scholarly journals Innate immunity to yeast prions: Btn2p and Cur1p curing of the [URE3] prion is prevented by 60S ribosomal protein deficiency or ubiquitin/proteasome system overactivity

Genetics ◽  
2021 ◽  
Author(s):  
Evgeny E Bezsonov ◽  
Herman K Edskes ◽  
Reed B Wickner
Keyword(s):  
Ubiquitin Ligase ◽  
Ribosomal Subunit ◽  
Ubiquitin Proteasome System ◽  
Negative Regulator ◽  
Large Ribosomal Subunit ◽  
Seed Number ◽  
Wild Type ◽  
Yeast Prions ◽  
In The Wild ◽  
Ubiquitin Proteasome

Abstract [URE3] is an amyloid-based prion of Ure2p, a negative regulator of poor nitrogen source catabolism in Saccharomyces cerevisiae. Overproduced Btn2p or its paralog Cur1p, in processes requiring Hsp42, cure the [URE3] prion. Btn2p cures by collecting Ure2p amyloid filaments at one place in the cell. We find that rpl4aΔ, rpl21aΔ, rpl21bΔ, rpl11bΔ and rpl16bΔ (large ribosomal subunit proteins) or ubr2Δ (ubiquitin ligase targeting Rpn4p, an activator of proteasome genes) reduce curing by overproduced Btn2p or Cur1p. Impaired curing in ubr2Δ or rpl21bΔ is restored by an rpn4Δ mutation. No effect of rps14aΔ or rps30bΔ on curing was observed, indicating that 60S subunit deficiency specifically impairs curing. Levels of Hsp42p, Sis1p or Btn3p are unchanged in rpl4aΔ, rpl21bΔ or ubr2Δ mutants. Overproduction of Cur1p or Btn2p was enhanced in rpn4Δ and hsp42Δ mutants, lower in ubr2Δ strains, and restored to above wild type levels in rpn4Δ ubr2Δ strains. As in the wild-type, Ure2N-GFP colocalizes with Btn2-RFP in rpl4aΔ, rpl21bΔ or ubr2Δ strains, but not in hsp42Δ. Btn2p/Cur1p overproduction cures [URE3] variants with low seed number, but seed number is not increased in rpl4aΔ, rpl21bΔ or ubr2Δ mutants. Knockouts of genes required for the protein sorting function of Btn2p did not affect curing of [URE3], nor did inactivation of the Hsp104 prion-curing activity. Overactivity of the ubiquitin/proteasome system, resulting from 60S subunit deficiency or ubr2Δ, may impair Cur1p and Btn2p curing of [URE3] by degrading Cur1p, Btn2p or another component of these curing systems.

scholarly journals CBL-C E3 ubiquitin ligase acts as a host defense to mediate ubiquitin-proteasomal degradation of enteropathogenic Escherichia coli Tir protein

2021 ◽  
Author(s):  
Jinhyeob Ryu ◽  
Ryota Otsubo ◽  
Hiroshi Ashida ◽  
Tamako Iida ◽  
Akio Abe ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cell ◽  
Host Defense ◽  
Ubiquitin Ligase ◽  
Bacterial Colonization ◽  
Ubiquitin Proteasome System ◽  
Host Cells ◽  
Wild Type ◽  
Ubiquitin Protein Ligase ◽  
Ubiquitin Proteasome

SummaryTranslocated intimin receptor (Tir) is an essential bacterial factor for enteropathogenic Escherichia coli (EPEC) to establish Tir-intimin interaction-mediated adherence to the epithelial cell and to form actin pedestal structures beneath the adherent bacteria. However, it remains unclear how the host cells eliminate Tir protein after infection. Here we show that intracellular translocated Tir is degraded via the host ubiquitin- proteasome system. We found that host CBL-C, an E3 ubiquitin-protein ligase, bound to and ubiquitinated the 454 tyrosine-phosphorylated Tir protein. Tir ubiquitination leads to proteasome-dependent degradation and attenuated EPEC colonization of the epithelial cell. Using Citrobacter rodentium, a mouse model for EPEC, we demonstrated that infection with C. rodentium mutant expressing a tyrosine- phenylalanine-substituted Tir (CBL-C resistant) showed increased bacterial loads in the colon and lethality compared with infection with C. rodentium expressing wild-type Tir. These results indicate that CBL-C is a critical host defense factor that determines the fate of cytosolic Tir and terminates bacterial colonization.Graphical Abstracts

scholarly journals Interaction between Parkin and α-Synuclein in PARK2-Mediated Parkinson’s Disease

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 283
Author(s):  
Daniel Aghaie Madsen ◽  
Sissel Ida Schmidt ◽  
Morten Blaabjerg ◽  
Morten Meyer
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Ubiquitin Ligase ◽  
Current Knowledge ◽  
Lewy Bodies ◽  
Ubiquitin Proteasome System ◽  
Loss Of Function ◽  
Functional Interaction ◽  
Future Studies ◽  
Ubiquitin Proteasome

Parkin and α-synuclein are two key proteins involved in the pathophysiology of Parkinson’s disease (PD). Neurotoxic alterations of α-synuclein that lead to the formation of toxic oligomers and fibrils contribute to PD through synaptic dysfunction, mitochondrial impairment, defective endoplasmic reticulum and Golgi function, and nuclear dysfunction. In half of the cases, the recessively inherited early-onset PD is caused by loss of function mutations in the PARK2 gene that encodes the E3-ubiquitin ligase, parkin. Parkin is involved in the clearance of misfolded and aggregated proteins by the ubiquitin-proteasome system and regulates mitophagy and mitochondrial biogenesis. PARK2-related PD is generally thought not to be associated with Lewy body formation although it is a neuropathological hallmark of PD. In this review article, we provide an overview of post-mortem neuropathological examinations of PARK2 patients and present the current knowledge of a functional interaction between parkin and α-synuclein in the regulation of protein aggregates including Lewy bodies. Furthermore, we describe prevailing hypotheses about the formation of intracellular micro-aggregates (synuclein inclusions) that might be more likely than Lewy bodies to occur in PARK2-related PD. This information may inform future studies aiming to unveil primary signaling processes involved in PD and related neurodegenerative disorders.

scholarly journals Selective Microautophagy of Proteasomes is Initiated by ESCRT-0 and Is Promoted by Proteasome Ubiquitylation

2021 ◽  
Author(s):  
Jianhui Li ◽  
Mark Hochstrasser
Keyword(s):  
Ubiquitin Ligase ◽  
Normal Growth ◽  
Ubiquitin Proteasome System ◽  
Growth Conditions ◽  
Endosomal Sorting ◽  
Glucose Depletion ◽  
Ubiquitin Binding ◽  
Ubiquitin Proteasome ◽  
Low Glucose ◽  
Amp Activated Protein Kinase

The proteasome is central to proteolysis by the ubiquitin-proteasome system under normal growth conditions but is itself degraded through macroautophagy under nutrient stress. A recently described AMPK (AMP-activated protein kinase)-regulated ESCRT (endosomal sorting complex required for transport)-dependent microautophagy pathway also regulates proteasome trafficking and degradation in low glucose conditions in yeast. Aberrant proteasomes are more prone to microautophagy, suggesting the ESCRT system fine-tunes proteasome quality control under low glucose stress. Here we uncover additional features of the selective microautophagy of proteasomes. Genetic or pharmacological induction of aberrant proteasomes is associated with increased mono- or oligo-ubiquitylation of proteasome components, which appear to be recognized by ESCRT-0. AMPK controls this pathway in part by regulating the trafficking of ESCRT-0 to the vacuole surface, which also leads to degradation of the Vps27 subunit of ESCRT-0. The Rsp5 ubiquitin ligase contributes to proteasome subunit ubiquitylation, and multiple ubiquitin-binding elements in Vps27 are involved in their recognition. We propose that ESCRT-0 at the vacuole surface recognizes ubiquitylated proteasomes and initiates their microautophagic elimination during glucose depletion.

scholarly journals USP7 inhibits Wnt/β-catenin signaling through promoting stabilization of Axin

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Lei Ji ◽  
Bo Lu ◽  
Raffaella Zamponi ◽  
Olga Charlat ◽  
Robert Aversa ◽  
...  
Keyword(s):  
Osteoblast Differentiation ◽  
Adipocyte Differentiation ◽  
Ubiquitin Proteasome System ◽  
Cellular Systems ◽  
Negative Regulator ◽  
Scaffolding Protein ◽  
Complex Stability ◽  
Genetic Ablation ◽  
Ubiquitin Proteasome ◽  
Potent Negative Regulator

Abstract Axin is a key scaffolding protein responsible for the formation of the β-catenin destruction complex. Stability of Axin protein is regulated by the ubiquitin-proteasome system, and modulation of cellular concentration of Axin protein has a profound effect on Wnt/β-catenin signaling. Although E3s promoting Axin ubiquitination have been identified, the deubiquitinase responsible for Axin deubiquitination and stabilization remains unknown. Here, we identify USP7 as a potent negative regulator of Wnt/β-catenin signaling through CRISPR screens. Genetic ablation or pharmacological inhibition of USP7 robustly increases Wnt/β-catenin signaling in multiple cellular systems. USP7 directly interacts with Axin through its TRAF domain, and promotes deubiquitination and stabilization of Axin. Inhibition of USP7 regulates osteoblast differentiation and adipocyte differentiation through increasing Wnt/β-catenin signaling. Our study reveals a critical mechanism that prevents excessive degradation of Axin and identifies USP7 as a target for sensitizing cells to Wnt/β-catenin signaling.

scholarly journals Effects of ubiquitin C-terminal hydrolase L1 deficiency on mouse ova

Reproduction ◽  
2012 ◽  
Vol 143 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Sayaka Koyanagi ◽  
Hiroko Hamasaki ◽  
Satoshi Sekiguchi ◽  
Kenshiro Hara ◽  
Yoshiyuki Ishii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Proteomic Analysis ◽  
Ubiquitin Proteasome System ◽  
Underlying Mechanism ◽  
Wild Type ◽  
Transmission Electron ◽  
Ubiquitin Proteasome

Maternal proteins are rapidly degraded by the ubiquitin–proteasome system during oocyte maturation in mice. Ubiquitin C-terminal hydrolase L1 (UCHL1) is highly and specifically expressed in mouse ova and is involved in the polyspermy block. However, the role of UCHL1 in the underlying mechanism of polyspermy block is poorly understood. To address this issue, we performed a comprehensive proteomic analysis to identify maternal proteins that were relevant to the role of UCHL1 in mouse ova using UCHL1-deficientgad. Furthermore, we assessed morphological features ingadmouse ova using transmission electron microscopy. NACHT, LRR, and PYD domain-containing (NALP) family proteins and endoplasmic reticulum (ER) chaperones were identified by proteomic analysis. We also found that the ‘maternal antigen that embryos require’ (NLRP5 (MATER)) protein level increased significantly ingadmouse ova compared with that in wild-type mice. In an ultrastructural study,gadmouse ova contained less ER in the cortex than in wild-type mice. These results provide new insights into the role of UCHL1 in the mechanism of polyspermy block in mouse ova.

scholarly journals Sexual Differentiation Is Coordinately Regulated by Cryptococcus neoformans CRK1 and GAT1

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 669
Author(s):  
Kuang-Hung Liu ◽  
Wei-Chiang Shen
Keyword(s):  
Cryptococcus Neoformans ◽  
Sexual Differentiation ◽  
Regulatory Networks ◽  
Genetic Interaction ◽  
Negative Regulator ◽  
Wild Type ◽  
Basidiomycetous Fungus ◽  
Regulatory Circuit ◽  
Expression Of Genes ◽  
In The Wild

The heterothallic basidiomycetous fungus Cryptococcus neoformans has two mating types, MATa and MATα. Morphological progression of bisexual reproduction in C. neoformans is as follows: yeast to hyphal transition, filament extension, basidium formation, meiosis, and sporulation. C. neoformans Cdk-related kinase 1 (CRK1) is a negative regulator of bisexual mating. In this study, we characterized the morphological features of mating structures in the crk1 mutant and determined the genetic interaction of CRK1 in the regulatory networks of sexual differentiation. In the bilateral crk1 mutant cross, despite shorter length of filaments than in the wild-type cross, dikaryotic filaments and other structures still remained intact during bisexual mating, but the timing of basidium formation was approximately 18 h earlier than in the cross between wild type strains. Furthermore, gene expression analyses revealed that CRK1 modulated the expression of genes involved in the progression of hyphal elongation, basidium formation, karyogamy and meiosis. Phenotypic results showed that, although deletion of C. neoformans CRK1 gene increased the efficiency of bisexual mating, filamentation in the crk1 mutant was blocked by MAT2 or ZNF2 mutation. A bioinformatics survey predicted the C. neoformans GATA transcriptional factor Gat1 as a potential substrate of Crk1 kinase. Our genetic and phenotypic findings revealed that C. neoformans GAT1 and CRK1 formed a regulatory circuit to negatively regulate MAT2 to control filamentation progression and transition during bisexual mating.

scholarly journals p97 Negatively Regulates NRF2 by Extracting Ubiquitylated NRF2 from the KEAP1-CUL3 E3 Complex

2017 ◽  
Vol 37 (8) ◽  
Author(s):  
Shasha Tao ◽  
Pengfei Liu ◽  
Gang Luo ◽  
Montserrat Rojo de la Vega ◽  
Heping Chen ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Protein Complexes ◽  
E3 Ubiquitin Ligase ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Ubiquitin Ligase Complex ◽  
Ubiquitin Proteasome ◽  
Client Proteins

ABSTRACT Activation of the stress-responsive transcription factor NRF2 is the major line of defense to combat oxidative or electrophilic insults. Under basal conditions, NRF2 is continuously ubiquitylated by the KEAP1-CUL3-RBX1 E3 ubiquitin ligase complex and is targeted to the proteasome for degradation (the canonical mechanism). However, the path from the CUL3 complex to ultimate proteasomal degradation was previously unknown. p97 is a ubiquitin-targeted ATP-dependent segregase that extracts ubiquitylated client proteins from membranes, protein complexes, or chromatin and has an essential role in autophagy and the ubiquitin proteasome system (UPS). In this study, we show that p97 negatively regulates NRF2 through the canonical pathway by extracting ubiquitylated NRF2 from the KEAP1-CUL3 E3 complex, with the aid of the heterodimeric cofactor UFD1/NPL4 and the UBA-UBX-containing protein UBXN7, for efficient proteasomal degradation. Given the role of NRF2 in chemoresistance and the surging interest in p97 inhibitors to treat cancers, our results indicate that dual p97/NRF2 inhibitors may offer a more potent and long-term avenue of p97-targeted treatment.

Gfi1 ubiquitination and proteasomal degradation is inhibited by the ubiquitin ligase Triad1

Blood ◽  
2007 ◽  
Vol 110 (9) ◽  
pp. 3128-3135 ◽  
Author(s):  
Jurgen A. F. Marteijn ◽  
Laurens T. van der Meer ◽  
Liesbeth van Emst ◽  
Simon van Reijmersdal ◽  
Willemijn Wissink ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Ubiquitin Ligase ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Binding Domain ◽  
U937 Cells ◽  
Dna Binding Domain ◽  
Protein Levels ◽  
Ubiquitin Ligase Activity ◽  
Ubiquitin Proteasome

Abstract Growth factor independence 1 (Gfi1) is a transcriptional repressor essential for the function and development of many different hematopoietic lineages. The Gfi1 protein expression is regulated by the ubiquitin-proteasome system. In granulocytes, Gfi1 is rapidly degraded by the proteasome, while it is more stable in monocytes. How the ubiquitination and degradation of Gfi1 is regulated is unclear. Here, we show that the ubiquitin ligase Triad1 interacts with the DNA-binding domain of Gfi1. Unexpectedly, we found that Triad1 inhibited Gfi1 ubiquitination, resulting in a prolonged half-life. Down-regulation of endogenous Triad1 by siRNAs resulted in increased Gfi1 ubiquitination. In U937 cells, Triad1 caused an increase in endogenous Gfi1 protein levels and slowed cell proliferation in a similar manner when Gfi1 itself was expressed. A Triad1 mutant that lacks the Gfi1-binding domain did not affect Gfi1 levels and proliferation. Because neither proteasome-ubiquitin nor Triad1 ubiquitin ligase activity was required for the inhibition of Gfi1 ubiquitination, these data suggest that Triad1 competes for Gfi1 binding with as yet to be identified E3 ubiquitin ligases that do mark Gfi1 for proteasomal degradation. The finetuning of Gfi1 protein levels regulated by Triad1 defines an unexpected role for this protein in hematopoiesis.

scholarly journals Aggregation and Prion-Inducing Properties of the G-Protein Gamma Subunit Ste18 are Regulated by Membrane Association

2020 ◽  
Vol 21 (14) ◽  
pp. 5038
Author(s):  
Tatiana A. Chernova ◽  
Zhen Yang ◽  
Tatiana S. Karpova ◽  
John R. Shanks ◽  
Natalia Shcherbik ◽  
...  
Keyword(s):  
G Protein ◽  
De Novo ◽  
Ubiquitin Proteasome System ◽  
Membrane Association ◽  
Protein Assemblies ◽  
Gamma Subunit ◽  
Yeast Prions ◽  
Extracellular Stimuli ◽  
Ubiquitin Proteasome ◽  
And Control

Yeast prions and mnemons are respectively transmissible and non-transmissible self-perpetuating protein assemblies, frequently based on cross-β ordered detergent-resistant aggregates (amyloids). Prions cause devastating diseases in mammals and control heritable traits in yeast. It was shown that the de novo formation of the prion form [PSI+] of yeast release factor Sup35 is facilitated by aggregates of other proteins. Here we explore the mechanism of the promotion of [PSI+] formation by Ste18, an evolutionarily conserved gamma subunit of a G-protein coupled receptor, a key player in responses to extracellular stimuli. Ste18 forms detergent-resistant aggregates, some of which are colocalized with de novo generated Sup35 aggregates. Membrane association of Ste18 is required for both Ste18 aggregation and [PSI+] induction, while functional interactions involved in signal transduction are not essential for these processes. This emphasizes the significance of a specific location for the nucleation of protein aggregation. In contrast to typical prions, Ste18 aggregates do not show a pattern of heritability. Our finding that Ste18 levels are regulated by the ubiquitin-proteasome system, in conjunction with the previously reported increase in Ste18 levels upon the exposure to mating pheromone, suggests that the concentration-dependent Ste18 aggregation may mediate a mnemon-like response to physiological stimuli.

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