How to Inactivate Human Ubiquitin E3 Ligases by Mutation

: Atherosclerosis is a chronic inflammatory vascular disease. Atherosclerotic cardiovascular disease is the main cause of death in both developed and developing countries. Many pathophysiological factors, including abnormal cholesterol metabolism, vascular inflammatory response, endothelial dysfunction and vascular smooth muscle cell proliferation and apoptosis, contribute to the development of atherosclerosis and the molecular mechanisms underlying the development of atherosclerosis are not fully understood. Ubiquitination is a multistep post-translational protein modification that participates in many important cellular processes. Emerging evidence suggests that ubiquitination plays important roles in the pathogenesis of atherosclerosis in many ways, including regulation of vascular inflammation, endothelial cell and vascular smooth muscle cell function, lipid metabolism and atherosclerotic plaque stability. This review summarizes important contributions of various E3 ligases to the development of atherosclerosis. Targeting ubiquitin E3 ligases may provide a novel strategy for the prevention of the progression of atherosclerosis.

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Gene Synthesis, Expression, and Processing of Human Ubiquitin Carboxyl Extension Proteins

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)84967-0 ◽

1989 ◽

Vol 264 (7) ◽

pp. 4093-4103

Author(s):

B P Monia ◽

D J Ecker ◽

S Jonnalagadda ◽

J Marsh ◽

L Gotlib ◽

...

Keyword(s):

Gene Synthesis ◽

Human Ubiquitin

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E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein

International Journal of Molecular Sciences ◽

10.3390/ijms22115712 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5712

Author(s):

Michał Tracz ◽

Ireneusz Górniak ◽

Andrzej Szczepaniak ◽

Wojciech Białek

Keyword(s):

Ubiquitin Ligase ◽

Conformational Changes ◽

Protein Interactions ◽

E3 Ubiquitin Ligase ◽

Lanthanide Ions ◽

E3 Ligases ◽

Fluorescence Measurements ◽

Partial Unfolding

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.

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The Multifaceted Roles of USP15 in Signal Transduction

International Journal of Molecular Sciences ◽

10.3390/ijms22094728 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4728

Author(s):

Tanuza Das ◽

Eun Joo Song ◽

Eunice EunKyeong Kim

Keyword(s):

Signal Transduction ◽

Signaling Pathways ◽

Cellular Networks ◽

Clinical Applications ◽

Regulatory Mechanisms ◽

Signaling Networks ◽

Post Translational Modification ◽

Comprehensive Overview ◽

E3 Ligases ◽

Disease Markers

Ubiquitination and deubiquitination are protein post-translational modification processes that have been recognized as crucial mediators of many complex cellular networks, including maintaining ubiquitin homeostasis, controlling protein stability, and regulating several signaling pathways. Therefore, some of the enzymes involved in ubiquitination and deubiquitination, particularly E3 ligases and deubiquitinases, have attracted attention for drug discovery. Here, we review recent findings on USP15, one of the deubiquitinases, which regulates diverse signaling pathways by deubiquitinating vital target proteins. Even though several basic previous studies have uncovered the versatile roles of USP15 in different signaling networks, those have not yet been systematically and specifically reviewed, which can provide important information about possible disease markers and clinical applications. This review will provide a comprehensive overview of our current understanding of the regulatory mechanisms of USP15 on different signaling pathways for which dynamic reverse ubiquitination is a key regulator.

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A Novel Signature of CCNF-Associated E3 Ligases Collaborate and Counter Each Other in Breast Cancer

Cancers ◽

10.3390/cancers13122873 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2873

Author(s):

Shu-Chun Chang ◽

Chin-Sheng Hung ◽

Bo-Xiang Zhang ◽

Tsung-Han Hsieh ◽

Wayne Hsu ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cell ◽

Mrna Level ◽

Breast Carcinogenesis ◽

E3 Ligases ◽

Anti Cancer ◽

Cancer Initiation ◽

Cell Progression ◽

F Box Protein ◽

Cancer Activity

Breast cancer (BRCA) malignancy causes major fatalities amongst women worldwide. SCF (Skp1-cullin-F-box proteins) E3 ubiquitin ligases are the most well-known members of the ubiquitination–proteasome system (UPS), which promotes cancer initiation and progression. Recently, we demonstrated that FBXL8, a novel F-box protein (SCFF-boxes) of SCF E3 ligase, accelerates BRCA advancement and metastasis. Since SCFF-boxes is a key component of E3 ligases, we hypothesized that other SCFF-boxes besides FBXL8 probably collaborate in regulating breast carcinogenesis. In this study, we retrospectively profiled the transcriptome of BRCA tissues and found a notable upregulation of four SCFF-box E3 ligases (FBXL8, FBXO43, FBXO15, and CCNF) in the carcinoma tissues. Similar to FBXL8, the knockdown of FBXO43 reduced cancer cell viability and proliferation, suggesting its pro-tumorigenic role. The overexpression of CCNF inhibited cancer cell progression, indicating its anti-tumorigenic role. Unexpectedly, CCNF protein was markedly downregulated in BRCA tissues, although its mRNA level was high. We showed that both E3 ligases, FBXL8 and FZR1, pulled down CCNF. Double knockdown of FBXL8 and FZR1 caused CCNF accumulation. On the other hand, CCNF itself pulled down a tumorigenic factor, RRM2, and CCNF overexpression reduced RRM2. Altogether, we propose a signature network of E3 ligases that collaboratively modulates CCNF anti-cancer activity. There is potential to target BRCA through modulation of the partnership axes of (i) CCNF-FBXL8, (ii) CCNF-FZR1, and (iii) CCNF-RRM2, particularly, via CCNF overexpression and activation and FBXL8/FZR1 suppression.

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Nucleotide sequence analysis of a cDNA encoding human ubiquitin reveals that ubiquitin is synthesized as a precursor.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)39652-7 ◽

1985 ◽

Vol 260 (12) ◽

pp. 7609-7613 ◽

Cited By ~ 17

Author(s):

P K Lund ◽

B M Moats-Staats ◽

J G Simmons ◽

E Hoyt ◽

A J D'Ercole ◽

...

Keyword(s):

Sequence Analysis ◽

Nucleotide Sequence ◽

Nucleotide Sequence Analysis ◽

Human Ubiquitin

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PSVII-6 Effects of heat stress on proteolysis in dairy cattle skeletal muscle

Journal of Animal Science ◽

10.1093/jas/skaa054.298 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 168-168

Author(s):

Melissa S Roths ◽

Megan A Abeyta ◽

Tori Rudolph ◽

Brittany Wilson ◽

Matthew B Hudson ◽

...

Keyword(s):

Skeletal Muscle ◽

Heat Stress ◽

Dairy Cattle ◽

Electric Heating ◽

Economic Loss ◽

Urea Nitrogen ◽

Plasma Urea ◽

E3 Ligases ◽

Acclimation Period ◽

Milk Urea

Abstract Heat stress (HS) occurs when internal body temperatures are elevated above a thermoneutral zone in response to extreme environmental temperatures. In the U.S. dairy industry, HS results in economic loss due to decreased feed intake, milk quality, and milk yield. Previous work has demonstrated increased plasma urea nitrogen in heat stressed dairy cattle which is thought to originate from increased skeletal muscle proteolysis, however this has not been empirically established. The objective of this investigation was to determine the extent to which HS promotes proteolysis in skeletal muscle of dairy cattle. We hypothesized HS would increase activation of the calpain and proteasome systems in skeletal muscle. To test this hypothesis, following a 3-d acclimation period in individual box stalls, all lactating dairy cows were held under thermoneutral (TN) conditions for 4-d for collection of baseline measures and then exposed to TN or HS conditions for 7-d followed by a biopsy of semitendinosus (n=8/group). To induce HS, cattle were fitted with electric heating blankets, which they wore for the duration of the heating period. This approach increased rectal temperature 1.1°C (P< 0.05), respiratory rate by 33 bpm (P< 0.05), plasma urea nitrogen by 19% (P=0.08) and milk urea nitrogen by 26% (P< 0.05), and decreased dry matter intake by 32% (P< 0.05) and milk production by 26% (P< 0.05) confirming HS. Contrary to our expectations, we discovered that calpain I and II abundance and activation, and calpain activity were similar between groups. Likewise, protein expression of E3 ligases, MafBx and Murf1, were similar between groups as was total ubiquitinated proteins and proteasome activity. Collectively, and counter to our hypothesis, these results suggest skeletal muscle proteolysis is not increased following 7-d of HS. These data question the presumed dogma that increased blood urea nitrogen is due to elevated proteolysis in skeletal muscle.

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