scholarly journals Oxidative stress–dependent phosphorylation activates ZNRF1 to induce neuronal/axonal degeneration

2015 ◽  
Vol 211 (4) ◽  
pp. 881-896 ◽  
Author(s):  
Shuji Wakatsuki ◽  
Akiko Furuno ◽  
Makiko Ohshima ◽  
Toshiyuki Araki
Keyword(s):  
Oxidative Stress ◽  
Ubiquitin Ligase ◽  
Wallerian Degeneration ◽  
Neuronal Apoptosis ◽  
Axonal Degeneration ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Growth Factor Receptor ◽  
Ubiquitin Proteasome System ◽  
Ubiquitin Ligase Activity ◽  
Stress Dependent

Oxidative stress is a well-known inducer of neuronal apoptosis and axonal degeneration. We previously showed that the E3 ubiquitin ligase ZNRF1 promotes Wallerian degeneration by degrading AKT to induce GSK3B activation. We now demonstrate that oxidative stress serves as an activator of the ubiquitin ligase activity of ZNRF1 by inducing epidermal growth factor receptor (EGFR)–mediated phosphorylation at the 103rd tyrosine residue and that the up-regulation of ZNRF1 activity by oxidative stress leads to neuronal apoptosis and Wallerian degeneration. We also show that nicotinamide adenine dinucleotide phosphate–reduced oxidase activity is required for the EGFR-dependent phosphorylation-induced activation of ZNRF1 and resultant AKT degradation via the ubiquitin proteasome system to induce Wallerian degeneration. These results indicate the pathophysiological significance of the EGFR–ZNRF1 pathway induced by oxidative stress in the regulation of neuronal apoptosis and Wallerian degeneration. A deeper understanding of the regulatory mechanism for ZNRF1 catalytic activity via phosphorylation will provide a potential therapeutic avenue for neurodegeneration.

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 Stress-induced phospho-ubiquitin formation causes parkin degradation

2018 ◽  
Author(s):  
Lyudmila Kovalchuke ◽  
Eugene V. Mosharov ◽  
Oren A. Levy ◽  
Lloyd A. Greene
Keyword(s):  
Oxidative Stress ◽  
Ubiquitin Ligase ◽  
Autosomal Recessive ◽  
Oxygen Species ◽  
Metabolic Dysfunction ◽  
Protein Levels ◽  
Sporadic Parkinson’S Disease ◽  
Stress Dependent ◽  
Dependent Pathway

Mutations in the E3 ubiquitin ligase parkin are the most common known cause of autosomal recessive parkinsonism. Multiple types of stress decrease parkin protein levels, an effect that may be relevant to sporadic Parkinson's disease (PD), but the mechanism(s) involved in this loss remain largely unclear. We sought to elucidate these mechanisms using a PD-relevant stressor, L-DOPA, the precursor to dopamine, which forms reactive oxygen species (ROS) as well as toxic quinones via auto-oxidation. We find that L-DOPA causes parkin loss through both an oxidative stress-independent and an oxidative stress-dependent pathway. Characterization of the latter reveals that it requires both the kinase PINK1 and parkin's interaction with phosphorylated ubiquitin (phospho-Ub) and is mediated by proteasomal degradation. Surprisingly, mitochondrial parkin activity and autoubiquitination as well as mitophagy are not required for such loss. During stress induced by the oxidative stressor hydrogen peroxide or the metabolic uncoupler CCCP, parkin degradation also requires its association with phospho-Ub, indicating that this mechanism is broadly generalizable. As oxidative stress, metabolic dysfunction and phospho-Ub levels are all elevated in PD patients, we suggest that these changes may lead to the loss of parkin expression in PD.

scholarly journals Linear Ubiquitination Mediates EGFR-Induced NF-κB Pathway and Tumor Development

2021 ◽  
Vol 22 (21) ◽  
pp. 11875
Author(s):  
Fang Hua ◽  
Wenzhuo Hao ◽  
Lingyan Wang ◽  
Shitao Li
Keyword(s):  
Cell Proliferation ◽  
Ubiquitin Ligase ◽  
Tumor Development ◽  
E3 Ubiquitin Ligase ◽  
Growth Factor Receptor ◽  
Ubiquitin Chain ◽  
Plakophilin 2 ◽  
Ubiquitin Ligase Activity ◽  
Signaling Axis ◽  
Differentiation And Proliferation

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that instigates several signaling cascades, including the NF-κB signaling pathway, to induce cell differentiation and proliferation. Overexpression and mutations of EGFR are found in up to 30% of solid tumors and correlate with a poor prognosis. Although it is known that EGFR-mediated NF-κB activation is involved in tumor development, the signaling axis is not well elucidated. Here, we found that plakophilin 2 (PKP2) and the linear ubiquitin chain assembly complex (LUBAC) were required for EGFR-mediated NF-κB activation. Upon EGF stimulation, EGFR recruited PKP2 to the plasma membrane, and PKP2 bridged HOIP, the catalytic E3 ubiquitin ligase in the LUBAC, to the EGFR complex. The recruitment activated the LUBAC complex and the linear ubiquitination of NEMO, leading to IκB phosphorylation and subsequent NF-κB activation. Furthermore, EGF-induced linear ubiquitination was critical for tumor cell proliferation and tumor development. Knockout of HOIP impaired EGF-induced NF-κB activity and reduced cell proliferation. HOIP knockout also abrogated the growth of A431 epidermal xenograft tumors in nude mice by more than 70%. More importantly, the HOIP inhibitor, HOIPIN-8, inhibited EGFR-mediated NF-κB activation and cell proliferation of A431, MCF-7, and MDA-MB-231 cancer cells. Overall, our study reveals a novel linear ubiquitination signaling axis of EGFR and that perturbation of HOIP E3 ubiquitin ligase activity is potential targeted cancer therapy.

scholarly journals Linear Ubiquitination Mediates EGFR-Induced NF-kB Pathway and Tumor Development

2021 ◽  
Author(s):  
Fang Hua ◽  
Wenzhuo Hap ◽  
Lingyan Wang ◽  
Shitao Li
Keyword(s):  
Cell Proliferation ◽  
Ubiquitin Ligase ◽  
Tumor Development ◽  
E3 Ubiquitin Ligase ◽  
Growth Factor Receptor ◽  
Signaling Cascades ◽  
Ubiquitin Ligase Activity ◽  
Signaling Axis ◽  
Epidermal Growth ◽  
Differentiation And Proliferation

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that instigates several signaling cascades, including the NF-kB signaling pathway, to induce cell differentiation and proliferation. Overexpression and mutations of EGFR are found in up to 30% of solid tumors and correlate with a poor prognosis. Although it is known that EGFR-mediated NF-kB activation is involved in tumor development, the signaling axis is not well elucidated. Here, we found that PKP2 and the LUBAC complex were required for EGFR-mediated NF-kB activation. Upon EGF stimulation, EGFR recruited PKP2 to the plasma membrane, and PKP2 bridged HOIP, the catalytic E3 ubiquitin ligase in the LUBAC, to the EGFR complex. The recruitment activated the LUBAC complex and the linear ubiquitination of NEMO, leading to IkB phosphorylation and subsequent NF-kB activation. Furthermore, EGF-induced linear ubiquitination was critical for tumor cell proliferation and tumor development. Knockout of HOIP impaired EGF-induced NF-kB activity and reduced cell proliferation. HOIP knockout also abrogated the growth of A431 epidermal xenograft tumors in nude mice by more than 70%. More importantly, the HOIP inhibitor, HOIPIN-8, inhibited EGFR-mediated NF-kB activation and cell proliferation of A431, MCF-7, and MDA-MB-231 cancer cells. Overall, our study reveals a novel linear ubiquitination signaling axis of EGFR, and perturbation of HOIP E3 ubiquitin ligase activity is potential targeted cancer therapy.

scholarly journals Stabilization of the E3 Ubiquitin Ligase Nrdp1 by the Deubiquitinating Enzyme USP8

2004 ◽  
Vol 24 (17) ◽  
pp. 7748-7757 ◽  
Author(s):  
Xiuli Wu ◽  
Lily Yen ◽  
Lisa Irwin ◽  
Colleen Sweeney ◽  
Kermit L. Carraway
Keyword(s):  
Ubiquitin Ligase ◽  
Tyrosine Kinases ◽  
E3 Ubiquitin Ligase ◽  
Ring Finger ◽  
Growth Factor Receptor ◽  
Deubiquitinating Enzyme ◽  
Ubiquitin Ligase Activity ◽  
Apoptosis Protein ◽  
Epidermal Growth ◽  
The Stability

ABSTRACT Nrdp1 is a RING finger-containing E3 ubiquitin ligase that physically interacts with and regulates steady-state cellular levels of the ErbB3 and ErbB4 receptor tyrosine kinases and has been implicated in the degradation of the inhibitor-of-apoptosis protein BRUCE. Here we demonstrate that the Nrdp1 protein undergoes efficient proteasome-dependent degradation and that mutations in its RING finger domain that disrupt ubiquitin ligase activity enhance stability. These observations suggest that Nrdp1 self-ubiquitination and stability could play an important role in regulating the activity of this protein. Using affinity chromatography, we identified the deubiquitinating enzyme USP8 (also called Ubpy) as a protein that physically interacts with Nrdp1. Nrdp1 and USP8 could be coimmunoprecipitated, and in transfected cells USP8 specifically bound to Nrdp1 but not cbl, a RING finger E3 ligase involved in ligand-stimulated epidermal growth factor receptor down-regulation. The USP8 rhodanese and catalytic domains mediated Nrdp1 binding. USP8 markedly enhanced the stability of Nrdp1, and a point mutant that disrupts USP8 catalytic activity destabilized endogenous Nrdp1. Our results indicate that Nrdp1 is a specific target for the USP8 deubiquitinating enzyme and are consistent with a model where USP8 augments Nrdp1 activity by mediating its stabilization.

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