scholarly journals SIP/CacyBP promotes autophagy by regulating levels of BRUCE/Apollon, which stimulates LC3-I degradation

2019 ◽  
Vol 116 (27) ◽  
pp. 13404-13413 ◽  
Author(s):  
Tian-Xia Jiang ◽  
Jiang-Bo Zou ◽  
Qian-Qian Zhu ◽  
Cui Hua Liu ◽  
Guang-Fei Wang ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cultured Cells ◽  
Proteasomal Degradation ◽  
Related Protein ◽  
Topoisomerase Inhibitors ◽  
Autophagosome Formation ◽  
Recycling Endosome ◽  
Proteasome Activator ◽  
Apoptosis Protein ◽  
Autophagic Degradation

BRUCE/Apollon is a membrane-associated inhibitor of apoptosis protein that is essential for viability and has ubiquitin-conjugating activity. On initiation of apoptosis, the ubiquitin ligase Nrdp1/RNF41 promotes proteasomal degradation of BRUCE. Here we demonstrate that BRUCE together with the proteasome activator PA28γ causes proteasomal degradation of LC3-I and thus inhibits autophagy. LC3-I on the phagophore membrane is conjugated to phosphatidylethanolamine to form LC3-II, which is required for the formation of autophagosomes and selective recruitment of substrates. SIP/CacyBP is a ubiquitination-related protein that is highly expressed in neurons and various tumors. Under normal conditions, SIP inhibits the ubiquitination and degradation of BRUCE, probably by blocking the binding of Nrdp1 to BRUCE. On DNA damage by topoisomerase inhibitors, Nrdp1 causes monoubiquitination of SIP and thus promotes apoptosis. However, on starvation, SIP together with Rab8 enhances the translocation of BRUCE into the recycling endosome, formation of autophagosomes, and degradation of BRUCE by optineurin-mediated autophagy. Accordingly, deletion of SIP in cultured cells reduces the autophagic degradation of damaged mitochondria and cytosolic protein aggregates. Thus, by stimulating proteasomal degradation of LC3-I, BRUCE also inhibits autophagy. Conversely, SIP promotes autophagy by blocking BRUCE-dependent degradation of LC3-I and by enhancing autophagosome formation and autophagic destruction of BRUCE. These actions of BRUCE and SIP represent mechanisms that link the regulation of autophagy and apoptosis under different conditions.

Abstract 085: CHIP: E3 Ubiquitin Ligase Mediates Proteasomal Degradation of Neuronal Nitric Oxide Synthase in the Paraventricular Nucleus of Rats with Heart Failure

Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Neeru M Sharma ◽  
Kenichi Katsurada ◽  
Xuefei Liu ◽  
Kaushik P Patel
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Nitric Oxide Synthase ◽  
Paraventricular Nucleus ◽  
Ubiquitin Ligase ◽  
Protein A ◽  
Neuronal Nitric Oxide Synthase ◽  
Proteasomal Degradation ◽  
Oxide Synthase

The exaggerated sympathetic drive is a characteristic of heart failure (HF) due to reduced neuronal nitric oxide synthase (nNOS) within the paraventricular nucleus (PVN). Previously we have shown that there were increased accumulation of nNOS-ubiquitin (nNOS-Ub) conjugates in the PVN of rats with HF (1.0±0.05 Sham vs. 1.29±0.06 HF) due to the increased levels of PIN (a protein inhibitor of nNOS, known to dissociate nNOS dimers into monomers) (0.76±0.10 Sham vs. 1.12±0.09 HF) and decreased levels of tetrahydrobiopterin (BH4): a cofactor required for stabilization of nNOS dimers (0.62±0.02 Sham vs. 0.44±0.03 HF). We also showed that there is blunted nitric oxide-mediated inhibition of sympathetic tone via the PVN in HF. Here we examined whether CHIP(C-terminus of Hsp70 -interacting protein), a chaperone-dependent E3 ubiquitin-protein isopeptide ligase known to ubiquitylate Hsp90-chaperoned proteins could act as an ubiquitin ligase for nNOS in the PVN. Immunofluorescence studies revealed colocalization of nNOS and CHIP in the PVN indicating their possible interaction. CHIP expression was increased by 50% in the PVN of rats with HF(0.96±0.08 Sham vs.1.44±0.10* HF). It is shown that Hsp90 protects nNOS from ubiquitination while Hsp70 promotes the ubiquitination and degradation. We observed significant upregulation of Hsp70 (0.49±0.03 Sham vs. 0.65±0.02* HF) with a trend toward the decrease in Hsp90 expression (0.90±0.07 Sham vs. 0.71±0.06 HF). The opposing effects of the two chaperones could account for the increased CHIP-mediated ubiquitination and degradation of dysfunctional nNOS monomers in the PVN of rats with HF. Furthermore, neuronal NG108-15 cell line transfected with the pCMV3-CHIP-GFP spark (CHIP overexpression plasmid) showed approximately 74% increase in CHIP with concomitant 49% decrease in nNOS expression. In vitro ubiquitination assay in NG108 cells transfected with pCMV-(HA-Ub) 8 and pCMV3-CHIP-GFP spark plasmid reveal increased HA-Ub-nNOS conjugates (1.13 ± 0.09 Scramble vs. 1.65 ± 0.12* CHIP plasmid). Taken together, our results identify CHIP as an E3 ligase for ubiquitination of dysfunctional nNOS and CHIP expression is augmented during HF leading to increased proteasomal degradation of nNOS in the PVN.

The ubiquitin specific protease USP34 protects the ubiquitin ligase gp78 from proteasomal degradation

2019 ◽  
Vol 509 (2) ◽  
pp. 348-353 ◽  
Author(s):  
Hui Wang ◽  
Donghong Ju ◽  
Dhong-Hyo Kho ◽  
Huanjie Yang ◽  
Li Li ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Proteasomal Degradation ◽  
Specific Protease ◽  
Ubiquitin Specific Protease

E3 ubiquitin ligase HECW2 mediates the proteasomal degradation of HP1 isoforms

2018 ◽  
Vol 503 (4) ◽  
pp. 2478-2484 ◽  
Author(s):  
Vidhya Krishnamoorthy ◽  
Richa Khanna ◽  
Veena K. Parnaik
Keyword(s):  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Proteasomal Degradation

scholarly journals The yeast arrestin-related protein Bul1 is a novel actor of glucose-induced endocytosis

2018 ◽  
Vol 29 (9) ◽  
pp. 1012-1020 ◽  
Author(s):  
Junie Hovsepian ◽  
Véronique Albanèse ◽  
Michel Becuwe ◽  
Vasyl Ivashov ◽  
David Teis ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Endocytic Pathway ◽  
Yeast Cells ◽  
Monocarboxylate Transporter ◽  
Related Protein ◽  
Related Family ◽  
Nutrient Signaling ◽  
Mechanistic Basis ◽  
A Current ◽  
Glucose Availability

Yeast cells have a remarkable ability to adapt to nutritional changes in their environment. During adaptation, nutrient-signaling pathways drive the selective endocytosis of nutrient transporters present at the cell surface. A current challenge is to understand the mechanistic basis of this regulation. Transporter endocytosis is triggered by their ubiquitylation, which involves the ubiquitin ligase Rsp5 and its adaptors of the arrestin-related family (ART). This step is highly regulated by nutrient availability. For instance, the monocarboxylate transporter Jen1 is ubiquitylated, endocytosed, and degraded upon exposure to glucose. The ART protein Rod1 is required for this overall process; yet Rod1 rather controls Jen1 trafficking later in the endocytic pathway and is almost dispensable for Jen1 internalization. Thus, how glucose triggers Jen1 internalization remains unclear. We report that another ART named Bul1, but not its paralogue Bul2, contributes to Jen1 internalization. Bul1 responds to glucose availability, and preferentially acts at the plasma membrane for Jen1 internalization. Thus, multiple ARTs can act sequentially along the endocytic pathway to control transporter homeostasis. Moreover, Bul1 is in charge of Jen1 endocytosis after cycloheximide treatment, suggesting that the functional redundancy of ARTs may be explained by their ability to interact with multiple cargoes in various conditions.

scholarly journals Helicobacter pylori infection impairs chaperone-assisted maturation of Na-K-ATPase in gastric epithelium

2020 ◽  
Vol 318 (5) ◽  
pp. G931-G945 ◽  
Author(s):  
Elizabeth A. Marcus ◽  
Elmira Tokhtaeva ◽  
Jossue L. Jimenez ◽  
Yi Wen ◽  
Bita V. Naini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Helicobacter Pylori ◽  
Cultured Cells ◽  
Proteasomal Degradation ◽  
Helicobacter Pylori Infection ◽  
Gastric Epithelium ◽  
Native Enzyme ◽  
Gastric Injury ◽  
Atpase Subunits ◽  
H Pylori

This work provides evidence that Helicobacter pylori decreases levels of Na-K-ATPase, a vital transport enzyme, in gastric epithelia, both in acutely infected cultured cells and in chronically infected patients and animals. The bacteria interfere with BiP-assisted folding of newly-made Na-K-ATPase subunits in the endoplasmic reticulum, accelerating their ubiquitylation and proteasomal degradation and decreasing efficiency of the assembly of native enzyme. Decreased Na-K-ATPase expression contributes to H. pylori-induced gastric injury.

scholarly journals Deubiquitinating enzyme USP30 maintains basal peroxisome abundance by regulating pexophagy

2019 ◽  
Vol 218 (3) ◽  
pp. 798-807 ◽  
Author(s):  
Victoria Riccio ◽  
Nicholas Demers ◽  
Rong Hua ◽  
Miluska Vissa ◽  
Derrick T. Cheng ◽  
...  
Keyword(s):  
Amino Acid ◽  
Ubiquitin Ligase ◽  
Cell Function ◽  
E3 Ubiquitin Ligase ◽  
Metabolic Stress ◽  
Amino Acid Starvation ◽  
Deubiquitinating Enzyme ◽  
Potential Therapeutic Target ◽  
Autophagic Degradation

The regulation of organelle abundance is critical for cell function and survival; however, the mechanisms responsible are not fully understood. In this study, we characterize a role of the deubiquitinating enzyme USP30 in peroxisome maintenance. Peroxisomes are highly dynamic, changing in abundance in response to metabolic stress. In our recent study identifying the role of USP30 in mitophagy, we observed USP30 to be localized to punctate structures resembling peroxisomes. We report here that USP30, best known as a mitophagy regulator, is also necessary for regulating pexophagy, the selective autophagic degradation of peroxisomes. We find that overexpressing USP30 prevents pexophagy during amino acid starvation, and its depletion results in pexophagy induction under basal conditions. We demonstrate that USP30 prevents pexophagy by counteracting the action of the peroxisomal E3 ubiquitin ligase PEX2. Finally, we show that USP30 can rescue the peroxisome loss observed in some disease-causing peroxisome mutations, pointing to a potential therapeutic target.

Dual regulation of transcription factor Nrf2 by Keap1 and by the combined actions of β-TrCP and GSK-3

2015 ◽  
Vol 43 (4) ◽  
pp. 611-620 ◽  
Author(s):  
John D. Hayes ◽  
Sudhir Chowdhry ◽  
Albena T. Dinkova-Kostova ◽  
Calum Sutherland
Keyword(s):  
Transcription Factor ◽  
Growth Factors ◽  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Glycogen Synthase ◽  
Proteasomal Degradation ◽  
Regulation Of Transcription ◽  
Related Factor ◽  
Nrf2 Target Gene ◽  
The Stability

Nuclear factor-erythroid 2 p45 (NF-E2 p45)-related factor 2 (Nrf2) is a master regulator of redox homoeostasis that allows cells to adapt to oxidative stress and also promotes cell proliferation. In this review, we describe the molecular mechanisms by which oxidants/electrophilic agents and growth factors increase Nrf2 activity. In the former case, oxidants/electrophiles increase the stability of Nrf2 by antagonizing the ability of Kelch-like ECH-associated protein 1 (Keap1) to target the transcription factor for proteasomal degradation via the cullin-3 (Cul3)–RING ubiquitin ligase CRLKeap1. In the latter case, we speculate that growth factors increase the stability of Nrf2 by stimulating phosphoinositide 3-kinase (PI3K)−protein kinase B (PKB)/Akt signalling, which in turn results in inhibitory phosphorylation of glycogen synthase kinase-3 (GSK-3) and in doing so prevents the formation of a DSGIS motif-containing phosphodegron in Nrf2 that is recognized by the β-transducin repeat-containing protein (β-TrCP) Cul1-based E3 ubiquitin ligase complex SCFβ-TrCP. We present data showing that in the absence of Keap1, the electrophile tert-butyl hydroquinone (tBHQ) can stimulate Nrf2 activity and induce the Nrf2-target gene NAD(P)H:quinone oxidoreductase-1 (NQO1), whilst simultaneously causing inhibitory phosphorylation of GSK-3β at Ser9. Together, these observations suggest that tBHQ can suppress the ability of SCFβ-TrCP to target Nrf2 for proteasomal degradation by increasing PI3K−PKB/Akt signalling. We also propose a scheme that explains how other protein kinases that inhibit GSK-3 could stimulate induction of Nrf2-target genes by preventing formation of the DSGIS motif-containing phosphodegron in Nrf2.

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