scholarly journals Vhlh Gene Deletion Induces Hif-1-Mediated Cell Death in Thymocytes

2004 ◽  
Vol 24 (20) ◽  
pp. 9038-9047 ◽  
Author(s):  
Mangatt P. Biju ◽  
Aaron K. Neumann ◽  
Steven J. Bensinger ◽  
Randall S. Johnson ◽  
Laurence A. Turka ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Germ Line ◽  
Hypoxia Inducible Factor ◽  
Caspase 8 ◽  
Thymocyte Development ◽  
Double Positive ◽  
Α Subunit ◽  
Von Hippel Lindau

ABSTRACT The von Hippel-Lindau gene product (pVHL) targets the α subunit of basic helix-loop-helix transcription factor hypoxia-inducible factor (HIF) for proteasomal degradation. Inactivation of pVhl in the mouse germ line results in embryonic lethality, indicating that tight control of Hif-mediated adaptive responses to hypoxia is required for normal development and tissue function. In order to investigate the role of pVhl in T-cell development, we generated mice with thymocyte-specific inactivation of Vhlh resulting in constitutive transcriptional activity of Hif-1, as well as mice with thymocyte-specific repression of Hif-1 in a wild-type and Vhlh-deficient background. Thymi from Vhlh-deficient mice were small due to a severe reduction in the total number of CD4/CD8-double-positive thymocytes which was associated with increased apoptosis in vivo and in vitro. Increased apoptosis was a result of enhanced caspase 8 activity, while Bcl-2 and Bcl-XL transgene expression had little effect on this phenotype. Inactivation of Hif-1 in Vhlh-deficient thymocytes restored thymic cellularity as well as thymocyte viability in vitro. Our data suggest that tight regulation of Hif-1 via pVhl is required for normal thymocyte development and viability and that an increase in Hif-1 transcriptional activity enhances caspase 8-mediated apoptosis in thymocytes.

scholarly journals A Feedback Loop Involving the Phd3 Prolyl Hydroxylase Tunes the Mammalian Hypoxic Response In Vivo

2009 ◽  
Vol 29 (21) ◽  
pp. 5729-5741 ◽  
Author(s):  
Yoji Andrew Minamishima ◽  
Javid Moslehi ◽  
Robert F. Padera ◽  
Roderick T. Bronson ◽  
Ronglih Liao ◽  
...  
Keyword(s):  
Feedback Loop ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Premature Mortality ◽  
Prolyl Hydroxylase ◽  
Α Subunit ◽  
Von Hippel Lindau ◽  
Regulatory Feedback Loop

ABSTRACT Hypoxia-inducible factor (HIF), consisting of a labile α subunit and a stable β subunit, is a master regulator of hypoxia-responsive mRNAs. HIFα undergoes oxygen-dependent prolyl hydroxylation, which marks it for polyubiquitination by a complex containing the von Hippel-Lindau protein (pVHL). Among the three Phd family members, Phd2 appears to be the primary HIF prolyl hydroxylase. Phd3 is induced by HIF and, based on findings from in vitro studies, may participate in a HIF-regulatory feedback loop. Here, we report that Phd3 loss exacerbates the HIF activation, hepatic steatosis, dilated cardiomyopathy, and premature mortality observed in mice lacking Phd2 alone and produces a closer phenocopy of the changes seen in mice lacking pVHL than the loss of Phd2 alone. Importantly, the degree to which Phd3 can compensate for Phd2 loss and the degree to which the combined loss of Phd2 and Phd3 resembles pVHL loss appear to differ for different HIF-responsive genes and in different tissues. These findings highlight that the responses of different HIF target genes to changes in prolyl hydroxylase activity differ, quantitatively and qualitatively, in vivo and have implications for the development of paralog-specific prolyl hydroxylase inhibitors as therapeutic agents.

scholarly journals A small molecule HIF-1α stabilizer that accelerates diabetic wound healing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guodong Li ◽  
Chung-Nga Ko ◽  
Dan Li ◽  
Chao Yang ◽  
Wanhe Wang ◽  
...  
Keyword(s):  
Wound Healing ◽  
Small Molecule ◽  
Hypoxia Inducible Factor ◽  
Diabetic Patients ◽  
Diabetic Mice ◽  
Impaired Wound Healing ◽  
Von Hippel Lindau ◽  
Design And Synthesis

AbstractImpaired wound healing and ulcer complications are a leading cause of death in diabetic patients. In this study, we report the design and synthesis of a cyclometalated iridium(III) metal complex 1a as a stabilizer of hypoxia-inducible factor-1α (HIF-1α). In vitro biophysical and cellular analyses demonstrate that this compound binds to Von Hippel-Lindau (VHL) and inhibits the VHL–HIF-1α interaction. Furthermore, the compound accumulates HIF-1α levels in cellulo and activates HIF-1α mediated gene expression, including VEGF, GLUT1, and EPO. In in vivo mouse models, the compound significantly accelerates wound closure in both normal and diabetic mice, with a greater effect being observed in the diabetic group. We also demonstrate that HIF-1α driven genes related to wound healing (i.e. HSP-90, VEGFR-1, SDF-1, SCF, and Tie-2) are increased in the wound tissue of 1a-treated diabetic mice (including, db/db, HFD/STZ and STZ models). Our study demonstrates a small molecule stabilizer of HIF-1α as a promising therapeutic agent for wound healing, and, more importantly, validates the feasibility of treating diabetic wounds by blocking the VHL and HIF-1α interaction.

scholarly journals USP29-mediated HIF1α stabilization is associated with Sorafenib resistance of hepatocellular carcinoma cells by upregulating glycolysis

Oncogenesis ◽  
2021 ◽  
Vol 10 (7) ◽  
Author(s):  
Ruize Gao ◽  
David Buechel ◽  
Ravi K. R. Kalathur ◽  
Marco F. Morini ◽  
Mairene Coto-Llerena ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Transcriptional Activity ◽  
Kinase Inhibitor ◽  
Aerobic Glycolysis ◽  
Hypoxia Inducible Factor ◽  
Aberrant Expression ◽  
Key Enzyme ◽  
Hcc Cells

AbstractUnderstanding the mechanisms underlying evasive resistance in cancer is an unmet medical need to improve the efficacy of current therapies. In hepatocellular carcinoma (HCC), aberrant expression of hypoxia-inducible factor 1 α (HIF1α) and increased aerobic glycolysis metabolism are drivers of resistance to therapy with the multi-kinase inhibitor Sorafenib. However, it has remained unknown how HIF1α is activated and how its activity and the subsequent induction of aerobic glycolysis promote Sorafenib resistance in HCC. Here, we report the ubiquitin-specific peptidase USP29 as a new regulator of HIF1α and of aerobic glycolysis during the development of Sorafenib resistance in HCC. In particular, we identified USP29 as a critical deubiquitylase (DUB) of HIF1α, which directly deubiquitylates and stabilizes HIF1α and, thus, promotes its transcriptional activity. Among the transcriptional targets of HIF1α is the gene encoding hexokinase 2 (HK2), a key enzyme of the glycolytic pathway. The absence of USP29, and thus of HIF1α transcriptional activity, reduces the levels of aerobic glycolysis and restores sensitivity to Sorafenib in Sorafenib-resistant HCC cells in vitro and in xenograft transplantation mouse models in vivo. Notably, the absence of USP29 and high HK2 expression levels correlate with the response of HCC patients to Sorafenib therapy. Together, the data demonstrate that, as a DUB of HIF1α, USP29 promotes Sorafenib resistance in HCC cells, in parts by upregulating glycolysis, thereby opening new avenues for therapeutically targeting Sorafenib-resistant HCC in patients.

scholarly journals Diverse Effects of Mutations in Exon II of the von Hippel-Lindau (VHL) Tumor Suppressor Gene on the Interaction of pVHL with the Cytosolic Chaperonin and pVHL-Dependent Ubiquitin Ligase Activity

2002 ◽  
Vol 22 (6) ◽  
pp. 1947-1960 ◽  
Author(s):  
William J. Hansen ◽  
Michael Ohh ◽  
Javid Moslehi ◽  
Keiichi Kondo ◽  
William G. Kaelin ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Ubiquitin Ligase ◽  
Hypoxia Inducible Factor ◽  
Detectable Effect ◽  
Missense Mutations ◽  
Subsequent Formation ◽  
Von Hippel Lindau ◽  
Ubiquitin Ligase Activity

ABSTRACT We examined the biogenesis of the von Hippel-Lindau (VHL) tumor suppressor protein (pVHL) in vitro and in vivo. pVHL formed a complex with the cytosolic chaperonin containing TCP-1 (CCT or TRiC) en route to assembly with elongin B/C and the subsequent formation of the VCB-Cul2 ubiquitin ligase. Blocking the interaction of pVHL with elongin B/C resulted in accumulation of pVHL within the CCT complex. pVHL present in purified VHL-CCT complexes, when added to rabbit reticulocyte lysate, proceeded to form VCB and VCB-Cul2. Thus, CCT likely functions, at least in part, by retaining VHL chains pending the availability of elongin B/C for final folding and/or assembly. Tumor-associated mutations within exon II of the VHL syndrome had diverse effects upon the stability and/or function of pVHL-containing complexes. First, a pVHL mutant lacking the entire region encoded by exon II did not bind to CCT and yet could still assemble into complexes with elongin B/C and elongin B/C-Cul2. Second, a number of tumor-derived missense mutations in exon II did not decrease CCT binding, and most had no detectable effect upon VCB-Cul2 assembly. Many exon II mutants, however, were found to be defective in the binding to and subsequent ubiquitination of hypoxia-inducible factor 1α (HIF-1α), a substrate of the VCB-Cul2 ubiquitin ligase. We conclude that the selection pressure to mutate VHL exon II during tumorigenesis does not relate to loss of CCT binding but may reflect quantitative or qualitative defects in HIF binding and/or in pVHL-dependent ubiquitin ligase activity.

Monoclonal Antibody-Based Screening Assay for Factor Inhibiting Hypoxia-Inducible Factor Inhibitors

2008 ◽  
Vol 13 (6) ◽  
pp. 494-503 ◽  
Author(s):  
Sang-Hyeup Lee ◽  
Jeong Hee Moon ◽  
Eun Ah Cho ◽  
Seong-Eon Ryu ◽  
Myung Kyu Lee
Keyword(s):  
Monoclonal Antibody ◽  
High Throughput Screening ◽  
Transcriptional Activity ◽  
Hypoxia Inducible Factor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sensitive Assay ◽  
Screening Assay ◽  
Hypoxic Conditions

The factor-inhibiting hypoxia-inducible factor (FIH) hydroxylates the asparagine 803 (Asn803) residue of the hypoxia-inducible factor 1α (HIF-1α), and the modification abrogates the transcriptional activity of HIF-1α. Because FIH is more active on HIF-1α than prolyl hydroxylase domain proteins under hypoxic conditions, its inhibitors have potential to be developed as anti-ischemic drugs targeting normal cells stressed by hypoxia. In this study, the authors developed the first monoclonal antibody, SHN-HIF1α, specifically to Asn803 hydroxylated HIF-1α and a sensitive assay system for FIH inhibitors using the monoclonal antibody (Mab). SHN-HIF1α showed 740 times higher affinity to the Asn803 hydroxylated HIF-1α peptide than the unmodified one. An enzyme-linked immunosorbent assay—based system using SHN-HIF1α displayed at least 30 times more sensitivity than previous methods for screening FIH inhibitors and was easily applicable to develop a high-throughput screening system. SHN-HIF1α also showed an Asn803 hydroxylation-dependent specificity to HIF-1α in cells. Taken together, the results suggest that it may be used to analyze the in vivo and in vitro activities of FIH inhibitors. ( Journal of Biomolecular Screening 2008:494-503)

scholarly journals The E3 ubiquitin-protein ligase MDM2 is a novel interactor of the von Hippel–Lindau tumor suppressor

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Antonella Falconieri ◽  
Giovanni Minervini ◽  
Raissa Bortolotto ◽  
Damiano Piovesan ◽  
Raffaele Lopreiato ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Protein Interactions ◽  
Specific Interaction ◽  
Hypoxia Inducible Factor ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Von Hippel Lindau ◽  
Intrinsically Disordered

Abstract Mutations of the von Hippel–Lindau (pVHL) tumor suppressor are causative of a familiar predisposition to develop different types of cancer. pVHL is mainly known for its role in regulating hypoxia-inducible factor 1 α (HIF-1α) degradation, thus modulating the hypoxia response. There are different pVHL isoforms, including pVHL30 and pVHL19. However, little is known about isoform-specific functions and protein–protein interactions. Integrating in silico predictions with in vitro and in vivo assays, we describe a novel interaction between pVHL and mouse double minute 2 homolog (MDM2). We found that pVHL30, and not pVHL19, forms a complex with MDM2, and that the N-terminal acidic tail of pVHL30 is required for its association with MDM2. Further, we demonstrate that an intrinsically disordered region upstream of the tetramerization domain of MDM2 is responsible for its isoform-specific association with pVHL30. This region is highly conserved in higher mammals, including primates, similarly to what has been already shown for the N-terminal tail of pVHL30. Finally, we show that overexpression of pVHL30 and MDM2 together reduces cell metabolic activity and necrosis, suggesting a synergistic effect of these E3 ubiquitin ligases. Collectively, our data show an isoform-specific interaction of pVHL with MDM2, suggesting an interplay between these two E3 ubiquitin ligases.

scholarly journals Repurposing propranolol as an antitumor agent in von Hippel-Lindau disease

2019 ◽  
Vol 131 (4) ◽  
pp. 1106-1114 ◽  
Author(s):  
Matthew J. Shepard ◽  
Alejandro Bugarini ◽  
Nancy A. Edwards ◽  
Jie Lu ◽  
Qi Zhang ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Hypoxia Inducible Factor ◽  
Antitumor Agent ◽  
Antitumor Effects ◽  
Von Hippel Lindau ◽  
Adrenergic Antagonist ◽  
Von Hippel Lindau Disease ◽  
Propranolol Treatment

OBJECTIVEVon Hippel-Lindau disease (VHL) is a tumor predisposition syndrome characterized by CNS hemangioblastomas (HBs) and clear cell renal cell carcinomas (RCCs) due to hypoxia-inducible factor activation (pseudohypoxia). Because of the lack of effective medical therapies for VHL, HBs and RCCs account for significant morbidity and mortality, ultimately necessitating numerous neurological and renal surgeries. Propranolol is an FDA-approved pan-beta adrenergic antagonist with antitumor effects against infantile hemangiomas (IHs) and possibly VHL HBs. Here, the authors investigated the antitumor efficacy of propranolol against pseudohypoxia-driven VHL-HBs and VHL-RCCs.METHODSPatient-derived VHL-associated HBs (VHL-HBs) or 786-O-VHL−/− RCC cells were treated with clinically relevant concentrations of propranolol in vitro and assessed with viability assays, flow cytometry, quantitative real-time polymerase chain reaction, and western blotting. In vivo confirmation of propranolol antitumor activity was confirmed in athymic nude mice bearing 786-O xenograft tumors. Lastly, patients enrolled in a VHL natural history study (NCT00005902) were analyzed for incidental propranolol intake. Propranolol activity against VHL-HBs was assessed retrospectively with volumetric HB growth kinetic analysis.RESULTSPropranolol decreased HB and RCC viability in vitro with IC50 (half maximal inhibitory concentration) values of 50 µM and 200 µM, respectively. Similar to prior reports in infantile hemangiomas, propranolol induced apoptosis and paradoxically increased VEGF-A mRNA expression in patient-derived VHL-HBs and 786-O cells. While intracellular VEGF protein levels were not affected by propranolol treatment, propranolol decreased HIF expression in 786-O cells (7.6-fold reduction, p < 0.005). Propranolol attenuated tumor progression compared with control (33% volume reduction at 7 days, p < 0.005) in 786-O xenografted tumor-bearing mice. Three patients (harboring 25 growing CNS HBs) started propranolol therapy during the longitudinal VHL-HB study. HBs in these patients tended to grow slower (median growth rate 27.1 mm3/year vs 13.3 mm3/year) during propranolol treatment (p < 0.0004).CONCLUSIONSPropranolol decreases VHL-HB and VHL-related RCC viability in vitro likely by modulation of VEGF expression and by inducing apoptosis. Propranolol abrogates 786-O xenograft tumor progression in vivo, and retrospective clinical data suggest that propranolol curtails HB growth. These results suggest that propranolol may play a role in the treatment of VHL-related tumors.

Targeting the Leukemia Initiating Cells in a Mouse T-ALL Model.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3474-3474
Author(s):  
Jessica Tatarek ◽  
Kathleen Cullion ◽  
Michelle Kelliher
Keyword(s):  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Fold Increase ◽  
Thymocyte Development ◽  
Double Positive ◽  
Self Renewal ◽  
Oncogenic Pathways ◽  
Single Positive

Abstract Abstract 3474 Poster Board III-411 T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy that is largely caused by aberrant activation of the TAL1/SCL, LMO1/2 and NOTCH1 oncogenic pathways. Although most patients respond to cytotoxic therapy, 20-30% relapse and currently we cannot distinguish children likely to relapse from those who will respond to therapy. Evidence is emerging that some malignancies are driven by a rare initiating population that is capable of extensive self-renewal and is resistant to conventional chemotherapy. Although the leukemia-initiating cells (L-ICs) have been well documented in AML and CML, it is unclear whether T-ALL is driven by a rare L-IC and whether relapse reflects an inability to eliminate L-ICs. To determine whether T-ALL is driven by a rare L-IC, we utilized a murine model of T-ALL in which expression of the Tal1 and Lmo2 oncogenes arrests thymocyte development via E47/HEB inhibition and 75% of tumors develop spontaneous gain of function mutations in Notch1. We have shown that treatment with γ-secretase inhibitors (GSIs) to inhibit Notch1 activity induces apoptosis of mouse T-ALL cells in vitro and when administered in vivo extends the survival of leukemic mice. We demonstrate that clonal mouse T-ALL tumors are phenotypically heterogeneous, containing immature CD4- and CD8-negative, double negative (DN) 3 and 4 thymic progenitors and differentiated double positive (DP) and/or single positive (SP) leukemic blasts. Importantly, the DN3 or DN4 progenitors are maintained upon serial transplantation of the tumor into syngeneic recipient mice. Injection of serial dilutions of murine T-ALL cells reveal that the tumors are also functionally heterogeneous; with 1/5000-1/50,000 tumor cells exhibiting leukemia initiating activity. We found the CD44-, CD25+ DN3 progenitors enriched in disease potential, whereas mice injected with DP leukemic blasts failed to develop leukemia. Consistently, our preleukemic studies reveal a 3.5-fold increase in the percentage of Notch1 active, DN3/4 thymic progenitors, raising the possibility that Notch1 drives L-IC growth. Collectively, these studies suggest that activation of the Notch1-c-Myc pathway may confer self-renewal capabilities on committed thymic progenitors. The effects of Notch inhibitors on mouse L-IC survival and activity will be discussed. Disclosures: No relevant conflicts of interest to declare.

scholarly journals New HIF2α inhibitors: potential implications as therapeutics for advanced pheochromocytomas and paragangliomas

2017 ◽  
Vol 24 (9) ◽  
pp. C9-C19 ◽  
Author(s):  
Rodrigo Almeida Toledo
Keyword(s):  
Amino Acids ◽  
Human Cancer ◽  
Hypoxia Inducible Factor ◽  
Fumarate Hydratase ◽  
Elongation Factor ◽  
Cell Renal Cell Carcinoma ◽  
Von Hippel Lindau ◽  
Therapeutic Opportunity

Two recent independent studies published in Nature show robust responses of clear cell renal cell carcinoma (ccRCC) cell lines, preclinical ccRCC xenograft models and, remarkably, a patient with progressive ccRCC despite receiving multiple lines of treatment, to the long-awaited, recently developed inhibitors of hypoxia-inducible factor 2-alpha (HIF2α). This commentary published in Endocrine-Related Cancer is based on the recognition of similar molecular drivers in ccRCC and the endocrine neoplasias pheochromocytomas and paragangliomas (PPGLs), ultimately leading to stabilization of HIFs. HIF-stabilizing mutations have been detected in the von Hippel–Lindau (VHL) gene, as well as in other genes, such as succinate dehydrogenase (SDHx), fumarate hydratase (FH) and transcription elongation factor B subunit 1 (TCEB1), as well as the gene that encodes HIF2α itself: EPAS1HIF2α. Importantly, the recent discovery of EPAS1 mutations in PPGLs and the results of comprehensive in vitro and in vivo studies revealing their oncogenic roles characterized a hitherto unknown direct mechanism of HIF2α activation in human cancer. The now available therapeutic opportunity to successfully inhibit HIF2α pharmacologically with PT2385 and PT2399 will certainly spearhead a series of investigations in several types of cancers, including patients with SDHB-related metastatic PPGL for whom limited therapeutic options are currently available. Future studies will determine the efficacy of these promising drugs against the hotspot EPAS1 mutations affecting HIF2α amino acids 529–532 (in PPGLs) and amino acids 533–540 (in erythrocytosis type 4), as well as against HIF2α protein activated by VHL, SDHx and FH mutations in PPGL-derived chromatin cells.

scholarly journals CD6 modulates thymocyte selection and peripheral T cell homeostasis

2016 ◽  
Vol 213 (8) ◽  
pp. 1387-1397 ◽  
Author(s):  
Marc Orta-Mascaró ◽  
Marta Consuegra-Fernández ◽  
Esther Carreras ◽  
Romain Roncagalli ◽  
Amado Carreras-Sureda ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immunological Synapse ◽  
Cell Receptor ◽  
Autoimmune Response ◽  
Effector Memory ◽  
Thymocyte Development ◽  
Double Positive

The CD6 glycoprotein is a lymphocyte surface receptor putatively involved in T cell development and activation. CD6 facilitates adhesion between T cells and antigen-presenting cells through its interaction with CD166/ALCAM (activated leukocyte cell adhesion molecule), and physically associates with the T cell receptor (TCR) at the center of the immunological synapse. However, its precise role during thymocyte development and peripheral T cell immune responses remains to be defined. Here, we analyze the in vivo consequences of CD6 deficiency. CD6−/− thymi showed a reduction in both CD4+ and CD8+ single-positive subsets, and double-positive thymocytes exhibited increased Ca2+ mobilization to TCR cross-linking in vitro. Bone marrow chimera experiments revealed a T cell–autonomous selective disadvantage of CD6−/− T cells during development. The analysis of TCR-transgenic mice (OT-I and Marilyn) confirmed that abnormal T cell selection events occur in the absence of CD6. CD6−/− mice displayed increased frequencies of antigen-experienced peripheral T cells generated under certain levels of TCR signal strength or co-stimulation, such as effector/memory (CD4+TEM and CD8+TCM) and regulatory (T reg) T cells. The suppressive activity of CD6−/− T reg cells was diminished, and CD6−/− mice presented an exacerbated autoimmune response to collagen. Collectively, these data indicate that CD6 modulates the threshold for thymocyte selection and the generation and/or function of several peripheral T cell subpopulations, including T reg cells.

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