Recombinant immune interferon (IFN-gamma) induced a dose-related increase in the synthesis and ex... more Recombinant immune interferon (IFN-gamma) induced a dose-related increase in the synthesis and expression of HLA class II antigens by the cultured melanoma cells COLO 38. Although IFN-gamma-treated melanoma cells COLO 38 continue to express higher levels of HLA-DR antigens than of HLA-DQ antigens, the effect of IFN-gamma was more marked on HLA-DQ antigens than on HLA-DR antigens, as indicated by the dose and incubation time required to induce the changes and by the extent and duration of the increase. The effect of IFN-gamma on HLA class II antigens is significantly higher than that of leukocyte and fibroblast interferons. Analysis by one- and two-dimensional gel electrophoresis of antigens synthesized by melanoma cells COLO 38 in the presence of IFN-gamma did not detect any significant change in the structural profile of the subunits of HLA-DR and -DQ antigens.
The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are... more The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are expressed in synaptic membranes in vivo. In the central nervous system the fibrinolytic system is associated with excitotoxin-mediated neurotoxicity and Alzheimer's disease. Recently binding of the disease associated isoform of the prion protein (PrP(Sc)) to plasminogen and stimulation of t-PA activity have been reported. In this study the interaction of PrP(c) and plasminogen was investigated using chromogenic assays in vitro. We found that plasmin is able to cleave recombinant PrP(c) at lysine residue 110 generating an NH(2)-terminal truncated molecule that has previously been described as a major product of PrP(c) metabolism. We further characterized the proteolytic fragments with respect to their ability to stimulate plasminogen activation in vitro. Our results show that the NH(2)-terminal part of PrP(c) spanning amino acids 23-110 (PrP23-110) together with low molecular weight ...
Spongiform encephalopathies are infectious neurodegenerative diseases caused by pathogens that se... more Spongiform encephalopathies are infectious neurodegenerative diseases caused by pathogens that seem to be devoid of any informational nucleic acids. Histopathologically, these diseases are characterized by spongiform degeneration of the central nervous system. Although the main pathological changes during the course of the disease occur in the brain, the infectious agent accumulates early in lymphoid tissue. The consecutive development of clinical disease depends on the presence of an intact immune system including mature B-cells and follicular dendritic cells. In this article we review the state of knowledge on the routes of neuroinvasion used by the infectious agent in order to gain access to the central nervous system upon entry into extracerebral sites.
Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in ... more Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in endocrine cells and tumors of the gastrointestinal tract, pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptides are the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, alpha-MSH and CLIP (corticotropin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenaline-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.
Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer&... more Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer's disease and have been suggested to induce neurotoxicity by binding to a plethora of cell-surface receptors. However, the heterogeneous mixtures of oligomers of varying sizes and conformations formed by Aβ42 have obscured the nature of the oligomeric species that bind to a given receptor. Here, we have used single-molecule imaging to characterize Aβ42 oligomers (oAβ42) and to confirm the controversial interaction of oAβ42 with the cellular prion protein (PrP(C)) on live neuronal cells. Our results show that, at nanomolar concentrations, oAβ42 interacts with PrP(C) and that the species bound to PrP(C) are predominantly small oligomers (dimers and trimers). Single-molecule biophysical studies can thus aid in deciphering the mechanisms that underlie receptor-mediated oAβ-induced neurotoxicity, and ultimately facilitate the discovery of novel inhibitors of these pathways.
Prions cause neurodegeneration in vivo, yet prion-infected cultured cells do not show cytotoxicit... more Prions cause neurodegeneration in vivo, yet prion-infected cultured cells do not show cytotoxicity. This has hampered mechanistic studies of prion-induced neurodegeneration. Here we report that prion-infected cultured organotypic cerebellar slices (COCS) experienced progressive spongiform neurodegeneration closely reproducing prion disease, with three different prion strains giving rise to three distinct patterns of prion protein deposition. Neurodegeneration did not occur when PrP was genetically removed from neurons, and a comprehensive pharmacological screen indicated that neurodegeneration was abrogated by compounds known to antagonize prion replication. Prion infection of COCS and mice led to enhanced fodrin cleavage, suggesting the involvement of calpains or caspases in pathogenesis. Accordingly, neurotoxicity and fodrin cleavage were prevented by calpain inhibitors but not by caspase inhibitors, whereas prion replication proceeded unimpeded. Hence calpain inhibition can uncouple prion replication from its neurotoxic sequelae. These data validate COCS as a powerful model system that faithfully reproduces most morphological hallmarks of prion infections. The exquisite accessibility of COCS to pharmacological manipulations was instrumental in recognizing the role of calpains in neurotoxicity, and significantly extends the collection of tools necessary for rigorously dissecting prion pathogenesis.
Recombinant immune interferon (IFN-gamma) induced a dose-related increase in the synthesis and ex... more Recombinant immune interferon (IFN-gamma) induced a dose-related increase in the synthesis and expression of HLA class II antigens by the cultured melanoma cells COLO 38. Although IFN-gamma-treated melanoma cells COLO 38 continue to express higher levels of HLA-DR antigens than of HLA-DQ antigens, the effect of IFN-gamma was more marked on HLA-DQ antigens than on HLA-DR antigens, as indicated by the dose and incubation time required to induce the changes and by the extent and duration of the increase. The effect of IFN-gamma on HLA class II antigens is significantly higher than that of leukocyte and fibroblast interferons. Analysis by one- and two-dimensional gel electrophoresis of antigens synthesized by melanoma cells COLO 38 in the presence of IFN-gamma did not detect any significant change in the structural profile of the subunits of HLA-DR and -DQ antigens.
The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are... more The cellular prion protein (PrP(c)), tissue-type plasminogen activator (t-PA) and plasminogen are expressed in synaptic membranes in vivo. In the central nervous system the fibrinolytic system is associated with excitotoxin-mediated neurotoxicity and Alzheimer's disease. Recently binding of the disease associated isoform of the prion protein (PrP(Sc)) to plasminogen and stimulation of t-PA activity have been reported. In this study the interaction of PrP(c) and plasminogen was investigated using chromogenic assays in vitro. We found that plasmin is able to cleave recombinant PrP(c) at lysine residue 110 generating an NH(2)-terminal truncated molecule that has previously been described as a major product of PrP(c) metabolism. We further characterized the proteolytic fragments with respect to their ability to stimulate plasminogen activation in vitro. Our results show that the NH(2)-terminal part of PrP(c) spanning amino acids 23-110 (PrP23-110) together with low molecular weight ...
Spongiform encephalopathies are infectious neurodegenerative diseases caused by pathogens that se... more Spongiform encephalopathies are infectious neurodegenerative diseases caused by pathogens that seem to be devoid of any informational nucleic acids. Histopathologically, these diseases are characterized by spongiform degeneration of the central nervous system. Although the main pathological changes during the course of the disease occur in the brain, the infectious agent accumulates early in lymphoid tissue. The consecutive development of clinical disease depends on the presence of an intact immune system including mature B-cells and follicular dendritic cells. In this article we review the state of knowledge on the routes of neuroinvasion used by the infectious agent in order to gain access to the central nervous system upon entry into extracerebral sites.
Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in ... more Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in endocrine cells and tumors of the gastrointestinal tract, pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptides are the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, alpha-MSH and CLIP (corticotropin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenaline-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.
Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer&... more Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer's disease and have been suggested to induce neurotoxicity by binding to a plethora of cell-surface receptors. However, the heterogeneous mixtures of oligomers of varying sizes and conformations formed by Aβ42 have obscured the nature of the oligomeric species that bind to a given receptor. Here, we have used single-molecule imaging to characterize Aβ42 oligomers (oAβ42) and to confirm the controversial interaction of oAβ42 with the cellular prion protein (PrP(C)) on live neuronal cells. Our results show that, at nanomolar concentrations, oAβ42 interacts with PrP(C) and that the species bound to PrP(C) are predominantly small oligomers (dimers and trimers). Single-molecule biophysical studies can thus aid in deciphering the mechanisms that underlie receptor-mediated oAβ-induced neurotoxicity, and ultimately facilitate the discovery of novel inhibitors of these pathways.
Prions cause neurodegeneration in vivo, yet prion-infected cultured cells do not show cytotoxicit... more Prions cause neurodegeneration in vivo, yet prion-infected cultured cells do not show cytotoxicity. This has hampered mechanistic studies of prion-induced neurodegeneration. Here we report that prion-infected cultured organotypic cerebellar slices (COCS) experienced progressive spongiform neurodegeneration closely reproducing prion disease, with three different prion strains giving rise to three distinct patterns of prion protein deposition. Neurodegeneration did not occur when PrP was genetically removed from neurons, and a comprehensive pharmacological screen indicated that neurodegeneration was abrogated by compounds known to antagonize prion replication. Prion infection of COCS and mice led to enhanced fodrin cleavage, suggesting the involvement of calpains or caspases in pathogenesis. Accordingly, neurotoxicity and fodrin cleavage were prevented by calpain inhibitors but not by caspase inhibitors, whereas prion replication proceeded unimpeded. Hence calpain inhibition can uncouple prion replication from its neurotoxic sequelae. These data validate COCS as a powerful model system that faithfully reproduces most morphological hallmarks of prion infections. The exquisite accessibility of COCS to pharmacological manipulations was instrumental in recognizing the role of calpains in neurotoxicity, and significantly extends the collection of tools necessary for rigorously dissecting prion pathogenesis.
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Papers by Adriano Aguzzi