scholarly journals LUBAC Formation Is Impaired in the Livers of Mice with MCD-Dependent Nonalcoholic Steatohepatitis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yasuka Matsunaga ◽  
Yusuke Nakatsu ◽  
Toshiaki Fukushima ◽  
Hirofumi Okubo ◽  
Misaki Iwashita ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Nonalcoholic Steatohepatitis ◽  
Molecular Mechanisms ◽  
Regulatory Protein ◽  
Gel Filtration ◽  
Native Page ◽  
Ubiquitin Chain ◽  
Interacting Protein ◽  
Hepatic Lipid Accumulation ◽  
Pathway Activation

Nonalcoholic steatohepatitis (NASH) is a disorder characterized by hepatic lipid accumulation followed by the inflammation-induced death of hepatocytes and fibrosis. In this process, oxidative stress contributes to the induction of several inflammatory cytokines including TNF-αand　IL-1βin macrophages, while, in hepatocytes, NF-κB reportedly induces the expressions of cell survival genes for protection from apoptosis. Recently, it was reported that the new ubiquitin ligase complex termed linear ubiquitin chain assembly complex (LUBAC), composed of SHARPIN (SHANK-associated RH domain-interacting protein), HOIL-1L (longer isoform of heme-oxidized iron-regulatory protein 2 ubiquitin ligase-1), and HOIP (HOIL-1L interacting protein), forms linear ubiquitin on NF-κB essential modulator (NEMO) and thereby induces NF-κB pathway activation. In this study, we demonstrated the formation of LUBAC to be impaired in the livers of NASH rodent models produced by methionine and choline deficient (MCD) diet feeding, first by either gel filtration or Blue Native-PAGE, with subsequent confirmation by western blotting. The reduction of LUBAC is likely to be attributable to markedly reduced expression of SHARPIN, one of its components. Thus, impaired LUBAC formation, which would result in insufficient NF-κB activation, may be one of the molecular mechanisms underlying the enhanced apoptotic response of hepatocytes in MCD diet-induced NASH livers.

scholarly journals Linear Ubiquitin Code: Its Writer, Erasers, Decoders, Inhibitors, and Implications in Disorders

2020 ◽  
Vol 21 (9) ◽  
pp. 3381 ◽  
Author(s):  
Daisuke Oikawa ◽  
Yusuke Sato ◽  
Hidefumi Ito ◽  
Fuminori Tokunaga
Keyword(s):  
Ubiquitin Ligase ◽  
Specific Binding ◽  
Nuclear Factor Κb ◽  
Innate Immune Responses ◽  
Deubiquitinating Enzymes ◽  
Ubiquitin Chain ◽  
Interacting Protein ◽  
Binding Domains ◽  
Ubiquitination Pathway ◽  
And Control

The linear ubiquitin chain assembly complex (LUBAC) is a ubiquitin ligase composed of the Heme-oxidized IRP2 ubiquitin ligase-1L (HOIL-1L), HOIL-1L-interacting protein (HOIP), and Shank-associated RH domain interactor (SHARPIN) subunits. LUBAC specifically generates the N-terminal Met1-linked linear ubiquitin chain and regulates acquired and innate immune responses, such as the canonical nuclear factor-κB (NF-κB) and interferon antiviral pathways. Deubiquitinating enzymes, OTULIN and CYLD, physiologically bind to HOIP and control its function by hydrolyzing the linear ubiquitin chain. Moreover, proteins containing linear ubiquitin-specific binding domains, such as NF-κB-essential modulator (NEMO), optineurin, A20-binding inhibitors of NF-κB (ABINs), and A20, modulate the functions of LUBAC, and the dysregulation of the LUBAC-mediated linear ubiquitination pathway induces cancer and inflammatory, autoimmune, and neurodegenerative diseases. Therefore, inhibitors of LUBAC would be valuable to facilitate investigations of the molecular and cellular bases for LUBAC-mediated linear ubiquitination and signal transduction, and for potential therapeutic purposes. We identified and characterized α,β-unsaturated carbonyl-containing chemicals, named HOIPINs (HOIP inhibitors), as LUBAC inhibitors. We summarize recent advances in elucidations of the pathophysiological functions of LUBAC-mediated linear ubiquitination and identifications of its regulators, toward the development of LUBAC inhibitors.

scholarly journals trans-Fatty acids promote p53-dependent apoptosis triggered by cisplatin-induced DNA interstrand crosslinks via the Nox-RIP1-ASK1-MAPK pathway

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yusuke Hirata ◽  
Miki Takahashi ◽  
Yuto Yamada ◽  
Ryosuke Matsui ◽  
Aya Inoue ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mapk Pathway ◽  
Regulatory Protein ◽  
Strand Break ◽  
Mitogen Activated Protein Kinase ◽  
Ros Generation ◽  
Apoptotic Pathway ◽  
Interstrand Crosslinks ◽  
Pathway Activation ◽  
Dna Interstrand Crosslinks

Abstracttrans-Fatty acids (TFAs) are food-derived fatty acids associated with various diseases including cardiovascular diseases. However, the underlying etiology is poorly understood. Here, we show a pro-apoptotic mechanism of TFAs such as elaidic acid (EA), in response to DNA interstrand crosslinks (ICLs) induced by cisplatin (CDDP). We previously reported that TFAs promote apoptosis induced by doxorubicin (Dox), a double strand break (DSB)-inducing agent, via a non-canonical apoptotic pathway independent of tumor suppressor p53 and apoptosis signal-regulating kinase (ASK1), a reactive oxygen species (ROS)-responsive kinase. However, here we found that in the case of CDDP-induced apoptosis, EA-mediated pro-apoptotic action was reversed by knockout of either p53 or ASK1, despite no increase in p53 apoptotic activity. Upon CDDP treatment, EA predominantly enhanced ROS generation, ASK1-p38/c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathway activation, and ultimately cell death, all of which were suppressed either by co-treatment of the NADPH oxidase (Nox) inhibitor Apocynin, or by knocking out its regulatory protein, receptor-interacting protein 1 (RIP1). These results demonstrate that in response to CDDP ICLs, TFAs promote p53-dependent apoptosis through the enhancement of the Nox-RIP1-ASK1-MAPK pathway activation, providing insight into the diverse pathogenetic mechanisms of TFAs according to the types of DNA damage.

scholarly journals Identification of Nucleolin as a Novel AEG-1-Interacting Protein in Breast Cancer via Interactome Profiling

Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2842
Author(s):  
Seong-Jae Lee ◽  
Kyoung-Min Choi ◽  
Geul Bang ◽  
Seo-Gyu Park ◽  
Eun-Bi Kim ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Cells ◽  
Molecular Mechanisms ◽  
Affinity Purification ◽  
Ectopic Expression ◽  
Cancer Cell Proliferation ◽  
Breast Cancer Cell Proliferation ◽  
Interacting Protein ◽  
Proliferation And Invasion ◽  
Oncogenic Function

Breast cancer is one of the most common malignant diseases worldwide. Astrocyte elevated gene-1 (AEG-1) is upregulated in breast cancer and regulates breast cancer cell proliferation and invasion. However, the molecular mechanisms by which AEG-1 promotes breast cancer have yet to be fully elucidated. In order to delineate the function of AEG-1 in breast cancer development, we mapped the AEG-1 interactome via affinity purification followed by LC-MS/MS. We identified nucleolin (NCL) as a novel AEG-1 interacting protein, and co-immunoprecipitation experiments validated the interaction between AEG-1 and NCL in breast cancer cells. The silencing of NCL markedly reduced not only migration/invasion, but also the proliferation induced by the ectopic expression of AEG-1. Further, we found that the ectopic expression of AEG-1 induced the tyrosine phosphorylation of c-Met, and NCL knockdown markedly reduced this AEG-1 mediated phosphorylation. Taken together, our report identifies NCL as a novel mediator of the oncogenic function of AEG-1, and suggests that c-Met could be associated with the oncogenic function of the AEG-1-NCL complex in the context of breast cancer.

scholarly journals Autographa californica Nucleopolyhedrovirus AC141 (Exon0), a Potential E3 Ubiquitin Ligase, Interacts with Viral Ubiquitin and AC66 To Facilitate Nucleocapsid Egress

2017 ◽  
Vol 92 (3) ◽  
Author(s):  
Siddhartha Biswas ◽  
Leslie G. Willis ◽  
Minggang Fang ◽  
Yingchao Nie ◽  
David A. Theilmann
Keyword(s):  
Ubiquitin Ligase ◽  
Nuclear Export ◽  
Molecular Mechanisms ◽  
Nuclear Periphery ◽  
E3 Ubiquitin Ligase ◽  
Autographa Californica ◽  
Nucleocapsid Proteins ◽  
Systemic Spread ◽  
Autographa Californica Nucleopolyhedrovirus ◽  
Budded Virus

ABSTRACTDuring the infection cycle of Autographa californica multiple nucleopolyhedrovirus (AcMNPV), two forms of virions are produced, budded virus (BV) and occlusion-derived virus (ODV). Nucleocapsids that form BV have to egress from the nucleus, whereas nucleocapsids that form ODV remain inside the nucleus. The molecular mechanism that determines whether nucleocapsids remain inside or egress from the nucleus is unknown. AC141 (a predicted E3 ubiquitin ligase) and viral ubiquitin (vUbi) have both been shown to be required for efficient BV production. In this study, it was hypothesized that vUbi interacts with AC141, and in addition, that this interaction was required for BV production. Deletion of bothac141andvubirestricted viral infection to a single cell, and BV production was completely eliminated. AC141 was ubiquitinated by either vUbi or cellular Ubi, and this interaction was required for optimal BV production. Nucleocapsids in BV, but not ODV, were shown to be specifically ubiquitinated by vUbi, including a 100-kDa protein, as well as high-molecular-weight conjugates. The viral ubiquitinated 100-kDa BV-specific nucleocapsid protein was identified as AC66, which is known to be required for BV production and was shown by coimmunoprecipitation and mass spectrometry to interact with AC141. Confocal microscopy also showed that AC141, AC66, and vUbi interact at the nuclear periphery. These results suggest that ubiquitination of nucleocapsid proteins by vUbi functions as a signal to determine if a nucleocapsid will egress from the nucleus and form BV or remain in the nucleus to form ODV.IMPORTANCEBaculoviruses produce two types of virions called occlusion-derived virus (ODV) and budded virus (BV). ODVs are required for oral infection, whereas BV enables the systemic spread of virus to all host tissues, which is critical for killing insects. One of the important steps for BV production is the export of nucleocapsids out of the nucleus. This study investigated the molecular mechanisms that enable the selection of nucleocapsids for nuclear export instead of being retained within the nucleus, where they would become ODV. Our data show that ubiquitination, a universal cellular process, specifically tags nucleocapsids of BV, but not those found in ODV, using a virus-encoded ubiquitin (vUbi). Therefore, ubiquitination may be the molecular signal that determines if a nucleocapsid is destined to form a BV, thus ensuring lethal infection of the host.

scholarly journals Prognostic value of the ubiquitin ligase carboxyl terminus of the Hsc70‐interacting protein in postmenopausal breast cancer

2016 ◽  
Vol 5 (8) ◽  
pp. 1873-1882 ◽  
Author(s):  
Sasagu Kurozumi ◽  
Yuri Yamaguchi ◽  
Shin‐ichi Hayashi ◽  
Hiromi Hiyoshi ◽  
Tetsuji Suda ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Ubiquitin Ligase ◽  
Prognostic Value ◽  
Postmenopausal Breast Cancer ◽  
Carboxyl Terminus ◽  
Interacting Protein

scholarly journals Identification of a PGXPP degron motif in dishevelled and structural basis for its binding to the E3 ligase KLHL12

Open Biology ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 200041 ◽  
Author(s):  
Zhuoyao Chen ◽  
Gregory A. Wasney ◽  
Sarah Picaud ◽  
Panagis Filippakopoulos ◽  
Masoud Vedadi ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Hydrophobic Interactions ◽  
E3 Ubiquitin Ligase ◽  
Structural Basis ◽  
E3 Ligases ◽  
Kelch Domain ◽  
Ring E3 Ligases ◽  
Ring E3 ◽  
New Protein

Wnt signalling is dependent on dishevelled proteins (DVL1-3), which assemble an intracellular Wnt signalosome at the plasma membrane. The levels of DVL1-3 are regulated by multiple Cullin-RING E3 ligases that mediate their ubiquitination and degradation. The BTB-Kelch protein KLHL12 was the first E3 ubiquitin ligase to be identified for DVL1-3, but the molecular mechanisms determining its substrate interactions have remained unknown. Here, we mapped the interaction of DVL1-3 to a ‘PGXPP' motif that is conserved in other known partners and substrates of KLHL12, including PLEKHA4, PEF1, SEC31 and DRD4. To determine the binding mechanism, we solved a 2.4 Å crystal structure of the Kelch domain of KLHL12 in complex with a DVL1 peptide that bound with low micromolar affinity. The DVL1 substrate adopted a U-shaped turn conformation that enabled hydrophobic interactions with all six blades of the Kelch domain β-propeller. In cells, the mutation or deletion of this motif reduced the binding and ubiquitination of DVL1 and increased its stability confirming this sequence as a degron motif for KLHL12 recruitment. These results define the molecular mechanisms determining DVL regulation by KLHL12 and establish the KLHL12 Kelch domain as a new protein interaction module for a novel proline-rich motif.

scholarly journals SKIP Downregulation Increases TGF-β1-Induced Matrix Metalloproteinase-9 Production in Transformed Keratinocytes

Scientifica ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jelena Kocić ◽  
Victor Villar ◽  
Aleksandra Krstić ◽  
Juan F. Santibanez
Keyword(s):  
Matrix Metalloproteinase ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Regulatory Protein ◽  
Mek Inhibitor ◽  
Matrix Metalloproteinase 9 ◽  
Transformed Cells ◽  
Interacting Protein ◽  
Metalloproteinase 9

Transforming growth factor-beta (TGF-β1) is a potent inductor of matrix metalloproteinase-9 (MMP-9) in transformed cells. Recently, Ski-interacting protein (SKIP) has been described as a regulator of TGF-β1 signal transduction, but its role in the induction of cell malignance by TGF-β1 has not been fully elucidated so far. In the present study, we analyzed the role of SKIP on TGF-β1-induced MMP-9 production. Mouse transformed keratinocytes (PDV) were stably transfected with SKIP antisense construct. We observed that SKIP depletion provoked an enhancement in the expression of MMP-9 in response to TGF-β1 treatment. The downregulation of SKIP produced an enhancement in TGF-β1-activated ERK1,2 MAP kinase as well as increased transactivation of downstream Elk1 transcription factor. The increased MMP-9 production in response to TGF-β1 was dependent of MAPK activation as PD98059, an MEK inhibitor, reduced MMP-9 expression in SKIP antisense transfected cells. Thus, we propose SKIP as a regulatory protein in TGF-β1-induced MMP-9 expression acting by controlling ERK1,2 signaling in transformed cells.

scholarly journals RIPK1 promotes death receptor-independent caspase-8-mediated apoptosis under unresolved ER stress conditions

2014 ◽  
Vol 5 (12) ◽  
pp. e1555-e1555 ◽  
Author(s):  
Y Estornes ◽  
M A Aguileta ◽  
C Dubuisson ◽  
J De Keyser ◽  
V Goossens ◽  
...  
Keyword(s):  
Er Stress ◽  
Molecular Mechanisms ◽  
Death Receptor ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Life And Death ◽  
Unfolded Protein ◽  
Induced Apoptosis ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and results in the activation of the unfolded protein response (UPR), which aims at restoring ER homeostasis. However, when the stress is too severe the UPR switches from being a pro-survival response to a pro-death one, and the molecular mechanisms underlying ER stress-mediated death have remained incompletely understood. In this study, we identified receptor interacting protein kinase 1 (RIPK1)—a kinase at the crossroad between life and death downstream of various receptors—as a new regulator of ER stress-induced death. We found that Ripk1-deficient MEFs are protected from apoptosis induced by ER stressors, which is reflected by reduced caspase activation and PARP processing. Interestingly, the pro-apoptotic role of Ripk1 is independent of its kinase activity, is not regulated by its cIAP1/2-mediated ubiquitylation, and does not rely on the direct regulation of JNK or CHOP, two reportedly main players in ER stress-induced death. Instead, we found that ER stress-induced apoptosis in these cells relies on death receptor-independent activation of caspase-8, and identified Ripk1 upstream of caspase-8. However, in contrast to RIPK1-dependent apoptosis downstream of TNFR1, we did not find Ripk1 associated with caspase-8 in a death-inducing complex upon unresolved ER stress. Our data rather suggest that RIPK1 indirectly regulates caspase-8 activation, in part via interaction with the ER stress sensor inositol-requiring protein 1 (IRE1).

scholarly journals Micronized Palmitoylethanolamide Ameliorates Methionine- and Choline-Deficient Diet–Induced Nonalcoholic Steatohepatitis via Inhibiting Inflammation and Restoring Autophagy

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiaji Hu ◽  
Hanglu Ying ◽  
Jie Yao ◽  
Longhe Yang ◽  
Wenhui Jin ◽  
...  
Keyword(s):  
Nonalcoholic Steatohepatitis ◽  
Underlying Mechanism ◽  
Protective Role ◽  
Hepatocellular Injury ◽  
Deficient Diet ◽  
Neuroprotective Effects ◽  
Pathway Activation ◽  
Elevated Expression ◽  
Anti Inflammatory

Nonalcoholic steatohepatitis (NASH) has become one of the serious causes of chronic liver diseases, characterized by hepatic steatosis, hepatocellular injury, inflammation and fibrosis, and lack of efficient therapeutic agents. Palmitoylethanolamide (PEA) is an endogenous bioactive lipid with various pharmacological activities, including anti-inflammatory, analgesic, and neuroprotective effects. However, the effect of PEA on nonalcoholic steatohepatitis is still unknown. Our study aims to explore the potential protective role of PEA on NASH and to reveal the underlying mechanism. In this study, the C57BL/6 mice were used to establish the NASH model through methionine- and choline-deficient (MCD) diet feeding. Here, we found that PEA treatment significantly improved liver function, alleviated hepatic pathological changes, and attenuated the lipid accumulation and hepatic fibrosis in NASH mice induced by MCD diet feeding. Mechanistically, the anti-steatosis effect of PEA may be due to the suppressed expression of ACC1 and CD36, elevated expression of PPAR-α, and the phosphorylation levels of AMPK. In addition, hepatic oxidative stress was greatly inhibited in MCD-fed mice treated with PEA via enhancing the expression and activities of antioxidant enzymes, including GSH-px and SOD. Moreover, PEA exerted a clear anti-inflammatory effect though ameliorating the expression of inflammatory mediators and suppressing the NLRP3 inflammasome pathway activation. Furthermore, the impaired autophagy in MCD-induced mice was reactivated with PEA treatment. Taken together, our research suggested that PEA protects against NASH through the inhibition of inflammation and restoration of autophagy. Thus, PEA may represent an efficient therapeutic agent to treat NASH.

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