Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increased titres of anti-neurofilament antibodies have been reported in neurodegenerative disorders, and it has been suggested that such antibodies might be pathogenic. We investigated the specificity of an IgA monoclonal antibody (MAb) from a patient with amyotrophic lateral sclerosis which reacted with neurofilaments and bound to the surface of neuroblastoma cells. In Western blots, the immunoaffinity-purified IgA bound to the 220-kD, high-molecular-weight neurofilament protein (NFH) and cross-reacted with several closely migrating protein bands with apparent mobility of 62-68 kD in neuroblastoma cells and extracts of normal human spinal cord. Following crosslinking to the surface of radiolabeled neuroblastoma cells, the IgA MAb immunoprecipitated a 65-kD protein, indicating that the protein was present on the cell surface and available to the antibodies for binding. Several other MAbs to NFH did not immunostain the surface of neuroblastoma cells or bind to the 65-kD protein, indicating that the protein was not a fragment of NFH. Thus, antibody binding to the 65-kD protein, possibly by cross-reacting with NFH, may have contributed to the neuronal degeneration.
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PMID:Human monoclonal antineurofilament antibody cross-reacts with a neuronal surface protein. 192 May 32

A 75-year-old woman had breast carcinoma, an IgA paraprotein and autopsy-proven amyotrophic lateral sclerosis. Autopsy tissues showed immune-reactive IgA within surviving motor neurons and deposits of IgA and C3 within renal glomeruli. By indirect immunofluorescence, the patient's serum contained high-titer IgA that bound to axons and to the perikarya of nerve cells in central and peripheral nervous system. The IgA paraprotein reacted with the 200 kDa, high molecular weight subunit of neurofilament protein (NFH) in Western blots of purified neurofilaments. It also reacted with dephosphorylated NFH and with NFH expressed as a fusion protein in E. coli, suggesting that the autoantibody recognized a peptide epitope. The IgA crossreacted with a surface antigen of cultured human neuroblastoma cells but mouse monoclonal antibodies to NFH did not. Absorption of the patient's serum with neurofilaments eliminated IgA binding to neuroblastoma cells, indicating that the same antibodies bound to both determinants. The IgA paraprotein seems to be an autoantibody with specificity for neurofilament protein and a cell surface component of neuronal cells; the antibody may have been important in the pathogenesis of neuronal degeneration.
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PMID:A monoclonal IgA in a patient with amyotrophic lateral sclerosis reacts with neurofilaments and surface antigen on neuroblastoma cells. 236 86

We discuss the evidence, based on the analysis of transgenic mice overexpressing the human neurofilament (NF) heavy gene, that abnormal NF accumulations can provoke neurodegeneration of motor neurons. Transgenic mice overexpressing by two-fold the normal levels of human NF-H proteins develop a progressive motor neuron disease with several pathologic features reminiscent of those found in amyotrophic lateral sclerosis (ALS). A plausible mechanism for the selective motor neuron degeneration is that exceeding levels of NF-H cross-linkages impede transport of newly synthesized NF structures. The abnormal NF accumulations in perikarya and proximal axons is accompanied by a disruption in axonal transport of not only NF proteins but also of other components required for maintenance of axons. The relevance of the NF-H transgenics as a model of ALS is discussed in light of our current knowledge of motor neuron disease.
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PMID:Mice overexpressing the human neurofilament heavy gene as a model of ALS. 756 55

Neurofilaments (NFs) are the most abundant structural components in large-diameter myelinated axons. Assembled as obligate heteropolymers requiring NF-L and substoichiometric amounts of NF-M and/or NF-H, NF investment into axons is essential for establishment of axonal caliber, itself a key determinant of conduction velocity. Use of transgenic mice to increase axonal accumulation of NFs or to express mutant NFs subunits has proven that aberrant organization or assembly of NFs is sufficient to cause disease arising from selective dysfunction and degeneration of motor neurons. Because aberrant accumulation of NFs is a common pathology in a series of motor neuron diseases-including amyotrophic lateral sclerosis-NF misaccumulation, and the resultant disruption in axonal transport, is probably a key intermediate in the pathogenesis of these diseases.
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PMID:Neuronal intermediate filaments. 883 41

Neurofilaments, assembled from NF-L (68 kd), NF-M (95 kd), and NF-H (115 kd), are the most abundant structural components in large myelinated axons, particularly those of motor neurons. Aberrant neurofilament accumulation in cell bodies and axons of motor neurons is a prominent pathological feature of several motor neuron diseases, including sporadic and familial amyotrophic lateral sclerosis (ALS). Transgenic methods have proved in mice that mutation in or increased expression of neurofilament subunits can be primary causes of motor neuron disease that mimics the neurofilamentous pathology often reported in human disease. To examine whether mutation in neurofilament subunits causes or predisposes to ALS, we used single-strand conformation polymorphism coupled with DNA sequencing to search for mutations in the entirety of the human NF-L, NF-M, and NF-H genes from 100 familial ALS patients known not to carry mutations in superoxide dismutase 1 (SOD1), as well as from 75 sporadic ALS patients. Six polypeptide sequence variants were identified in rod and tail domains of NF-L, NF-M, or NF-H. However, all were found at comparable frequency in DNAs from normal individuals and no variant cosegregated with familial disease. Two deletions found previously in NF-H genes of sporadic ALS patients were not seen in this group of familial or sporadic ALS patients.
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PMID:Sequence variants in human neurofilament proteins: absence of linkage to familial amyotrophic lateral sclerosis. 887 80

The properties regulating the supramolecular organization of neural intermediate filament (NIF) networks have been investigated in cultured dorsal root ganglion (DRG) neurons. The studies described take advantage of the ability of endogenous NIF to incorporate purified biotinylated neurofilament triplet (NFT) proteins, NF-L, NF-M and NF-H. When injected at concentrations of 0.8-1.0 mg/ml injection buffer, each of these proteins is incorporated without perturbing the endogenous NIF network. However, at progressively higher concentrations, NF-H induces the aggregation and accumulation of NIF in the cell body. Subsequent to the induction of these aggregates, numerous alterations in the cytoarchitecture of neurons can be detected. The latter occur in a temporal sequence which appears to begin with the fragmentation of the Golgi complex. At later times, accumulation of mitochondria within the proximal region of neurites, peripheralization of the nucleus, and a significant decrease in neurite caliber become obvious. After longer time periods, the NIF aggregates are seen to react with an antibody which reveals abnormally phosphorylated NF-H. These observations demonstrate that an imbalance in the normal stoichiometric relationships among the NFT proteins rapidly alters the supramolecular organization of the NIF network. These changes most likely reflect the normal functions of neurofilaments in cell shape and the organization and cytoplasmic distribution of membranous organelles. Interestingly, virtually all of these changes closely resemble those which have been reported in motor neuron diseases such as amyotrophic lateral sclerosis (ALS). These findings suggest that cultured neurons can be used as models for more precisely defining the relationships between the formation of NIF aggregates and the sequence of cytopathological events which typify neurodegenerative diseases.
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PMID:Alterations in neural intermediate filament organization: functional implications and the induction of pathological changes related to motor neuron disease. 888 82

A number of free radicals such as superoxide and nitric oxide may cause damage to motor neurons but the exact mechanism remains to be elucidated. A potent free radical, peroxynitrite, is readily formed from superoxide and nitric oxide, which captures superoxide three times faster than SOD-1. Peroxynitrite may nitrate tyrosine residues of light neurofilaments (NF-I), thereby altering NF assembly and causing NF accumulation in motor neurons. To test this hypothesis we have probed the massive NF aggregates which are histopathological hallmarks of ALS/MND with immunohistochemistry. We investigated localization of reaction products related to SOD-1, nitric oxide synthase (NOS) and cyclic GMP activities. Our studies show colocalization of NF aggregates with SOD-1/b-NOS/calmodulin /citrulline/cGMP and nitrotyrosine in upper motor neuron conglomerates (Cgl) and lower motor neutron axonal spheroids (Axs). This strongly supports the notion that peroxynitrite deranges NF phosphorylation and assembly, by nitrating tyrosine residues in NF-L. Impaired phosphorylation of NF subunits, either at NF-I or at NF-H, may affect the slow axonal transport culminating in proximo-distal accumulation of NF and slowly progressive motoneuron death.
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PMID:Role of SOD-1 and nitric oxide/cyclic GMP cascade on neurofilament aggregation in ALS/MND. 889 53

Alterations in cytoskeletal proteins such as the perikaryal accumulation of neurofilaments (NFs) occur in a number of human neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis and may contribute to their debilitating effects. The administration of aluminum salts to rabbits induces the aberrant accumulation of NFs within the proximal axons and perikarya of vulnerable neurons and is one animal model which has been extensively studied in an attempt to gain insight into the mechanism(s) of NF perturbations in human disease. Previous studies using Northern blotting techniques to examine mRNA levels in the aluminum-induced neuropathy model have led to seemingly contradictory results. We have used in situ hybridization which provides the cellular resolution needed to: 1) determine whether there are generalized decreases in the levels of mRNA expression or decreases in mRNA encoding specific proteins; 2) determine whether alterations in mRNA levels occur specifically in neurons with NF accumulations; and 3) begin to resolve some of the apparent contradictions in the literature. A moderate dose of aluminum lactate administered on two consecutive days produced neurofibrillary tangles in spinal cord neurons seven days after the first dose. Polyadenylated mRNA levels were not altered in spinal cord neurons in aluminum-treated compared to saline-treated control animals or in tangle-bearing compared to non tangle-bearing neurons in aluminum-treated animals. Middle and high NF subunit (NFH) mRNA levels were not significantly different from polyadenylated mRNA levels in spinal cord neurons in aluminum-treated/control animals. NFH mRNA levels were decreased in neurons containing aluminum-induced NF accumulations. These results suggest that NFH gene expression may be down regulated by an inhibitory feedback mechanism induced by perikaryal accumulations of NFs. This inhibitory feedback regulation for NFH may have implications for neurodegenerative diseases in which NFs accumulate in neuronal perikarya.
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PMID:Neuronal gene expression in aluminum-induced neurofibrillary pathology: an in situ hybridization study. 921 90

Mutations in superoxide dismutase 1 (SOD1), the only proven cause of amyotrophic lateral sclerosis (ALS), provoke disease through an unidentified toxic property. Neurofilament aggregates are pathologic hallmarks of both sporadic and SOD1-mediated familial ALS. By deleting NF-L, the major neurofilament subunit required for filament assembly, onset and progression of disease caused by familial ALS-linked SOD1 mutant G85R are significantly slowed, while selectivity of mutant-mediated toxicity for motor neurons is reduced. In NF-L-deleted animals, levels of the two remaining neurofilament subunits, NF-M and NF-H, are markedly reduced in axons but are elevated in motor neuron cell bodies. Thus, while neither perikaryal nor axonal neurofilaments are essential for SOD1-mediated disease, the absence of assembled neurofilaments both diminishes selective vulnerability and slows SOD1(G85R) mutant-mediated toxicity to motor neurons.
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PMID:Absence of neurofilaments reduces the selective vulnerability of motor neurons and slows disease caused by a familial amyotrophic lateral sclerosis-linked superoxide dismutase 1 mutant. 968 32

This article reviews current knowledge of neurofilament structure, phosphorylation, and function and neurofilament involvement in disease. Neurofilaments are obligate heteropolymers requiring the NF-L subunit together with either the NF-M or the NF-H subunit for polymer formation. Neurofilaments are very dynamic structures; they contain phosphorylation sites for a large number of protein kinases, including protein kinase A (PKA), protein kinase C (PKC), cyclin-dependent kinase 5 (Cdk5), extracellular signal regulated kinase (ERK), glycogen synthase kinase-3 (GSK-3), and stress-activated protein kinase gamma (SAPK gamma). Most of the neurofilament phosphorylation sites, located in tail regions of NF-M and NF-H, consist of the repeat sequence motif, Lys-Ser-Pro (KSP). In addition to the well-established role of neurofilaments in the control of axon caliber, there is growing evidence based on transgenic mouse studies that neurofilaments can affect the dynamics and perhaps the function of other cytoskeletal elements, such as microtubules and actin filaments. Perturbations in phosphorylation or in metabolism of neurofilaments are frequently observed in neurodegenerative diseases. A down-regulation of mRNA encoding neurofilament proteins and the presence of neurofilament deposits are common features of human neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Parkinson's disease, and Alzheimer's disease. Although the extent to which neurofilament abnormalities contribute to pathogenesis in these human diseases remains unknown, emerging evidence, based primarily on transgenic mouse studies and on the discovery of deletion mutations in the NF-H gene of some ALS eases, suggests that disorganized neurofilaments can provoke selective degeneration and death of neurons. An interference of axonal transport by disorganized neurofilaments has been proposed as one possible mechanism of neurofilament-induced pathology. Other factors that can potentially lead to the accumulation of neurofilaments will be discussed as well as the emerging evidence for neurofilaments as being possible targets of oxidative damage by mutations in the superoxide dismutase enzyme (SOD1); such mutations are responsible for approximately 20% of familial ALS cases.
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PMID:Neurofilaments in health and disease. 975 17


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