Synthesis and Application of a Clickable Epoxomicin‐Based Probe for Proteasome Activity Analysis

Salazar-Chaparro, Andres F; Halder, Saayak; Trader, Darci J.

doi:10.1002/cpz1.490

Cited by 6 publications

(5 citation statements)

References 26 publications

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“…To test the role for proteasomes in any physiology, the gold standard experiments are to either interfere with the factors important for substrate ubiquitylation and delivery 81 or to impinge on the proteasome itself using inhibitors 49, 82 . Such studies have not been able to determine the sole action of NMPs or cytosolic proteasomes because of compensatory responses by autophagy or the proteasome bounce-back response.…”

Section: Discussionmentioning

confidence: 99%

Dysregulation of neuroproteasomes by ApoE isoforms drives endogenous Tau aggregation

Paradise

Sabu

Bafia

et al. 2022

Preprint

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Neuronal membrane proteasomes (NMPs) are a functionally transmembrane subset of 20S proteasomes that degrade newly synthesized proteins. To date, the molecular composition of NMPs is undefined, and moreover, whether NMPs can influence any aspect of protein aggregation with relevance to neurodegenerative disorders remains unexplored. Using a Cre-dependent conditional knock-in mouse line to endogenously tag the proteasome, we find that NMPs co-purify with ApoE. We discover that NMP membrane localization is differentially modulated by ApoE isoforms (E4<E3<E2)in vitro,in vivo, and in human postmortem samples. This isoform-dependent change in NMP localization inversely correlates with the risk that ApoE isoforms pose for Alzheimer’s Disease. ApoE4-dependent reduction of NMP localization is strongest in brain regions selectively vulnerable to neurodegeneration. We synthesized selective NMP-specific inhibitors and discovered that NMP inhibition induces aggregation of endogenous and newly synthesized mouse and human Tau isoforms, without the need for seeding or pathogenic mutations. We posit that newly synthesized Tau is exceptionally susceptible to aggregation due to NMP dysfunction. Stereotactic injection of NMP inhibitorsin vivoinduces aggregation, phosphorylation, somatodendritic mislocalization and pathology of endogenous newly synthesized Tau. Finally, using ApoE-KI/hTau-KI crosses, we find that ApoE isoforms differentially shift the aggregation threshold for Tau. Overall, our data define NMPs as a pivotal proteostasis mechanism underlying the formation of endogenous Tau aggregates, which is directly regulated by the largest genetic risk factor for late-onset Alzheimer’s Disease.

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Section: Discussionmentioning

confidence: 99%

Dysregulation of neuroproteasomes by ApoE isoforms drives endogenous Tau aggregation

Paradise

Sabu

Bafia

et al. 2022

Preprint

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“…Flow cytometry allows for the study of proteasomal activity in physiologically relevant conditions and presents a highthroughput alternative to traditional gel electrophoresis and western blotting techinques. [67][68][69] To test the assay, a covalent fluorescent-based probe [70,71] was applied in HEK293T cells to quantify proteasome stimulation of CyPPSs, a known proteasome stimulator (miconazole [MO]) and proteasome inhibitor (MG132) (Figure S3). The covalent fluorescent-based probe is based on the proteasome inhibitor epoxomicin, which interacts with the β5 subunit of the proteasome, with a fluorophore appended to the N-termini.…”

Section: Cell-based Activitymentioning

confidence: 99%

Discovery and Development of Cyclic Peptide Proteasome Stimulators

Nelson,

Harris,

Muli

et al. 2023

ChemBioChem

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The proteasome degrades proteins, which is essential for cellular homeostasis. Ubiquitin independent proteolysis degrades highly disordered and misfolded proteins. A decline of proteasomal activity has been associated with multiple neurodegenerative diseases due to the accumulation of misfolded proteins. In this work, cyclic peptide proteasome stimulators (CyPPSs) that enhance the clearance of misfolded proteins were discovered. In the initial screen of predicted natural products (pNPs), several cyclic peptides were found to stimulate the 20S core particle (20S CP). Development of a robust structural activity relationship led to the identification of potent, cell permeable CyPPSs. In vitro assays revealed that CyPPSs stimulate degradation of highly disordered and misfolded proteins without affecting ordered proteins. Furthermore, using a novel flow‐based assay for proteasome activity, several CyPPSs were found to stimulate the 20S CP in cellulo. Overall, this work describes the development of CyPPSs as chemical tools capable of stimulating the proteasome and provides strong support for proteasome stimulation as a therapeutic strategy for neurodegenerative diseases.

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“…Both meiotic and mitotic cell errors occur spontaneously in plants through variable frequencies depending on the species. This is a widespread phenomenon, occurring naturally and very gradually in flowering plants, but can also be rapidly synthetically induced using mutagenic chemicals such as colchicine, oryzalin, epoxomicin, and nitroxide as described in Figure 1 [ 14 , 15 , 16 ].…”

Section: Role Of Autopolyploidy On Legume Response To Salinity Stressmentioning

confidence: 99%

“… Chemical structures of naturally and synthetically produced mutagenic compounds are used to achieve the multiplication of complete sets of chromosomes and the production of random mutations in the genetic materials of plant species, giving rise to the formation of new genetic variations. These multiple sets of chromosomes and nucleotide alterations (particularly, the substitution of guanine (G)- cytosine (C) to adenine (A) alkylation [G:C to A] induced by ethyl methane sulfonate) may take place in one nucleus and can be stably inherited to progenies [ 12 , 14 , 16 ]. …”

Section: Figurementioning

confidence: 99%

Cell Mutagenic Autopolyploidy Enhances Salinity Stress Tolerance in Leguminous Crops

Mangena

2023

Cells

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Salinity stress affects plant growth and development by causing osmotic stress and nutrient imbalances through excess Na+, K+, and Cl− ion accumulations that induce toxic effects during germination, seedling development, vegetative growth, flowering, and fruit set. However, the effects of salt stress on growth and development processes, especially in polyploidized leguminous plants, remain unexplored and scantly reported compared to their diploid counterparts. This paper discusses the physiological and molecular response of legumes towards salinity stress-based osmotic and ionic imbalances in plant cells. A multigenic response involving various compatible solutes, osmolytes, ROS, polyamines, and antioxidant activity, together with genes encoding proteins involved in the signal transduction, regulation, and response mechanisms to this stress, were identified and discussed. This discussion reaffirms polyploidization as the driving force in plant evolution and adaptation to environmental stress constraints such as drought, feverish temperatures, and, in particular, salt stress. As a result, thorough physiological and molecular elucidation of the role of gene duplication through induced autopolyploidization and possible mechanisms regulating salinity stress tolerance in grain legumes must be further studied.

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Synthesis and Application of a Clickable Epoxomicin‐Based Probe for Proteasome Activity Analysis

Cited by 6 publications

References 26 publications

Dysregulation of neuroproteasomes by ApoE isoforms drives endogenous Tau aggregation

Dysregulation of neuroproteasomes by ApoE isoforms drives endogenous Tau aggregation

Discovery and Development of Cyclic Peptide Proteasome Stimulators

Cell Mutagenic Autopolyploidy Enhances Salinity Stress Tolerance in Leguminous Crops

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