functions.Complex multifactorial processes underlie AD pathophysiology,including amyloid-beta(Aβ)toxicity,tau protein hyperphosphorylation,syna ptic dysfunction,oxidative stress,and neuroinflammation(J u and Tam,2022).     

Nerve bundle formation during the promotion of peripheral nerve regeneration:collagenⅥ-neural cell adhesion molecule 1 interaction

The formation of nerve bundles,which is partially regulated by neural cell adhesion molecule 1(NCAM1),is important for neural network organization during peripheral nerve regeneration.However,little is known about how the extracellular matrix(ECM)microenvironment affects this process.Here,we seeded dorsal root ganglion tissue blocks on different ECM substrates of peripheral nerve ECM-derived matrixgel,Matrigel,laminin 521,collagen I,and collagen IV,and observed well-aligned axon bundles growing in the peripheral nerve ECM-derived environment.We confirmed that NCAM1 is necessary but not sufficient to trigger this phenomenon.A protein interaction assay identified collagen VI as an extracellular partner of NCAM1 in the regulation of axonal fasciculation.Collagen VI interacted with NCAM1 by directly binding to the FNIII domain,thereby increasing the stability of NCAM1 at the axolemma.Our in vivo experiments on a rat sciatic nerve defect model also demonstrated orderly nerve bundle regeneration with improved projection accuracy and functional recovery after treatment with 10 mg/m L Matrigel and 20μg/m L collagen VI.These findings suggest that the collagen VI-NCAM1 pathway plays a regulatory role in nerve bundle formation.This study was approved by the Animal Ethics Committee of Guangzhou Medical University(approval No.GY2019048)on April 30,2019.     

LGI1: a gene involved in epileptogenesis and glioma progression?

The leucine-rich, glioma inactivated gene 1 (LGI1) gene on human chromosome 10q24 was first identified as a candidate tumor suppressor gene for glioma. Surprisingly, mutations in LGI1 were also shown to cause an idiopathic epilepsy syndrome, autosomal dominant lateral temporal lobe epilepsy (ADLTE). LGI1 is one of the only two currently known non-ion channel genes whose mutations cause idiopathic epilepsy in humans. In this review we summarize the current data on structure and function of the LGI1 protein and discuss clinical aspects of ADLTE and their correlation with LGI1. We also propose that the evidence supporting the tumor suppressor role of LGI1 in malignant gliomas is weak and that further work is necessary to establish LGI1 role in glial cells.     

Assessment of β-amyloid deposits in human brain: a study of the BrainNet Europe Consortium

β-Amyloid (Aβ) related pathology shows a range of lesions which differ both qualitatively and quantitatively. Pathologists, to date, mainly focused on the assessment of both of these aspects but attempts to correlate the findings with clinical phenotypes are not convincing. It has been recently proposed in the same way as ι and α synuclein related lesions, also Aβ related pathology may follow a temporal evolution, i.e. distinct phases, characterized by a step-wise involvement of different brain-regions. Twenty-six independent observers reached an 81% absolute agreement while assessing the phase of Aβ, i.e. phase 1 = deposition of Aβ exclusively in neocortex, phase 2 = additionally in allocortex, phase 3 = additionally in diencephalon, phase 4 = additionally in brainstem, and phase 5 = additionally in cerebellum. These high agreement rates were reached when at least six brain regions were evaluated. Likewise, a high agreement (93%) was reached while assessing the absence/presence of cerebral amyloid angiopathy (CAA) and the type of CAA (74%) while examining the six brain regions. Of note, most of observers failed to detect capillary CAA when it was only mild and focal and thus instead of type 1, type 2 CAA was diagnosed. In conclusion, a reliable assessment of Aβ phase and presence/absence of CAA was achieved by a total of 26 observers who examined a standardized set of blocks taken from only six anatomical regions, applying commercially available reagents and by assessing them as instructed. Thus, one may consider rating of Aβ-phases as a diagnostic tool while analyzing subjects with suspected Alzheimer’s disease (AD). Because most of these blocks are currently routinely sampled by the majority of laboratories, assessment of the Aβ phase in AD is feasible even in large scale retrospective studies.     

Interferon-β1b leads to a short-term increase of soluble but long-term stabilisation of cell surface bound adhesion molecules in multiple sclerosis

Abstract. Adhesion molecules (AMs) are believed to regulate the transmigration of blood leukocytes across the blood-brain barrier (BBB), which is an essential step in the pathogenesis of multiple sclerosis (MS). Previous studies have investigated changes of the soluble forms of AM during interferon-_1b (IFN-_1b) treatment in MS patients. In this study, we analysed the influence of IFN-_1b treatment on the cell surface bound forms of the AMs cICAM-1 and cICAM-3 on blood mononuclear cells (MNC). Sixty-eight patients with relapsing-remitting MS were enrolled in this open study; thirty of them were treated with IFN-_1b. Blood samples were collected every three months over a period of 18 months. The expression levels of cell surface bound forms of AM on blood MNC were measured by two colour flow cytometry analysis. sVCAM-1, sICAM-1 and sICAM-3 were determined by ELISA. We found a short-term induction effect on the serum concentrations of sICAM-1 and sVCAM-1 after three months of IFN-_1b treatment. The expression levels of cell surface bound AMs on blood MNC remained stable during treatment. Untreated MS patients, however, showed a continuous decrease in the expression of cell surface bound AM expression over 18 months. Stabilisation of the expression of cell surface bound AMs on blood MNC may indicate the beneficial effects of IFN-_1b therapy in MS patients.     

Elevated β-secretase 1 expression mediates CD4+ T cell dysfunction via PGE2 signalling in Alzheimer’s disease

Circulating CD4⁺ T cells are dysfunctional in Alzheimer’s disease (AD), however, the underlying molecular mechanisms are not clear. In this study, we demonstrate that CD4⁺ T cells from AD patients and 5xFAD transgenic mice exhibit elevated levels of β-secretase 1 (BACE1). Overexpression of BACE1 in CD4⁺ T cells potentiated CD4⁺ T-cell activation and T-cell-dependent immune responses. Mechanistically, BACE1 modulates prostaglandin E2 (PGE2) synthetase—microsomal prostaglandin E synthase 2 (mPGES2)—to promote mPGES2 maturation and PGE2 production, which increases T-cell receptor (TCR) signalling. Moreover, administration of peripheral PGE2 signalling antagonists partially ameliorates CD4⁺ T cell overactivation and AD pathology in 5xFAD mice. Overall, our results reveal a potential role for BACE1 in mediating CD4⁺ T-cell dysfunction in AD.     

Targeted deletion of β1-syntrophin causes a loss of Kir4.1 from Müller cell endfeet in mouse retina

Proper function of the retina depends heavily on a specialized form of retinal glia called Müller cells. These cells carry out important homeostatic functions that are contingent on their polarized nature. Specifically, the Müller cell endfeet that contact retinal microvessels and the corpus vitreum show a tenfold higher concentration of the inwardly rectifying potassium channel K_ir4.1 than other Müller cell plasma membrane domains. This highly selective enrichment of K_ir4.1 allows K+ to be siphoned through endfoot membranes in a special form of spatial buffering. Here, we show that K_ir4.1 is enriched in endfoot membranes through an interaction with β1-syntrophin. Targeted disruption of this syntrophin caused a loss of K_ir4.1 from Müller cell endfeet without affecting the total level of K_ir4.1 expression in the retina. Targeted disruption of α1-syntrophin had no effect on K_ir4.1 localization. Our findings show that the K_ir4.1 aggregation that forms the basis for K+ siphoning depends on a specific syntrophin isoform that colocalizes with K_ir4.1 in Müller endfoot membranes.     

Attempted endogenous tissue repair following experimental spinal cord injury in the rat: involvement of cell adhesion molecules L1 and NCAM?

It is widely accepted that the devastating consequences of spinal cord injury are due to the failure of lesioned CNS axons to regenerate. The current study of the spontaneous tissue repair processes following dorsal hemisection of the adult rat spinal cord demonstrates a phase of rapid and substantial nerve fibre in-growth into the lesion that was derived largely from both rostral and caudal spinal tissues. The response was characterized by increasing numbers of axons traversing the clearly defined interface between the lesion and the adjacent intact spinal cord, beginning by 5 days post operation (p.o.). Having penetrated the lesion, axons became associated with a framework of NGFr-positive non-neuronal cells (Schwann cells and leptomeningeal cells). Surprisingly few of these axons were derived from CGRP- or SP-immunoreactive dorsal root ganglion neurons. At the longest survival time (56 days p.o.), there was a marked shift in the overall orientation of fibres from a largely rostro-caudal to a dorso-ventral axis. Attempts to identify which recognition molecules may be important for these re-organizational processes during attempted tissue repair demonstrated the widespread and intense expression of the cell adhesion molecules (CAM) L1 and N-CAM. Double immunofluorescence suggested that both Schwann cells and leptomeningeal cells contributed to the pattern of CAM expression associated with the cellular framework within the lesion.     

Glial-derived transforming growth factor β1(TGF-β1):a key factor in multiple sclerosis neuroinflammation

正Glial cell activation and neuroinflammation in multiple sclerosis (MS):MS is an irreversible and progressive central nervous system (CNS) disease which originates in the autoimmune attack of lymphocytes against CNS myelin.This specialized membrane,synthesized by oligodendrocytes (OL) in the CNS,provides metabolic support to axons and allows for     

Neurine, an acetylcholine autolysis product, elevates secreted amyloid-beta protein precursor and amyloid-beta peptide levels, and lowers neuronal cell viability in culture: a role in Alzheimer's disease?

Classical hallmarks of Alzheimer's disease (AD) are a synaptic loss, cholinergic neuron death, and abnormal protein deposition, particularly of toxic amyloid-beta peptide (Abeta) that is derived from amyloid-beta protein precursor (AbetaPP) by the action of beta- and gamma-secretases. The trigger(s) initiating the biochemical cascades that underpin these hallmarks have yet to be fully elucidated. The typical forebrain cholinergic cell demise associated with AD brain results in a loss of presynaptic cholinergic markers and acetylcholine (ACh). Neurine (vinyl-trimethyl-ammonium hydroxide) is a breakdown product of ACh, consequent to autolysis and is an organic poison found in cadavre brain. The time- and concentration-dependent actions of neurine were assessed in human neuroblastoma (NB, SK-N-SH) cells in culture by quantifying cell viability by lactate dehydrogenase (LDH) and MTS assay, and AbetaPP and Abeta levels by Western blot and ELISA. NB cells displayed evidence of toxicity to neurine at > or = 3 mg/ml, as demonstrated by elevated LDH levels in the culture media and a reduced cell viability shown by the MTS assay. Using subtoxic concentrations of neurine, elevations in AbetaPP and Abeta1-40 peptide levels were detected in conditioned media samples.     

Apoptotic retinal ganglion cell loss is accompanied by complement and cytokine response in the βB1-CTGF primary open-angle glaucoma mouse model

<正>Glaucoma is a multifactorial disease and occurs in many different species.In humans,glaucoma is accounted one of the leading causes for blindness worldwide.Due to glaucoma’s complexity,it is still unclear what pathomechanisms may be involved in its development in humans as well as in other species,such as canines.Diagnosis of glaucoma can be delayed because patients often do not notice a visual field loss until approximately30%of retinal ganglion cells (RGCs) are lost(Kerrigan-Baumrind ...     

Comparative expression patterns of T-, N-, E-cadherins,beta-catenin,and polysialic acid neural cell adhesion molecule in rat cochlea during development: implications for the nature of Kölliker's organ

We investigated the expression patterns of several cell adhesion molecules (CAMs) during rat cochlea ontogeny, from embryo day 16 to adulthood, with the use of immunohistochemistry: neural cadherin (N-cad) and polysialic acid neural CAM (PSA-NCAM) as two different neural CAM paradigms; epithelial cadherin (E-cad), which was restricted to the epitheloid phenotype; and the cytoplasmic domain-free truncated-cadherin (T-cad). We made the following observations. (1) T-cad was present in all types of fibrocyte and in subdomains within the pillar cells. (2) E- and N-cad were expressed with mutually exclusive patterns and did not overlap with T-cad. All cochlear epithelial cells, including the sensory outer hair cells (OHCs), were E-cad-positive, except for the negative inner hair cells (IHCs) and the nonsensory K?lliker's organ domain close to the IHCs. N-cad expression appeared first in the developing IHCs and then in the neighboring K?lliker's organ in an increasingly mediolateral gradient in opposition to the E-cad gradient. The OHCs, which are never N-cad positive, intensively expressed E-cad, as did the Hensen cells at the beginning of their differentiation. (3) The cadherin-linked molecule beta-catenin, absent in fibrocytes, was detected in all epithelial cell membranes and was prominent in the E-cad-rich modiolar extremity of K?lliker's organ. (4) Gradual PSA-NCAM expression was observed in the lateral portion of K?lliker's organ, and the intense PSA-NCAM expression was seen surrounding the IHCs. As development proceeded, PSA-NCAM immunoreactivity progressively became restricted to the basal poles of the IHCs, where it remained in the adult rat cochlea, suggesting a synaptic plasticity. Synaptic plasticity in rat cochlea and hypotheses about T-cad functions and neosensory features of the K?lliker's organ are discussed.     

Neuron-associated class III β-tubulin isotype,retinal S-antigen,synaptophysin, and glial fibrillary acidic protein in human medulloblastomas: a clinicopathological analysis of 36 cases

Summary Surgical specimens from 36 medulloblastomas (25 classic and 11 desmoplastic) were studied by peroxidase-antiperoxidase (PAP) immunohistochemistry with antibodies against the class III -tubulin isotype (-tubulin), synaptophysin, retinal S-antigen (S–Ag), and glial fibrillary acidic protein (GFAP). We found that neoplastic cells expressed -tubulin in 91% of the tumors (23 classic and 10 desmoplastic), synaptophysin in 75% (19 classic and 8 desmoplastic), S–Ag in 44% (11 classic and 5 desmoplastic), and GFAP in 11% of medulloblastomas (2 classic and 2 desmoplastic). Synaptophysin and -tubulin positivities were observed in undifferentiated neoplastic cells, in cells forming neuroplastic rosettes, and in pale islands, while S–Ag immunopositivity was noted in undifferentiated cells, occasionally in -tubulin-negative neuroblastic rosettes, and exceptionally in pale islands. Large pale islands, in two desmoplastic medulloblastomas, exhibited distinct patterns of immunoreactivity to the above markers, suggesting neuronal and glial differentiation in the central area, and intense neuritic development in the peripheral zone. Our findings confirm the predominant capacity of medulloblastoma cells to differentiate along neuronal cell lines and indicate that large pale islands, in desmoplastic medulloblastomas, represent well-organized areas for neuronal and, to a lesser degree, astroglial differentiation. Furthermore, it appears, in our cases, that immunohistochemical features do not represent clear-cut prognostic indicators in patients with medulloblastomas.Presented in part at the 14th Meeting of Swiss Neuropathologists with International Participation, Saint-Moritz, Switzerland, March 1992