scholarly journals VHL inhibitor binding increases intracellular level of VHL

2021 ◽  
Author(s):  
Julianty Frost ◽  
Sonia Rocha ◽  
Alessio Ciulli
Keyword(s):  
Enzyme Inhibitor ◽  
Hypoxia Inducible Factor ◽  
High Specificity ◽  
Protein Levels ◽  
Tumour Suppressor Protein ◽  
Functional Characterisation ◽  
Vhl Protein ◽  
Factor Alpha ◽  
Vhl Disease ◽  
Protein Stabilisation

The vonHippel Lindau (VHL) protein is a tumour suppressor protein frequently mutated in the VHL disease, which functions as substrate recognition subunit of a Cul2 E3 ubiquitin ligase (CRL2VHL). CRL2VHL plays an important role in oxygen sensing, by binding and targeting Hypoxia Inducible Factor-alpha subunits (HIF-alpha) for ubiquitination and degradation. VHL is also commonly hijacked by heterobifunctional degrader molecules known as proteolysis-targeting chimeras (PROTACs). In previous work we reported the structure-based design and functional characterisation of VHL inhibitors (VH032 and VH298) that induce the HIF response in cells. Here, we use unbiased quantitative mass spectrometry to identify the proteomic changes elicited by the VHL inhibitor and compare this to hypoxia or broad-spectrum prolyl-hydroxylase domain (PHD) enzyme inhibitor IOX2. Our results demonstrate the VHL inhibitor selectively activates the HIF response that vastly overlaps with hypoxia- and IOX2-induced proteomic changes. Interestingly, VHL inhibitors were found to selectively upregulate a single protein, which is VHL itself. Our analysis revealed that this occurs via protein stabilisation of VHL isoforms and not via changes in transcript levels. Increased VHL levels upon VH298 treatment resulted in turn to reduced levels of HIF-1 protein. Our results demonstrate the high specificity of VHL inhibitors and suggest that use of these inhibitors would not produce overtly side effects due to prolonged HIF stabilisation. They also exemplify the concept that small-molecule binding induced protein stabilisation can increase protein levels inside cells.

scholarly journals von Hippel-Lindau Disease: an Update

2019 ◽  
Vol 7 (4) ◽  
pp. 227-235 ◽  
Author(s):  
Eamonn R Maher ◽  
Richard N Sandford
Keyword(s):  
Natural History ◽  
Patient Outcomes ◽  
Molecular Characterisation ◽  
Von Hippel Lindau ◽  
Functional Characterisation ◽  
History Of ◽  
Vhl Protein ◽  
Von Hippel Lindau Disease ◽  
Vhl Disease ◽  
Improve Patient

Abstract Purpose of Review In this review, we discuss the key molecular and clinical developments in VHL disease that have the potential to impact on the natural history of the disease and improve patient outcomes. Recent Findings Identifiable mutations in VHL underlie most cases of VHL and define clear genotype-phenotype correlations. Detailed clinical and molecular characterisation has allowed the implementation of lifelong screening programmes that have improved clinical outcomes. Functional characterisation of the VHL protein complex has revealed its role in oxygen sensing and the mechanisms of tumourigenesis that are now being exploited to develop novel therapies for VHL and renal cancer. Summary The molecular and cellular landscape of VHL-associated tumours is revealing new opportunities to modify the natural history of the disease and develop therapies. Drugs are now entering clinical trials and combined with improved clinical and molecular diagnosis, and lifelong surveillance programmes, further progress towards reducing the morbidity and mortality associated with VHL disease is anticipated.

scholarly journals SDHC Promoter Methylation, a Novel Pathogenic Mechanism in Parasympathetic Paragangliomas

2017 ◽  
Vol 103 (1) ◽  
pp. 295-305 ◽  
Author(s):  
Cristóbal Bernardo-Castiñeira ◽  
Nuria Valdés ◽  
Marta I Sierra ◽  
Inés Sáenz-de-Santa-María ◽  
Gustavo F Bayón ◽  
...  
Keyword(s):  
Copy Number ◽  
Messenger Rna ◽  
Hypoxia Inducible Factor ◽  
Mrna Levels ◽  
Cluster Assembly ◽  
Iron Sulfur Cluster ◽  
Genetic Event ◽  
Protein Levels ◽  
First Case ◽  
Vhl Protein

Abstract Context Germline mutations in the succinate dehydrogenase A, B, C, and D genes (collectively, SDHx) predispose to the development of paragangliomas (PGLs) arising at the parasympathetic or sympathetic neuroendocrine systems. SDHx mutations cause absence of tumoral immunostaining for SDHB. However, negative SDHB immunostaining has also been found in a subset of PGLs that lack SDHx mutations. Settings Here, we report the comprehensive molecular characterization of one such a tumor of parasympathetic origin compared with healthy paraganglia and other PGLs with or without SDHx mutations. Results Integration of multiplatform data revealed somatic SDHC methylation and loss of the 1q23.3 region containing the SDHC gene. This correlated with decreased SDHC messenger RNA (mRNA) and protein levels. Furthermore, another genetic event found affected the VHL gene, which showed a decreased DNA copy number, associated with low VHL mRNA levels, and an absence of VHL protein detected by immunohistochemistry. In addition, the tumor displayed a pseudohypoxic phenotype consisting in overexpression of the hypoxia-inducible factor (HIF)-1α and miR-210, as well as downregulation of the iron-sulfur cluster assembly enzyme (ISCU) involved in SDHB maturation. This profile resembles that of SDHx- or VHL-mutated PGLs but not of PGLs with decreased VHL copy number, pointing to SDHC rather than VHL as the pathogenic driver. Conclusions Collectively, these findings demonstrate the potential importance of both the SDHC epigenomic event and the activation of the HIF-1α/miR-210/ISCU axis in the pathogenesis of SDHx wild-type/SDHB-negative PGLs. To our knowledge, this is the first case of a sporadic parasympathetic PGL that carries silencing of SDHC, fulfilling the two-hit Knudson’s model for tumorigenesis.

Familial tumour syndromes: von Hippel–Lindau disease

2017 ◽  
Author(s):  
Hiroshi Kanno ◽  
Joachim P. Steinbach
Keyword(s):  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Laboratory Data ◽  
Von Hippel Lindau ◽  
Vhl Protein ◽  
Von Hippel Lindau Disease ◽  
The Central Nervous System ◽  
Microsurgical Techniques ◽  
Vhl Disease ◽  
Hif Pathway

Von Hippel–Lindau (VHL) disease, an autosomal dominant familial tumour syndrome, is often associated with haemangioblastoma of the central nervous system. In the presence of oxygen, VHL protein serves to prevent the accumulation of hypoxia-inducible factor (HIF) protein by targeting it to the proteasomal pathway, while biallelic inactivation of the VHL gene blocks degradation of HIF and leads to constitutive activation of the HIF pathway although oxygen is present. HIF-target genes are involved in angiogenesis, proliferation, and metabolism enabling tumour growth. Haemangioblastoma is a highly vascularized, begin tumour commonly associated with a cyst, but it is linked with neurological morbidity and mortality based on its location and multiplicity. Haemangioblastoma in VHL is diagnosed according to symptoms and signs, past and family histories, laboratory data, neuroradiological findings, pathological findings, and genetic testing. Surgical treatment is usually the most recommended therapy for haemangioblastomas, and using well-defined microsurgical techniques, the majority can be resected safely.

scholarly journals An affinity-directed protein missile system for targeted proteolysis

Open Biology ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 160255 ◽  
Author(s):  
Luke J. Fulcher ◽  
Thomas Macartney ◽  
Polyxeni Bozatzi ◽  
Annika Hornberger ◽  
Alejandro Rojas-Fernandez ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Hypoxia Inducible Factor ◽  
Green Fluorescence Protein ◽  
Human Kidney ◽  
Target Proteins ◽  
Von Hippel Lindau ◽  
Vhl Protein ◽  
Fluorescence Protein ◽  
Factor Alpha ◽  
Vacuolar Protein

The von Hippel–Lindau (VHL) protein serves to recruit the hypoxia-inducible factor alpha (HIF1α) protein under normoxia to the CUL2 E3 ubiquitin ligase for its ubiquitylation and degradation through the proteasome. In this report, we modify VHL to engineer an affinity-directed protein missile (AdPROM) system to direct specific endogenous target proteins for proteolysis in mammalian cells. The proteolytic AdPROM construct harbours a cameloid anti-green fluorescence protein (aGFP) nanobody that is fused to VHL for either constitutive or tetracycline-inducible expression. For target proteins, we exploit CRISPR/Cas9 to rapidly generate human kidney HEK293 and U2OS osteosarcoma homozygous knock-in cells harbouring GFP tags at the VPS34 (vacuolar protein sorting 34) and protein associated with SMAD1 (PAWS1, aka FAM83G) loci, respectively. Using these cells, we demonstrate that the expression of the VHL-aGFP AdPROM system results in near-complete degradation of the endogenous GFP-VPS34 and PAWS1-GFP proteins through the proteasome. Additionally, we show that Tet-inducible destruction of GFP-VPS34 results in the degradation of its associated partner, UVRAG, and reduction in levels of cellular phosphatidylinositol 3-phosphate.

scholarly journals Inactivation of the Arylhydrocarbon Receptor Nuclear Translocator (Arnt) Suppresses von Hippel-Lindau Disease-Associated Vascular Tumors in Mice

2005 ◽  
Vol 25 (8) ◽  
pp. 3163-3172 ◽  
Author(s):  
Erinn B. Rankin ◽  
Debra F. Higgins ◽  
Jacqueline A. Walisser ◽  
Randall S. Johnson ◽  
Christopher A. Bradfield ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Germ Line ◽  
Hypoxia Inducible Factor ◽  
Suppressor Gene ◽  
Vascular Tumors ◽  
Von Hippel Lindau ◽  
Von Hippel Lindau Disease ◽  
Arylhydrocarbon Receptor ◽  
Vhl Disease ◽  
Endothelial Growth Factor

ABSTRACT Patients with germ line mutations in the VHL tumor suppressor gene are predisposed to the development of highly vascularized tumors within multiple tissues. Loss of pVHL results in constitutive activation of the transcription factors HIF-1 and HIF-2, whose relative contributions to the pathogenesis of the VHL phenotype have yet to be defined. In order to examine the role of HIF in von Hippel-Lindau (VHL)-associated vascular tumorigenesis, we utilized Cre-loxP-mediated recombination to inactivate hypoxia-inducible factor-1α (Hif-1α) and arylhydrocarbon receptor nuclear translocator (Arnt) genes in a VHL mouse model of cavernous liver hemangiomas and polycythemia. Deletion of Hif-1α did not affect the development of vascular tumors and polycythemia, nor did it suppress the increased expression of vascular endothelial growth factor (Vegf) and erythropoietin (Epo). In contrast, phosphoglycerokinase (Pgk) expression was substantially decreased, providing evidence for target gene-dependent functional redundancy between different Hif transcription factors. Inactivation of Arnt completely suppressed the development of hemangiomas, polycythemia, and Hif-induced gene expression. Here, we demonstrate genetically that the development of VHL-associated vascular tumors in the liver depends on functional ARNT. Furthermore, we provide evidence that individual HIF transcription factors may play distinct roles in the development of specific VHL disease manifestations.

scholarly journals FBXW7 mutations reduce binding of NOTCH1, leading to cleaved NOTCH1 accumulation and target gene activation in CLL

Blood ◽  
2019 ◽  
Vol 133 (8) ◽  
pp. 830-839 ◽  
Author(s):  
Viola Close ◽  
William Close ◽  
Sabrina Julia Kugler ◽  
Michaela Reichenzeller ◽  
Deyan Yordanov Yosifov ◽  
...  
Keyword(s):  
Target Gene ◽  
Hypoxia Inducible Factor ◽  
Gene Activation ◽  
Lymphocytic Leukemia ◽  
Negative Regulator ◽  
Missense Mutations ◽  
Protein Levels ◽  
In Silico Modeling ◽  
Functional Consequences ◽  
Wd40 Domain

Abstract NOTCH1 is mutated in 10% of chronic lymphocytic leukemia (CLL) patients and is associated with poor outcome. However, NOTCH1 activation is identified in approximately one-half of CLL cases even in the absence of NOTCH1 mutations. Hence, there appear to be additional factors responsible for the impairment of NOTCH1 degradation. E3-ubiquitin ligase F-box and WD40 repeat domain containing-7 (FBXW7), a negative regulator of NOTCH1, is mutated in 2% to 6% of CLL patients. The functional consequences of these mutations in CLL are unknown. We found heterozygous FBXW7 mutations in 36 of 905 (4%) untreated CLL patients. The majority were missense mutations (78%) that mostly affected the WD40 substrate binding domain; 10% of mutations occurred in the first exon of the α-isoform. To identify target proteins of FBXW7 in CLL, we truncated the WD40 domain in CLL cell line HG-3 via clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9). Homozygous truncation of FBXW7 resulted in an increase of activated NOTCH1 intracellular domain (NICD) and c-MYC protein levels as well as elevated hypoxia-inducible factor 1-α activity. In silico modeling predicted that novel mutations G423V and W425C in the FBXW7-WD40 domain change the binding of protein substrates. This differential binding was confirmed via coimmunoprecipitation of overexpressed FBXW7 and NOTCH1. In primary CLL cells harboring FBXW7 mutations, activated NICD levels were increased and remained stable upon translation inhibition. FBXW7 mutations coincided with an increase in NOTCH1 target gene expression and explain a proportion of patients characterized by dysregulated NOTCH1 signaling.

scholarly journals Crosstalk in oxygen homeostasis networks: SKN-1/NRF inhibits the HIF-1 hypoxia-inducible factor in Caenorhabditis elegans

2021 ◽  
Author(s):  
Dingxia Feng ◽  
Zhiwei Zhai ◽  
Zhiyong Shao ◽  
Yi Zhang ◽  
Jo Anne Powell-Coffman
Keyword(s):  
Oxidative Stress ◽  
Hypoxia Inducible Factor ◽  
Regulatory Sequences ◽  
Low Oxygen ◽  
Transcriptional Responses ◽  
C Elegans ◽  
Protein Levels ◽  
Oxygen Homeostasis ◽  
Genome Wide ◽  
A Genome

AbstractDuring development, homeostasis, and disease, organisms must balance responses that allow adaptation to low oxygen (hypoxia) with those that protect cells from oxidative stress. The evolutionarily conserved hypoxia-inducible factors are central to these processes, as they orchestrate transcriptional responses to oxygen deprivation. Here, we employ genetic strategies in C. elegans to identify stress-responsive genes and pathways that modulate the HIF-1 hypoxia-inducible factor and facilitate oxygen homeostasis. Through a genome-wide RNAi screen, we show that RNAi-mediated mitochondrial or proteasomal dysfunction increases the expression of hypoxia-responsive reporter Pnhr-57:GFP in C. elegans. Interestingly, only a subset of these effects requires hif-1. Of particular importance, we found that skn-1 RNAi increases the expression of hypoxia-responsive reporter Pnhr-57:GFP and elevates HIF-1 protein levels. The SKN-1/NRF transcription factor has been shown to promote oxidative stress resistance. We present evidence that the crosstalk between HIF-1 and SKN-1 is mediated by EGL-9, the prolyl hydroxylase that targets HIF-1 for oxygen-dependent degradation. Treatment that induces SKN-1, such as heat, increases expression of a Pegl-9:GFP reporter, and this effect requires skn-1 function and a putative SKN-1 binding site in egl-9 regulatory sequences. Collectively, these data support a model in which SKN-1 promotes egl-9 transcription, thereby inhibiting HIF-1. We propose that this interaction enables animals to adapt quickly to changes in cellular oxygenation and to better survive accompanying oxidative stress.

Protective effect of hydralazine on a cellular model of Parkinson’s disease: a possible role of hypoxia-inducible factor (HIF)-1α

2020 ◽  
Vol 98 (3) ◽  
pp. 405-414 ◽  
Author(s):  
Mehrnaz Mehrabani ◽  
Mohammad Hadi Nematollahi ◽  
Mojde Esmaeili Tarzi ◽  
Kobra Bahrampour Juybari ◽  
Moslem Abolhassani ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Antioxidant Power ◽  
Expression Levels ◽  
Downstream Target ◽  
Protein Levels ◽  
Ferric Reducing Antioxidant Power ◽  
6 Hydroxydopamine

Parkinson’s disease (PD) is a neurodegenerative disease accompanied by a low expression level of cerebral hypoxia-inducible factor (HIF-1α). Hence, activating the hypoxia-signaling pathway may be a favorable therapeutic approach for curing PD. This study explored the efficacy of hydralazine, a well-known antihypertensive agent, for restoring the impaired HIF-1 signaling in PD, with the aid of 6-hydroxydopamine (6-OHDA)-exposed SH-SY5Y cells. The cytotoxicity of hydralazine and 6-OHDA on the SH-SY5Y cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and apoptosis detection assays. The activities of malondialdehyde, nitric oxide (NO), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) were also measured. Expression levels of HIF-1α and its downstream genes at the protein level were assessed by Western blotting. Hydralazine showed no toxic effects on SH-SY5Y cells, at the concentration of ≤50 μmol/L. Hydralazine decreased the levels of apoptosis, malondialdehyde, and NO, and increased the activities of FRAP and SOD in cells exposed to 6-OHDA. Furthermore, hydralazine up-regulated the protein expression levels of HIF-1α, vascular endothelial growth factor, tyrosine hydroxylase, and dopamine transporter in the cells also exposed to 6-OHDA, by comparison with the cells exposed to 6-OHDA alone. In summary, hydralazine priming could attenuate the deleterious effects of 6-OHDA on SH-SY5Y cells by increasing cellular antioxidant capacity, as well as the protein levels of HIF-1α and its downstream target genes.

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