The ubiquitin–proteasome system and neurodegenerative disorders

2005 ◽  
Vol 41 ◽  
pp. 157-171 ◽  
Author(s):  
Robert Layfield ◽  
James Lowe ◽  
Lynn Bedford
Keyword(s):  
Neurodegenerative Disorders ◽  
Ubiquitin Proteasome System ◽  
Normal Brain ◽  
Pathological State ◽  
Neurodegenerative Process ◽  
Mammalian Tissues ◽  
Normal Brain Function ◽  
Ubiquitin Proteasome ◽  
Consistent Feature ◽  
Related Proteins

As in all other mammalian tissues, the UPS (ubiquitin–proteasome system) is fundamental to normal brain function. A consistent feature of the major human neurodegenerative disorders is the accumulation of disease-related proteins, in non-native conformations, as protein aggregates within neurons or glial cells. Often the proteins in these aggregates are post-translationally conjugated with ubiquitin, suggesting a possible link between pathological protein-aggregation events in the nervous system and dysfunction of the UPS. Genetic evidence clearly demonstrates that disruption of ubiquitin-mediated processes can lead to neurodegeneration; however, the relationship between the UPS and idiopathic neurodegenerative disorders is less clear. In the latter cases, although a number of different mechanisms could potentially contribute to dysfunction of the UPS and promote the neurodegenerative process, whether UPS dysfunction is causally related to disease pathogenesis, or alternatively arises as a result of the pathological state, and indeed whether ubiquitinated inclusions are harmful or beneficial to cells, remains to be clarified.

Protein Quality Control in Neurodegeneration and Neuroprotection

2020 ◽  
pp. 1-24
Author(s):  
Yasmeena Akhter ◽  
Jahangir Nabi ◽  
Hinna Hamid ◽  
Nahida Tabassum ◽  
Faheem Hyder Pottoo ◽  
...  
Keyword(s):  
Quality Control ◽  
Neurodegenerative Disorders ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Security System ◽  
Conformational Disorders ◽  
Ubiquitin Proteasome ◽  
Multi Level

Proteostasis is essential for regulating the integrity of the proteome. Disruption of proteostasis under some rigorous conditions leads to the aggregation and accumulation of misfolded toxic proteins, which plays a central role in the pathogenesis of protein conformational disorders. The protein quality control (PQC) system serves as a multi-level security system to shield cells from abnormal proteins. The intrinsic PQC systems maintaining proteostasis include the ubiquitin-proteasome system (UPS), chaperon-mediated autophagy (CMA), and autophagy-lysosome pathway (ALP) that serve to target misfolded proteins for unfolding, refolding, or degradation. Alterations of PQC systems in neurons have been implicated in the pathogenesis of various neurodegenerative disorders. This chapter provides an overview of PQC pathways to set a framework for discussion of the role of PQC in neurodegenerative disorders. Additionally, various pharmacological approaches targeting PQC are summarized.

scholarly journals The ubiquitin proteasome system in synaptic and axonal degeneration

2004 ◽  
Vol 165 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Laura Korhonen ◽  
Dan Lindholm
Keyword(s):  
Neurodegenerative Diseases ◽  
Neurodegenerative Disorders ◽  
Drug Targets ◽  
Axonal Degeneration ◽  
Fruit Fly ◽  
Ubiquitin Proteasome System ◽  
Synaptic Protein ◽  
Ubiquitin Proteasome ◽  
Novel Drug ◽  
Novel Drug Targets

The ubiquitin proteasome system (UPS) contributes to the pathophysiology of neurodegenerative diseases, and it is also a major determinant of synaptic protein degradation and activity. Recent studies in rodents and in the fruit fly Drosophila have shown that the activity of the UPS is involved in axonal degeneration. Increased knowledge of the UPS in synaptic and axonal reactions may provide novel drug targets for treatments of neuronal injuries and neurodegenerative disorders.

scholarly journals Progress in the pathogenesis and genetics of Parkinson's disease

2008 ◽  
Vol 363 (1500) ◽  
pp. 2215-2227 ◽  
Author(s):  
Yoshikuni Mizuno ◽  
Nobutaka Hattori ◽  
Shin-ichiro Kubo ◽  
Shigeto Sato ◽  
Kenya Nishioka ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
Disease Process ◽  
Ubiquitin Proteasome System ◽  
Neurodegenerative Process ◽  
Molecular Events ◽  
Ubiquitin Proteasome ◽  
Sporadic Parkinson’S Disease ◽  
Synuclein Proteins

Recent progresses in the pathogenesis of sporadic Parkinson's disease (PD) and genetics of familial PD are reviewed. There are common molecular events between sporadic and familial PD, particularly between sporadic PD and PARK1 -linked PD due to α - synuclein ( SNCA ) mutations. In sporadic form, interaction of genetic predisposition and environmental factors is probably a primary event inducing mitochondrial dysfunction and oxidative damage resulting in oligomer and aggregate formations of α-synuclein. In PARK1 -linked PD, mutant α-synuclein proteins initiate the disease process as they have increased tendency for self-aggregation. As highly phosphorylated aggregated proteins are deposited in nigral neurons in PD, dysfunctions of proteolytic systems, i.e. the ubiquitin–proteasome system and autophagy–lysosomal pathway, seem to be contributing to the final neurodegenerative process. Studies on the molecular mechanisms of nigral neuronal death in familial forms of PD will contribute further on the understanding of the pathogenesis of sporadic PD.

scholarly journals Selective Accumulation of Aggregation-Prone Proteasome Substrates in Response to Proteotoxic Stress

2009 ◽  
Vol 29 (7) ◽  
pp. 1774-1785 ◽  
Author(s):  
Florian A. Salomons ◽  
Victoria Menéndez-Benito ◽  
Claudia Böttcher ◽  
Brett A. McCray ◽  
J. Paul Taylor ◽  
...  
Keyword(s):  
Ubiquitin Proteasome System ◽  
Insoluble Protein ◽  
Conformational Diseases ◽  
Proteotoxic Stress ◽  
Ubiquitin Proteasome ◽  
Consistent Feature ◽  
Stressed Cells ◽  
Underlying Mechanisms ◽  
Selective Accumulation ◽  
Free Ubiquitin

ABSTRACT Conditions causing an increase in misfolded or aberrant proteins can impair the activity of the ubiquitin/proteasome system (UPS). This observation is of particular interest, given the fact that proteotoxic stress is closely associated with a large variety of disorders. Although impairment of the UPS appears to be a general consequence of proteotoxic insults, the underlying mechanisms remain enigmatic. Here, we show that heat shock-induced proteotoxic stress resulted in conjugation of ubiquitin to detergent-insoluble protein aggregates, which coincided with reduced levels of free ubiquitin and impediment of ubiquitin-dependent proteasomal degradation. Interestingly, whereas soluble proteasome substrates returned to normal levels after a transient accumulation, the levels of an aggregation-prone substrate remained high even when the free ubiquitin levels were restored. Consistently, overexpression of ubiquitin prevented accumulation of soluble but not aggregation-prone substrates in thermally stressed cells. Notably, cells were also unable to resume degradation of aggregation-prone substrates after treatment with the translation inhibitor puromycin, indicating that selective accumulation of aggregation-prone proteins is a consistent feature of proteotoxic stress. Our data suggest that the failure of the UPS to clear aggregated proteins in the aftermath of proteotoxic stress episodes may contribute to the selective deposition of aggregation-prone proteins in conformational diseases.

scholarly journals The Roles of Ubiquitin in Mediating Autophagy

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2025 ◽  
Author(s):  
Zhangyuan Yin ◽  
Hana Popelka ◽  
Yuchen Lei ◽  
Ying Yang ◽  
Daniel J. Klionsky
Keyword(s):  
Molecular Mechanisms ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Post Translational Modification ◽  
Subcellular Organelles ◽  
Precise Control ◽  
Ubiquitin Proteasome ◽  
Autophagy Pathway ◽  
Structural Architecture ◽  
Related Proteins

Ubiquitination, the post-translational modification essential for various intracellular processes, is implicated in multiple aspects of autophagy, the major lysosome/vacuole-dependent degradation pathway. The autophagy machinery adopted the structural architecture of ubiquitin and employs two ubiquitin-like protein conjugation systems for autophagosome biogenesis. Ubiquitin chains that are attached as labels to protein aggregates or subcellular organelles confer selectivity, allowing autophagy receptors to simultaneously bind ubiquitinated cargos and autophagy-specific ubiquitin-like modifiers (Atg8-family proteins). Moreover, there is tremendous crosstalk between autophagy and the ubiquitin-proteasome system. Ubiquitination of autophagy-related proteins or regulatory components plays significant roles in the precise control of the autophagy pathway. In this review, we summarize and discuss the molecular mechanisms and functions of ubiquitin and ubiquitination, in the process and regulation of autophagy.

scholarly journals Amyloid Precursor Protein (APP) May Act as a Substrate and a Recognition Unit for CRL4CRBN and Stub1 E3 Ligases Facilitating Ubiquitination of Proteins Involved in Presynaptic Functions and Neurodegeneration

2016 ◽  
Vol 291 (33) ◽  
pp. 17209-17227 ◽  
Author(s):  
Dolores Del Prete ◽  
Richard C. Rice ◽  
Anjali M. Rajadhyaksha ◽  
Luciano D'Adamio
Keyword(s):  
Amyloid Precursor Protein ◽  
Transmitter Release ◽  
Ubiquitin Proteasome System ◽  
Precursor Protein ◽  
E3 Ligases ◽  
Ubiquitin Proteasome ◽  
Functional Pathway ◽  
Related Proteins

The amyloid precursor protein (APP), whose mutations cause Alzheimer disease, plays an important in vivo role and facilitates transmitter release. Because the APP cytosolic region (ACR) is essential for these functions, we have characterized its brain interactome. We found that the ACR interacts with proteins that regulate the ubiquitin-proteasome system, predominantly with the E3 ubiquitin-protein ligases Stub1, which binds the NH2 terminus of the ACR, and CRL4CRBN, which is formed by Cul4a/b, Ddb1, and Crbn, and interacts with the COOH terminus of the ACR via Crbn. APP shares essential functions with APP-like protein-2 (APLP2) but not APP-like protein-1 (APLP1). Noteworthy, APLP2, but not APLP1, interacts with Stub1 and CRL4CRBN, pointing to a functional pathway shared only by APP and APLP2. In vitro ubiquitination/ubiquitome analysis indicates that these E3 ligases are enzymatically active and ubiquitinate the ACR residues Lys649/650/651/676/688. Deletion of Crbn reduces ubiquitination of Lys676 suggesting that Lys676 is physiologically ubiquitinated by CRL4CRBN. The ACR facilitated in vitro ubiquitination of presynaptic proteins that regulate exocytosis, suggesting a mechanism by which APP tunes transmitter release. Other dementia-related proteins, namely Tau and apoE, interact with and are ubiquitinated via the ACR in vitro. This, and the evidence that CRBN and CUL4B are linked to intellectual disability, prompts us to hypothesize a pathogenic mechanism, in which APP acts as a modulator of E3 ubiquitin-protein ligase(s), shared by distinct neuronal disorders. The well described accumulation of ubiquitinated protein inclusions in neurodegenerative diseases and the link between the ubiquitin-proteasome system and neurodegeneration make this concept plausible.

scholarly journals Proteostasis and Mitochondrial Role on Psychiatric and Neurodegenerative Disorders: Current Perspectives

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Pablo Olivero ◽  
Carlo Lozano ◽  
Ramón Sotomayor-Zárate ◽  
Nicolás Meza-Concha ◽  
Marcelo Arancibia ◽  
...  
Keyword(s):  
Neurodegenerative Disorders ◽  
Protein Misfolding ◽  
Cell Damage ◽  
Mitochondrial Dynamics ◽  
Ubiquitin Proteasome System ◽  
Compensatory Mechanisms ◽  
Mitochondrial Functions ◽  
Ubiquitin Proteasome ◽  
Psychiatric Conditions ◽  
Therapeutic Alternatives

Proteostasis involves processes that are fundamental for neural viability. Thus, protein misfolding and the formation of toxic aggregates at neural level, secondary to dysregulation of the conservative mechanisms of proteostasis, are associated with several neuropsychiatric conditions. It has been observed that impaired mitochondrial function due to a dysregulated proteostasis control system, that is, ubiquitin-proteasome system and chaperones, could also have effects on neurodegenerative disorders. We aimed to critically analyze the available findings regarding the neurobiological implications of proteostasis on the development of neurodegenerative and psychiatric diseases, considering the mitochondrial role. Proteostasis alterations in the prefrontal cortex implicate proteome instability and accumulation of misfolded proteins. Altered mitochondrial dynamics, especially in proteostasis processes, could impede the normal compensatory mechanisms against cell damage. Thereby, altered mitochondrial functions on regulatory modulation of dendritic development, neuroinflammation, and respiratory function may underlie the development of some psychiatric conditions, such as schizophrenia, being influenced by a genetic background. It is expected that with the increasing evidence about proteostasis in neuropsychiatric disorders, new therapeutic alternatives will emerge.

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