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Barbieri F, Bosio AG, Pattarozzi A, Tonelli M, Bajetto A, Verduci I, Cianci F, Cannavale G, Palloni LMG, Francesconi V, Thellung S, Fiaschi P, Mazzetti S, Schenone S, Balboni B, Girotto S, Malatesta P, Daga A, Zona G, Mazzanti M, Florio T. Chloride intracellular channel 1 activity is not required for glioblastoma development but its inhibition dictates glioma stem cell responsivity to novel biguanide derivatives. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2022; 41:53. [PMID: 35135603 PMCID: PMC8822754 DOI: 10.1186/s13046-021-02213-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 12/07/2021] [Indexed: 11/10/2022]
Abstract
Abstract
Background
Chloride intracellular channel-1 (CLIC1) activity controls glioblastoma proliferation. Metformin exerts antitumor effects in glioblastoma stem cells (GSCs) inhibiting CLIC1 activity, but its low potency hampers its translation in clinical settings.
Methods
We synthesized a small library of novel biguanide-based compounds that were tested as antiproliferative agents for GSCs derived from human glioblastomas, in vitro using 2D and 3D cultures and in vivo in the zebrafish model. Compounds were compared to metformin for both potency and efficacy in the inhibition of GSC proliferation in vitro (MTT, Trypan blue exclusion assays, and EdU labeling) and in vivo (zebrafish model), migration (Boyden chamber assay), invasiveness (Matrigel invasion assay), self-renewal (spherogenesis assay), and CLIC1 activity (electrophysiology recordings), as well as for the absence of off-target toxicity (effects on normal stem cells and toxicity for zebrafish and chick embryos).
Results
We identified Q48 and Q54 as two novel CLIC1 blockers, characterized by higher antiproliferative potency than metformin in vitro, in both GSC 2D cultures and 3D spheroids. Q48 and Q54 also impaired GSC self-renewal, migration and invasion, and displayed low systemic in vivo toxicity. Q54 reduced in vivo proliferation of GSCs xenotransplanted in zebrafish hindbrain. Target specificity was confirmed by recombinant CLIC1 binding experiments using microscale thermophoresis approach. Finally, we characterized GSCs from GBMs spontaneously expressing low CLIC1 protein, demonstrating their ability to grow in vivo and to retain stem-like phenotype and functional features in vitro. In these GSCs, Q48 and Q54 displayed reduced potency and efficacy as antiproliferative agents as compared to high CLIC1-expressing tumors. However, in 3D cultures, metformin and Q48 (but not Q54) inhibited proliferation, which was dependent on the inhibition dihydrofolate reductase activity.
Conclusions
These data highlight that, while CLIC1 is dispensable for the development of a subset of glioblastomas, it acts as a booster of proliferation in the majority of these tumors and its functional expression is required for biguanide antitumor class-effects. In particular, the biguanide-based derivatives Q48 and Q54, represent the leads to develop novel compounds endowed with better pharmacological profiles than metformin, to act as CLIC1-blockers for the treatment of CLIC1-expressing glioblastomas, in a precision medicine approach.
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Thellung S, Corsaro A, Bosio AG, Zambito M, Barbieri F, Mazzanti M, Florio T. Emerging Role of Cellular Prion Protein in the Maintenance and Expansion of Glioma Stem Cells. Cells 2019; 8:cells8111458. [PMID: 31752162 PMCID: PMC6912268 DOI: 10.3390/cells8111458] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 02/07/2023] Open
Abstract
Cellular prion protein (PrPC) is a membrane-anchored glycoprotein representing the physiological counterpart of PrP scrapie (PrPSc), which plays a pathogenetic role in prion diseases. Relatively little information is however available about physiological role of PrPC. Although PrPC ablation in mice does not induce lethal phenotypes, impairment of neuronal and bone marrow plasticity was reported in embryos and adult animals. In neurons, PrPC stimulates neurite growth, prevents oxidative stress-dependent cell death, and favors antiapoptotic signaling. However, PrPC activity is not restricted to post-mitotic neurons, but promotes cell proliferation and migration during embryogenesis and tissue regeneration in adult. PrPC acts as scaffold to stabilize the binding between different membrane receptors, growth factors, and basement proteins, contributing to tumorigenesis. Indeed, ablation of PrPC expression reduces cancer cell proliferation and migration and restores cell sensitivity to chemotherapy. Conversely, PrPC overexpression in cancer stem cells (CSCs) from different tumors, including gliomas—the most malignant brain tumors—is predictive for poor prognosis, and correlates with relapses. The mechanisms of the PrPC role in tumorigenesis and its molecular partners in this activity are the topic of the present review, with a particular focus on PrPC contribution to glioma CSCs multipotency, invasiveness, and tumorigenicity.
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Affiliation(s)
- Stefano Thellung
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
| | - Alessandro Corsaro
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
| | - Alessia G. Bosio
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
| | - Martina Zambito
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
| | - Federica Barbieri
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
| | - Michele Mazzanti
- Dipartimento di Bioscienze, Università di Milano, 20133 Milano, Italy
- Correspondence: (T.F.); (M.M.); Tel.: +39-01-0353-8806 (T.F.); +39-02-5031-4958 (M.M.)
| | - Tullio Florio
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy; (S.T.); (A.C.); (A.G.B.); (M.Z.); (F.B.)
- IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
- Correspondence: (T.F.); (M.M.); Tel.: +39-01-0353-8806 (T.F.); +39-02-5031-4958 (M.M.)
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Thellung S, Corsaro A, Nizzari M, Barbieri F, Florio T. Autophagy Activator Drugs: A New Opportunity in Neuroprotection from Misfolded Protein Toxicity. Int J Mol Sci 2019; 20:ijms20040901. [PMID: 30791416 PMCID: PMC6412775 DOI: 10.3390/ijms20040901] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/11/2019] [Accepted: 02/14/2019] [Indexed: 02/06/2023] Open
Abstract
The aim of this review is to critically analyze promises and limitations of pharmacological inducers of autophagy against protein misfolding-associated neurodegeneration. Effective therapies against neurodegenerative disorders can be developed by regulating the “self-defense” equipment of neurons, such as autophagy. Through the degradation and recycling of the intracellular content, autophagy promotes neuron survival in conditions of trophic factor deprivation, oxidative stress, mitochondrial and lysosomal damage, or accumulation of misfolded proteins. Autophagy involves the activation of self-digestive pathways, which is different for dynamics (macro, micro and chaperone-mediated autophagy), or degraded material (mitophagy, lysophagy, aggrephagy). All neurodegenerative disorders share common pathogenic mechanisms, including the impairment of autophagic flux, which causes the inability to remove the neurotoxic oligomers of misfolded proteins. Pharmacological activation of autophagy is typically achieved by blocking the kinase activity of mammalian target of rapamycin (mTOR) enzymatic complex 1 (mTORC1), removing its autophagy suppressor activity observed under physiological conditions; acting in this way, rapamycin provided the first proof of principle that pharmacological autophagy enhancement can induce neuroprotection through the facilitation of oligomers’ clearance. The demand for effective disease-modifying strategies against neurodegenerative disorders is currently stimulating the development of a wide number of novel molecules, as well as the re-evaluation of old drugs for their pro-autophagic potential.
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Affiliation(s)
- Stefano Thellung
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy.
| | - Alessandro Corsaro
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy.
| | - Mario Nizzari
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy.
| | - Federica Barbieri
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy.
| | - Tullio Florio
- Sezione di Farmacologia, Dipartimento di Medicina Interna & Centro di Eccellenza per la Ricerca Biomedica (CEBR), Università di Genova, 16132 Genova, Italy.
- IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy.
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Inflammatory response of microglia to prions is controlled by sialylation of PrP Sc. Sci Rep 2018; 8:11326. [PMID: 30054538 PMCID: PMC6063910 DOI: 10.1038/s41598-018-29720-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
Neuroinflammation is recognized as one of the obligatory pathogenic features of neurodegenerative diseases including Alzheimer’s, Parkinson’s or prion diseases. In prion diseases, space and time correlations between deposition of disease-associated, pathogenic form of the prion protein or PrPSc and microglial-mediated neuroinflammation has been established. Yet, it remains unclear whether activation of microglia is triggered directly by a contact with PrPSc, and what molecular features of PrPSc microglia sense and respond to that drive microglia to inflammatory states. The current study asked the questions whether PrPSc can directly trigger activation of microglia and whether the degree of microglia response depends on the nature of terminal carbohydrate groups on the surface of PrPSc particles. PrPSc was purified from brains of mice infected with mouse-adapted prion strain 22L or neuroblastoma N2a cells stably infected with 22L. BV2 microglial cells or primary microglia were cultured in the presence of purified 22L. We found that exposure of BV2 cells or primary microglia to purified PrPSc triggered proinflammatory responses characterized by an increase in the levels of TNFα, IL6, nitric oxide (NO) and expression of inducible Nitric Oxide Synthase (iNOS). Very similar patterns of inflammatory response were induced by PrPSc purified from mouse brains and neuroblastoma cells arguing that microglia response is independent of the source of PrPSc. To test whether the microglial response is mediated by carbohydrate epitopes on PrPSc surface, the levels of sialylation of PrPSc N-linked glycans was altered by treatment of purified PrPSc with neuraminidase. Partial cleavage of sialic acid residues was found to boost the inflammatory response of microglia to PrPSc. Moreover, transient degradation of Iκβα observed upon treatment with partially desialylated PrPSc suggests that canonical NFκB activation pathway is involved in inflammatory response. The current study is the first to demonstrate that PrPSc can directly trigger inflammatory response in microglia. In addition, this work provides direct evidence that the chemical nature of the carbohydrate groups on PrPSc surface is important for microglial activation.
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Cellular prion protein controls stem cell-like properties of human glioblastoma tumor-initiating cells. Oncotarget 2018; 7:38638-38657. [PMID: 27229535 PMCID: PMC5122417 DOI: 10.18632/oncotarget.9575] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/04/2016] [Indexed: 12/17/2022] Open
Abstract
Prion protein (PrPC) is a cell surface glycoprotein whose misfolding is responsible for prion diseases. Although its physiological role is not completely defined, several lines of evidence propose that PrPC is involved in self-renewal, pluripotency gene expression, proliferation and differentiation of neural stem cells. Moreover, PrPC regulates different biological functions in human tumors, including glioblastoma (GBM). We analyzed the role of PrPC in GBM cell pathogenicity focusing on tumor-initiating cells (TICs, or cancer stem cells, CSCs), the subpopulation responsible for development, progression and recurrence of most malignancies. Analyzing four GBM CSC-enriched cultures, we show that PrPC expression is directly correlated with the proliferation rate of the cells. To better define its role in CSC biology, we knocked-down PrPC expression in two of these GBM-derived CSC cultures by specific lentiviral-delivered shRNAs. We provide evidence that CSC proliferation rate, spherogenesis and in vivo tumorigenicity are significantly inhibited in PrPC down-regulated cells. Moreover, PrPC down-regulation caused loss of expression of the stemness and self-renewal markers (NANOG, Sox2) and the activation of differentiation pathways (i.e. increased GFAP expression). Our results suggest that PrPC controls the stemness properties of human GBM CSCs and that its down-regulation induces the acquisition of a more differentiated and less oncogenic phenotype.
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Thellung S, Scoti B, Corsaro A, Villa V, Nizzari M, Gagliani MC, Porcile C, Russo C, Pagano A, Tacchetti C, Cortese K, Florio T. Pharmacological activation of autophagy favors the clearing of intracellular aggregates of misfolded prion protein peptide to prevent neuronal death. Cell Death Dis 2018; 9:166. [PMID: 29416016 PMCID: PMC5833808 DOI: 10.1038/s41419-017-0252-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/13/2017] [Accepted: 12/19/2017] [Indexed: 12/22/2022]
Abstract
According to the “gain-of-toxicity mechanism”, neuronal loss during cerebral proteinopathies is caused by accumulation of aggregation-prone conformers of misfolded cellular proteins, although it is still debated which aggregation state actually corresponds to the neurotoxic entity. Autophagy, originally described as a variant of programmed cell death, is now emerging as a crucial mechanism for cell survival in response to a variety of cell stressors, including nutrient deprivation, damage of cytoplasmic organelles, or accumulation of misfolded proteins. Impairment of autophagic flux in neurons often associates with neurodegeneration during cerebral amyloidosis, suggesting a role in clearing neurons from aggregation-prone misfolded proteins. Thus, autophagy may represent a target for innovative therapies. In this work, we show that alterations of autophagy progression occur in neurons following in vitro exposure to the amyloidogenic and neurotoxic prion protein-derived peptide PrP90-231. We report that the increase of autophagic flux represents a strategy adopted by neurons to survive the intracellular accumulation of misfolded PrP90-231. In particular, PrP90-231 internalization in A1 murine mesencephalic neurons occurs in acidic structures, showing electron microscopy hallmarks of autophagosomes and autophagolysosomes. However, these structures do not undergo resolution and accumulate in cytosol, suggesting that, in the presence of PrP90-231, autophagy is activated but its progression is impaired; the inability to clear PrP90-231 via autophagy induces cytotoxicity, causing impairment of lysosomal integrity and cytosolic diffusion of hydrolytic enzymes. Conversely, the induction of autophagy by pharmacological blockade of mTOR kinase or trophic factor deprivation restored autophagy resolution, reducing intracellular PrP90-231 accumulation and neuronal death. Taken together, these data indicate that PrP90-231 internalization induces an autophagic defensive response in A1 neurons, although incomplete and insufficient to grant survival; the pharmacological enhancement of this process exerts neuroprotection favoring the clearing of the internalized peptide and could represents a promising neuroprotective tool for neurodegenerative proteinopathies.
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Affiliation(s)
- Stefano Thellung
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Beatrice Scoti
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Alessandro Corsaro
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Valentina Villa
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Mario Nizzari
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Maria Cristina Gagliani
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy
| | - Carola Porcile
- Department of Health Sciences, University of Molise, Campobasso, Italy
| | - Claudio Russo
- Department of Health Sciences, University of Molise, Campobasso, Italy
| | - Aldo Pagano
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy.,Ospedale Policlinico San Martino, IRCCS per l'Oncologia, Genova, Italy
| | - Carlo Tacchetti
- Centro Imaging Sperimentale, IRCCS Istituto Scientifico San Raffaele, Milano, Italy.,Vita-Salute San Raffaele University, Milano, Italy
| | - Katia Cortese
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy
| | - Tullio Florio
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy.
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Bajetto A, Pattarozzi A, Corsaro A, Barbieri F, Daga A, Bosio A, Gatti M, Pisaturo V, Sirito R, Florio T. Different Effects of Human Umbilical Cord Mesenchymal Stem Cells on Glioblastoma Stem Cells by Direct Cell Interaction or Via Released Soluble Factors. Front Cell Neurosci 2017; 11:312. [PMID: 29081734 PMCID: PMC5645520 DOI: 10.3389/fncel.2017.00312] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/20/2017] [Indexed: 01/03/2023] Open
Abstract
Glioblastoma (GBM), the most common primary brain tumor in adults, is an aggressive, fast-growing and highly vascularized tumor, characterized by extensive invasiveness and local recurrence. In GBM and other malignancies, cancer stem cells (CSCs) are believed to drive invasive tumor growth and recurrence, being responsible for radio- and chemo-therapy resistance. Mesenchymal stem cells (MSCs) are multipotent progenitors that exhibit tropism for tumor microenvironment mediated by cytokines, chemokines and growth factors. Initial studies proposed that MSCs might exert inhibitory effects on tumor development, although, to date, contrasting evidence has been provided. Different studies reported either MSC anti-tumor activity or their support to tumor growth. Here, we examined the effects of umbilical cord (UC)-MSCs on in vitro GBM-derived CSC growth, by direct cell-to-cell interaction or indirect modulation, via the release of soluble factors. We demonstrate that UC-MSCs and CSCs exhibit reciprocal tropism when co-cultured as 3D spheroids and their direct cell interaction reduces the proliferation of both cell types. Contrasting effects were obtained by UC-MSC released factors: CSCs, cultured in the presence of conditioned medium (CM) collected from UC-MSCs, increased proliferation rate through transient ERK1/2 and Akt phosphorylation/activation. Analysis of the profile of the cytokines released by UC-MSCs in the CM revealed a strong production of molecules involved in inflammation, angiogenesis, cell migration and proliferation, such as IL-8, GRO, ENA-78 and IL-6. Since CXC chemokine receptor 2 (CXCR2), a receptor shared by several of these ligands, is expressed in GBM CSCs, we evaluated its involvement in CSC proliferation induced by UC-MSC-CM. Using the CXCR2 antagonist SB225002, we observed a partial but statistically significant inhibition of CSC proliferation and migration induced by the UC-MSC-released cytokines. Conversely, CXCR2 blockade did not reduce the reciprocal tropism between CSCs and UC-MSCs grown as spheroids. In conclusion, we show that direct (cell-to-cell contact) or indirect (via the release of soluble factors) interactions between GBM CSCs and UC-MSCs in co-culture produce divergent effects on cell growth, invasion and migration, with the former mainly causing an inhibitory response and the latter a stimulatory one, involving a paracrine activation of CXCR2.
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Affiliation(s)
- Adriana Bajetto
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Alessandra Pattarozzi
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Alessandro Corsaro
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Federica Barbieri
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Antonio Daga
- Gene Transfer Lab, IRCCS-AOU San Martino-IST, Genova, Italy
| | - Alessia Bosio
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Monica Gatti
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy.,International Evangelical Hospital, Genova, Italy
| | | | | | - Tullio Florio
- Section of Pharmacology, Department of Internal Medicine and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
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Different Molecular Mechanisms Mediate Direct or Glia-Dependent Prion Protein Fragment 90-231 Neurotoxic Effects in Cerebellar Granule Neurons. Neurotox Res 2017; 32:381-397. [PMID: 28540665 DOI: 10.1007/s12640-017-9749-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 12/16/2022]
Abstract
Glia over-stimulation associates with amyloid deposition contributing to the progression of central nervous system neurodegenerative disorders. Here we analyze the molecular mechanisms mediating microglia-dependent neurotoxicity induced by prion protein (PrP)90-231, an amyloidogenic polypeptide corresponding to the protease-resistant portion of the pathological prion protein scrapie (PrPSc). PrP90-231 neurotoxicity is enhanced by the presence of microglia within neuronal culture, and associated to a rapid neuronal [Ca++] i increase. Indeed, while in "pure" cerebellar granule neuron cultures, PrP90-231 causes a delayed intracellular Ca++ entry mediated by the activation of NMDA receptors; when neuron and glia are co-cultured, a transient increase of [Ca++] i occurs within seconds after treatment in both granule neurons and glial cells, then followed by a delayed and sustained [Ca++] i raise, associated with the induction of the expression of inducible nitric oxide synthase and phagocytic NADPH oxidase. [Ca++] i fast increase in neurons is dependent on the activation of multiple pathways since it is not only inhibited by the blockade of voltage-gated channel activity and NMDA receptors but also prevented by the inhibition of nitric oxide and PGE2 release from glial cells. Thus, Ca++ homeostasis alteration, directly induced by PrP90-231 in cerebellar granule cells, requires the activation of NMDA receptors, but is greatly enhanced by soluble molecules released by activated glia. In glia-enriched cerebellar granule cultures, the activation of inducible nitric oxide (iNOS) and NADPH oxidase represents the main mechanism of toxicity since their pharmacological inhibition prevented PrP90-231 neurotoxicity, whereas NMDA blockade by D(-)-2-amino-5-phosphonopentanoic acid is ineffective; conversely, in pure cerebellar granule cultures, NMDA blockade but not iNOS inhibition strongly reduced PrP90-231 neurotoxicity. These data indicate that amyloidogenic peptides induce neurotoxic signals via both direct neuron interaction and glia activation through different mechanisms responsible of calcium homeostasis disruption in neurons and potentiating each other: the activation of excitotoxic pathways via NMDA receptors and the release of radical species that establish an oxidative milieu.
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Villa V, Thellung S, Bajetto A, Gatta E, Robello M, Novelli F, Tasso B, Tonelli M, Florio T. Novel celecoxib analogues inhibit glial production of prostaglandin E2, nitric oxide, and oxygen radicals reverting the neuroinflammatory responses induced by misfolded prion protein fragment 90-231 or lipopolysaccharide. Pharmacol Res 2016; 113:500-514. [PMID: 27667770 DOI: 10.1016/j.phrs.2016.09.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/05/2016] [Accepted: 09/12/2016] [Indexed: 12/24/2022]
Abstract
We tested the efficacy of novel cyclooxygenase 2 (COX-2) inhibitors in counteracting glia-driven neuroinflammation induced by the amyloidogenic prion protein fragment PrP90-231 or lipopolysaccharide (LPS). In search for molecules with higher efficacy than celecoxib, we focused our study on its 2,3-diaryl-1,3-thiazolidin-4-one analogues. As experimental models, we used the immortalized microglial cell line N9, rat purified microglial primary cultures, and mixed cultures of astrocytes and microglia. Microglia activation in response to PrP90-231 or LPS was characterized by growth arrest, morphology changes and the production of reactive oxygen species (ROS). Moreover, PrP90-231 treatment caused the overexpression of the inducible nitric oxide synthase (iNOS) and COX-2, with the consequent nitric oxide (NO), and prostaglandin E2 (PGE2) accumulation. These effects were challenged by different celecoxib analogues, among which Q22 (3-[4-(sulfamoyl)phenyl]-2-(4-tolyl)thiazolidin-4-one) inhibited microglia activation more efficiently than celecoxib, lowering both iNOS and COX-2 activity and reducing ROS release. During neurodegenerative diseases, neuroinflammation induced by amyloidogenic peptides causes the activation of both astrocytes and microglia with these cell populations mutually regulating each other. Thus the effects of PrP90-231 and LPS were also studied on mixed glial cultures containing astrocytes and microglia. PrP90-231 treatment elicited different responses in the co-cultures induced astrocyte proliferation and microglia growth arrest, resulting in a differential ability to release proinflammatory molecules with the production of NO and ROS mainly attributable on microglia, while COX-2 expression was induced also in astrocytes. Q22 effects on both NO and PGE2 secretion were more significant in the mixed glial cultures than in purified microglia, demonstrating Q22 ability to revert the functional interaction between astrocytes and microglia. These results demonstrate that Q22 is a powerful drug able to revert glial neuroinflammatory responses and might represent a lead to explore the chemical space around celecoxib frameworks to design even more effective agents, paving the way to novel approaches to contrast the neuroinflammation-dependent toxicity.
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Affiliation(s)
- Valentina Villa
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Stefano Thellung
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Adriana Bajetto
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Elena Gatta
- Department of Physics, University of Genova, Genoa, Italy
| | - Mauro Robello
- Department of Physics, University of Genova, Genoa, Italy
| | - Federica Novelli
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Bruno Tasso
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Michele Tonelli
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Tullio Florio
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy.
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Haigh CL, McGlade AR, Collins SJ. MEK1 transduces the prion protein N2 fragment antioxidant effects. Cell Mol Life Sci 2015; 72:1613-29. [PMID: 25391659 PMCID: PMC11114014 DOI: 10.1007/s00018-014-1777-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/13/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022]
Abstract
The prion protein (PrP(C)) when mis-folded is causally linked with a group of fatal neurodegenerative diseases called transmissible spongiform encephalopathies or prion diseases. PrP(C) normal function is still incompletely defined with such investigations complicated by PrP(C) post-translational modifications, such as internal cleavage, which feasibly could change, activate, or deactivate the function of this protein. Oxidative stress induces β-cleavage and the N-terminal product of this cleavage event, N2, demonstrates a cellular protective response against oxidative stress. The mechanisms by which N2 mediates cellular antioxidant protection were investigated within an in vitro cell model. N2 protection was regulated by copper binding to the octarepeat domain, directing the route of internalisation, which stimulated MEK1 signalling. Precise membrane interactions of N2, determined by copper saturation, and involving both the copper-co-ordinating octarepeat region and the structure conferred upon the N-terminal polybasic region by the proline motif, were essential for the correct engagement of this pathway. The phenomenon of PrP(C) post-translational modification, such as cleavage and copper co-ordination, as a molecular "switch" for activation or deactivation of certain functions provides new insight into the apparent multi-functionality of PrP(C).
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Affiliation(s)
- C. L. Haigh
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
| | - A. R. McGlade
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
- Mental Health Research Institute, The University of Melbourne, Parkville, Melbourne, 3010 Australia
| | - S. J. Collins
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC 3010 Australia
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11
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Falsone A, Falsone SF. Legal but lethal: functional protein aggregation at the verge of toxicity. Front Cell Neurosci 2015; 9:45. [PMID: 25741240 PMCID: PMC4332346 DOI: 10.3389/fncel.2015.00045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/30/2015] [Indexed: 12/21/2022] Open
Abstract
Many neurodegenerative disorders are linked to irreversible protein aggregation, a process that usually comes along with toxicity and serious cellular damage. However, it is emerging that protein aggregation can also serve for physiological purposes, as impressively shown for prions. While the aggregation of this protein family was initially considered exclusively toxic in mammalians organisms, it is now almost clear that many other proteins adopt prion-like attributes to rationally polymerize into higher order complexes with organized physiologic roles. This implies that cells can tolerate at least in some measure the accumulation of inherently dangerous protein aggregates for functional profit. This review summarizes currently known strategies that living organisms adopt to preserve beneficial aggregation, and to prevent the catastrophic accumulation of toxic aggregates that frequently accompany neurodegeneration.
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Affiliation(s)
- Angelika Falsone
- Institute of Pharmaceutical Sciences, University of Graz Graz, Austria
| | - S Fabio Falsone
- Institute of Pharmaceutical Sciences, University of Graz Graz, Austria
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12
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Celecoxib Inhibits Prion Protein 90-231-Mediated Pro-inflammatory Responses in Microglial Cells. Mol Neurobiol 2014; 53:57-72. [PMID: 25404089 DOI: 10.1007/s12035-014-8982-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/03/2014] [Indexed: 12/21/2022]
Abstract
Activation of microglia is a central event in the atypical inflammatory response occurring during prion encephalopathies. We report that the prion protein fragment encompassing amino acids 90-231 (PrP90-231), a model of the neurotoxic activity of the pathogenic prion protein (PrP(Sc)), causes activation of both primary microglia cultures and N9 microglial cells in vitro. This effect was characterized by cell proliferation arrest and induction of a secretory phenotype, releasing prostaglandin E2 (PGE2) and nitric oxide (NO). Conditioned medium from PrP90-231-treated microglia induced in vitro cytotoxicity of A1 mesencephalic neurons, supporting the notion that soluble mediators released by activated microglia contributes to the neurodegeneration during prion diseases. The neuroinflammatory role of COX activity, and its potential targeting for anti-prion therapies, was tested measuring the effects of ketoprofen and celecoxib (preferential inhibitors of COX1 and COX2, respectively) on PrP90-231-induced microglial activation. Celecoxib, but not ketoprofen significantly reverted the growth arrest as well as NO and PGE2 secretion induced by PrP90-231, indicating that PrP90-231 pro-inflammatory response in microglia is mainly dependent on COX2 activation. Taken together, these data outline the importance of microglia in the neurotoxicity occurring during prion diseases and highlight the potentiality of COX2-selective inhibitors to revert microglia as adjunctive pharmacological approach to contrast the neuroinflammation-dependent neurotoxicity.
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13
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HIV-1 Nef induces CCL5 production in astrocytes through p38-MAPK and PI3K/Akt pathway and utilizes NF-kB, CEBP and AP-1 transcription factors. Sci Rep 2014; 4:4450. [PMID: 24658403 PMCID: PMC3963078 DOI: 10.1038/srep04450] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/07/2014] [Indexed: 12/18/2022] Open
Abstract
The prevalence of HIV-associated neurocognitive disorders (HAND) remains high in patients infected with HIV-1. The production of pro-inflammatory cytokines by astrocytes/microglia exposed to viral proteins is thought to be one of the mechanisms leading to HIV-1- mediated neurotoxicity. In the present study we examined the effects of Nef on CCL5 induction in astrocytes. The results demonstrate that CCL5 is significantly induced in Nef-transfected SVGA astrocytes. To determine the mechanisms responsible for the increased CCL5 caused by Nef, we employed siRNA and chemical antagonists. Antagonists of NF-κB, PI3K, and p38 significantly reduced the expression levels of CCL5 induced by Nef transfection. Furthermore, specific siRNAs demonstrated that the Akt, p38MAPK, NF-κB, CEBP, and AP-1 pathways play a role in Nef-mediated CCL5 expression. The results demonstrated that the PI3K/Akt and p38 MAPK pathways, along with the transcription factors NF-κB, CEBP, and AP-1, are involved in Nef-induced CCL5 production in astrocytes.
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Li Y, Chen G, Zhao J, Nie X, Wan C, Liu J, Duan Z, Xu G. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induces microglial nitric oxide production and subsequent rat primary cortical neuron apoptosis through p38/JNK MAPK pathway. Toxicology 2013; 312:132-41. [PMID: 23969120 DOI: 10.1016/j.tox.2013.08.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/09/2013] [Accepted: 08/10/2013] [Indexed: 12/22/2022]
Abstract
It has been widely accepted that microglia, which are the innate immune cells in the brain, upon activation can cause neuronal damage. In the present study, we investigated the role of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in regulating microglial nitric oxide production and its role in causing neuronal damage. The study revealed that TCDD stimulates the expression of inducible nitric oxide synthase (iNOS) as well as the production of nitric oxide (NO) in a dose- and time-dependent manner. Further, a rapid activation of p38 and JNK MAPKs was found in HAPI microglia following TCDD treatment. Blockage of p38 and JNK kinases with their specific inhibitors, SB202190 and SP600125, significantly reduced TCDD-induced iNOS expression and NO production. In addition, it was demonstrated through treating rat primary cortical neurons with media conditioned with TCDD treated microglia that microglial iNOS activation mediates neuronal apoptosis. Lastly, it was also found that p38 and JNK MAPK inhibitors could attenuate the apoptosis of rat cortical neurons upon exposure to medium conditioned by TCDD-treated HAPI microglial cells. Based on these observations, we highlight that the p38/JNK MAPK pathways play an important role in TCDD-induced iNOS activation in rat HAPI microglia and in the subsequent induction of apoptosis in primary cortical neurons.
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Affiliation(s)
- Yuanye Li
- Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China; Department of Occupational Medicine and Environmental Toxicology, School of Public Health, Nantong University, Nantong, 226001 Jiangsu, People's Republic of China
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Didonna A. Prion protein and its role in signal transduction. Cell Mol Biol Lett 2013; 18:209-30. [PMID: 23479001 PMCID: PMC6275729 DOI: 10.2478/s11658-013-0085-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/18/2013] [Indexed: 11/20/2022] Open
Abstract
Prion diseases are a class of fatal neurodegenerative disorders that can be sporadic, genetic or iatrogenic. They are characterized by the unique nature of their etiologic agent: prions (PrP(Sc)). A prion is an infectious protein with the ability to convert the host-encoded cellular prion protein (PrP(C)) into new prion molecules by acting as a template. Since Stanley B. Prusiner proposed the "protein-only" hypothesis for the first time, considerable effort has been put into defining the role played by PrP(C) in neurons. However, its physiological function remains unclear. This review summarizes the major findings that support the involvement of PrP(C) in signal transduction.
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Affiliation(s)
- Alessandro Didonna
- Davee Department of Neurology, Feinberg School of Medicine Northwestern University, Chicago, IL 60611, USA.
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Thellung S, Gatta E, Pellistri F, Corsaro A, Villa V, Vassalli M, Robello M, Florio T. Excitotoxicity through NMDA receptors mediates cerebellar granule neuron apoptosis induced by prion protein 90-231 fragment. Neurotox Res 2012; 23:301-14. [PMID: 22855343 DOI: 10.1007/s12640-012-9340-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/13/2012] [Accepted: 07/18/2012] [Indexed: 10/28/2022]
Abstract
Prion diseases recognize, as a unique molecular trait, the misfolding of CNS-enriched prion protein (PrP(C)) into an aberrant isoform (PrP(Sc)). In this work, we characterize the in vitro toxicity of amino-terminally truncated recombinant PrP fragment (amino acids 90-231, PrP90-231), on rat cerebellar granule neurons (CGN), focusing on glutamatergic receptor activation and Ca(2+) homeostasis impairment. This recombinant fragment assumes a toxic conformation (PrP90-231(TOX)) after controlled thermal denaturation (1 h at 53 °C) acquiring structural characteristics identified in PrP(Sc) (enrichment in β-structures, increased hydrophobicity, partial resistance to proteinase K, and aggregation in amyloid fibrils). By annexin-V binding assay, and evaluation of the percentage of fragmented and condensed nuclei, we show that treatment with PrP90-231(TOX), used in pre-fibrillar aggregation state, induces CGN apoptosis. This effect was associated with a delayed, but sustained elevation of [Ca(2+)]i. Both CGN apoptosis and [Ca(2+)]i increase were not observed using PrP90-231 in PrP(C)-like conformation. PrP90-231(TOX) effects were significantly reduced in the presence of ionotropic glutamate receptor antagonists. In particular, CGN apoptosis and [Ca(2+)]i increase were largely reduced, although not fully abolished, by pre-treatment with the NMDA antagonists APV and memantine, while the AMPA antagonist CNQX produced a lower, although still significant, effect. In conclusion, we report that CGN apoptosis induced by PrP90-231(TOX) correlates with a sustained elevation of [Ca(2+)]i mediated by the activation of NMDA and AMPA receptors.
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Affiliation(s)
- Stefano Thellung
- Department of Internal Medicine, Section of Pharmacology and Centre of Excellence for Biomedical Research (CEBR) School of Medicine, University of Genova, Viale Benedetto XV, 2, 16132, Genoa, Italy
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17
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Sorrentino S, Bucciarelli T, Corsaro A, Tosatto A, Thellung S, Villa V, Schininà ME, Maras B, Galeno R, Scotti L, Creati F, Marrone A, Re N, Aceto A, Florio T, Mazzanti M. Calcium binding promotes prion protein fragment 90-231 conformational change toward a membrane destabilizing and cytotoxic structure. PLoS One 2012; 7:e38314. [PMID: 22811758 PMCID: PMC3394757 DOI: 10.1371/journal.pone.0038314] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 05/08/2012] [Indexed: 02/05/2023] Open
Abstract
The pathological form of prion protein (PrP(Sc)), as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrP(Sc) extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90-231 (hPrP₉₀₋₂₃₁) increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrP(Sc). In the present study we demonstrate that hPrP₉₀₋₂₃₁, pre-incubated with 10 mM Ca⁺⁺ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP₉₀₋₂₃₁ bearing pathogenic mutations (D202N and E200K). We also report that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP₉₀₋₂₃₁ cytotoxicity. Finally, by in silico structural analysis, we propose that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity.
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Affiliation(s)
| | - Tonino Bucciarelli
- Dipartimento di Scienze Biomediche, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Alessandro Corsaro
- Sezione di Farmacologia, Dipartimento di Medicina Interna and Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Genova, Italy
| | - Alessio Tosatto
- Dipartimento di Bioscienze, University of Milan, Milan, Italy
| | - Stefano Thellung
- Sezione di Farmacologia, Dipartimento di Medicina Interna and Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Genova, Italy
| | - Valentina Villa
- Sezione di Farmacologia, Dipartimento di Medicina Interna and Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Genova, Italy
| | - M. Eugenia Schininà
- Dipartimento di Scienze Biochimiche, “Sapienza” University of Rome, Rome, Italy
| | - Bruno Maras
- Dipartimento di Scienze Biochimiche, “Sapienza” University of Rome, Rome, Italy
| | | | - Luca Scotti
- Dipartimento di Scienze Biomediche, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Francesco Creati
- Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Alessandro Marrone
- Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Nazzareno Re
- Dipartimento di Scienze del Farmaco, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Antonio Aceto
- Dipartimento di Scienze Biomediche, Università “G. d’Annunzio” di Chieti-Pescara, Chieti, Italy
| | - Tullio Florio
- Sezione di Farmacologia, Dipartimento di Medicina Interna and Centro di Eccellenza per la Ricerca Biomedica (CEBR), University of Genova, Genova, Italy
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Role of prion protein aggregation in neurotoxicity. Int J Mol Sci 2012; 13:8648-8669. [PMID: 22942726 PMCID: PMC3430257 DOI: 10.3390/ijms13078648] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/29/2012] [Accepted: 07/02/2012] [Indexed: 11/17/2022] Open
Abstract
In several neurodegenerative diseases, such as Parkinson, Alzheimer’s, Huntington, and prion diseases, the deposition of aggregated misfolded proteins is believed to be responsible for the neurotoxicity that characterizes these diseases. Prion protein (PrP), the protein responsible of prion diseases, has been deeply studied for the peculiar feature of its misfolded oligomers that are able to propagate within affected brains, inducing the conversion of the natively folded PrP into the pathological conformation. In this review, we summarize the available experimental evidence concerning the relationship between aggregation status of misfolded PrP and neuronal death in the course of prion diseases. In particular, we describe the main findings resulting from the use of different synthetic (mainly PrP106-126) and recombinant PrP-derived peptides, as far as mechanisms of aggregation and amyloid formation, and how these different spatial conformations can affect neuronal death. In particular, most data support the involvement of non-fibrillar oligomers rather than actual amyloid fibers as the determinant of neuronal death.
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Corsaro A, Thellung S, Villa V, Nizzari M, Aceto A, Florio T. Recombinant human prion protein fragment 90-231, a useful model to study prion neurotoxicity. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2012; 16:50-9. [PMID: 22321015 DOI: 10.1089/omi.2011.0038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Transmissible spongiform encephalopathies (TSE), or prion diseases, are a group of fatal neurodegenerative disorders of animals and humans. Human diseases include Creutzfeldt-Jakob (CJD) and Gerstmann-Straussler-Scheinker (GSSD) diseases, fatal familial insomnia, and Kuru. Human and animal TSEs share a common histopathology with a pathognomonic triad: spongiform vacuolation of the grey matter, neuronal death, glial proliferation, and, more inconstantly, amyloid deposition. According to the "protein only" hypothesis, TSEs are caused by a unique post-translational conversion of normal, host-encoded, protease-sensitive prion protein (PrP(sen) or PrP(C)) to an abnormal disease-associated isoform (PrP(res) or PrP(Sc)). To investigate the molecular mechanism of neurotoxicity induced by PrP(Sc) we developed a protocol to obtain millimolar amounts of soluble recombinant polypeptide encompassing the amino acid sequence 90-231 of human PrP (hPrP90-231). This protein corresponds to the protease-resistant prion protein fragment that originates after amino-terminal truncation. Importantly, hPrP90-231 has a flexible backbone that, similar to PrP(C), can undergo to structural rearrangement. This peptide, structurally resembling PrP(C), can be converted in a PrP(Sc)-like conformation, and thus represents a valuable model to study prion neurotoxicity. In this article we summarized our experimental evidence on the molecular and structural mechanisms responsible of hPrP90-231 neurotoxicity on neuroectodermal cell line SHSY5Y and the effects of some PrP pathogen mutations identified in familial TSE.
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Affiliation(s)
- Alessandro Corsaro
- Laboratory of Pharmacology, Department of Oncology Biology and Genetics, University of Genova, Italy
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War SA, Kumar U. Coexpression of human somatostatin receptor-2 (SSTR2) and SSTR3 modulates antiproliferative signaling and apoptosis. J Mol Signal 2012; 7:5. [PMID: 22651821 PMCID: PMC3403965 DOI: 10.1186/1750-2187-7-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 05/31/2012] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Somatostatin (SST) via five Gi coupled receptors namely SSTR1-5 is known to inhibit cell proliferation by cytostatic and cytotoxic mechanisms. Heterodimerization plays a crucial role in modulating the signal transduction pathways of SSTR subtypes. In the present study, we investigated human SSTR2/SSTR3 heterodimerization, internalization, MAPK signaling, cell proliferation and apoptosis in HEK-293 cells in response to SST and specific agonists for SSTR2 and SSTR3. RESULTS Although in basal conditions, SSTR2 and SSTR3 colocalize at the plasma membrane and exhibit heterodimerization, the cell surface distribution of both receptors decreased upon agonist activation and was accompanied by a parallel increase in intracellular colocalization. Receptors activation by SST and specific agonists significantly decreased cAMP levels in cotransfected cells in comparison to control. Agonist-mediated modulation of pERK1/2 was time and concentration-dependent, and pronounced in serum-deprived conditions. pERK1/2 was inhibited in response to SST; conversely receptor-specific agonist treatment caused inhibition at lower concentration and activation at higher concentration. Strikingly, ERK1/2 phosphorylation was sustained upon prolonged treatment with SST but not with receptor-specific agonists. On the other hand, SST and receptor-specific agonists modulated p38 phosphorylation time-dependently. The receptor activation in cotransfected cells exhibits Gi-dependent inhibition of cell proliferation attributed to increased PARP-1 expression and TUNEL staining, whereas induction of p21 and p27Kip1 suggests a cytostatic effect. CONCLUSION Our study provides new insights in SSTR2/SSTR3 mediated signaling which might help in better understanding of the molecular interactions involving SSTRs in tumor biology.
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Affiliation(s)
- Sajad A War
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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21
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Carducci C, Carducci C, Santagata S, Adriano E, Artiola C, Thellung S, Gatta E, Robello M, Florio T, Antonozzi I, Leuzzi V, Balestrino M. In vitro study of uptake and synthesis of creatine and its precursors by cerebellar granule cells and astrocytes suggests some hypotheses on the physiopathology of the inherited disorders of creatine metabolism. BMC Neurosci 2012; 13:41. [PMID: 22536786 PMCID: PMC3355046 DOI: 10.1186/1471-2202-13-41] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 04/26/2012] [Indexed: 10/28/2022] Open
Abstract
BACKGROUND The discovery of the inherited disorders of creatine (Cr) synthesis and transport in the last few years disclosed the importance of blood Cr supply for the normal functioning of the brain. These putatively rare diseases share a common pathogenetic mechanism (the depletion of brain Cr) and similar phenotypes characterized by mental retardation, language disturbances, seizures and movement disorders. In the effort to improve our knowledge on the mechanisms regulating Cr pool inside the nervous tissue, Cr transport and synthesis and related gene transcripts were explored in primary cultures of rat cerebellar granule cells and astrocytes. METHODS Cr uptake and synthesis were explored in vitro by incubating monotypic primary cultures of rat type I astrocytes and cerebellar granule cells with: a) D3-Creatine (D3Cr) and D3Cr plus β-guanidinopropionate (GPA, an inhibitor of Cr transporter), and b) labelled precursors of Guanidinoacetate (GAA) and Cr (Arginine, Arg; Glycine, Gly). Intracellular D3Cr and labelled GAA and Cr were assessed by ESI-MS/MS. Creatine transporter (CT1), L-arginine:glycine amidinotransferase (AGAT), and S-adenosylmethionine:guanidinoacetate N-methyltransferase (GAMT) gene expression was assessed in the same cells by real time PCR. RESULTS D3Cr signal was extremely high in cells incubated with this isotope (labelled/unlabelled Cr ratio reached about 10 and 122, respectively in cerebellar granule cells and astrocytes) and was reduced by GPA. Labelled Arg and Gly were taken up by the cells and incorporated in GAA, whose concentration paralleled that of these precursors both in the extracellular medium and inside the cells (astrocytes). In contrast, the increase of labelled Cr was relatively much more limited since labelled Cr after precursors' supplementation did not exceed 2,7% (cerebellar granule cells) and 21% (astrocytes) of unlabelled Cr. Finally, AGAT, GAMT and SLC6A8 were expressed in both kind of cells. CONCLUSIONS Our results confirm that both neurons and astrocytes have the capability to synthesize and uptake Cr, and suggest that at least in vitro intracellular Cr can increase to a much greater extent through uptake than through de novo synthesis. Our results are compatible with the clinical observations that when the Cr transporter is defective, intracellular Cr is absent despite the brain should be able to synthesize it. Further research is needed to fully understand to what extent our results reflect the in vivo situation.
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Affiliation(s)
- Claudia Carducci
- Department of Experimental Medicine, La Sapienza Università di Roma, Viale del Policlinico 155, Rome 00161, Italy
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Human PrP90-231-induced cell death is associated with intracellular accumulation of insoluble and protease-resistant macroaggregates and lysosomal dysfunction. Cell Death Dis 2011; 2:e138. [PMID: 21451573 PMCID: PMC3101817 DOI: 10.1038/cddis.2011.21] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To define the mechanisms by which hPrP90-231 induces cell death, we analyzed its interaction with living cells and monitored its intracellular fate. Treatment of SH-SY5Y cells with fluorescein-5-isothiocyanate (FITC)-conjugated hPrP90-231 caused the accumulation of cytosolic aggregates of the prion protein fragment that increased in number and size in a time-dependent manner. The formation of large intracellular hPrP90-231 aggregates correlated with the activation of apoptosis. hPrP90-231 aggregates occurred within lysotracker-positive vesicles and induced the formation of activated cathepsin D (CD), indicating that hPrP90-231 is partitioned into the endosomal-lysosomal system structures, activating the proteolytic machinery. Remarkably, the inhibition of CD activity significantly reduced hPrP-90-231-dependent apoptosis. Internalized hPrP90-231 forms detergent-insoluble and SDS-stable aggregates, displaying partial resistance to proteolysis. By confocal microscopy analysis of lucifer yellow (LY) intracellular partition, we show that hPrP90-231 accumulation induces lysosome destabilization and loss of lysosomal membrane impermeability. In fact, although control cells evidenced a vesicular pattern of LY fluorescence (index of healthy lysosomes), hPrP90-231-treated cells showed diffuse cytosolic fluorescence, indicating LY diffusion through damaged lysosomes. In conclusion, these data indicate that exogenously added hPrP90-231 forms intralysosomal deposits having features of insoluble, protease-resistant aggregates and could trigger a lysosome-mediated apoptosis by inducing lysosome membrane permeabilization, followed by the release of hydrolytic enzymes.
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Corsaro A, Thellung S, Bucciarelli T, Scotti L, Chiovitti K, Villa V, D'Arrigo C, Aceto A, Florio T. High hydrophobic amino acid exposure is responsible of the neurotoxic effects induced by E200K or D202N disease-related mutations of the human prion protein. Int J Biochem Cell Biol 2010; 43:372-82. [PMID: 21094273 DOI: 10.1016/j.biocel.2010.11.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 10/19/2010] [Accepted: 11/11/2010] [Indexed: 02/05/2023]
Abstract
Mutations in prion protein are thought to be causative of inherited prion diseases favoring the spontaneous conversion of the normal prion protein into the scrapie-like pathological prion protein. We previously reported that, by controlled thermal denaturation, human prion protein fragment 90-231 acquires neurotoxic properties when transformed in a β-rich conformation, resembling the scrapie-like conformation. In this study we generated prion protein fragment 90-231 bearing mutations identified in familial prion diseases (D202N and E200K), to analyze their role in the induction of a neurotoxic conformation. Prion protein fragment 90-231(wild type) and the D202N mutant were not toxic in native conformation but induced cell death only after thermal denaturation. Conversely, prion protein fragment 90-231(E200K) was highly toxic in its native structure, suggesting that E200K mutation per se favors the acquisition of a peptide neurotoxic conformation. To identify the structural determinants of prion protein fragment 90-231 toxicity, we show that while the wild type peptide is structured in α-helix, hPrP90-231 E200K is spontaneously refolded in a β-structured conformer characterized by increased proteinase K resistance and propensity to generate fibrils. However, the most significant difference induced by E200K mutation in prion protein fragment 90-231 structure in native conformation we observed, was an increase in the exposure of hydrophobic amino-acids on protein surface that was detected in wild type and D202N proteins only after thermal denaturation. In conclusion, we propose that increased hydrophobicity is one of the main determinants of toxicity induced by different mutations in prion protein-derived peptides.
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Affiliation(s)
- Alessandro Corsaro
- Laboratory of Pharmacology, Dept. Oncology, Biology and Genetics, University of Genova, Genova, Italy
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Efficacy of novel acridine derivatives in the inhibition of hPrP90-231 prion protein fragment toxicity. Neurotox Res 2010; 19:556-74. [PMID: 20405353 DOI: 10.1007/s12640-010-9189-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 03/26/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
Quinacrine is one of the few molecules tested to treat patients affected by prion diseases, although the clinical outcome is largely unsatisfactory. To identify novel derivatives with higher neuroprotective activity, we evaluated the effects of a small library of acridine derivatives. The 6-chloro-2-methoxyacridine derivatives bearing on position 9 a quinolizidin-1-ylamino (Q1, Q2) or a quinolizidin-1-ylalkylamino residue (Q3, Q4, Q6, Q7), the thio-bioisoster of Q3 (Q5), the 9-(N-lupinylthiopropyl)amino derivative (Q8) and simple acridines (Q9 and Q10) were considered. We compared the effects of quinacrine and these novel analogues in the inhibition of the cytotoxic activity and protease K (PK) resistance of the human prion protein fragment 90-231 (hPrP90-231). We demonstrate that quinacrine caused a significant reduction of hPrP90-231 toxicity due to its binding to the fragment and the prevention of its conversion in a toxic isoform. All acridine derivatives analyzed showed high affinity binding for hPrP90-231, but only Q3 and Q10, caused a significant reduction of hPrP90-231 cytotoxicity, with higher efficacy than quinacrine. We attempted to correlate the cytoprotective effects of the new compounds with some biochemical parameters (binding affinity to hPrP90-231, intrinsic fluorescence quenching, hydrophobic amino acid exposure), but a direct relationship occurred only with the reduction of PK resistance, likely due to the prevention of the acquisition of the β-sheet-rich toxic conformation. These data represent interesting leads for further modifications of the basic side chain and the substituent pattern of the acridine nucleus to develop novel compounds with improved antiprion activity to be tested in in vivo experimental setting.
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25
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Role of GFAP in morphological retention and distribution of reactive astrocytes induced by scrapie encephalopathy in mice. Brain Res 2009; 1312:156-67. [PMID: 19931516 DOI: 10.1016/j.brainres.2009.11.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 11/10/2009] [Accepted: 11/11/2009] [Indexed: 11/20/2022]
Abstract
We have previously demonstrated that mutant mice bearing astrocytes deficient in glial fibrillary acidic protein (GFAP) exhibited typical spongiform degeneration and prion plaque deposition. However, it remains to be determined whether there are astrocyte-specific alterations in the reactive response of astrocytes. Herein, we analyzed morphological features of Gfap(-)(/)(-) reactive astrocytes. Light microscopic morphometry of mutant reactive astrocytes revealed reduced outlined cell area and shorter distances among expanded cell space but with larger nuclei. Electron microscopy revealed mutant cells containing very few and sparse glial filaments as well as abnormal cytoarchitecture of reactive astrocytic processes. Furthermore, paired cell formation appeared frequently. The results suggest that GFAP is necessary for morphological retention and distribution of reactive astrocytes during prion disease, and that there is a GFAP-dependent function of glial filaments in reactive astrocytes.
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Loss of cerebellar granule neurons is associated with punctate but not with large focal deposits of prion protein in Creutzfeldt-Jakob disease. J Neuropathol Exp Neurol 2009; 68:892-901. [PMID: 19606064 DOI: 10.1097/nen.0b013e3181af7f23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Whether aggregates of prion protein (PrP) reflect neurotoxicity or are neuroprotective in prion diseases is unclear. To address this question, we performed a clinicopathologic study of cerebellar granular neurons in 100 patients affected with sporadic Creutzfeldt-Jakob disease (CJD). There was significant loss of these neurons in the subset of cases with Val/Val genotype at PRNP Codon 129 and Molecular Isotype 2 of abnormal PrP (sporadic CJD-VV2) (n=32) compared with both the other CJD subtypes and to controls. Pathological PrP deposits of the punctate-type (synaptic-type) in this subgroup correlated with neuronal loss and proliferation of astrocytes and microglia. By contrast, the numbers of large deposits (5- to 50-microm-diameter) and numbers of amyloid plaques did not correlate with neuronal loss. These findings are consistent with the view that large aggregates may protect neurons by sequestering neurotoxic PrP oligomers, whereas punctate deposits may indicate the location of neuronal death processes in CJD.
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Shvartsman I, Dvir T, Harel-Adar T, Cohen S. Perfusion cell seeding and cultivation induce the assembly of thick and functional hepatocellular tissue-like construct. Tissue Eng Part A 2009; 15:751-60. [PMID: 18636945 DOI: 10.1089/ten.tea.2008.0024] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Developing advanced technologies for encouraging the ex vivo assembly of functional hepatic tissue for implantation into the human body or for in vitro drug testing is one of the challenging tasks facing tissue engineers. In the present study, we utilized a perfusion bioreactor system equipped with a novel flow-distributing mesh for online cell seeding into macroporous alginate scaffolds and cultivation of multiple constructs of the C3A human hepatocyte cell line. Optimization of the medium flow rate (100 mL/min) and perfusion duration (12 h) yielded cell constructs with high cell seeding efficiency (98% of the input cells) and cell distribution throughout the entire scaffold. Further, we show that interstitial medium flow enabled uniform cell delivery into 35 constructs lined across the bioreactor cross section. Perfusion-cultivated cell constructs revealed much greater rates of cell proliferation, albumin-specific secretion, and gene expression of the phase I enzyme, CYP3A4, and phase II enzyme, UGT2B7, than did static-cultivated constructs. Most impressive was the 50-fold increase in CYP3A4 expression of the perfused cell constructs as compared to the level in static-cultivated cell constructs. We thus believe that the hepatic tissue constructs developed herein may be used in drug discovery programs for elucidating drug metabolism and toxicity profiles and for treating failing livers.
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Affiliation(s)
- Irena Shvartsman
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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Corsaro A, Thellung S, Chiovitti K, Villa V, Simi A, Raggi F, Paludi D, Russo C, Aceto A, Florio T. Dual modulation of ERK1/2 and p38 MAP kinase activities induced by minocycline reverses the neurotoxic effects of the prion protein fragment 90-231. Neurotox Res 2009; 15:138-54. [PMID: 19384577 DOI: 10.1007/s12640-009-9015-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 08/15/2008] [Accepted: 09/18/2008] [Indexed: 11/27/2022]
Abstract
Several in vitro and in vivo studies addressed the identification of molecular determinants of the neuronal death induced by PrP(Sc) or related peptides. We developed an experimental model to assess PrP(Sc) neurotoxicity using a recombinant polypeptide encompassing amino acids 90-231 of human PrP (hPrP90-231) that corresponds to the protease-resistant core of PrP(Sc) identified in prion-infected brains. By means of mild thermal denaturation, we can convert hPrP90-231 from a PrP(C)-like conformation into a PrP(Sc)-like structure. In virtue of these structural changes, hPrP90-231 powerfully affected the survival of SH-SY5Y cells, inducing caspase 3 and p38-dependent apoptosis, while in the native alpha-helix-rich conformation, hPrP90-231 did not induce cell toxicity. The aim of this study was to identify drugs able to block hPrP90-231 neurotoxic effects, focusing on minocycline, a tetracycline with known neuroprotective activity. hPrP90-231 caused a caspase 3-dependent apoptosis via the blockade of ERK1/2 activation and the subsequent activation of p38 MAP kinase. We propose that hPrP90-231-induced apoptosis is dependent on the inhibition of ERK1/2 responsiveness to neurotrophic factors, removing a tonic inhibition of p38 activity and resulting in caspase 3 activation. Minocycline prevented hPrP90-231-induced toxicity interfering with this mechanism: the pretreatment with this tetracycline restored ERK1/2 activity and reverted p38 and caspase 3 activities. The effects of minocycline were not mediated by the prevention of hPrP90-231 structural changes or cell internalization (differently from Congo Red). In conclusion, minocycline elicits anti-apoptotic effects against the neurotoxic activity of hPrP90-231 and these effects are mediated by opposite modulation of ERK1/2 and p38 MAP kinase activities.
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Affiliation(s)
- Alessandro Corsaro
- Laboratory of Pharmacology and Neuroscience, Department of Oncology Biology and Genetics, University of Genova, Viale Benedetto XV, 2, Genova 16132, Italy
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Crozet C, Beranger F, Lehmann S. Cellular pathogenesis in prion diseases. Vet Res 2008; 39:44. [DOI: 10.1051/vetres:2008021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 04/15/2008] [Indexed: 01/15/2023] Open
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30
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Hyperosmotic stress-induced caspase-3 activation is mediated by p38 MAPK in the hippocampus. Brain Res 2007; 1186:1-11. [DOI: 10.1016/j.brainres.2007.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 10/02/2007] [Accepted: 10/05/2007] [Indexed: 01/13/2023]
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