scholarly journals Identification of the von Hippel-Lindau tumor-suppressor protein as part of an active E3 ubiquitin ligase complex

1999 ◽  
Vol 96 (22) ◽  
pp. 12436-12441 ◽  
Author(s):  
K. Iwai ◽  
K. Yamanaka ◽  
T. Kamura ◽  
N. Minato ◽  
R. C. Conaway ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Tumor Suppressor Protein ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Complex

Regulation of p14ARF by Siva1 in H. pylori-infected gastric epithelial cells.

2021 ◽  
Vol 39 (3_suppl) ◽  
pp. 243-243
Author(s):  
Manikandan Palrasu ◽  
Elena Zaika ◽  
El-Rifai Wael ◽  
Richard Peek ◽  
Alexander Zaika
Keyword(s):  
Gastric Cancer ◽  
Tumor Suppressor ◽  
Epithelial Cells ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Bacterial Degradation ◽  
Tumor Suppressor Protein ◽  
Gastric Epithelial Cells ◽  
H Pylori ◽  
Oncogenic Stress

243 Background: Helicobacter pylori ( H. pylori) is the strongest known risk factor for gastric cancer. Bacterial degradation of tumor suppressor proteins affect the host microbe’s interactions and host cellular response, which contribute to tumorigenesis. p14ARF, a crucial tumor suppressor protein that activates p53 protein under oncogenic stress plays a major role in oncogenic stress response (OSR) regulation. However, little is known about the mechanism of ARF and OSR regulation in H. pylori-infected gastric epithelial cells. Methods: The expression of p14ARF and cytotoxin-associated gene A (CagA) were analyzed in gastric cells co-cultured with H. pylori strains isolated from high-gastric risk and low-gastric risk areas by immunoblotting. To investigate the potential role of CagA in regulation of p14ARF, we employed isogenic cagA− and cagE− H. pylori mutants in gastric epithelial cells, and C57BL/6 mice (n = 10). We also analyzed the expression of Siva1 in human individual infected with cagA-positive (n = 13) and cagA-negative (n = 13) bacteria as well as uninfected human subjects (n = 6). siRNA was used to inhibit activity of Siva1 protein. Results: In this study, H. pylori strains expressing high levels of CagA virulence factor and associated with a higher gastric cancer risk more strongly suppress p14ARF compared with low-risk strains in vivo and in vitro. We found that degradation of p14ARF induced by CagA is mediated by E3 ubiquitin ligase Siva1, which works in concert with another E3 ubiquitin ligase TRIP12. Decreased expression of Siva1 protein and consequent up-regulation of p14ARF was also found in gastric mucosa of H. pylori-infected mice and human individuals. Tumorigenic strain 7.13 was more potent in upregulation of Siva1 and downregulation of p14ARF than non-tumorigenic strain B128. Inhibition of p14ARF protein by H. pylori causes inhibition of autophagy in infected cells. Conclusions: Our results provide first evidence that carcinogenic H. pylori strains significantly alter the host tumor suppressor protein p14ARF, leading to suppression of host OSR and autophagy, which may affect host-bacteria interactions and tumorigenic alteration in the stomach.

scholarly journals Playing Tag with HIF: The VHL Story

2002 ◽  
Vol 2 (3) ◽  
pp. 131-135 ◽  
Author(s):  
Sherri K. Leung ◽  
Michael Ohh
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
E3 Ubiquitin Ligase ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Matrix Assembly ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Complex

Inactivation of the von Hippel-Lindau (VHL) tumour suppressor gene product pVHL is the cause of inherited VHL disease and is associated with sporadic kidney cancer. pVHL is found in a multiprotein complex with elongins B/C, Cul2, and Rbx1 forming an E3 ubiquitin ligase complex called VEC. This modular enzyme targets theαsubunits of hypoxia-inducible factor (HIF) for ubiquitin-mediated destruction. Consequently, tumour cells lacking functional pVHL overproduce the products of HIF-target genes such as vascular endothelial growth factor (VEGF), which promotes angiogenesis. This likely accounts for the hypervascular nature of VHL-associated neoplasms. Although pVHL has been linked to the cell-cycle, differentiation, and the regulation of extracellular matrix assembly, microenvironment pH, and tissue invasiveness, this review will focus on the recent insights into the molecular mechanisms governing the E3 ubiquitin ligase function of VEC.

scholarly journals Multiple Splice Variants of the Human HIF-3α Locus Are Targets of the von Hippel-Lindau E3 Ubiquitin Ligase Complex

2003 ◽  
Vol 278 (13) ◽  
pp. 11032-11040 ◽  
Author(s):  
Mindy A. Maynard ◽  
Heng Qi ◽  
Jacky Chung ◽  
Eric H. L. Lee ◽  
Yukihiro Kondo ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Splice Variants ◽  
E3 Ubiquitin Ligase ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Complex

scholarly journals Therapeutically actionable signaling node to rescue AURKA driven loss of primary cilia in VHL-deficient cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pratim Chowdhury ◽  
Dimuthu Perera ◽  
Reid T. Powell ◽  
Tia Talley ◽  
Durga Nand Tripathi ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Primary Cilia ◽  
Mtor Inhibitor ◽  
E3 Ubiquitin Ligase ◽  
Xenograft Model ◽  
Aurora Kinase ◽  
Tumor Burden ◽  
Aurora Kinase A ◽  
Von Hippel Lindau ◽  
In Cells

AbstractLoss of primary cilia in cells deficient for the tumor suppressor von Hippel Lindau (VHL) arise from elevated Aurora Kinase A (AURKA) levels. VHL in its role as an E3 ubiquitin ligase targets AURKA for degradation and in the absence of VHL, high levels of AURKA result in destabilization of the primary cilium. We identified NVP-BEZ235, a dual PI3K/AKT and mTOR inhibitor, in an image-based high throughput screen, as a small molecule that restored primary cilia in VHL-deficient cells. We identified the ability of AKT to modulate AURKA expression at the transcript and protein level. Independent modulation of AKT and mTOR signaling decreased AURKA expression in cells confirming AURKA as a new signaling node downstream of the PI3K cascade. Corroborating these data, a genetic knockdown of AKT in cells deficient for VHL rescued the ability of these cells to ciliate. Finally, inhibition of AKT/mTOR using NVP-BEZ235 was efficacious in reducing tumor burden in a 786-0 xenograft model of renal cell carcinoma. These data highlight a previously unappreciated signaling node downstream of the AKT/mTOR pathway via AURKA that can be targeted in VHL-null cells to restore ciliogenesis.

scholarly journals An E3 Ubiquitin Ligase RNF139 Serves as a Tumor-Suppressor in Glioma

2021 ◽  
Author(s):  
Xiaofeng Chen ◽  
Weiping Kuang ◽  
Yong Zhu ◽  
Bin Zhou ◽  
Xiaosong Li ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Cell Lines ◽  
Ubiquitin Ligase ◽  
Glioma Cell ◽  
Protein Modification ◽  
E3 Ubiquitin Ligase ◽  
Ring Finger ◽  
Glioma Cells ◽  
Migration And Invasion ◽  
Tissue Samples

AbstractGlioma is highly lethal because of its high malignancy. Ubiquitination, a type of ubiquitin-dependent protein modification, has been reported to play an oncogenic or tumor-suppressive role in glioma development, depending on the targets. Ring finger protein 139 (RNF139) is a membrane-bound E3 ubiquitin ligase serving as a tumor suppressor by ubiquitylation-dependently suppressing cell growth. Herein, we firstly confirmed the abnormal downregulation of RNF139 in glioma tissues and cell lines. In glioma cells, ectopic RNF139 overexpression could inhibit, whereas RNF139 knockdown could aggravate the aggressive behaviors of glioma cells, including hyperproliferation, migration, and invasion. Moreover, in two glioma cell lines, RNF139 overexpression inhibited, whereas RNF139 knockdown enhanced the phosphorylation of phosphatidylinositol 3-kinase (PI3K) and AKT serine/threonine kinase 1 (AKT). In a word, we demonstrate the aberration in RNF139 expression in glioma tissue samples and cell lines. RNF139 serves as a tumor-suppressor in glioma by inhibiting glioma cell proliferation, migration, and invasion and promoting glioma cell apoptosis through regulating PI3K/AKT signaling.

scholarly journals The von Hippel–Lindau Cullin-RING E3 ubiquitin ligase regulates APOBEC3 cytidine deaminases

2021 ◽  
Author(s):  
Gaël K. Scholtès ◽  
Aubrey M. Sawyer ◽  
Cristina C. Vaca ◽  
Isabelle Clerc ◽  
Meejeon Roh ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Cytidine Deaminases ◽  
Von Hippel Lindau ◽  
Ring E3
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