S. Debiasi - Academia.edu (original) (raw)

Papers by S. Debiasi

Research paper thumbnail of Differences in protein quality control correlate with phenotype variability in 2 mouse models of familial amyotrophic lateral sclerosis

Neurobiology of aging, 2015

Amyotrophic lateral sclerosis (ALS) is a disease of variable severity in terms of speed of progre... more Amyotrophic lateral sclerosis (ALS) is a disease of variable severity in terms of speed of progression of the disease course. We found a similar variability in disease onset and progression of 2 familial ALS mouse strains, despite the fact that they carry the same transgene copy number and express the same amount of mutant SOD1G93A messenger RNA and protein in the central nervous system. Comparative analysis of 2 SOD1G93A mouse strains highlights differences associated with the disease severity that are unrelated to the degree of motor neuron loss but that appear to promote early dysfunction of these cells linked to protein aggregation. Features of fast progressing phenotype are (1) abundant protein aggregates containing mutant SOD1 and multiple chaperones; (2) low basal expression of the chaperone alpha-B-crystallin (CRYAB) and β5 subunits of proteasome; and (3) downregulation of proteasome subunit expression at disease onset. In contrast, high levels of functional chaperones such ...

Research paper thumbnail of Activated p38MAPK is a novel component of the intracellular inclusions found in human amyotrophic lateral sclerosis and mutant SOD1 transgenic mice

Journal of neuropathology and experimental neurology, 2004

Cytoskeletal abnormalities with accumulation of ubiquilated inclusions in the anterior horn cells... more Cytoskeletal abnormalities with accumulation of ubiquilated inclusions in the anterior horn cells are a pathological hallmark of both familial and sporadic amyotrophic lateral sclerosis (ALS) and of mouse models for ALS. Phosphorylated neurofilaments besides ubiquitin and dorfin have been identified as one of the major components of the abnormal intracellular perikaryal aggregates. As we recently found that p38 mitogen-activated protein kinase (p38MAPK) colocalized with phosphorylated neurofilaments in spinal motor neurons of SOD1 mutant mice, a model of familial ALS, we investigated whether this kinase also contributed to the inclusions found in ALS patients and SOD1 mutant mice. Intense immunoreactivity for activated p38MAPK was observed in degenerating motor neurons and reactive astrocytes in ALS cases. The intracellular immunostaining for activated p38MAPK appeared in some neurons as filamentous skein-like and ball-like inclusions, with an immunohistochemical pattern identical t...

Research paper thumbnail of GAT-3, a high-affinity GABA plasma membrane transporter, is localized to astrocytic processes, and it is not confined to the vicinity of GABAergic synapses in the cerebral cortex

The Journal of neuroscience : the official journal of the Society for Neuroscience, 1996

The termination of GABA synaptic action by high-affinity, Na(+)-dependent, neuronal, and glial pl... more The termination of GABA synaptic action by high-affinity, Na(+)-dependent, neuronal, and glial plasma membrane transporters plays an important role in regulating neuronal activity in physiological and pathological conditions. We have investigated the cellular localization and distribution in the cerebral cortex of adult rats of one GABA transporter (GAT), GAT-3, by immunocytochemistry with affinity-purified polyclonal antibodies directed to its predicted C terminus that react monospecifically with a protein of approximately 70 kDa. Light microscopic studies revealed specific GAT-3 immunoreactivity (ir) in small punctate structures, and it was never observed in fibers or cell bodies. No changes in immunostaining were observed in sections incubated with GAT-3 antibodies preadsorbed with the related rat GAT-1 or mouse GAT-2/ BGT-1 C-terminal peptides, whereas in sections incubated with GAT-3 antibodies preadsorbed with rat GAT-3 C-terminal peptide, ir was not present. The highest numbe...

Research paper thumbnail of DISTRIBUTION, MORPHOLOGY, AND ORIGIN OF CALCITONIN GENE-RELATED PEPTIDE (CGRP)-CONTAINING FIBERS IN THE NEOCORTEX OF CATS

Research paper thumbnail of Accumulation of human SOD1 and ubiquitinated deposits in the spinal cord of SOD1G93A mice during motor neuron disease progression correlates with a decrease of proteasome

Neurobiology of Disease, 2005

Mutations in SOD1 cause selective motor neuron degeneration in familial amyotrophic lateral scler... more Mutations in SOD1 cause selective motor neuron degeneration in familial amyotrophic lateral sclerosis patients and transgenic mice overexpressing the mutant enzyme. Formation and accumulation of ubiquitinated aggregates in motor neurons are thought to be involved in the toxic gain of function of mutant SOD1. The present study shows that the accumulation of soluble and detergent-insoluble mutant SOD1 in spinal cord of symptomatic SOD1G93A transgenic mice is due to impaired degradation of mutant SOD1 rather than to increased transcript levels. This effect was accompanied by a decrease of constitutive proteasome levels and a concomitant increase of immunoproteasome in the spinal cord homogenate which resulted in overall unchanged proteasome activity. A decrease of constitutive proteasome occurred in the motor neurons of SOD1G93A mice at the presymptomatic stage and became remarkable with the progression of the disease. This provides further evidence for an involvement of proteasome impairment in the toxicity of mutant SOD1. D

Research paper thumbnail of Neuronal and glial localization of NMDA receptors in the cerebral cortex

Molecular Neurobiology, 1997

The crucial rote of glutamate receptors of the N-methyl-D-aspartate (NMDA) type in many fundament... more The crucial rote of glutamate receptors of the N-methyl-D-aspartate (NMDA) type in many fundamental cortical functions has been firmly established, as has its involvement in several neuropsychiatric diseases, but until recently, very little was known of the anatomical localization of NMDA receptors in the cerebral cortex of mammals. The recent application of molecular biological techniques to the study of NMDA receptors has allowed the production of specific tools, the use of which has much increased our understanding of the localization of NMDA receptors in the cerebral cortex. In particular, immunocytochemical studies on the distribution of cortical NMDA receptors have:

Research paper thumbnail of CLIC1 Function Is Required for  -Amyloid-Induced Generation of Reactive Oxygen Species by Microglia

Journal of Neuroscience, 2008

The Alzheimer's disease (AD) brain is characterized by plaques containing ␤-amyloid (A␤) protein ... more The Alzheimer's disease (AD) brain is characterized by plaques containing ␤-amyloid (A␤) protein surrounded by astrocytes and reactive microglia. Activation of microglia by A␤ initiates production of reactive oxygen species (ROS) by the plasmalemmal NADPH oxidase; the resultant oxidative stress is thought to contribute to neurodegeneration in AD. We have previously shown that A␤ upregulates a chloride current mediated by the chloride intracellular channel 1 (CLIC1) protein in microglia. We now demonstrate that A␤ promotes the acute translocation of CLIC1 from the cytosol to the plasma membrane of microglia, where it mediates a chloride conductance. Both the A␤ induced Cl Ϫ conductance and ROS generation were prevented by pharmacological inhibition of CLIC1, by replacement of chloride with impermeant anions, by an anti-CLIC1 antibody and by suppression of CLIC1 expression using siRNA. Thus, the CLIC1-mediated Cl Ϫ conductance is required for A␤-induced generation of neurotoxic ROS by microglia. Remarkably, CLIC1 activation is itself dependent on oxidation by ROS derived from the activated NADPH oxidase. We therefore propose that CLIC1 translocation from the cytosol to the plasma membrane, in response to redox modulation by NADPH oxidase-derived ROS, provides a feedforward mechanism that facilitates sustained microglial ROS generation by the NAPDH oxidase. R.H.M. is in the 4 year PhD program in Neuroscience at UCL. We are grateful to S. Sensi and F. La Ferla for providing the AD mouse model. We thank A. Y. Abramov for initiating the experiments in amyloid-induced ROS production and R. Tonini for critical reading of this manuscript. The Duchen and Mazzanti labs contributed equally to this work.

Research paper thumbnail of Differences in protein quality control correlate with phenotype variability in 2 mouse models of familial amyotrophic lateral sclerosis

Neurobiology of aging, 2015

Amyotrophic lateral sclerosis (ALS) is a disease of variable severity in terms of speed of progre... more Amyotrophic lateral sclerosis (ALS) is a disease of variable severity in terms of speed of progression of the disease course. We found a similar variability in disease onset and progression of 2 familial ALS mouse strains, despite the fact that they carry the same transgene copy number and express the same amount of mutant SOD1G93A messenger RNA and protein in the central nervous system. Comparative analysis of 2 SOD1G93A mouse strains highlights differences associated with the disease severity that are unrelated to the degree of motor neuron loss but that appear to promote early dysfunction of these cells linked to protein aggregation. Features of fast progressing phenotype are (1) abundant protein aggregates containing mutant SOD1 and multiple chaperones; (2) low basal expression of the chaperone alpha-B-crystallin (CRYAB) and β5 subunits of proteasome; and (3) downregulation of proteasome subunit expression at disease onset. In contrast, high levels of functional chaperones such ...

Research paper thumbnail of Activated p38MAPK is a novel component of the intracellular inclusions found in human amyotrophic lateral sclerosis and mutant SOD1 transgenic mice

Journal of neuropathology and experimental neurology, 2004

Cytoskeletal abnormalities with accumulation of ubiquilated inclusions in the anterior horn cells... more Cytoskeletal abnormalities with accumulation of ubiquilated inclusions in the anterior horn cells are a pathological hallmark of both familial and sporadic amyotrophic lateral sclerosis (ALS) and of mouse models for ALS. Phosphorylated neurofilaments besides ubiquitin and dorfin have been identified as one of the major components of the abnormal intracellular perikaryal aggregates. As we recently found that p38 mitogen-activated protein kinase (p38MAPK) colocalized with phosphorylated neurofilaments in spinal motor neurons of SOD1 mutant mice, a model of familial ALS, we investigated whether this kinase also contributed to the inclusions found in ALS patients and SOD1 mutant mice. Intense immunoreactivity for activated p38MAPK was observed in degenerating motor neurons and reactive astrocytes in ALS cases. The intracellular immunostaining for activated p38MAPK appeared in some neurons as filamentous skein-like and ball-like inclusions, with an immunohistochemical pattern identical t...

Research paper thumbnail of GAT-3, a high-affinity GABA plasma membrane transporter, is localized to astrocytic processes, and it is not confined to the vicinity of GABAergic synapses in the cerebral cortex

The Journal of neuroscience : the official journal of the Society for Neuroscience, 1996

The termination of GABA synaptic action by high-affinity, Na(+)-dependent, neuronal, and glial pl... more The termination of GABA synaptic action by high-affinity, Na(+)-dependent, neuronal, and glial plasma membrane transporters plays an important role in regulating neuronal activity in physiological and pathological conditions. We have investigated the cellular localization and distribution in the cerebral cortex of adult rats of one GABA transporter (GAT), GAT-3, by immunocytochemistry with affinity-purified polyclonal antibodies directed to its predicted C terminus that react monospecifically with a protein of approximately 70 kDa. Light microscopic studies revealed specific GAT-3 immunoreactivity (ir) in small punctate structures, and it was never observed in fibers or cell bodies. No changes in immunostaining were observed in sections incubated with GAT-3 antibodies preadsorbed with the related rat GAT-1 or mouse GAT-2/ BGT-1 C-terminal peptides, whereas in sections incubated with GAT-3 antibodies preadsorbed with rat GAT-3 C-terminal peptide, ir was not present. The highest numbe...

Research paper thumbnail of DISTRIBUTION, MORPHOLOGY, AND ORIGIN OF CALCITONIN GENE-RELATED PEPTIDE (CGRP)-CONTAINING FIBERS IN THE NEOCORTEX OF CATS

Research paper thumbnail of Accumulation of human SOD1 and ubiquitinated deposits in the spinal cord of SOD1G93A mice during motor neuron disease progression correlates with a decrease of proteasome

Neurobiology of Disease, 2005

Mutations in SOD1 cause selective motor neuron degeneration in familial amyotrophic lateral scler... more Mutations in SOD1 cause selective motor neuron degeneration in familial amyotrophic lateral sclerosis patients and transgenic mice overexpressing the mutant enzyme. Formation and accumulation of ubiquitinated aggregates in motor neurons are thought to be involved in the toxic gain of function of mutant SOD1. The present study shows that the accumulation of soluble and detergent-insoluble mutant SOD1 in spinal cord of symptomatic SOD1G93A transgenic mice is due to impaired degradation of mutant SOD1 rather than to increased transcript levels. This effect was accompanied by a decrease of constitutive proteasome levels and a concomitant increase of immunoproteasome in the spinal cord homogenate which resulted in overall unchanged proteasome activity. A decrease of constitutive proteasome occurred in the motor neurons of SOD1G93A mice at the presymptomatic stage and became remarkable with the progression of the disease. This provides further evidence for an involvement of proteasome impairment in the toxicity of mutant SOD1. D

Research paper thumbnail of Neuronal and glial localization of NMDA receptors in the cerebral cortex

Molecular Neurobiology, 1997

The crucial rote of glutamate receptors of the N-methyl-D-aspartate (NMDA) type in many fundament... more The crucial rote of glutamate receptors of the N-methyl-D-aspartate (NMDA) type in many fundamental cortical functions has been firmly established, as has its involvement in several neuropsychiatric diseases, but until recently, very little was known of the anatomical localization of NMDA receptors in the cerebral cortex of mammals. The recent application of molecular biological techniques to the study of NMDA receptors has allowed the production of specific tools, the use of which has much increased our understanding of the localization of NMDA receptors in the cerebral cortex. In particular, immunocytochemical studies on the distribution of cortical NMDA receptors have:

Research paper thumbnail of CLIC1 Function Is Required for  -Amyloid-Induced Generation of Reactive Oxygen Species by Microglia

Journal of Neuroscience, 2008

The Alzheimer's disease (AD) brain is characterized by plaques containing ␤-amyloid (A␤) protein ... more The Alzheimer's disease (AD) brain is characterized by plaques containing ␤-amyloid (A␤) protein surrounded by astrocytes and reactive microglia. Activation of microglia by A␤ initiates production of reactive oxygen species (ROS) by the plasmalemmal NADPH oxidase; the resultant oxidative stress is thought to contribute to neurodegeneration in AD. We have previously shown that A␤ upregulates a chloride current mediated by the chloride intracellular channel 1 (CLIC1) protein in microglia. We now demonstrate that A␤ promotes the acute translocation of CLIC1 from the cytosol to the plasma membrane of microglia, where it mediates a chloride conductance. Both the A␤ induced Cl Ϫ conductance and ROS generation were prevented by pharmacological inhibition of CLIC1, by replacement of chloride with impermeant anions, by an anti-CLIC1 antibody and by suppression of CLIC1 expression using siRNA. Thus, the CLIC1-mediated Cl Ϫ conductance is required for A␤-induced generation of neurotoxic ROS by microglia. Remarkably, CLIC1 activation is itself dependent on oxidation by ROS derived from the activated NADPH oxidase. We therefore propose that CLIC1 translocation from the cytosol to the plasma membrane, in response to redox modulation by NADPH oxidase-derived ROS, provides a feedforward mechanism that facilitates sustained microglial ROS generation by the NAPDH oxidase. R.H.M. is in the 4 year PhD program in Neuroscience at UCL. We are grateful to S. Sensi and F. La Ferla for providing the AD mouse model. We thank A. Y. Abramov for initiating the experiments in amyloid-induced ROS production and R. Tonini for critical reading of this manuscript. The Duchen and Mazzanti labs contributed equally to this work.