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Luan T, Li Q, Huang Z, Feng Y, Xu D, Zhou Y, Hu Y, Wang T. Axonopathy Underlying Amyotrophic Lateral Sclerosis: Unraveling Complex Pathways and Therapeutic Insights. Neurosci Bull 2024:10.1007/s12264-024-01267-2. [PMID: 39097850 DOI: 10.1007/s12264-024-01267-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 08/05/2024] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disorder characterized by progressive axonopathy, jointly leading to the dying back of the motor neuron, disrupting both nerve signaling and motor control. In this review, we highlight the roles of axonopathy in ALS progression, driven by the interplay of multiple factors including defective trafficking machinery, protein aggregation, and mitochondrial dysfunction. Dysfunctional intracellular transport, caused by disruptions in microtubules, molecular motors, and adaptors, has been identified as a key contributor to disease progression. Aberrant protein aggregation involving TDP-43, FUS, SOD1, and dipeptide repeat proteins further amplifies neuronal toxicity. Mitochondrial defects lead to ATP depletion, oxidative stress, and Ca2+ imbalance, which are regarded as key factors underlying the loss of neuromuscular junctions and axonopathy. Mitigating these defects through interventions including neurotrophic treatments offers therapeutic potential. Collaborative research efforts aim to unravel ALS complexities, opening avenues for holistic interventions that target diverse pathological mechanisms.
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Affiliation(s)
- Tongshu Luan
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Qing Li
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Zhi Huang
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yu Feng
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Duo Xu
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yujie Zhou
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yiqing Hu
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Tong Wang
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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2
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Rayner SL, Hogan A, Davidson JM, Cheng F, Luu L, Morsch M, Blair I, Chung R, Lee A. Cyclin F, Neurodegeneration, and the Pathogenesis of ALS/FTD. Neuroscientist 2024; 30:214-228. [PMID: 36062310 DOI: 10.1177/10738584221120182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease and is characterized by the degeneration of upper and lower motor neurons of the brain and spinal cord. ALS is also linked clinically, genetically, and pathologically to a form of dementia known as frontotemporal dementia (FTD). Identifying gene mutations that cause ALS/FTD has provided valuable insight into the disease process. Several ALS/FTD-causing mutations occur within proteins with roles in protein clearance systems. This includes ALS/FTD mutations in CCNF, which encodes the protein cyclin F: a component of a multiprotein E3 ubiquitin ligase that mediates the ubiquitylation of substrates for their timely degradation. In this review, we provide an update on the link between ALS/FTD CCNF mutations and neurodegeneration.
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Affiliation(s)
| | - Alison Hogan
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | | | - Flora Cheng
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | - Luan Luu
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | - Marco Morsch
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | - Ian Blair
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | - Roger Chung
- Macquarie Medical School, Macquarie University, Sydney, Australia
| | - Albert Lee
- Macquarie Medical School, Macquarie University, Sydney, Australia
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3
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Klotz S, Gelpi E. [Neuropathology of dementia]. Wien Med Wochenschr 2021; 171:257-273. [PMID: 34129141 PMCID: PMC8397629 DOI: 10.1007/s10354-021-00848-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/14/2021] [Indexed: 11/09/2022]
Abstract
Demenz ist die klinische Folge verschiedener neurologischer Erkrankungen mit einer Vielzahl von Ätiologien. Dabei ist die genaue Kenntnis der zugrunde liegenden pathologischen Veränderungen entscheidend für die passgenaue Versorgung der Patienten und für die Entwicklung geeigneter Krankheitsbiomarker. Eine definitive Diagnose vieler dieser Erkrankungen, insbesondere der neurodegenerativen Formen, kann nur nach gründlicher postmortaler neuropathologischer Untersuchung gestellt werden. Dies unterstreicht die Wichtigkeit der Durchführung einer Gehirnautopsie und die Relevanz einer engen Zusammenarbeit zwischen Klinikern, Neuroradiologen und Neuropathologen sowie mit Grundlagenforschern. Ziel der vorliegenden Arbeit ist es, einen kurzen Überblick über die Neuropathologie der Demenz mit Schwerpunkt auf neurodegenerative Erkrankungen zu geben, um die interdisziplinäre Zusammenarbeit weiter zu fördern.
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Affiliation(s)
- Sigrid Klotz
- Abteilung für Neuropathologie und Neurochemie, Universitätsklinik für Neurologie, Medizinischer Universitätscampus Wien, Ebene 4J, Währinger Gürtel 18-20, 1090, Wien, Österreich.,Österreichisches Referenzzentrum zur Erfassung und Dokumentation menschlicher Prionen-Erkrankungen (ÖRPE), Wien, Österreich
| | - Ellen Gelpi
- Abteilung für Neuropathologie und Neurochemie, Universitätsklinik für Neurologie, Medizinischer Universitätscampus Wien, Ebene 4J, Währinger Gürtel 18-20, 1090, Wien, Österreich. .,Österreichisches Referenzzentrum zur Erfassung und Dokumentation menschlicher Prionen-Erkrankungen (ÖRPE), Wien, Österreich.
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4
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Tan CT, Chang HC, Zhou Q, Yu C, Fu NY, Sabapathy K, Yu VC. MOAP-1-mediated dissociation of p62/SQSTM1 bodies releases Keap1 and suppresses Nrf2 signaling. EMBO Rep 2021; 22:e50854. [PMID: 33393215 PMCID: PMC7788458 DOI: 10.15252/embr.202050854] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
Nrf2 signaling is vital for protecting cells against oxidative stress. However, its hyperactivation is frequently found in liver cancer through excessive build‐up of p62/SQSTM1 bodies that sequester Keap1, an adaptor of the E3‐ubiquitin ligase complex for Nrf2. Here, we report that the Bax‐binding protein MOAP‐1 regulates p62‐Keap1‐Nrf2 signaling through disruption of p62 bodies. Upon induction of cellular stresses that stimulate formation of p62 bodies, MOAP‐1 is recruited to p62 bodies and reduces their levels independent of the autophagy pathway. MOAP‐1 interacts with the PB1‐ZZ domains of p62 and interferes with its self‐oligomerization and liquid–liquid phase separation, thereby disassembling the p62 bodies. Loss of MOAP‐1 can lead to marked upregulation of p62 bodies, enhanced sequestration of Keap1 by p62 and hyperactivation of Nrf2 antioxidant target genes. MOAP‐1‐deficient mice exhibit an elevated tumor burden with excessive levels of p62 bodies and Nrf2 signaling in a diethylnitrosamine (DEN)‐induced hepatocarcinogenesis model. Together, our data define MOAP‐1 as a negative regulator of Nrf2 signaling via dissociation of p62 bodies.
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Affiliation(s)
- Chong Teik Tan
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Hao-Chun Chang
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Qiling Zhou
- Department of Pharmacy, National University of Singapore, Singapore, Singapore.,School of Life Sciences, Xiamen University, Xiamen, China
| | - Chundong Yu
- School of Life Sciences, Xiamen University, Xiamen, China
| | - Nai Yang Fu
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, Singapore, Singapore
| | - Kanaga Sabapathy
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, Singapore, Singapore.,Division of Cellular & Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre, Singapore, Singapore
| | - Victor C Yu
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
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5
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Trejo-Lopez JA, Sorrentino ZA, Riffe CJ, Prokop S, Dickson DW, Yachnis AT, Giasson BI. Generation and Characterization of Novel Monoclonal Antibodies Targeting p62/sequestosome-1 Across Human Neurodegenerative Diseases. J Neuropathol Exp Neurol 2020; 79:407-418. [PMID: 32106300 DOI: 10.1093/jnen/nlaa007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 01/25/2020] [Indexed: 12/17/2022] Open
Abstract
Human neurodegenerative diseases can be characterized as disorders of protein aggregation. As a key player in cellular autophagy and the ubiquitin proteasome system, p62 may represent an effective immunohistochemical target, as well as mechanistic operator, across neurodegenerative proteinopathies. In this study, 2 novel mouse-derived monoclonal antibodies 5G3 and 2A5 raised against residues 360-380 of human p62/sequestosome-1 were characterized via immunohistochemical application upon human tissues derived from cases of C9orf72-expansion spectrum diseases, Alzheimer disease, progressive supranuclear palsy, Lewy body disease, and multiple system atrophy. 5G3 and 2A5 reliably highlighted neuronal dipeptide repeat, tau, and α-synuclein inclusions in a distribution similar to a polyclonal antibody to p62, phospho-tau antibodies 7F2 and AT8, and phospho-α-synuclein antibody 81A. However, antibodies 5G3 and 2A5 consistently stained less neuropil structures, such as tau neuropil threads and Lewy neurites, while 2A5 marked fewer glial inclusions in progressive supranuclear palsy. Both 5G3 and 2A5 revealed incidental astrocytic tau immunoreactivity in cases of Alzheimer disease and Lewy body disease with resolution superior to 7F2. Through their unique ability to highlight specific types of pathological deposits in neurodegenerative brain tissue, these novel monoclonal p62 antibodies may provide utility in both research and diagnostic efforts.
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Affiliation(s)
- Jorge A Trejo-Lopez
- Department of Pathology, Immunology, and Laboratory Medicine.,Center for Translational Research in Neurodegenerative Disease
| | - Zachary A Sorrentino
- Center for Translational Research in Neurodegenerative Disease.,Department of Neuroscience
| | - Cara J Riffe
- Center for Translational Research in Neurodegenerative Disease.,Department of Neuroscience
| | - Stefan Prokop
- Department of Pathology, Immunology, and Laboratory Medicine.,Center for Translational Research in Neurodegenerative Disease.,McKnight Brain Institute.,Fixel Institute for Neurological Diseases, University of Florida, Gainesville, Florida
| | | | | | - Benoit I Giasson
- Center for Translational Research in Neurodegenerative Disease.,Department of Neuroscience.,McKnight Brain Institute
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6
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Mitra P, Deshmukh AS, Choudhury C. Molecular chaperone function of stress inducible Hsp70 is critical for intracellular multiplication of Toxoplasma gondii. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118898. [PMID: 33157166 DOI: 10.1016/j.bbamcr.2020.118898] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 11/27/2022]
Abstract
Intracellular pathogens like Toxoplasma gondii often target proteins and pathways critical for host cell survival and stress response. Molecular chaperones encoded by the evolutionary conserved Heat shock proteins (Hsps) maintain proteostasis and are vital to cell survival following exposure to any form of stress. A key protein of this family is Hsp70, an ATP-driven molecular chaperone, which is stress inducible and often indiscernible in normal cells. Role of this protein with respect to intracellular survival and multiplication of protozoan parasite like T. gondii remains to be examined. We find that T. gondii infection upregulates expression of host Hsp70. Hsp70 selective inhibitor 2-phenylethynesulfonamide (PES) attenuates intracellular T. gondii multiplication. Biotinylated PES confirms selective interaction of this small molecule inhibitor with Hsp70. We show that PES acts by disrupting Hsp70 chaperone function which leads to dysregulation of host autophagy. Silencing of host Hsp70 underscores its importance for intracellular multiplication of T. gondii, however, attenuation achieved using PES is not completely attributable to host Hsp70 indicating the presence of other intracellular targets of PES in infected host cells. We find that PES is also able to target T. gondii Hsp70 homologue which was shown using PES binding assay. Detailed molecular docking analysis substantiates PES targeting of TgHsp70 in addition to host Hsp70. While establishing the importance of protein quality control in infection, this study brings to the fore a unique opportunity of dual targeting of host and parasite Hsp70 demonstrating how structural conservation of these proteins may be exploited for therapeutic design.
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Affiliation(s)
- Pallabi Mitra
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India.
| | | | - Chinmayee Choudhury
- Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Research and Education, Chandigarh, India
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7
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Griffiths NW, Del Bel LM, Wilk R, Brill JA. Cellular homeostasis in the Drosophila retina requires the lipid phosphatase Sac1. Mol Biol Cell 2020; 31:1183-1199. [PMID: 32186963 PMCID: PMC7353163 DOI: 10.1091/mbc.e20-02-0161] [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] [Indexed: 11/21/2022] Open
Abstract
The complex functions of cellular membranes, and thus overall cell physiology, depend on the distribution of crucial lipid species. Sac1 is an essential, conserved, ER-localized phosphatase whose substrate, phosphatidylinositol 4-phosphate (PI4P), coordinates secretory trafficking and plasma membrane function. PI4P from multiple pools is delivered to Sac1 by oxysterol-binding protein and related proteins in exchange for other lipids and sterols, which places Sac1 at the intersection of multiple lipid distribution pathways. However, much remains unknown about the roles of Sac1 in subcellular homeostasis and organismal development. Using a temperature-sensitive allele (Sac1ts), we show that Sac1 is required for structural integrity of the Drosophila retinal floor. The βps-integrin Myospheroid, which is necessary for basal cell adhesion, is mislocalized in Sac1ts retinas. In addition, the adhesion proteins Roughest and Kirre, which coordinate apical retinal cell patterning at an earlier stage, accumulate within Sac1ts retinal cells due to impaired endo-lysosomal degradation. Moreover, Sac1 is required for ER homeostasis in Drosophila retinal cells. Together, our data illustrate the importance of Sac1 in regulating multiple aspects of cellular homeostasis during tissue development.
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Affiliation(s)
- Nigel W Griffiths
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Lauren M Del Bel
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ronit Wilk
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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8
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Pueraria lobata and Daidzein Reduce Cytotoxicity by Enhancing Ubiquitin-Proteasome System Function in SCA3-iPSC-Derived Neurons. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8130481. [PMID: 31687087 PMCID: PMC6800904 DOI: 10.1155/2019/8130481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/07/2019] [Accepted: 07/23/2019] [Indexed: 12/27/2022]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion within the ATXN3/MJD1 gene. The expanded CAG repeats encode a polyglutamine (polyQ) tract at the C-terminus of the ATXN3 protein. ATXN3 containing expanded polyQ forms aggregates, leading to subsequent cellular dysfunctions including an impaired ubiquitin-proteasome system (UPS). To investigate the pathogenesis of SCA3 and develop potential therapeutic strategies, we established induced pluripotent stem cell (iPSC) lines from SCA3 patients (SCA3-iPSC). Neurons derived from SCA3-iPSCs formed aggregates that are positive to the polyQ marker 1C2. Treatment with the proteasome inhibitor, MG132, on SCA3-iPSC-derived neurons downregulated proteasome activity, increased production of radical oxygen species (ROS), and upregulated the cleaved caspase 3 level and caspase 3 activity. This increased susceptibility to the proteasome inhibitor can be rescued by a Chinese herbal medicine (CHM) extract NH037 (from Pueraria lobata) and its constituent daidzein via upregulating proteasome activity and reducing protein ubiquitination, oxidative stress, cleaved caspase 3 level, and caspase 3 activity. Our results successfully recapitulate the key phenotypes of the neurons derived from SCA3 patients, as well as indicate the potential of NH037 and daidzein in the treatment for SCA3 patients.
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9
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Ma L, Herren AW, Espinal G, Randol J, McLaughlin B, Martinez-Cerdeño V, Pessah IN, Hagerman RJ, Hagerman PJ. Composition of the Intranuclear Inclusions of Fragile X-associated Tremor/Ataxia Syndrome. Acta Neuropathol Commun 2019; 7:143. [PMID: 31481131 PMCID: PMC6720097 DOI: 10.1186/s40478-019-0796-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 08/24/2019] [Indexed: 12/11/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder associated with a premutation repeat expansion (55-200 CGG repeats) in the 5' noncoding region of the FMR1 gene. Solitary intranuclear inclusions within FXTAS neurons and astrocytes constitute a hallmark of the disorder, yet our understanding of how and why these bodies form is limited. Here, we have discovered that FXTAS inclusions emit a distinct autofluorescence spectrum, which forms the basis of a novel, unbiased method for isolating FXTAS inclusions by preparative fluorescence-activated cell sorting (FACS). Using a combination of autofluorescence-based FACS and liquid chromatography/tandem mass spectrometry (LC-MS/MS)-based proteomics, we have identified more than two hundred proteins that are enriched within the inclusions relative to FXTAS whole nuclei. Whereas no single protein species dominates inclusion composition, highly enriched levels of conjugated small ubiquitin-related modifier 2 (SUMO 2) protein and p62/sequestosome-1 (p62/SQSTM1) protein were found within the inclusions. Many additional proteins involved with RNA binding, protein turnover, and DNA damage repair were enriched within inclusions relative to total nuclear protein. The current analysis has also allowed the first direct detection, through peptide sequencing, of endogenous FMRpolyG peptide, the product of repeat-associated non-ATG (RAN) translation of the FMR1 mRNA. However, this peptide was found only at extremely low levels and not within whole FXTAS nuclear preparations, raising the question whether endogenous RAN products exist at quantities sufficient to contribute to FXTAS pathogenesis. The abundance of the inclusion-associated ubiquitin- and SUMO-based modifiers supports a model for inclusion formation as the result of increased protein loads and elevated oxidative stress leading to maladaptive autophagy. These results highlight the need to further investigate FXTAS pathogenesis in the context of endogenous systems.
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Affiliation(s)
- Lisa Ma
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Anthony W Herren
- Genome Center, University of California Davis, Davis, California, USA
| | - Glenda Espinal
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Jamie Randol
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Bridget McLaughlin
- Department of Pathology and Laboratory Medicine, University of California Davis, School of Medicine, Sacramento, California, USA
| | - Veronica Martinez-Cerdeño
- Department of Pathology and Laboratory Medicine, University of California Davis, School of Medicine, Sacramento, California, USA
- Institute for Pediatric Regenerative Medicine, Shriners Hospital of Northern California, University of California Davis, School of Medicine, Sacramento, California, USA
- MIND Institute, University of California Davis Health, Sacramento, California, USA
| | - Isaac N Pessah
- MIND Institute, University of California Davis Health, Sacramento, California, USA
- Department of Molecular Biosciences, University of California Davis, School of Veterinary Medicine, Davis, California, USA
| | - Randi J Hagerman
- MIND Institute, University of California Davis Health, Sacramento, California, USA
- Department of Pediatrics, University of California Davis, School of Medicine, Sacramento, California, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA.
- MIND Institute, University of California Davis Health, Sacramento, California, USA.
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10
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Cullin-4B E3 ubiquitin ligase mediates Apaf-1 ubiquitination to regulate caspase-9 activity. PLoS One 2019; 14:e0219782. [PMID: 31329620 PMCID: PMC6645535 DOI: 10.1371/journal.pone.0219782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 07/01/2019] [Indexed: 11/25/2022] Open
Abstract
Apoptotic protease-activating factor 1 (Apaf-1) is a component of apoptosome, which regulates caspase-9 activity. In addition to apoptosis, Apaf-1 plays critical roles in the intra-S-phase checkpoint; therefore, impaired expression of Apaf-1 has been demonstrated in chemotherapy-resistant malignant melanoma and nuclear translocation of Apaf-1 has represented a favorable prognosis of patients with non-small cell lung cancer. In contrast, increased levels of Apaf-1 protein are observed in the brain in Huntington’s disease. The regulation of Apaf-1 protein is not yet fully understood. In this study, we show that etoposide triggers the interaction of Apaf-1 with Cullin-4B, resulting in enhanced Apaf-1 ubiquitination. Ubiquitinated Apaf-1, which was degraded in healthy cells, binds p62 and forms aggregates in the cytosol. This complex of ubiquitinated Apaf-1 and p62 induces caspase-9 activation following MG132 treatment of HEK293T cells that stably express bcl-xl. These results show that ubiquitinated Apaf-1 may activate caspase-9 under conditions of proteasome impairment.
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11
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Ma S, Attarwala IY, Xie XQ. SQSTM1/p62: A Potential Target for Neurodegenerative Disease. ACS Chem Neurosci 2019; 10:2094-2114. [PMID: 30657305 DOI: 10.1021/acschemneuro.8b00516] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neurodegenerative diseases, characterized by a progressive loss of brain function, affect the lives of millions of individuals worldwide. The complexity of the brain poses a challenge for scientists trying to map the biochemical and physiological pathways to identify areas of pathological errors. Brain samples of patients with neurodegenerative diseases have been shown to contain large amounts of misfolded and abnormally aggregated proteins, resulting in dysfunction in certain brain centers. Removal of these abnormal molecules is essential in maintaining protein homeostasis and overall neuronal health. Macroautophagy is a major route by which cells achieve this. Administration of certain autophagy-enhancing compounds has been shown to provide therapeutic effects for individuals with neurodegenerative conditions. SQSTM1/p62 is a scaffold protein closely involved in the macroautophagy process. p62 functions to anchor the ubiquitinated proteins to the autophagosome membrane, promoting degradation of unwanted molecules. Modulators targeting p62 to induce autophagy and promote its protective pathways for aggregate protein clearance have high potential in the treatment of these conditions. Additionally, causal relationships have been found between errors in regulation of SQSTM1/p62 and the development of a variety of neurodegenerative disorders, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, and frontotemporal lobar degeneration. Furthermore, SQSTM1/p62 also serves as a signaling hub for multiple pathways associated with neurodegeneration, providing a potential therapeutic target in the treatment of neurodegenerative diseases. However, rational design of a p62-oriented autophagy modulator that can balance the negative and positive functions of multiple domains in p62 requires further efforts in the exploration of the protein structure and pathological basis.
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Affiliation(s)
| | | | - Xiang-Qun Xie
- ID4Pharma LLC, Bridgeville, Pennsylvania 15017, United States
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12
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CNOT2 promotes degradation of p62/SQSTM1 as a negative regulator in ATG5 dependent autophagy. Oncotarget 2018; 8:46034-46046. [PMID: 28537904 PMCID: PMC5542246 DOI: 10.18632/oncotarget.17682] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 04/20/2017] [Indexed: 12/19/2022] Open
Abstract
Though CNOT2 is involved in regulation of adipogenic differentiation, apoptotic cell death and metastasis, the underlying autophagic mechanism of CNOT2 was unknown until now. Thus, in the present study, the critical role of CNOT2 in autophagy was elucidated in association with p62/SQSTM1 signaling. CNOT2 depletion induced p62/SQSTM1 accumulation and LC3B-II conversion, and also increased the number of puncta with impaired autophagic flux. In contrast, CNOT2 overexpression induced downregulation and ubiquitination of p62/SQSTM1 in HEK293 QBI. Furthermore, ubiquitination of p62/SQSTM1 was blocked by autophagy inhibition. Interestingly, CNOT2 was correlated with p62/SQSTM1 in HEK293 QBI cells and also was colocalized with p62/SQSTM1 in H1299 cells. Additionally, ATG5 was upregulated in CNOT2-depleted H1299 cells, while degradation of p62/SQSTM1 by CNOT2 was detected in ATG5+/+ MEF cells but not in ATG5−/− MEF cells. Of note, CNOT2 induced degradation of p62/SQSTM1 in HEK293 QBI cells co-transfected with Myc-ΔLIR/KIR or Myc-ΔUBA, but not with Myc-ΔPB1. Sub G1 population was increased in CNOT2-depleted H1299 cells by late autophagy inhibitors, ammonium chloride and chloroquine compared to 3-methyladenine. Overall, these findings provide novel insight into the critical role of CNOT2 as a negative regulator in ATG5 dependent autophagy.
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13
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Ramesh N, Pandey UB. Autophagy Dysregulation in ALS: When Protein Aggregates Get Out of Hand. Front Mol Neurosci 2017; 10:263. [PMID: 28878620 PMCID: PMC5572252 DOI: 10.3389/fnmol.2017.00263] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/03/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that results from the loss of upper and lower motor neurons. One of the key pathological hallmarks in diseased neurons is the mislocalization of disease-associated proteins and the formation of cytoplasmic aggregates of these proteins and their interactors due to defective protein quality control. This apparent imbalance in the cellular protein homeostasis could be a crucial factor in causing motor neuron death in the later stages of the disease in patients. Autophagy is a major protein degradation pathway that is involved in the clearance of protein aggregates and damaged organelles. Abnormalities in autophagy have been observed in numerous neurodegenerative disorders, including ALS. In this review, we discuss the contribution of autophagy dysfunction in various in vitro and in vivo models of ALS. Furthermore, we examine the crosstalk between autophagy and other cellular stresses implicated in ALS pathogenesis and the therapeutic implications of regulating autophagy in ALS.
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Affiliation(s)
- Nandini Ramesh
- Department of Human Genetics, University of Pittsburgh Graduate School of Public HealthPittsburgh, PA, United States.,Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburgh, PA, United States
| | - Udai Bhan Pandey
- Department of Human Genetics, University of Pittsburgh Graduate School of Public HealthPittsburgh, PA, United States.,Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburgh, PA, United States.,Department of Neurology, University of Pittsburgh School of MedicinePittsburgh, PA, United States
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14
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Jackson KL, Lin WL, Miriyala S, Dayton RD, Panchatcharam M, McCarthy KJ, Castanedes-Casey M, Dickson DW, Klein RL. p62 Pathology Model in the Rat Substantia Nigra with Filamentous Inclusions and Progressive Neurodegeneration. PLoS One 2017; 12:e0169291. [PMID: 28076378 PMCID: PMC5226781 DOI: 10.1371/journal.pone.0169291] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 12/14/2016] [Indexed: 12/11/2022] Open
Abstract
One of the proteins most frequently found in neuropathological lesions is the ubiquitin binding protein p62 (sequestosome 1). Post-mortem analysis of p62 is a defining diagnostic marker in several neurodegenerative diseases including amyotrophic lateral sclerosis and inclusion body myositis. Since p62 functions in protein degradation pathways including autophagy, the build-up of p62-positive inclusions suggests defects in protein clearance. p62 was expressed unilaterally in the rat substantia nigra with an adeno-associated virus vector (AAV9) in order to study p62 neuropathology. Inclusions formed within neurons from several days to several weeks after gene transfer. By electron microscopy, the inclusions were found to contain packed 10 nm thick filaments, and mitochondria cristae structure was disrupted, resulting in the formation of empty spaces. In corollary cell culture transfections, p62 clearly impaired mitochondrial function. To probe for potential effects on macroautophagy, we co-expressed p62 with a double fluorescent tagged reporter for the autophagosome protein LC3 in the rat. p62 induced a dramatic and specific dissociation of the two tags. By 12 weeks, a rotational behavior phenotype manifested, consistent with a significant loss of dopaminergic neurons analyzed post-mortem. p62 overexpression resulted in a progressive and robust pathology model with neuronal inclusions and neurodegeneration. p62 gene transfer could be a novel methodological probe to disrupt mitochondrial function or autophagy in the brain and other tissues in vivo.
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Affiliation(s)
- Kasey L. Jackson
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
| | - Wen-Lang Lin
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, United States of America
| | - Sumitra Miriyala
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
| | - Robert D. Dayton
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
| | - Manikandan Panchatcharam
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
| | - Kevin J. McCarthy
- Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
- Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
| | | | - Dennis W. Dickson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, United States of America
| | - Ronald L. Klein
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA, United States of America
- * E-mail:
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15
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Gurlo T, Costes S, Hoang JD, Rivera JF, Butler AE, Butler PC. β Cell-specific increased expression of calpastatin prevents diabetes induced by islet amyloid polypeptide toxicity. JCI Insight 2016; 1:e89590. [PMID: 27812546 DOI: 10.1172/jci.insight.89590] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The islet in type 2 diabetes (T2D) shares many features of the brain in protein misfolding diseases. There is a deficit of β cells with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein coexpressed with insulin. Small intracellular membrane-permeant oligomers, the most toxic form of IAPP, are more frequent in β cells of patients with T2D and rodents expressing human IAPP. β Cells in T2D, and affected cells in neurodegenerative diseases, share a comparable pattern of molecular pathology, including endoplasmic reticulum stress, mitochondrial dysfunction, attenuation of autophagy, and calpain hyperactivation. While this adverse functional cascade in response to toxic oligomers is well described, the sequence of events and how best to intervene is unknown. We hypothesized that calpain hyperactivation is a proximal event and tested this in vivo by β cell-specific suppression of calpain hyperactivation with calpastatin overexpression in human IAPP transgenic mice. β Cell-specific calpastatin overexpression was remarkably protective against β cell dysfunction and loss and diabetes onset. The critical autophagy/lysosomal pathway for β cell viability was protected with calpain suppression, consistent with findings in models of neurodegenerative diseases. We conclude that suppression of calpain hyperactivation is a potentially beneficial disease-modifying strategy for protein misfolding diseases, including T2D.
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16
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Ayyadevara S, Balasubramaniam M, Parcon PA, Barger SW, Griffin WST, Alla R, Tackett AJ, Mackintosh SG, Petricoin E, Zhou W, Shmookler Reis RJ. Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls. Aging Cell 2016; 15:924-39. [PMID: 27448508 PMCID: PMC5013017 DOI: 10.1111/acel.12501] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2016] [Indexed: 12/14/2022] Open
Abstract
Neurodegenerative diseases are distinguished by characteristic protein aggregates initiated by disease‐specific ‘seed’ proteins; however, roles of other co‐aggregated proteins remain largely unexplored. Compact hippocampal aggregates were purified from Alzheimer's and control‐subject pools using magnetic‐bead immunoaffinity pulldowns. Their components were fractionated by electrophoretic mobility and analyzed by high‐resolution proteomics. Although total detergent‐insoluble aggregates from Alzheimer's and controls had similar protein content, within the fractions isolated by tau or Aβ1–42 pulldown, the protein constituents of Alzheimer‐derived aggregates were more abundant, diverse, and post‐translationally modified than those from controls. Tau‐ and Aβ‐containing aggregates were distinguished by multiple components, and yet shared >90% of their protein constituents, implying similar accretion mechanisms. Alzheimer‐specific protein enrichment in tau‐containing aggregates was corroborated for individuals by three analyses. Five proteins inferred to co‐aggregate with tau were confirmed by precise in situ methods, including proximity ligation amplification that requires co‐localization within 40 nm. Nematode orthologs of 21 proteins, which showed Alzheimer‐specific enrichment in tau‐containing aggregates, were assessed for aggregation‐promoting roles in C. elegans by RNA‐interference ‘knockdown’. Fifteen knockdowns (71%) rescued paralysis of worms expressing muscle Aβ, and 12 (57%) rescued chemotaxis disrupted by neuronal Aβ expression. Proteins identified in compact human aggregates, bound by antibody to total tau, were thus shown to play causal roles in aggregation based on nematode models triggered by Aβ1–42. These observations imply shared mechanisms driving both types of aggregation, and/or aggregate‐mediated cross‐talk between tau and Aβ. Knowledge of protein components that promote protein accrual in diverse aggregate types implicates common mechanisms and identifies novel targets for drug intervention.
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Affiliation(s)
- Srinivas Ayyadevara
- McClellan Veterans Medical Center Central Arkansas Veterans Healthcare Service Little Rock AR 72205 USA
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Meenakshisundaram Balasubramaniam
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
- BioInformatics Program University of Arkansas for Medical Sciences and University of Arkansas at Little Rock Little Rock AR 72205 USA
| | - Paul A. Parcon
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Steven W. Barger
- McClellan Veterans Medical Center Central Arkansas Veterans Healthcare Service Little Rock AR 72205 USA
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - W. Sue T. Griffin
- McClellan Veterans Medical Center Central Arkansas Veterans Healthcare Service Little Rock AR 72205 USA
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Ramani Alla
- McClellan Veterans Medical Center Central Arkansas Veterans Healthcare Service Little Rock AR 72205 USA
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Alan J. Tackett
- Department of Biochemistry & Molecular Biology University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Samuel G. Mackintosh
- Department of Biochemistry & Molecular Biology University of Arkansas for Medical Sciences Little Rock AR 72205 USA
| | - Emanuel Petricoin
- Center for Applied Proteomics and Molecular Medicine George Mason University Manassas VA 20110 USA
| | - Weidong Zhou
- Center for Applied Proteomics and Molecular Medicine George Mason University Manassas VA 20110 USA
| | - Robert J. Shmookler Reis
- McClellan Veterans Medical Center Central Arkansas Veterans Healthcare Service Little Rock AR 72205 USA
- Department of Geriatrics University of Arkansas for Medical Sciences Little Rock AR 72205 USA
- Department of Biochemistry & Molecular Biology University of Arkansas for Medical Sciences Little Rock AR 72205 USA
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17
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Seidel K, Siswanto S, Fredrich M, Bouzrou M, den Dunnen WFA, Özerden I, Korf HW, Melegh B, de Vries JJ, Brunt ER, Auburger G, Rüb U. On the distribution of intranuclear and cytoplasmic aggregates in the brainstem of patients with spinocerebellar ataxia type 2 and 3. Brain Pathol 2016; 27:345-355. [PMID: 27377427 DOI: 10.1111/bpa.12412] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/22/2016] [Indexed: 11/28/2022] Open
Abstract
The polyglutamine (polyQ) diseases are a group of genetically and clinically heterogeneous neurodegenerative diseases, characterized by the expansion of polyQ sequences in unrelated disease proteins, which form different types of neuronal aggregates. The aim of this study was to characterize the aggregation pathology in the brainstem of spinocerebellar ataxia type 2 (SCA2) and 3 (SCA3) patients. For good recognition of neurodegeneration and rare aggregates, we employed 100 µm PEG embedded brainstem sections, which were immunostained with the 1C2 antibody, targeted at polyQ expansions, or with an antibody against p62, a reliable marker of protein aggregates. Brainstem areas were scored semiquantitatively for neurodegeneration, severity of granular cytoplasmic staining (GCS) and frequency of neuronal nuclear inclusions (NNI). SCA2 and SCA3 tissue exhibited the same aggregate types and similar staining patterns. Several brainstem areas showed statistically significant differences between disease groups, whereby SCA2 showed more severe GCS and SCA3 showed more numerous NNI. We observed a positive correlation between GCS severity and neurodegeneration in SCA2 and SCA3 and an inverse correlation between the frequency of NNI and neurodegeneration in SCA3. Although their respective disease proteins are unrelated, SCA2 and SCA3 showed the same aggregate types. Apparently, the polyQ sequence alone is sufficient as a driver of protein aggregation. This is then modified by protein context and intrinsic properties of neuronal populations. The severity of GCS was the best predictor of neurodegeneration in both disorders, while the inverse correlation of neurodegeneration and NNI in SCA3 tissue implies a protective role of these aggregates.
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Affiliation(s)
- Kay Seidel
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Sonny Siswanto
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Michaela Fredrich
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Mohamed Bouzrou
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Wilfred F A den Dunnen
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Inci Özerden
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Horst-Werner Korf
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
| | - Bela Melegh
- Department of Medical Genetics, University of Pécs, Pécs, Hungary
| | - Jeroen J de Vries
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Ewout R Brunt
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands
| | - Georg Auburger
- Experimental Neurology, J.W. Goethe University Medical School, Frankfurt, Germany
| | - Udo Rüb
- Institute of Clinical Neuroanatomy, Department of Anatomy II, J.W. Goethe-University, Frankfurt, Germany
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18
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Sergin I, Bhattacharya S, Emanuel R, Esen E, Stokes CJ, Evans TD, Arif B, Curci JA, Razani B. Inclusion bodies enriched for p62 and polyubiquitinated proteins in macrophages protect against atherosclerosis. Sci Signal 2016; 9:ra2. [PMID: 26732762 DOI: 10.1126/scisignal.aad5614] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Autophagy is a catabolic cellular mechanism that degrades dysfunctional proteins and organelles. Atherosclerotic plaque formation is enhanced in mice with macrophages deficient for the critical autophagy protein ATG5. We showed that exposure of macrophages to lipids that promote atherosclerosis increased the abundance of the autophagy chaperone p62 and that p62 colocalized with polyubiquitinated proteins in cytoplasmic inclusions, which are characterized by insoluble protein aggregates. ATG5-null macrophages developed further p62 accumulation at the sites of large cytoplasmic ubiquitin-positive inclusion bodies. Aortas from atherosclerotic mice and plaques from human endarterectomy samples showed increased abundance of p62 and polyubiquitinated proteins that colocalized with plaque macrophages, suggesting that p62-enriched protein aggregates were characteristic of atherosclerosis. The formation of the cytoplasmic inclusions depended on p62 because lipid-loaded p62-null macrophages accumulated polyubiquitinated proteins in a diffuse cytoplasmic pattern. Lipid-loaded p62-null macrophages also exhibited increased secretion of interleukin-1β (IL-1β) and had an increased tendency to undergo apoptosis, which depended on the p62 ubiquitin-binding domain and at least partly involved p62-mediated clearance of NLRP3 inflammasomes. Consistent with our in vitro observations, p62-deficient mice formed greater numbers of more complex atherosclerotic plaques, and p62 deficiency further increased atherosclerotic plaque burden in mice with a macrophage-specific ablation of ATG5. Together, these data suggested that sequestration of cytotoxic ubiquitinated proteins by p62 protects against atherogenesis, a condition in which the clearance of protein aggregates is disrupted.
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Affiliation(s)
- Ismail Sergin
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Somashubhra Bhattacharya
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Roy Emanuel
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Emel Esen
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Carl J Stokes
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Trent D Evans
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Batool Arif
- Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - John A Curci
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Babak Razani
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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19
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Rosebeck S, Alonge MM, Kandarpa M, Mayampurath A, Volchenboum SL, Jasielec J, Dytfeld D, Maxwell SP, Kraftson SJ, McCauley D, Shacham S, Kauffman M, Jakubowiak AJ. Synergistic Myeloma Cell Death via Novel Intracellular Activation of Caspase-10-Dependent Apoptosis by Carfilzomib and Selinexor. Mol Cancer Ther 2015; 15:60-71. [PMID: 26637366 DOI: 10.1158/1535-7163.mct-15-0488] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/14/2015] [Indexed: 11/16/2022]
Abstract
Exportin1 (XPO1; also known as chromosome maintenance region 1, or CRM1) controls nucleo-cytoplasmic transport of most tumor suppressors and is overexpressed in many cancers, including multiple myeloma, functionally impairing tumor suppressive function via target mislocalization. Selective inhibitor of nuclear export (SINE) compounds block XPO1-mediated nuclear escape by disrupting cargo protein binding, leading to retention of tumor suppressors, induction of cancer cell death, and sensitization to other drugs. Combined treatment with the clinical stage SINE compound selinexor and the irreversible proteasome inhibitor (PI) carfilzomib induced synergistic cell death of myeloma cell lines and primary plasma cells derived from relapsing/refractory myeloma patients and completely impaired the growth of myeloma cell line-derived tumors in mice. Investigating the details of SINE/PI-induced cell death revealed (i) reduced Bcl-2 expression and cleavage and inactivation of Akt, two prosurvival regulators of apoptosis and autophagy; (ii) intracellular membrane-associated aggregation of active caspases, which depended on caspase-10 protease activity; and (iii) novel association of caspase-10 and autophagy-associated proteins p62 and LC3 II, which may prime activation of the caspase cascade. Overall, our findings provide novel mechanistic rationale behind the potent cell death induced by combining selinexor with carfilzomib and support their use in the treatment of relapsed/refractory myeloma and potentially other cancers.
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Affiliation(s)
- Shaun Rosebeck
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - Mattina M Alonge
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - Malathi Kandarpa
- University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan
| | | | | | - Jagoda Jasielec
- Department of Medicine, University of Chicago, Chicago, Illinois
| | | | - Sean P Maxwell
- Department of Medicine, University of Chicago, Chicago, Illinois
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20
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Drosha inclusions are new components of dipeptide-repeat protein aggregates in FTLD-TDP and ALS C9orf72 expansion cases. J Neuropathol Exp Neurol 2015; 74:380-7. [PMID: 25756586 PMCID: PMC4362478 DOI: 10.1097/nen.0000000000000182] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Supplemental digital content is available in the text. Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are 2 neurodegenerative disorders that share clinical, genetic, and neuropathologic features. The presence of abnormal expansions of GGGGCC repeats (G4C2 repeats) in a noncoding region of the Chromosome 9 open reading frame 72 (C9orf72) gene is the major genetic cause of both FTLD and ALS. Transcribed G4C2 repeats can form nuclear RNA foci and recruit RNA-binding proteins, thereby inhibiting their normal function. Moreover, through a repeat-associated non-ATG translation mechanism, G4C2 repeats translation leads to dipeptide-repeat protein aggregation in the cytoplasm of neurons. Here, we identify Drosha protein as a new component of these dipeptide-repeat aggregates. In C9orf72 mutation cases of FTLD-TDP (c9FTLD-TDP) and ALS (c9ALS), but not in FTLD or ALS cases without C9orf72 mutation, Drosha is mislocalized to form neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum. Further characterization of Drosha-positive neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum revealed colocalization with p62 and ubiquilin-2, 2 pathognomonic signatures of c9FTLD-TDP and c9ALS cases; however, Drosha inclusions rarely colocalized with TDP-43 pathology. We conclude that Drosha may play a unique pathogenic role in the onset or progression of FTLD-TDP/ALS in patients with the C9orf72 mutation.
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21
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Kovacs GG, Adle-Biassette H, Milenkovic I, Cipriani S, van Scheppingen J, Aronica E. Linking pathways in the developing and aging brain with neurodegeneration. Neuroscience 2014; 269:152-72. [PMID: 24699227 DOI: 10.1016/j.neuroscience.2014.03.045] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/21/2014] [Accepted: 03/21/2014] [Indexed: 12/12/2022]
Abstract
The molecular and cellular mechanisms, which coordinate the critical stages of brain development to reach a normal structural organization with appropriate networks, are progressively being elucidated. Experimental and clinical studies provide evidence of the occurrence of developmental alterations induced by genetic or environmental factors leading to the formation of aberrant networks associated with learning disabilities. Moreover, evidence is accumulating that suggests that also late-onset neurological disorders, even Alzheimer's disease, might be considered disorders of aberrant neural development with pathological changes that are set up at early stages of development before the appearance of the symptoms. Thus, evaluating proteins and pathways that are important in age-related neurodegeneration in the developing brain together with the characterization of mechanisms important during brain development with relevance to brain aging are of crucial importance. In the present review we focus on (1) aspects of neurogenesis with relevance to aging; (2) neurodegenerative disease (NDD)-associated proteins/pathways in the developing brain; and (3) further pathways of the developing or neurodegenerating brains that show commonalities. Elucidation of complex pathogenetic routes characterizing the earliest stage of the detrimental processes that result in pathological aging represents an essential first step toward a therapeutic intervention which is able to reverse these pathological processes and prevent the onset of the disease. Based on the shared features between pathways, we conclude that prevention of NDDs of the elderly might begin during the fetal and childhood life by providing the mothers and their children a healthy environment for the fetal and childhood development.
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Affiliation(s)
- G G Kovacs
- Institute of Neurology, Medical University of Vienna, Austria.
| | - H Adle-Biassette
- Inserm U1141, F-75019 Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, UMRS 676, F-75019 Paris, France; Department of Pathology, Lariboisière Hospital, APHP, Paris, France
| | - I Milenkovic
- Institute of Neurology, Medical University of Vienna, Austria
| | | | - J van Scheppingen
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands
| | - E Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, The Netherlands; SEIN - Stichting Epilepsie Instellingen Nederland, Heemstede, The Netherlands; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, The Netherlands
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22
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Sahani MH, Itakura E, Mizushima N. Expression of the autophagy substrate SQSTM1/p62 is restored during prolonged starvation depending on transcriptional upregulation and autophagy-derived amino acids. Autophagy 2014; 10:431-41. [PMID: 24394643 PMCID: PMC4077882 DOI: 10.4161/auto.27344] [Citation(s) in RCA: 285] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
SQSTM1/p62 (sequestosome 1) is a multifunctional signaling molecule, involved in a variety of cellular pathways. SQSTM1 is one of the best-known autophagic substrates, and is therefore widely used as an indicator of autophagic degradation. Here we report that the expression level of SQSTM1 can be restored during prolonged starvation. Upon starvation, SQSTM1 is initially degraded by autophagy. However, SQSTM1 is restored back to basal levels during prolonged starvation in mouse embryonic fibroblasts and HepG2 cells, but not in HeLa and HEK293 cells. Restoration of SQSTM1 depends on its transcriptional upregulation, which is triggered by amino acid starvation. Furthermore, amino acids derived from the autophagy–lysosome pathway are used for de novo synthesis of SQSTM1 under starvation conditions. The restoration of SQSTM1 is independent of reactivation of MTORC1 (mechanistic target of rapamycin complex 1). These results suggest that the expression level of SQSTM1 in starved cells is determined by at least 3 factors: autophagic degradation, transcriptional upregulation, and availability of lysosomal-derived amino acids. The results of this study also indicate that the expression level of SQSTM1 does not always inversely correlate with autophagic activity.
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Affiliation(s)
- Mayurbhai Himatbhai Sahani
- Department of Physiology and Cell Biology; Tokyo Medical and Dental University; Tokyo, Japan; Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; University of Tokyo; Tokyo, Japan
| | - Eisuke Itakura
- Department of Physiology and Cell Biology; Tokyo Medical and Dental University; Tokyo, Japan
| | - Noboru Mizushima
- Department of Physiology and Cell Biology; Tokyo Medical and Dental University; Tokyo, Japan; Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; University of Tokyo; Tokyo, Japan
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23
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Lai AY, Lan CP, Hasan S, Brown ME, McLaurin J. scyllo-Inositol promotes robust mutant Huntingtin protein degradation. J Biol Chem 2013; 289:3666-76. [PMID: 24352657 DOI: 10.1074/jbc.m113.501635] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Huntington disease is characterized by neuronal aggregates and inclusions containing polyglutamine-expanded huntingtin protein and peptide fragments (polyQ-Htt). We have used an established cell-based assay employing a PC12 cell line overexpressing truncated exon 1 of Htt with a 103-residue polyQ expansion that yields polyQ-Htt aggregates to investigate the fate of polyQ-Htt-drug complexes. scyllo-Inositol is an endogenous inositol stereoisomer known to inhibit accumulation and toxicity of the amyloid-β peptide and α-synuclein. In light of these properties, we investigated the effect of scyllo-inositol on polyQ-Htt accumulation. We show that scyllo-inositol lowered the number of visible polyQ-Htt aggregates and robustly decreased polyQ-Htt protein abundance without concomitant cellular toxicity. We found that scyllo-inositol-induced polyQ-Htt reduction was by rescue of degradation pathways mediated by the lysosome and by the proteasome but not autophagosomes. The rescue of degradation pathways was not a direct result of scyllo-inositol on the lysosome or proteasome but due to scyllo-inositol-induced reduction in mutant polyQ-Htt protein levels.
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Affiliation(s)
- Aaron Y Lai
- From the Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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24
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Shapiro IM, Layfield R, Lotz M, Settembre C, Whitehouse C. Boning up on autophagy: the role of autophagy in skeletal biology. Autophagy 2013; 10:7-19. [PMID: 24225636 DOI: 10.4161/auto.26679] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
From an evolutionary perspective, the major function of bone is to provide stable sites for muscle attachment and affording protection of vital organs, especially the heart and lungs (ribs) and spinal cord (vertebrae and intervertebral discs). However, bone has a considerable number of other functions: serving as a store for mineral ions, providing a site for blood cell synthesis and participating in a complex system-wide endocrine system. Not surprisingly, bone and cartilage cell homeostasis is tightly controlled, as is the maintenance of tissue structure and mass. While a great deal of new information is accruing concerning skeletal cell homeostasis, one relatively new observation is that the cells of bone (osteoclasts osteoblasts and osteocytes) and cartilage (chondrocytes) exhibit autophagy. The focus of this review is to examine the significance of this process in terms of the functional demands of the skeleton in health and during growth and to provide evidence that dysregulation of the autophagic response is involved in the pathogenesis of diseases of bone (Paget disease of bone) and cartilage (osteoarthritis and the mucopolysaccharidoses). Delineation of molecular changes in the autophagic process is uncovering new approaches for the treatment of diseases that affect the axial and appendicular skeleton.
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Affiliation(s)
- Irving M Shapiro
- Jefferson Medical College; Thomas Jefferson University; Philadelphia, PA USA
| | - Robert Layfield
- School of Life Sciences; University of Nottingham Medical School; Nottingham UK
| | - Martin Lotz
- Arthritis Research; The Scripps Research Institute; La Jolla, CA USA
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM); Naples, Italy; Department of Molecular and Human Genetics; Baylor College of Medicine, Houston, TXUSA and Jan and Dan Duncan Neurological Research Institute; Texas Children's Hospital; Houston, TX USA; Medical Genetics; Department of Translational and Medical Science; Federico II University; Naples, Italy
| | - Caroline Whitehouse
- Department of Medical and Molecular Genetics; Kings College London; London UK
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25
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Lysosomal membrane permeability stimulates protein aggregate formation in neurons of a lysosomal disease. J Neurosci 2013; 33:10815-27. [PMID: 23804102 DOI: 10.1523/jneurosci.0987-13.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Protein aggregates are a common pathological feature of neurodegenerative diseases and several lysosomal diseases, but it is currently unclear what aggregates represent for pathogenesis. Here we report the accumulation of intraneuronal aggregates containing the macroautophagy adapter proteins p62 and NBR1 in the neurodegenerative lysosomal disease late-infantile neuronal ceroid lipofuscinosis (CLN2 disease). CLN2 disease is caused by a deficiency in the lysosomal enzyme tripeptidyl peptidase I, which results in aberrant lysosomal storage of catabolites, including the subunit c of mitochondrial ATP synthase (SCMAS). In an effort to define the role of aggregates in CLN2, we evaluated p62 and NBR1 accumulation in the CNS of Cln2(-/-) mice. Although increases in p62 and NBR1 often suggest compromised degradative mechanisms, we found normal ubiquitin-proteasome system function and only modest inefficiency in macroautophagy late in disease. Importantly, we identified that SCMAS colocalizes with p62 in extra-lysosomal aggregates in Cln2(-/-) neurons in vivo. This finding is consistent with SCMAS being released from lysosomes, an event known as lysosomal membrane permeability (LMP). We predicted that LMP and storage release from lysosomes results in the sequestration of this material as cytosolic aggregates by p62 and NBR1. Notably, LMP induction in primary neuronal cultures generates p62-positive aggregates and promotes p62 localization to lysosomal membranes, supporting our in vivo findings. We conclude that LMP is a previously unrecognized pathogenic event in CLN2 disease that stimulates cytosolic aggregate formation. Furthermore, we offer a novel role for p62 in response to LMP that may be relevant for other diseases exhibiting p62 accumulation.
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Current insights into the C9orf72 repeat expansion diseases of the FTLD/ALS spectrum. Trends Neurosci 2013; 36:450-9. [DOI: 10.1016/j.tins.2013.04.010] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 04/28/2013] [Accepted: 04/30/2013] [Indexed: 11/20/2022]
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Rea SL, Walsh JP, Layfield R, Ratajczak T, Xu J. New insights into the role of sequestosome 1/p62 mutant proteins in the pathogenesis of Paget's disease of bone. Endocr Rev 2013; 34:501-24. [PMID: 23612225 DOI: 10.1210/er.2012-1034] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Paget's disease of bone (PDB) is characterized by focal areas of aberrant and excessive bone turnover, specifically increased bone resorption and disorganized bone formation. Germline mutations in the sequestosome 1/p62 (SQSTM1/p62) gene are common in PDB patients, with most mutations affecting the ubiquitin-associated domain of the protein. In vitro, osteoclast precursor cells expressing PDB-mutant SQSTM1/p62 protein are associated with increases in nuclear factor κB activation, osteoclast differentiation, and bone resorption. Although the precise mechanisms by which SQSTM1/p62 mutations contribute to disease pathogenesis and progression are not well defined, it is apparent that as well as affecting nuclear factor κB signaling, SQSTM1/p62 is a master regulator of ubiquitinated protein turnover via autophagy and the ubiquitin-proteasome system. Additional roles for SQSTM1/p62 in the oxidative stress-induced Keap1/Nrf2 pathway and in caspase-mediated apoptosis that were recently reported are potentially relevant to the pathogenesis of PDB. Thus, SQSTM1/p62 may serve as a molecular link or switch between autophagy, apoptosis, and cell survival signaling. The purpose of this review is to outline recent advances in understanding of the multiple pathophysiological roles of SQSTM1/p62 protein, with particular emphasis on their relationship to PDB, including challenges associated with translating SQSTM1/p62 research into clinical diagnosis and treatment.
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Affiliation(s)
- Sarah L Rea
- Department of Endocrinology and Diabetes, Level 1, C Block, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Western Australia 6009, Australia.
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Lilienbaum A. Relationship between the proteasomal system and autophagy. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 4:1-26. [PMID: 23638318 PMCID: PMC3627065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/27/2013] [Indexed: 06/02/2023]
Abstract
TWO MAJOR PATHWAYS DEGRADE MOST CELLULAR PROTEINS IN EUKARYOTIC CELLS: the ubiquitin-proteasome system (UPS), which usually degrades the majority of proteins, and autophagy, primarily responsible for the degradation of most long-lived or aggregated proteins and cellular organelles. Disruption of these processes can contribute to pathology of a variety of diseases. Further, both pathways are critical for the maintenance of several aspects of cellular homeostasis, but, until recently, were thought to be largely distinct. Recent advances in this field, however, now strongly suggest that their activities are carefully orchestrated through several interfacing elements that are presented and discussed in this review.
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Affiliation(s)
- Alain Lilienbaum
- Laboratory of Stress and Pathologies of the Cytoskeleton, Unit of Functional and Adaptive Biology (BFA) affiliated with CNRS (EAC4413), University Paris Diderot-Paris 7 75250 Paris Cedex 13, France
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Seidel K, Meister M, Dugbartey GJ, Zijlstra MP, Vinet J, Brunt ERP, van Leeuwen FW, Rüb U, Kampinga HH, den Dunnen WFA. Cellular protein quality control and the evolution of aggregates in spinocerebellar ataxia type 3 (SCA3). Neuropathol Appl Neurobiol 2013; 38:548-58. [PMID: 21916928 DOI: 10.1111/j.1365-2990.2011.01220.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
AIMS A characteristic of polyglutamine diseases is the increased propensity of disease proteins to aggregate, which is thought to be a major contributing factor to the underlying neurodegeneration. Healthy cells contain mechanisms for handling protein damage, the protein quality control, which must be impaired or inefficient to permit proteotoxicity under pathological conditions. METHODS We used a quantitative analysis of immunohistochemistry of the pons of eight patients with the polyglutamine disorder spinocerebellar ataxia type 3. We employed the anti-polyglutamine antibody 1C2, antibodies against p62 that is involved in delivering ubiquitinated protein aggregates to autophagosomes, antibodies against the chaperones HSPA1A and DNAJB1 and the proteasomal stress marker UBB⁺¹. RESULTS The 1C2 antibody stained neuronal nuclear inclusions (NNIs), diffuse nuclear staining (DNS), granular cytoplasmic staining (GCS) and combinations, with reproducible distribution. P62 always co-localized with 1C2 in NNI. DNS and GCS co-stained with a lower frequency. UBB⁺¹ was present in a subset of neurones with NNI. A subset of UBB⁺¹-containing neurones displayed increased levels of HSPA1A, while DNAJB1 was sequestered into the NNI. CONCLUSION Based on our results, we propose a model for the aggregation-associated pathology of spinocerebellar ataxia type 3: GCS and DNS aggregation likely represents early stages of pathology, which progresses towards formation of p62-positive NNI. A fraction of NNI exhibits UBB⁺¹ staining, implying proteasomal overload at a later stage. Subsequently, the stress-inducible HSPA1A is elevated while DNAJB1 is recruited into NNIs. This indicates that the stress response is only induced late when all endogenous protein quality control systems have failed.
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Affiliation(s)
- K Seidel
- Department of Pathology and Medical Biology, University Medical Centre Groningen, Groningen, the Netherlands.
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Seibenhener ML, Du Y, Diaz-Meco MT, Moscat J, Wooten MC, Wooten MW. A role for sequestosome 1/p62 in mitochondrial dynamics, import and genome integrity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:452-9. [PMID: 23147249 DOI: 10.1016/j.bbamcr.2012.11.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/12/2012] [Accepted: 11/02/2012] [Indexed: 01/08/2023]
Abstract
As a signaling scaffold, p62/sequestosome (p62/SQSTM1) plays important roles in cell signaling and degradation of misfolded proteins. While localization of p62 to mitochondria has been reported, a description of its function once there, remains unclear. Here, we report that p62 is localized to mitochondria in non-stressed situations and demonstrate that deficiency in p62 exacerbates defects in mitochondrial membrane potential and energetics leading to mitochondrial dysfunction. We report on the relationship between mitochondrial protein import and p62. In a p62 null background, mitochondrial import of the mitochondrial transcription factor TFAM is disrupted. When p62 is returned, mitochondrial function is restored to more normal levels. We identify for the first time that p62 localization plays a role in regulating mitochondrial morphology, genome integrity and mitochondrial import of a key transcription factor. We present evidence that these responses to the presence of p62 extend beyond the protein's immediate influence on membrane potential.
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Affiliation(s)
- M Lamar Seibenhener
- Department of Biological Sciences, Cellular and Molecular Biosciences Program, Auburn University, AL 36849, USA
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31
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Myeku N, Wang H, Figueiredo-Pereira ME. cAMP stimulates the ubiquitin/proteasome pathway in rat spinal cord neurons. Neurosci Lett 2012; 527:126-31. [PMID: 22982149 DOI: 10.1016/j.neulet.2012.08.051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 08/24/2012] [Accepted: 08/26/2012] [Indexed: 01/03/2023]
Abstract
Proteasome impairment and accumulation of ubiquitinated proteins are implicated in neurodegeneration associated with different forms of spinal cord injury. We show herein that elevating cAMP in rat spinal cord neurons increases 26S proteasome activity in a protein kinase A-dependent manner. Treating spinal cord neurons with dibutyryl-cAMP (db-cAMP) also raised the levels of various components of the UPP including proteasome subunits Rpt6 and β5, polyubiquitin shuttling factor p62/sequestosome1, E3 ligase CHIP, AAA-ATPase p97 and the ubiquitin gene ubB. Finally, db-cAMP reduced the accumulation of ubiquitinated proteins, proteasome inhibition, and neurotoxicity triggered by the endogenous product of inflammation prostaglandin J2. We propose that optimizing the effects of cAMP/PKA-signaling on the UPP could offer an effective therapeutic approach to prevent UPP-related proteotoxicity in spinal cord neurons.
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Affiliation(s)
- Natura Myeku
- Department of Biological Sciences, Hunter College and Graduate Center, CUNY, New York, NY 10065, USA
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Magnaudeix A, Wilson CM, Page G, Bauvy C, Codogno P, Lévêque P, Labrousse F, Corre-Delage M, Yardin C, Terro F. PP2A blockade inhibits autophagy and causes intraneuronal accumulation of ubiquitinated proteins. Neurobiol Aging 2012; 34:770-90. [PMID: 22892312 DOI: 10.1016/j.neurobiolaging.2012.06.026] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 05/30/2012] [Accepted: 06/29/2012] [Indexed: 12/11/2022]
Abstract
Using cultured cortical neurons, we show that the blockade of protein phosphatase 2A (PP2A), either pharmacologically by okadaic acid or by short hairpin RNA (shRNA)-mediated silencing of PP2A catalytic subunit, inhibited basal autophagy and autophagy induced in several experimental settings (including serum deprivation, endoplasmic reticulum stress, rapamycin, and proteasome inhibition) at early stages before autophagosome maturation. Conversely, PP2A upregulation by PP2A catalytic subunit overexpression stimulates neuronal autophagy. In addition, PP2A blockade resulted in the activation of the negative regulator of autophagy mammalian target of rapamycin complex 1 and 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) and led to intraneuronal accumulation of p62- and ubiquitin-positive protein inclusions, likely due to autophagy downregulation. These data are consistent with previous findings showing that specific invalidation of the autophagy process in the nervous system of mouse resulted in the accumulation of p62- and ubiquitin-positive protein inclusion bodies. Furthermore, we showed that PP2A inhibition alters the distribution of the microtubule-associated protein 1 light chain(LC) 3-I (MAP LC3-I), a key component of the autophagy molecular machinery. Whether MAP LC3-I distribution in the cell accounts for autophagy regulation remains to be determined. These data are important to human neurodegenerative diseases, especially Alzheimer's disease, because they provide links for the first time between the pathological features of Alzheimer's disease:PP2A downregulation, autophagy disruption, and protein aggregation.
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Affiliation(s)
- Amandine Magnaudeix
- Laboratoire d'Histologie, de Biologie Cellulaire et de Cytogénétique, Faculté de Médecine, Université de Limoges, Limoges, France
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Xu Y, Tian C, Wang SB, Xie WL, Guo Y, Zhang J, Shi Q, Chen C, Dong XP. Activation of the macroautophagic system in scrapie-infected experimental animals and human genetic prion diseases. Autophagy 2012; 8:1604-20. [PMID: 22874564 DOI: 10.4161/auto.21482] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Macroautophagy is an important process for removing misfolded and aggregated protein in cells, the dysfunction of which has been directly linked to an increasing number of neurodegenerative disorders. However, the details of macroautophagy in prion diseases remain obscure. Here we demonstrated that in the terminal stages of scrapie strain 263K-infected hamsters and human genetic prion diseases, the microtubule-associated protein 1 light chain 3 (LC3) was converted from the cytosolic form to the autophagosome-bound membrane form. Macroautophagy substrate sequestosome 1 (SQSTM1) and polyubiquitinated proteins were downregulated in the brains of sick individuals, indicating enhanced macroautophagic protein degradation. The levels of mechanistic target of rapamycin (MTOR) and phosphorylated MTOR (p-MTOR) were significantly decreased, which implies that this enhancement of the macroautophagic response is likely through the MTOR pathway which is a negative regulator for the initiation of macroautophagy. Dynamic assays of the autophagic system in the brains of scrapie experimental hamsters after inoculation showed that alterations of the autophagic system appeared along with the deposits of PrP(Sc) in the infected brains. Immunofluorescent assays revealed specific staining of autophagosomes in neurons that were not colocalized with deposits of PrP(Sc) in the brains of scrapie infected hamsters, however, autophagosome did colocalize with PrP(Sc) in a prion-infected cell line after treatment with bafilomycin A(1). These results suggest that activation of macroautophagy in brains is a disease-correlative phenomenon in prion diseases.
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Affiliation(s)
- Yin Xu
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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Coaggregation of RNA-binding proteins in a model of TDP-43 proteinopathy with selective RGG motif methylation and a role for RRM1 ubiquitination. PLoS One 2012; 7:e38658. [PMID: 22761693 PMCID: PMC3380899 DOI: 10.1371/journal.pone.0038658] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 05/08/2012] [Indexed: 12/13/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is a major component within ubiquitin-positive inclusions of a number of neurodegenerative diseases that increasingly are considered as TDP-43 proteinopathies. Identities of other inclusion proteins associated with TDP-43 aggregation remain poorly defined. In this study, we identify and quantitate 35 co-aggregating proteins in the detergent-resistant fraction of HEK-293 cells in which TDP-43 or a particularly aggregate prone variant, TDP-S6, were enriched following overexpression, using stable isotope-labeled (SILAC) internal standards and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). We also searched for differential post-translational modification (PTM) sites of ubiquitination. Four sites of ubiquitin conjugation to TDP-43 or TDP-S6 were confirmed by dialkylated GST-TDP-43 external reference peptides, occurring on or near RNA binding motif (RRM) 1. RRM-containing proteins co-enriched in cytoplasmic granular structures in HEK-293 cells and primary motor neurons with insoluble TDP-S6, including cytoplasmic stress granule associated proteins G3BP, PABPC1, and eIF4A1. Proteomic evidence for TDP-43 co-aggregation with paraspeckle markers RBM14, PSF and NonO was also validated by western blot and by immunocytochemistry in HEK-293 cells. An increase in peptides from methylated arginine-glycine-glycine (RGG) RNA-binding motifs of FUS/TLS and hnRNPs was found in the detergent-insoluble fraction of TDP-overexpressing cells. Finally, TDP-43 and TDP-S6 detergent-insoluble species were reduced by mutagenesis of the identified ubiquitination sites, even following oxidative or proteolytic stress. Together, these findings define some of the aggregation partners of TDP-43, and suggest that TDP-43 ubiquitination influences TDP-43 oligomerization.
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Brettschneider J, Van Deerlin VM, Robinson JL, Kwong L, Lee EB, Ali YO, Safren N, Monteiro MJ, Toledo JB, Elman L, McCluskey L, Irwin DJ, Grossman M, Molina-Porcel L, Lee VMY, Trojanowski JQ. Pattern of ubiquilin pathology in ALS and FTLD indicates presence of C9ORF72 hexanucleotide expansion. Acta Neuropathol 2012; 123:825-39. [PMID: 22426854 DOI: 10.1007/s00401-012-0970-z] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 12/18/2022]
Abstract
C9ORF72-hexanucleotide repeat expansions and ubiquilin-2 (UBQLN2) mutations are recently identified genetic markers in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). We investigate the relationship between C9ORF72 expansions and the clinical phenotype and neuropathology of ALS and FTLD. Genetic analysis and immunohistochemistry (IHC) were performed on autopsy-confirmed ALS (N = 75), FTLD-TDP (N = 30), AD (N = 14), and controls (N = 11). IHC for neurodegenerative disease pathology consisted of C9ORF72, UBQLN, p62, and TDP-43. A C9ORF72 expansion was identified in 19.4 % of ALS and 31 % of FTLD-TDP cases. ALS cases with C9ORF72 expansions frequently showed a bulbar onset of disease (57 %) and more rapid disease progression to death compared to non-expansion cases. Staining with C9ORF72 antibodies did not yield specific pathology. UBQLN pathology showed a highly distinct pattern in ALS and FTLD-TDP cases with the C9ORF72 expansion, with UBQLN-positive cytoplasmic inclusions in the cerebellar granular layer and extensive UBQLN-positive aggregates and dystrophic neurites in the hippocampal molecular layer and CA regions. These UBQLN pathologies were sufficiently unique to allow correct prediction of cases that were later confirmed to have C9ORF72 expansions by genetic analysis. UBQLN pathology partially co-localized with p62, and to a minor extent with TDP-43 positive dystrophic neurites and spinal cord skein-like inclusions. Our data indicate a pathophysiological link between C9ORF72 expansions and UBQLN proteins in ALS and FTLD-TDP that is associated with a highly characteristic pattern of UBQLN pathology. Our study indicates that this pathology is associated with alterations in clinical phenotype, and suggests that the presence of C9ORF72 repeat expansions may indicate a worse prognosis in ALS.
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Affiliation(s)
- Johannes Brettschneider
- Center for Neurodegenerative Disease Research (CNDR), University of Pennsylvania School of Medicine, 3rd Floor Maloney Building, 3600 Spruce Street, Philadelphia, PA 19104, USA
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36
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Cartier AE, Ubhi K, Spencer B, Vazquez-Roque RA, Kosberg KA, Fourgeaud L, Kanayson P, Patrick C, Rockenstein E, Patrick GN, Masliah E. Differential effects of UCHL1 modulation on alpha-synuclein in PD-like models of alpha-synucleinopathy. PLoS One 2012; 7:e34713. [PMID: 22514658 PMCID: PMC3326048 DOI: 10.1371/journal.pone.0034713] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 03/05/2012] [Indexed: 12/16/2022] Open
Abstract
Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by genetic and environmental factors. Abnormal accumulation and aggregation of alpha-synuclein (a-syn) within neurons, and mutations in the a-syn and UCH-L1 genes have been shown to play a role in the pathogenesis of PD. In light of recent reports suggesting an interaction between a-synuclein and UCH-L1, we investigated the effects of UCH-L1 inhibition on a-syn distribution and expression levels in primary neurons and hippocampal tissues derived from non transgenic (non tg) and a-syn over expressing tg mice. We show that suppression of UCH-L1 activity increased a-syn levels in control, non tg neurons, and resulted in a concomitant accumulation of presynaptic a-syn in these neurons. In contrast, blocking UCH-L1 activity in a-syn over expressing neurons decreased a-syn levels, and enhanced its synaptic clearance. In vitro studies verified the LDN-induced inhibition of UCH-L1 had minimal effect on LC3 (a marker of autophagy) in control cells, in cells over expressing a-syn UCH-L1 inhibition resulted in increased LC3 activity. These findings suggest a possible differential role of UCH-L1 function under normal and pathological conditions. Furthermore, in the context of a-syn-induced pathology, modulation of UCH-L1 activity could serve as a therapeutic tool to enhance the autophagy pathway and induce clearance of the observed accumulated/aggregated a-syn species in the PD brain.
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Affiliation(s)
- Anna E. Cartier
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
| | - Kiren Ubhi
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Brian Spencer
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Ruben A. Vazquez-Roque
- Departamento de Fisiología, Escuela Nacional de Ciencias Biológicas, Instituto Politecnico Nacional, Mexico City, México
| | - Kori Ann Kosberg
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Lawrence Fourgeaud
- Molecular Neurobiology Laboratory, The Salk Institute of Biological Studies, La Jolla, California, United States of America
| | - Priya Kanayson
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Christina Patrick
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Edward Rockenstein
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Gentry N. Patrick
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
| | - Eliezer Masliah
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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Braak H, Thal DR, Matschke J, Ghebremedhin E, Del Tredici K. Age-related appearance of dendritic inclusions in catecholaminergic brainstem neurons. Neurobiol Aging 2012; 34:286-97. [PMID: 22503003 DOI: 10.1016/j.neurobiolaging.2012.02.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/27/2012] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
Abstract
We identified p62-immunoreactive inclusions in dendrites of catecholaminergic brainstem projection neurons using antibodies against p62, ubiquitin, α-synuclein, hyperphosphorylated tau, and tyrosine hydroxylase in 100-μm sections through the brainstem dorsal vagal area, locus coeruleus, and substantia nigra of 149 autopsy cases staged for intraneuronal Alzheimer's and Parkinson's disease-associated lesions. The inclusions resembled Marinesco bodies within cell nuclei of catecholaminergic neurons as well as the dot-like structures previously described by Dickson in specific neuropil areas in humans. The p62-positive inclusions were confined to dendrites of catecholaminergic neurons, lacked neuromelanin granules, and were tau- and α-synuclein-negative. Their immunoreactivity for ubiquitin varied and their prevalence significantly increased with advancing age. The presence or absence of Alzheimer's and/or Parkinson's disease-associated pathology did not influence their existence. There was a strong association between the presence of p62-positive inclusions and Marinesco bodies (p < 0.0001). Our results reveal a hitherto unknown alteration within specific neuronal types of the human brainstem that may be independent of the sequestosome-ubiquitin-proteasomal pathway and unrelated to proteinaceous aggregate-formation of neurodegenerative diseases.
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Affiliation(s)
- Heiko Braak
- Clinical Neuroanatomy, Center for Biomedical Research, Department of Neurology, University of Ulm, Ulm, Germany.
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McManus S, Roux S. The adaptor protein p62/SQSTM1 in osteoclast signaling pathways. J Mol Signal 2012; 7:1. [PMID: 22216904 PMCID: PMC3309942 DOI: 10.1186/1750-2187-7-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/04/2012] [Indexed: 02/07/2023] Open
Abstract
Paget's disease of bone (PDB) is a skeletal disorder characterized by focal and disorganized increases in bone turnover and overactive osteoclasts. The discovery of mutations in the SQSTM1/p62 gene in numerous patients has identified protein p62 as an important modulator of bone turnover. In both precursors and mature osteoclasts, the interaction between receptor activator of NF-κB ligand (RANKL) and its receptor RANK results in signaling cascades that ultimately activate transcription factors, particularly NF-κB and NFATc1, promoting and regulating the osteoclast differentiation, activity, and survival. As a scaffold with multiple protein-protein interaction motifs, p62 is involved in virtually all the RANKL-activated osteoclast signaling pathways, along with being implicated in numerous other cellular processes. The p62 adaptor protein is one of the functional links reported between RANKL and TRAF6-mediated NF-κB activation, and also plays a major role as a shuttling factor that targets polyubiquitinated proteins for degradation by either the autophagy or proteasome pathways. The dysregulated expression and/or activity of p62 in bone disease up-regulates osteoclast functions. This review aims to outline and summarize the role of p62 in RANKL-induced signaling pathways and in ubiquitin-mediated signaling in osteoclasts, and the impact of PDB-associated p62 mutations on these processes.
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Affiliation(s)
- Stephen McManus
- Division of Rheumatology, Faculty of Medicine, University of Sherbrooke, 3001, 12th Avenue North, Sherbrooke, PQ, Canada.
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Al-Sarraj S, King A, Troakes C, Smith B, Maekawa S, Bodi I, Rogelj B, Al-Chalabi A, Hortobágyi T, Shaw CE. p62 positive, TDP-43 negative, neuronal cytoplasmic and intranuclear inclusions in the cerebellum and hippocampus define the pathology of C9orf72-linked FTLD and MND/ALS. Acta Neuropathol 2011; 122:691-702. [PMID: 22101323 DOI: 10.1007/s00401-011-0911-2] [Citation(s) in RCA: 382] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 12/12/2022]
Abstract
Neuronal cytoplasmic inclusions (NCIs) containing phosphorylated TDP-43 (p-TDP-43) are the pathological hallmarks of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) and FTLD-TDP. The vast majority of NCIs in the brain and spinal cord also label for ubiquitin and p62, however, we have previously reported a subset of TDP-43 proteinopathy patients who have unusual and abundant p62 positive, TDP-43 negative inclusions in the cerebellum and hippocampus. Here we sought to determine whether these cases carry the hexanucleotide repeat expansion in C9orf72. Repeat primer PCR was performed in 36 MND/ALS, FTLD-MND/ALS and FTLD-TDP cases and four controls. Fourteen individuals with the repeat expansion were detected. In all the 14 expansion mutation cases there were abundant globular and star-shaped p62 positive NCIs in the pyramidal cell layer of the hippocampus, the vast majority of which were p-TDP-43 negative. p62 positive NCIs were also abundant in the cerebellar granular and molecular layers in all cases and in Purkinje cells in 12/14 cases but they were only positive for p-TDP-43 in the granular layer of one case. Abundant p62 positive, p-TDP-43 negative neuronal intranuclear inclusions (NIIs) were seen in 12/14 cases in the pyramidal cell layer of the hippocampus and in 6/14 cases in the cerebellar granular layer. This unusual combination of inclusions appears pathognomonic for C9orf72 repeat expansion positive MND/ALS and FTLD-TDP which we believe form a pathologically distinct subset of TDP-43 proteinopathies. Our results suggest that proteins other than TDP-43 are binding p62 and aggregating in response to the mutation which may play a mechanistic role in neurodegeneration.
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Affiliation(s)
- Safa Al-Sarraj
- Department of Clinical Neuropathology, Kings College Hospital, Denmark Hill, London SE5 9RS, UK
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Urbanczyk A, Enz R. Spartin recruits PKC-ζ via the PKC-ζ-interacting proteins ZIP1 and ZIP3 to lipid droplets. J Neurochem 2011; 118:737-48. [PMID: 21707618 DOI: 10.1111/j.1471-4159.2011.07367.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Protein kinase C-ζ interacting proteins (ZIP1-3) recruit the enzymatic activity of the atypical protein kinase C isoforms PKC-λ/ι or PKC-ζ to target proteins. In this study, we searched for binding partners of ZIP3 in the CNS and identified spartin, a multifunctional protein that is mutated in spastic paraplegia type 20. In transfected cells, spartin was present on the surface of lipid droplets (LD), whereas ZIP proteins appeared in intracellular speckles. In the presence of spartin, ZIP1 and ZIP3 were translocated to spartin-positive LD. This translocation was mediated by amino acids 196-393 of spartin that interacted with an N-terminal region of ZIP proteins. Furthermore, ZIP proteins interacted simultaneously with spartin and PKC-ζ, resulting in an enrichment of PKC-ζ on spartin/ZIP-labelled LD. Without spartin, neither ZIP proteins nor PKC-ζ were detected on LD. Interestingly, the presence of the spartin/ZIP/PKC-ζ complex increased LD size. This effect was most pronounced upon incorporation of the ZIP3 isoform into the trimer. Finally, we co-localized spartin, ZIP proteins and PKC-ζ in axon terminals of neurons in the mammalian retina. In summary, we describe spartin as new binding partner of the ZIP/PKC-ζ dimer that recruits PKC-ζ to LD and show that the expressed ZIP isoform regulates LD size.
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Affiliation(s)
- Andreas Urbanczyk
- Institut für Biochemie (Emil-Fischer-Zentrum), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Myeku N, Figueiredo-Pereira ME. Dynamics of the degradation of ubiquitinated proteins by proteasomes and autophagy: association with sequestosome 1/p62. J Biol Chem 2011; 286:22426-40. [PMID: 21536669 DOI: 10.1074/jbc.m110.149252] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteotoxicity resulting from accumulation of damaged/unwanted proteins contributes prominently to cellular aging and neurodegeneration. Proteasomal removal of these proteins upon covalent polyubiquitination is highly regulated. Recent reports proposed a role for autophagy in clearance of diffuse ubiquitinated proteins delivered by p62/SQSTM1. Here, we compared the turnover dynamics of endogenous ubiquitinated proteins by proteasomes and autophagy by assessing the effect of their inhibitors. Autophagy inhibitors bafilomycin A1, ammonium chloride, and 3-methyladenine failed to increase ubiquitinated protein levels. The proteasome inhibitor epoxomicin raised ubiquitinated protein levels at least 3-fold higher than the lysosomotropic agent chloroquine. These trends were observed in SK-N-SH cells under serum or serum-free conditions and in WT or Atg5(-/-) mouse embryonic fibroblasts (MEFs). Notably, chloroquine considerably inhibited proteasomes in SK-N-SH cells and MEFs. In these cells, elevation of p62/SQSTM1 was greater upon proteasome inhibition than with all autophagy inhibitors tested and was reduced in Atg5(-/-) MEFs. With epoxomicin, soluble p62/SQSTM1 associated with proteasomes and p62/SQSTM1 aggregates contained inactive proteasomes, ubiquitinated proteins, and autophagosomes. Prolonged autophagy inhibition (96 h) failed to elevate ubiquitinated proteins in rat cortical neurons, although epoxomicin did. Moreover, prolonged autophagy inhibition in cortical neurons markedly increased p62/SQSTM1, supporting its degradation mainly by autophagy and not by proteasomes. In conclusion, we clearly demonstrate that pharmacologic or genetic inhibition of autophagy fails to elevate ubiquitinated proteins unless the proteasome is affected. We also provide strong evidence that p62/SQSTM1 associates with proteasomes and that autophagy degrades p62/SQSTM1. Overall, the function of p62/SQSTM1 in the proteasomal pathway and autophagy requires further elucidation.
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Affiliation(s)
- Natura Myeku
- Department of Biological Sciences, Hunter College of City University of New York, New York, New York 10065, USA
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Abstract
The ubiquitin/proteasome pathway is the major proteolytic quality control system in cells. In this review we discuss the impact of a deregulation of this pathway on neuronal function and its causal relationship to the intracellular deposition of ubiquitin protein conjugates in pathological inclusion bodies in all the major chronic neurodegenerative disorders, such as Alzheimer's, Parkinson's and Huntington's diseases as well as amyotrophic lateral sclerosis. We describe the intricate nature of the ubiquitin/proteasome pathway and discuss the paradox of protein aggregation, i.e. its potential toxic/protective effect in neurodegeneration. The relations between some of the dysfunctional components of the pathway and neurodegeneration are presented. We highlight possible ubiquitin/proteasome pathway-targeting therapeutic approaches, such as activating the proteasome, enhancing ubiquitination and promoting SUMOylation that might be important to slow/treat the progression of neurodegeneration. Finally, a model time line is presented for neurodegeneration starting at the initial injurious events up to protein aggregation and cell death, with potential time points for therapeutic intervention.
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Itakura E, Mizushima N. p62 Targeting to the autophagosome formation site requires self-oligomerization but not LC3 binding. ACTA ACUST UNITED AC 2011; 192:17-27. [PMID: 21220506 PMCID: PMC3019556 DOI: 10.1083/jcb.201009067] [Citation(s) in RCA: 336] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
p62 is recruited to the ER at an early-stage autophagosome formation independently of most Atg proteins. Autophagy is an intracellular degradation process by which cytoplasmic contents are degraded in the lysosome. In addition to nonselective engulfment of cytoplasmic materials, the autophagosomal membrane can selectively recognize specific proteins and organelles. It is generally believed that the major selective substrate (or cargo receptor) p62 is recruited to the autophagosomal membrane through interaction with LC3. In this study, we analyzed loading of p62 and its related protein NBR1 and found that they localize to the endoplasmic reticulum (ER)–associated autophagosome formation site independently of LC3 localization to membranes. p62 colocalizes with upstream autophagy factors such as ULK1 and VMP1 even when autophagosome formation is blocked by wortmannin or FIP200 knockout. Self-oligomerization of p62 is essential for its localization to the autophagosome formation site. These results suggest that p62 localizes to the autophagosome formation site on the ER, where autophagosomes are nucleated. This process is similar to the yeast cytoplasm to vacuole targeting pathway.
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Affiliation(s)
- Eisuke Itakura
- Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
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PKCζ-interacting protein ZIP3 is generated by intronic polyadenylation, and is expressed in the brain and retina of the rat. Biochem J 2011; 433:43-50. [PMID: 20979579 DOI: 10.1042/bj20101111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Scaffold proteins contain multiple protein-protein interaction modules that physically assemble functionally related proteins into larger complexes. ZIPs [PKC (protein kinase C) ζ-interacting proteins] link the enzymatic activity of the atypical PKC isoforms PKCλ/ι or PKCζ to target proteins and are associated with neurodegenerative disorders. In the rat, alternative splicing generates three ZIP variants. Previously, we identified the ZIP3 transcript, containing 13 C-terminal amino acids encoded by intron 4, in the rat CNS (central nervous system). In the present study, we identified intronic polyadenylation signals in rat and human ZIP genes [known as SQSTM1 (sequestosome-1) in humans] and detected the corresponding ZIP3-like transcripts. In addition, we generated ZIP3-specific immune sera and observed expression of the protein in the brain and retina of the adult rat. In the retina, ZIP3 is present in nuclear layers where it co-localizes with PKCζ. An immune serum recognizing all three ZIP isoforms labelled the same cells as the newly generated ZIP3-specific antibodies and, in addition, stained both synaptic layers of the retina. There, ZIPs are localized in axon terminals of rod bipolar cells that also contain ZIP-interacting PKCζ and GABA(C) (γ-aminobutyric acid type C) receptors. In summary, we detected ZIP3-like transcripts in rat- and human-derived samples and describe the expression of ZIP3 in the rat CNS.
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Weide T, Huber TB. Implications of autophagy for glomerular aging and disease. Cell Tissue Res 2011; 343:467-73. [PMID: 21286756 DOI: 10.1007/s00441-010-1115-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Accepted: 12/03/2010] [Indexed: 12/19/2022]
Abstract
Glomerular diseases lead to a progressive decline in renal function and account for the vast majority of end-stage kidney diseases. Injury and loss of glomerular podocytes are common determining factors of glomerular disease progression and renal failure. Podocytes are a primary glomerular target of toxic, immune, metabolic, and oxidant stress, but little is known of the factors that counteract cellular stress signaling pathways. This review focuses on recent findings that identify autophagy as a critical homeostatic and quality control mechanism maintaining glomerular homeostasis.
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Affiliation(s)
- Thomas Weide
- Division of Molecular Nephrology, University Hospital Muenster, Muenster, Germany.
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King A, Maekawa S, Bodi I, Troakes C, Al-Sarraj S. Ubiquitinated, p62 immunopositive cerebellar cortical neuronal inclusions are evident across the spectrum of TDP-43 proteinopathies but are only rarely additionally immunopositive for phosphorylation-dependent TDP-43. Neuropathology 2010; 31:239-49. [DOI: 10.1111/j.1440-1789.2010.01171.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Braak H, Thal DR, Del Tredici K. Nerve cells immunoreactive for p62 in select hypothalamic and brainstem nuclei of controls and Parkinson's disease cases. J Neural Transm (Vienna) 2010; 118:809-19. [PMID: 21052746 DOI: 10.1007/s00702-010-0508-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 10/05/2010] [Indexed: 12/28/2022]
Abstract
The protein p62 plays an important role in the proteasomal and/or autophagic clearance of misfolded and aggregation-prone proteins. Immunoreactivity for p62, however, not only characterizes pathological proteinaceous inclusions but also occurs in the form of homogeneous nerve cell labeling in brains of both healthy and diseased individuals, e.g., in the vagal dorsal motor nucleus and other subcortical nuclei. In sporadic Parkinson's disease (PD), the pathological process initially involves preganglionic neurons of the parasympathetic and sympathetic system and probably advances caudo-rostrally from there along the neuroaxis. Since all subsequently affected nuclei (lower raphe nuclei, magnocellular reticular formation, locus coeruleus, and central subnucleus of the amygdala) generate descending projections that terminate in the vagal dorsal motor nucleus and intermediolateral column, it has been conjectured that retrograde axonal transport and transsynaptic transmission of a pathogen contribute to the pathogenesis of PD. The hypothalamic paraventricular nucleus also sends projections to the preganglionic nuclei under consideration and, thus, should belong to the nuclei endangered by the pathological process. However, it remains uninvolved for the duration of the disorder. For this reason, we performed a retrospective study of the relevant nuclei in a cohort of 36 individuals, including 17 with clinically documented PD, one case with incidental Lewy body disease (ILBD), and 18 controls using p62-immunocytochemistry. Remarkably, the neurosecretory cells of the paraventricular nucleus were among the sites showing homogeneous p62-immunolabeling with the greatest consistency. Its p62-immunoreactive profile may indicate that the hypothalamic paraventricular nucleus is somehow capable of effectively metabolizing misfolded proteins and/or preventing their aggregation.
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Affiliation(s)
- Heiko Braak
- Clinical Neuroanatomy, Department of Neurology, Center for Clinical Research, University of Ulm, Ulm, Germany.
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Curcio-Morelli C, Charles FA, Micsenyi MC, Cao Y, Venugopal B, Browning MF, Dobrenis K, Cotman SL, Walkley SU, Slaugenhaupt SA. Macroautophagy is defective in mucolipin-1-deficient mouse neurons. Neurobiol Dis 2010; 40:370-7. [PMID: 20600908 PMCID: PMC4392647 DOI: 10.1016/j.nbd.2010.06.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 06/15/2010] [Accepted: 06/22/2010] [Indexed: 11/17/2022] Open
Abstract
Mucolipidosis type IV is a neurodegenerative lysosomal disease clinically characterized by psychomotor retardation, visual impairment, and achlorhydria. In this study we report the development of a neuronal cell model generated from cerebrum of Mcoln1(-/-) embryos. Prior functional characterization of MLIV cells has been limited to fibroblast cultures gleaned from patients. The current availability of the mucolipin-1 knockout mouse model Mcoln1(-/-) allows the study of mucolipin-1-defective neurons, which is important since the disease is characterized by severe neurological impairment. Electron microscopy studies reveal significant membranous intracytoplasmic storage bodies, which correlate with the storage morphology observed in cerebral cortex of Mcoln1(-/-) P7 pups and E17 embryos. The Mcoln1(-/-) neuronal cultures show an increase in size of LysoTracker and Lamp1 positive vesicles. Using this neuronal model system, we show that macroautophagy is defective in mucolipin-1-deficient neurons and that LC3-II levels are significantly elevated. Treatment with rapamycin plus protease inhibitors did not increase levels of LC3-II in Mcoln1(-/-) neuronal cultures, indicating that the lack of mucolipin-1 affects LC3-II clearance. P62/SQSTM1 and ubiquitin levels were also increased in Mcoln1(-/-) neuronal cultures, suggesting an accumulation of protein aggregates and a defect in macroautophagy which could help explain the neurodegeneration observed in MLIV. This study describes, for the first time, a defect in macroautophagy in mucolipin-1-deficient neurons, which corroborates recent findings in MLIV fibroblasts and provides new insight into the neuronal pathogenesis of this disease.
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Affiliation(s)
- Cyntia Curcio-Morelli
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Florie A. Charles
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Matthew C. Micsenyi
- Dominick P. Purpura Department of Neuroscience, Rose F. Kennedy Center for Research in Mental Retardation and Human Development, Albert Einstein College of Medicine, Bronx, New York
| | - Yi Cao
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Bhuvarahamurthy Venugopal
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Marsha F. Browning
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Kostantin Dobrenis
- Dominick P. Purpura Department of Neuroscience, Rose F. Kennedy Center for Research in Mental Retardation and Human Development, Albert Einstein College of Medicine, Bronx, New York
| | - Susan L. Cotman
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
| | - Steven U. Walkley
- Dominick P. Purpura Department of Neuroscience, Rose F. Kennedy Center for Research in Mental Retardation and Human Development, Albert Einstein College of Medicine, Bronx, New York
| | - Susan A. Slaugenhaupt
- Center for Human Genetic Research, Massachusetts General Hospital/Harvard Medical School, Richard B. Simches Research Center, CPZN-5254, 185 Cambridge Street, Boston, MA 02114
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Human-IAPP disrupts the autophagy/lysosomal pathway in pancreatic β-cells: protective role of p62-positive cytoplasmic inclusions. Cell Death Differ 2010; 18:415-26. [PMID: 20814419 DOI: 10.1038/cdd.2010.111] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In type II diabetes (T2DM), there is a deficit in β-cells, increased β-cell apoptosis and formation of intracellular membrane-permeant oligomers of islet amyloid polypeptide (IAPP). Human-IAPP (h-IAPP) is an amyloidogenic protein co-expressed with insulin by β-cells. IAPP expression is increased with obesity, the major risk factor for T2DM. In this study we report that increased expression of human-IAPP led to impaired autophagy, due at least in part to the disruption of lysosome-dependent degradation. This action of IAPP to alter lysosomal clearance in vivo depends on its propensity to form toxic oligomers and is independent of the confounding effect of hyperglycemia. We report that the scaffold protein p62 that delivers polyubiquitinated proteins to autophagy may have a protective role against human-IAPP-induced apoptosis, apparently by sequestrating protein targets for degradation. Finally, we found that inhibition of lysosomal degradation increases vulnerability of β-cells to h-IAPP-induced toxicity and, conversely, stimulation of autophagy protects β-cells from h-IAPP-induced apoptosis. Collectively, these data imply an important role for the p62/autophagy/lysosomal degradation system in protection against toxic oligomer-induced apoptosis.
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50
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Physiological role of autophagy as an intracellular recycling system: With an emphasis on nutrient metabolism. Semin Cell Dev Biol 2010; 21:683-90. [DOI: 10.1016/j.semcdb.2010.03.002] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 02/19/2010] [Accepted: 03/03/2010] [Indexed: 01/07/2023]
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