Ubiquitin-Dependent Proteolysis in Neurons

Physiology ◽  
2003 ◽  
Vol 18 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Lars Klimaschewski
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Degradation ◽  
Current Knowledge ◽  
Neurological Diseases ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Present Review ◽  
Major Protein ◽  
Ubiquitin Proteasome ◽  
The Brain

Various studies identified the ubiquitin-proteasome system as the prime suspect in causing neurodegenerative diseases. The present review summarizes our current knowledge about the expression, regulation, and functions of this major protein degradation pathway in the brain, with particular reference to the pathogenesis of associated neurological diseases.

scholarly journals Methods to Discover and Evaluate Proteasome Small Molecule Stimulators

Molecules ◽  
2019 ◽  
Vol 24 (12) ◽  
pp. 2341 ◽  
Author(s):  
Rachel A. Coleman ◽  
Darci J. Trader
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Degradation ◽  
Small Molecule ◽  
Protease Activity ◽  
Ubiquitin Proteasome System ◽  
Proteasome Activity ◽  
Protein Accumulation ◽  
Toxic Protein ◽  
Disease States ◽  
Ubiquitin Proteasome

Protein accumulation has been identified as a characteristic of many degenerative conditions, such as neurodegenerative diseases and aging. In most cases, these conditions also present with diminished protein degradation. The ubiquitin-proteasome system (UPS) is responsible for the degradation of the majority of proteins in cells; however, the activity of the proteasome is reduced in these disease states, contributing to the accumulation of toxic protein. It has been hypothesized that proteasome activity, both ubiquitin-dependent and -independent, can be chemically stimulated to reduce the load of protein in diseased cells. Several methods exist to identify and characterize stimulators of proteasome activity. In this review, we detail the ways in which protease activity can be enhanced and analyze the biochemical and cellular methods of identifying stimulators of both the ubiquitin-dependent and -independent proteasome activities.

scholarly journals Blood–Brain Barrier and Neurodegenerative Diseases—Modeling with iPSC-Derived Brain Cells

2021 ◽  
Vol 22 (14) ◽  
pp. 7710
Author(s):  
Ying-Chieh Wu ◽  
Tuuli-Maria Sonninen ◽  
Sanni Peltonen ◽  
Jari Koistinaho ◽  
Šárka Lehtonen
Keyword(s):  
Stem Cell ◽  
Neurodegenerative Diseases ◽  
Blood Brain Barrier ◽  
Current Knowledge ◽  
Neurological Diseases ◽  
Induced Pluripotent Stem Cell ◽  
Brain Barrier ◽  
Blood Brain ◽  
Induced Pluripotent ◽  
The Brain

The blood–brain barrier (BBB) regulates the delivery of oxygen and important nutrients to the brain through active and passive transport and prevents neurotoxins from entering the brain. It also has a clearance function and removes carbon dioxide and toxic metabolites from the central nervous system (CNS). Several drugs are unable to cross the BBB and enter the CNS, adding complexity to drug screens targeting brain disorders. A well-functioning BBB is essential for maintaining healthy brain tissue, and a malfunction of the BBB, linked to its permeability, results in toxins and immune cells entering the CNS. This impairment is associated with a variety of neurological diseases, including Alzheimer’s disease and Parkinson’s disease. Here, we summarize current knowledge about the BBB in neurodegenerative diseases. Furthermore, we focus on recent progress of using human-induced pluripotent stem cell (iPSC)-derived models to study the BBB. We review the potential of novel stem cell-based platforms in modeling the BBB and address advances and key challenges of using stem cell technology in modeling the human BBB. Finally, we highlight future directions in this area.

scholarly journals Intracellular Dynamics of the Ubiquitin-Proteasome-System

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 367 ◽  
Author(s):  
Maisha Chowdhury ◽  
Cordula Enenkel
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Yeast Cells ◽  
Ubiquitin Chain ◽  
Dividing Cells ◽  
Ubiquitin Proteasome

The ubiquitin-proteasome system is the major degradation pathway for short-lived proteins in eukaryotic cells. Targets of the ubiquitin-proteasome-system are proteins regulating a broad range of cellular processes including cell cycle progression, gene expression, the quality control of proteostasis and the response to geno- and proteotoxic stress. Prior to degradation, the proteasomal substrate is marked with a poly-ubiquitin chain. The key protease of the ubiquitin system is the proteasome. In dividing cells, proteasomes exist as holo-enzymes composed of regulatory and core particles. The regulatory complex confers ubiquitin-recognition and ATP dependence on proteasomal protein degradation. The catalytic sites are located in the proteasome core particle. Proteasome holo-enzymes are predominantly nuclear suggesting a major requirement for proteasomal proteolysis in the nucleus. In cell cycle arrested mammalian or quiescent yeast cells, proteasomes deplete from the nucleus and accumulate in granules at the nuclear envelope (NE) / endoplasmic reticulum ( ER) membranes. In prolonged quiescence, proteasome granules drop off the nuclear envelopeNE / ER membranes and migrate as droplet-like entitiesstable organelles  throughout the cytoplasm, as thoroughly investigated in yeast. When quiescence yeast cells are allowed to resume growth, proteasome granules clear and proteasomes are rapidly imported into the nucleus.Here, we summarize our knowledge about the enigmatic structure of proteasome storage granules and the trafficking of proteasomes and their substrates between the cyto- and nucleoplasm.Most of our current knowledge is based on studies in yeast. Their translation to mammalian cells promises to provide keen insight into protein degradation in non-dividing cells, which comprise the majority of our body’s cells.

scholarly journals The switch-like expression of heme-regulated kinase 1 mediates neuronal proteostasis following proteasome inhibition

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Beatriz Alvarez-Castelao ◽  
Susanne tom Dieck ◽  
Claudia M Fusco ◽  
Paul Donlin-Asp ◽  
Julio D Perez ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Kinase Inhibitor ◽  
Neuronal Cell ◽  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Major Protein ◽  
Protein Levels ◽  
Eif2α Phosphorylation

We examined the feedback between the major protein degradation pathway, the ubiquitin-proteasome system (UPS), and protein synthesis in rat and mouse neurons. When protein degradation was inhibited, we observed a coordinate dramatic reduction in nascent protein synthesis in neuronal cell bodies and dendrites. The mechanism for translation inhibition involved the phosphorylation of eIF2α, surprisingly mediated by eIF2α kinase 1, or heme-regulated kinase inhibitor (HRI). Under basal conditions, neuronal expression of HRI is barely detectable. Following proteasome inhibition, HRI protein levels increase owing to stabilization of HRI and enhanced translation, likely via the increased availability of tRNAs for its rare codons. Once expressed, HRI is constitutively active in neurons because endogenous heme levels are so low; HRI activity results in eIF2α phosphorylation and the resulting inhibition of translation. These data demonstrate a novel role for neuronal HRI that senses and responds to compromised function of the proteasome to restore proteostasis.

Targeting Protein Degradation in Cancer Treatment

2020 ◽  
Vol 14 ◽  
Author(s):  
Imane Bjij ◽  
Ismail Hdoufane ◽  
Mahmoud Soliman ◽  
Menče Najdoska-Bogdanov ◽  
Driss Cherqaoui
Keyword(s):  
Protein Degradation ◽  
Therapeutic Potential ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Cellular Protein ◽  
Cellular Level ◽  
Cancerous Cell ◽  
Promising Target ◽  
Anti Cancer ◽  
Ubiquitin Proteasome

: The ubiquitin proteasome system (UPS) is a crucial protein degradation pathway that involves several enzymes to maintain cellular protein homeostasis. This system has emerged as a major drug target against certain types of cancer as a disruption at the cellular level of UPS enzyme components forces the transformation of normal cell into cancerous cell. Although enormous advancements have been achieved in the understanding of tumorigenesis, efficient cancer therapy remains a goal towards alleviating this serious health issue. Since UPS has become a promising target for anticancer therapies, herein we provide comprehensive review of the ubiquitin proteasome system as a significant process for protein degradation. Herein, the anti-cancer therapeutic potential of this pathway is also discussed.

scholarly journals Canonical and non-canonical autophagy pathways in microglia

2020 ◽  
Author(s):  
Julia Jülg ◽  
Laura Strohm ◽  
Christian Behrends
Keyword(s):  
Neurodegenerative Disorders ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Brain Health ◽  
The Past ◽  
Long Time ◽  
Ubiquitin Proteasome ◽  
Autophagy Activity

Besides the ubiquitin-proteasome-system, autophagy is a major degradation pathway within cells. It delivers invading pathogens, damaged organelles, aggregated proteins and other macromolecules from the cytosol to the lysosome for bulk degradation. This so-called canonical autophagy activity contributes to the maintenance of organelle, protein and metabolite homeostasis as well as innate immunity. Over the past years, numerous studies rapidly deepened our knowledge on the autophagy machinery and its regulation; driven by the fact that impairment of autophagy is associated with several human pathologies including cancer, immune diseases and neurodegenerative disorders. Unexpectedly, components of the autophagic machinery were also found to participate in various processes that did not involve lysosomal delivery of cytosolic constituents. These functions are hereafter defined as non-canonical autophagy. Regarding neurodegenerative diseases, most research was performed in neurons, while for a long-time microglia received considerably less attention. Concomitant with the notion that microglia greatly contribute to brain health, the understanding of the role of autophagy in microglia expanded. To facilitate an overview of the current knowledge, we present herein the fundamentals as well as the recent advances of canonical and non-canonical autophagy functions in microglia.

scholarly journals Chemical-Mediated Targeted Protein Degradation in Neurodegenerative Diseases

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 607
Author(s):  
Soonsil Hyun ◽  
Dongyun Shin
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Degradation ◽  
Drug Targets ◽  
Ubiquitin Proteasome System ◽  
Cellular Protein ◽  
Therapeutic Modality ◽  
Target Proteins ◽  
Bifunctional Molecules ◽  
Ubiquitin Proteasome ◽  
Related Proteins

Neurodegenerative diseases, including Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease, are a class of diseases that lead to dysfunction of cognition and mobility. Aggregates of misfolded proteins such as β-amyloid, tau, α-synuclein, and polyglutamates are known to be among the main causes of neurodegenerative diseases; however, they are considered to be some of the most challenging drug targets because they cannot be modulated by conventional small-molecule agents. Recently, the degradation of target proteins by small molecules has emerged as a new therapeutic modality and has garnered the interest of the researchers in the pharmaceutical industry. Bifunctional molecules that recruit target proteins to a cellular protein degradation machinery, such as the ubiquitin–proteasome system and autophagy–lysosome pathway, have been designed. The representative targeted protein degradation technologies include molecular glues, proteolysis-targeting chimeras, hydrophobic tagging, autophagy-targeting chimeras, and autophagosome-tethering compounds. Although these modalities have been shown to degrade many disease-related proteins, such technologies are expected to be potentially important for neurogenerative diseases caused by protein aggregation. Herein, we review the recent progress in chemical-mediated targeted protein degradation toward the discovery of drugs for neurogenerative diseases.

Degradation of tau protein by autophagy and proteasomal pathways

2012 ◽  
Vol 40 (4) ◽  
pp. 644-652 ◽  
Author(s):  
Yipeng Wang ◽  
Eckhard Mandelkow
Keyword(s):  
Neurodegenerative Diseases ◽  
Protein Degradation ◽  
Tau Protein ◽  
Therapeutic Strategy ◽  
Ubiquitin Proteasome System ◽  
Memory Deficit ◽  
Ubiquitin Proteasome ◽  
Ad Alzheimer’S Disease ◽  
Tau Aggregation ◽  
Stimulation Of

Tau aggregates are present in several neurodegenerative diseases and correlate with the severity of memory deficit in AD (Alzheimer's disease). However, the triggers of tau aggregation and tau-induced neurodegeneration are still elusive. The impairment of protein-degradation systems might play a role in such processes, as these pathways normally keep tau levels at a low level which may prevent aggregation. Some proteases can process tau and thus contribute to tau aggregation by generating amyloidogenic fragments, but the complete clearance of tau mainly relies on the UPS (ubiquitin–proteasome system) and the ALS (autophagy–lysosome system). In the present paper, we focus on the regulation of the degradation of tau by the UPS and ALS and its relation to tau aggregation. We anticipate that stimulation of these two protein-degradation systems might be a potential therapeutic strategy for AD and other tauopathies.

scholarly journals Neuronal Proteostasis is mediated by the switch-like expression of Heme-regulated Kinase 1, acting as both a sensor and effector

2019 ◽  
Author(s):  
Beatriz Alvarez-Castelao ◽  
Susanne tom Dieck ◽  
Claudia M. Fusco ◽  
Paul G. Donlin-Asp ◽  
Julio D. Perez ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Kinase Inhibitor ◽  
Neuronal Cell ◽  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
Degradation Pathway ◽  
Major Protein ◽  
Early Protein ◽  
Constitutively Active

AbstractAll cells, including neurons, have regulatory feedback mechanisms that couple protein synthesis and degradation to maintain and optimize protein concentrations in the face of intra- and extracellular perturbations. We examined the feedback between the major protein degradation pathway, the ubiquitin-proteasome system (UPS), and protein synthesis in neurons. When protein degradation by the UPS was inhibited we observed a coordinate dramatic reduction in nascent protein synthesis in both neuronal cell bodies and dendrites. The mechanism for translation inhibition involved the phosphorylation of eIF2a, surprisingly mediated by eIF2a kinase 1, or heme-regulated kinase inhibitor (HRI), known for its sensitivity to heme levels in erythrocyte precursors (Han et al., 2001). Under basal conditions, neuronal expression of HRI is barely detectable. Following proteasome inhibition, HRI protein levels increase owing to stabilization of the short-lived HRI protein and enhanced translation via the increased availability of tRNAs for rare codons. Once expressed, HRI is constitutively active in neurons because endogenous heme levels are so low; HRI activity results in eIF2a phosphorylation and the resulting inhibition of translation. These data demonstrate a novel role for HRI in neurons, acting as an “immediate early protein” that senses and responds to compromised function of the proteasome to restore proteostasis.One sentence summaryProteasome inhibition leads to a compensatory reduction in neuronal protein synthesis via the stabilization and enhanced translation of short-lived HRI kinase, which is constitutively active upon expression owing to low neuronal heme levels.

scholarly journals The Role of Primary Cilia in the Crosstalk between the Ubiquitin–Proteasome System and Autophagy

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 241 ◽  
Author(s):  
Antonia Wiegering ◽  
Ulrich Rüther ◽  
Christoph Gerhardt
Keyword(s):  
Protein Degradation ◽  
Primary Cilia ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Review Article ◽  
The Other ◽  
Novel Studies ◽  
Safety Mechanism ◽  
Ubiquitin Proteasome

Protein degradation is a pivotal process for eukaryotic development and homeostasis. The majority of proteins are degraded by the ubiquitin–proteasome system and by autophagy. Recent studies describe a crosstalk between these two main eukaryotic degradation systems which allows for establishing a kind of safety mechanism. If one of these degradation systems is hampered, the other compensates for this defect. The mechanism behind this crosstalk is poorly understood. Novel studies suggest that primary cilia, little cellular protrusions, are involved in the regulation of the crosstalk between the two degradation systems. In this review article, we summarise the current knowledge about the association between cilia, the ubiquitin–proteasome system and autophagy.

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