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Thellung S, Corsaro A, Dellacasagrande I, Nizzari M, Zambito M, Florio T. Proteostasis unbalance in prion diseases: Mechanisms of neurodegeneration and therapeutic targets. Front Neurosci 2022; 16:966019. [PMID: 36148145 PMCID: PMC9485628 DOI: 10.3389/fnins.2022.966019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/05/2022] [Indexed: 01/18/2023] Open
Abstract
Transmissible spongiform encephalopathies (TSEs), or prion diseases, are progressive neurodegenerative disorders of the central nervous system that affect humans and animals as sporadic, inherited, and infectious forms. Similarly to Alzheimer's disease and other neurodegenerative disorders, any attempt to reduce TSEs' lethality or increase the life expectancy of affected individuals has been unsuccessful. Typically, the onset of symptoms anticipates the fatal outcome of less than 1 year, although it is believed to be the consequence of a decades-long process of neuronal death. The duration of the symptoms-free period represents by itself a major obstacle to carry out effective neuroprotective therapies. Prions, the infectious entities of TSEs, are composed of a protease-resistant protein named prion protein scrapie (PrPSc) from the prototypical TSE form that afflicts ovines. PrPSc misfolding from its physiological counterpart, cellular prion protein (PrPC), is the unifying pathogenic trait of all TSEs. PrPSc is resistant to intracellular turnover and undergoes amyloid-like fibrillation passing through the formation of soluble dimers and oligomers, which are likely the effective neurotoxic entities. The failure of PrPSc removal is a key pathogenic event that defines TSEs as proteopathies, likewise other neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's disease, characterized by alteration of proteostasis. Under physiological conditions, protein quality control, led by the ubiquitin-proteasome system, and macroautophagy clears cytoplasm from improperly folded, redundant, or aggregation-prone proteins. There is evidence that both of these crucial homeostatic pathways are impaired during the development of TSEs, although it is still unclear whether proteostasis alteration facilitates prion protein misfolding or, rather, PrPSc protease resistance hampers cytoplasmic protein quality control. This review is aimed to critically analyze the most recent advancements in the cause-effect correlation between PrPC misfolding and proteostasis alterations and to discuss the possibility that pharmacological restoring of ubiquitin-proteasomal competence and stimulation of autophagy could reduce the intracellular burden of PrPSc and ameliorate the severity of prion-associated neurodegeneration.
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Affiliation(s)
- Stefano Thellung
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Alessandro Corsaro
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Irene Dellacasagrande
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Mario Nizzari
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Martina Zambito
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
| | - Tullio Florio
- Section of Pharmacology, Department of Internal Medicine (DiMI), University of Genova, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
- *Correspondence: Tullio Florio
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Huntington's disease: lessons from prion disorders. J Neurol 2021; 268:3493-3504. [PMID: 33625583 DOI: 10.1007/s00415-021-10418-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 02/06/2023]
Abstract
Decades of research on the prion protein and its associated diseases have caused a paradigm shift in our understanding of infectious agents. More recent years have been marked by a surge of studies supporting the application of these findings to a broad array of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Here, we present evidence to suggest that Huntington's disease, a monogenic disorder of the central nervous system, shares features with prion disorders and that, it too, may be governed by similar mechanisms. We further posit that these similarities could suggest that, like other common neurodegenerative disorders, sporadic forms of Huntington's disease may exist.
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López-Pérez Ó, Badiola JJ, Bolea R, Ferrer I, Llorens F, Martín-Burriel I. An Update on Autophagy in Prion Diseases. Front Bioeng Biotechnol 2020; 8:975. [PMID: 32984276 PMCID: PMC7481332 DOI: 10.3389/fbioe.2020.00975] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/27/2020] [Indexed: 12/18/2022] Open
Abstract
Autophagy is a dynamic intracellular mechanism involved in protein and organelle turnover through lysosomal degradation. When properly regulated, autophagy supports normal cellular and developmental processes, whereas defects in autophagic degradation have been associated with several pathologies, including prion diseases. Prion diseases, or transmissible spongiform encephalopathies (TSE), are a group of fatal neurodegenerative disorders characterized by the accumulation of the pathological misfolded isoform (PrPSc) of the physiological cellular prion protein (PrPc) in the central nervous system. Autophagic vacuoles have been described in experimental models of TSE and in the natural disease in humans. The precise connection of this process with prion-related neuropathology, or even whether autophagy is completely beneficial or pathogenic during neurodegeneration, is poorly understood. Thus, the biological role of autophagy in these diseases is still open to debate. During the last years, researchers have used a wide range of morphological, genetic and biochemical methods to monitor and manipulate the autophagic pathway and thus determine the specific role of this process in TSE. It has been suggested that PrPc could play a crucial role in modulating the autophagic pathway in neuronal cells, and the presence of abnormal autophagic activity has been frequently observed in several models of TSE both in vitro and in vivo, as well as in human prion diseases. Altogether, these findings suggest that autophagy is implicated in prion neuropathology and points to an impairment or failure of the process, potentially contributing to the pathogenesis of the disease. Additionally, autophagy is now emerging as a host defense response in controlling prion infection that plays a protective role by facilitating the clearance of aggregation-prone proteins accumulated within neurons. Since autophagy is one of the pathways of PrPSc degradation, and drug-induced stimulation of autophagic flux (the dynamic process of autophagic degradation activity) produces anti-prion effects, new treatments based on its activation have been tested to develop therapeutic strategies for prion diseases. In this review, we summarize previous and recent findings concerning the role of autophagy in TSE.
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Affiliation(s)
- Óscar López-Pérez
- Laboratorio de Genética Bioquímica (LAGENBIO), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain.,Centro de Encefalopatías y Enfermedades Transmisibles Emergentes (CEETE), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain.,Instituto de Investigación Biomédica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Juan José Badiola
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes (CEETE), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain
| | - Rosa Bolea
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes (CEETE), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain
| | - Isidro Ferrer
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain.,Instituto de Investigación Biomédica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Departamento de Patología y Terapéutica Experimental, Universidad de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Franc Llorens
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain.,Instituto de Investigación Biomédica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.,Department of Neurology, Clinical Dementia Center and National Reference Center for CJD Surveillance, University Medical School, Göttingen, Germany
| | - Inmaculada Martín-Burriel
- Laboratorio de Genética Bioquímica (LAGENBIO), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain.,Centro de Encefalopatías y Enfermedades Transmisibles Emergentes (CEETE), Instituto Agroalimentario de Aragón-IA2, Instituto de Investigación Sanitaria Aragón-IISA, Universidad de Zaragoza, Zaragoza, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto Carlos III, Zaragoza, Spain
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Liberski PP. Axonal changes in experimental prion diseases recapitulate those following constriction of postganglionic branches of the superior cervical ganglion: a comparison 40 years later. Prion 2019; 13:83-93. [PMID: 30966865 PMCID: PMC7000151 DOI: 10.1080/19336896.2019.1595315] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The major neurological feature of prion diseases is a neuronal loss accomplished through either apoptosis or autophagy. In this review, I compared axonal alterations in prion diseases to those described 40 years earlier as a result of nerve ligation. I also demonstrated that autophagic vacuoles and autophagosomes are a major part of dystrophic neurites. Furthermore, I summarized the current status of the autophagy in prion diseases and hypothesize, that spongiform change may originate from the autophagic vacuoles. This conclusion should be supported by other methods, in particular laser confocal microscopy. We observed neuronal autophagic vacuoles in different stages of formation, and our interpretation of the ‘maturity’ of their formation may or may not equate to actual developmental stages. Initially, a part of the neuronal cytoplasm was sequestrated within double or multiple membranes (phagophores) and often exhibited increased electron-density. The intracytoplasmic membranes formed labyrinth-like structures that suggest a multiplication of those membranes. The autophagic vacuoles then expand and eventually, a vast area of the cytoplasm was transformed into a merging mass of autophagic vacuoles. Margaret R. Matthews published a long treatise in the Philosophical Transactions of the Royal Society of London in which she had described in great detail the ultrastructure of postganglionic branches of the superior cervical ganglion in the rat following ligation of them. The earliest changes observed by Matthews between 6 h to 2 days in the proximal stump were distensions of proximal axons. Analogously, in our models, an increased number of ‘regular’ (round) and ‘irregular’ MVB and some autophagic vacuoles were observed collectively, both processes were similar.
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Affiliation(s)
- Paweł P Liberski
- a Laboratory of Electron Microscopy and Neuropathology, Department of Molecular Pathology and Neuropathology , Medical University of Lodz , Lodz , Poland
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Abstract
The cellular prion protein, PrPC, is a small, cell surface glycoprotein with a function that is currently somewhat ill defined. It is also the key molecule involved in the family of neurodegenerative disorders called transmissible spongiform encephalopathies, which are also known as prion diseases. The misfolding of PrPC to a conformationally altered isoform, designated PrPTSE, is the main molecular process involved in pathogenesis and appears to precede many other pathologic and clinical manifestations of disease, including neuronal loss, astrogliosis, and cognitive loss. PrPTSE is also believed to be the major component of the infectious "prion," the agent responsible for disease transmission, and preparations of this protein can cause prion disease when inoculated into a naïve host. Thus, understanding the biochemical and biophysical properties of both PrPC and PrPTSE, and ultimately the mechanisms of their interconversion, is critical if we are to understand prion disease biology. Although entire books could be devoted to research pertaining to the protein, herein we briefly review the state of knowledge of prion biochemistry, including consideration of prion protein structure, function, misfolding, and dysfunction.
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Affiliation(s)
- Andrew C Gill
- School of Chemistry, Joseph Banks Laboratories, University of Lincoln, Lincoln, United Kingdom; Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom.
| | - Andrew R Castle
- Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Sinha RA, Singh BK, Yen PM. Reciprocal Crosstalk Between Autophagic and Endocrine Signaling in Metabolic Homeostasis. Endocr Rev 2017; 38:69-102. [PMID: 27901588 DOI: 10.1210/er.2016-1103] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/28/2016] [Indexed: 12/19/2022]
Abstract
Autophagy is a cellular quality control and energy-providing process that is under strict control by intra- and extracellular stimuli. Recently, there has been an exponential increase in autophagy research and its implications for mammalian physiology. Autophagy deregulation is now being implicated in many human diseases, and its modulation has shown promising results in several preclinical studies. However, despite the initial discovery of autophagy as a hormone-regulated process by De Duve in the early 1960s, endocrine regulation of autophagy still remains poorly understood. In this review, we provide a critical summary of our present understanding of the basic mechanism of autophagy, its regulation by endocrine hormones, and its contribution to endocrine and metabolic homeostasis under physiological and pathological settings. Understanding the cross-regulation of hormones and autophagy on endocrine cell signaling and function will provide new insight into mammalian physiology as well as promote the development of new therapeutic strategies involving modulation of autophagy in endocrine and metabolic disorders.
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Affiliation(s)
- Rohit A Sinha
- Program of Cardiovascular and Metabolic Disorders, Duke-National University of Singapore Medical School Singapore, Singapore 169016
| | - Brijesh K Singh
- Program of Cardiovascular and Metabolic Disorders, Duke-National University of Singapore Medical School Singapore, Singapore 169016
| | - Paul M Yen
- Program of Cardiovascular and Metabolic Disorders, Duke-National University of Singapore Medical School Singapore, Singapore 169016
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Synaptic dysfunction in prion diseases: a trafficking problem? Int J Cell Biol 2013; 2013:543803. [PMID: 24369467 PMCID: PMC3863542 DOI: 10.1155/2013/543803] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 10/08/2013] [Indexed: 11/26/2022] Open
Abstract
Synaptic dysfunction is an important cause of neurological symptoms in prion diseases, a class of clinically heterogeneous neurodegenerative disorders caused by misfolding of the cellular prion protein (PrPC). Experimental data suggest that accumulation of misfolded PrPC in the endoplasmic reticulum (ER) may be crucial in synaptic failure, possibly because of the activation of the translational repression pathway of the unfolded protein response. Here, we report that this pathway is not operative in mouse models of genetic prion disease, consistent with our previous observation that ER stress is not involved. Building on our recent finding that ER retention of mutant PrPC impairs the secretory trafficking of calcium channels essential for synaptic function, we propose a model of pathogenicity in which intracellular retention of misfolded PrPC results in loss of function or gain of toxicity of PrPC-interacting proteins. This neurotoxic modality may also explain the phenotypic heterogeneity of prion diseases.
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Yang Y, Coleman M, Zhang L, Zheng X, Yue Z. Autophagy in axonal and dendritic degeneration. Trends Neurosci 2013; 36:418-28. [PMID: 23639383 DOI: 10.1016/j.tins.2013.04.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 12/19/2022]
Abstract
Degeneration of axons and dendrites is a common and early pathological feature of many neurodegenerative disorders, and is thought to be regulated by mechanisms distinct from those determining death of the cell body. The unique structures of axons and dendrites (collectively neurites) may cause them to be particularly vulnerable to the accumulation of protein aggregates and damaged organelles. Autophagy is a catabolic mechanism in which cells clear protein aggregates and damaged organelles. Basal autophagy occurs continuously as a housekeeping function, and can be acutely expanded in response to stress or injury. Emerging evidence shows that insufficient or excessive autophagy contributes to neuritic degeneration. Here, we review the recent progress that has begun to reveal the role of autophagy in neurite function and degeneration.
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Affiliation(s)
- Yi Yang
- Department of Pharmacology, Hangzhou Key Laboratory of Medical Neurobiology, School of Medicine, Hangzhou Normal University, Hangzhou 310036, PR China.
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Intraneuronal immunoreactivity for the prion protein distinguishes a subset of E200K genetic from sporadic Creutzfeldt-Jakob Disease. J Neuropathol Exp Neurol 2012; 71:223-32. [PMID: 22318125 DOI: 10.1097/nen.0b013e318248aa70] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Recently, we reported widespread intraneuronal prion protein (PrP) immunoreactivity in genetic Creutzfeldt-Jakob disease (CJD) associated with the E200K mutation. Here, we evaluated 6 cases ofsporadic CJD MM type 1, 5 MV type 2, and 7 VV type 2 and compared their anatomical appearance with that of 29 E200K genetic CJD (gCJD) cases. We also performed double immunolabeling for ubiquitin, p62, early endosomal marker rab5, and immunogold electronmicroscopy in 3 cases. We identified 4 morphological types of intraneuronal PrP immunoreactivity: one type, defined as multiple globular structures, was significantly associated with a subset of E200K gCJD cases and was distinct from the intraneuronal small dotlike PrP immunoreactivity seen in sporadic CJD. Whereas the latter colocalized with rab5, there were single large (7.5 μm-15 μm) globular inclusion body-like structures detected predominantly but not exclusively in E200K gCJD; these were immunoreactive in part for ubiquitin and p62 and showed focal γ-tubulin immunoreactivity, suggesting aggresome features. Ultrastructural examination using immunogold revealed PrP localization in aggresome-like structures and in autophagic vacuoles. These findings suggest that the permanent production of mutant PrP in the E200K gCJD cases overwhelms the ubiquitin-proteasome system and shifts the balance toward selectivemacroautophagy and/or to ubiquitinated inclusion body and aggresome formation as a cytoprotective effort to sequester the mutant protein.
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Aluminum maltolate induces primary rat astrocyte apoptosis via overactivation of the class III PI3K/Beclin 1-dependent autophagy signal. Toxicol In Vitro 2012; 26:215-20. [DOI: 10.1016/j.tiv.2011.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 10/23/2011] [Accepted: 11/17/2011] [Indexed: 11/22/2022]
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