scholarly journals The Hypoxia-Inducible Factor 2α N-Terminal and C-Terminal Transactivation Domains Cooperate To Promote Renal Tumorigenesis In Vivo

2007 ◽  
Vol 27 (6) ◽  
pp. 2092-2102 ◽  
Author(s):  
Qin Yan ◽  
Steven Bartz ◽  
Mao Mao ◽  
Lianjie Li ◽  
William G. Kaelin
Keyword(s):  
Transcriptional Activation ◽  
Hypoxia Inducible Factor ◽  
Gene Activation ◽  
Tumor Formation ◽  
Transactivation Domain ◽  
Renal Carcinogenesis ◽  
Von Hippel Lindau ◽  
Transactivation Domains ◽  
Relative Contribution

ABSTRACT Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor, consisting of an alpha subunit and a beta subunit, that controls cellular responses to hypoxia. HIFα contains two transcriptional activation domains called the N-terminal transactivation domain (NTAD) and the C-terminal transactivation domain (CTAD). HIFα is destabilized by prolyl hydroxylation catalyzed by EglN family members. In addition, CTAD function is inhibited by asparagine hydroxylation catalyzed by FIH1. Both hydroxylation reactions are linked to oxygen availability. The von Hippel-Lindau tumor suppressor protein (pVHL) is frequently mutated in kidney cancer and is part of the ubiquitin ligase complex that targets prolyl hydroxylated HIFα for destruction. Recent studies suggest that HIF2α plays an especially important role in promoting tumor formation by pVHL-defective renal carcinoma cells among the three HIFα paralogs. Here we dissected the relative contribution of the two HIF2α transactivation domains to hypoxic gene activation and renal carcinogenesis and investigated the regulation of the HIF2α CTAD by FIH1. We found that the HIF2α NTAD is capable of activating both artificial and naturally occurring HIF-responsive promoters in the absence of the CTAD. Moreover, we found that the HIF2α CTAD, in contrast to the HIF1α CTAD, is relatively resistant to the inhibitory effects of FIH1 under normoxic conditions and that, perhaps as a result, both the NTAD and CTAD cooperate to promote renal carcinogenesis in vivo.

scholarly journals Differential Contribution of N- and C-Terminal Regions of HIF1α and HIF2α to Their Target Gene Selectivity

2020 ◽  
Vol 21 (24) ◽  
pp. 9401
Author(s):  
Antonio Bouthelier ◽  
Florinda Meléndez-Rodríguez ◽  
Andrés A. Urrutia ◽  
Julián Aragonés
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Cellular Response ◽  
Target Gene ◽  
Target Genes ◽  
Transactivation Domain ◽  
Transactivation Domains ◽  
Relative Contribution

Cellular response to hypoxia is controlled by the hypoxia-inducible transcription factors HIF1α and HIF2α. Some genes are preferentially induced by HIF1α or HIF2α, as has been explored in some cell models and for particular sets of genes. Here we have extended this analysis to other HIF-dependent genes using in vitro WT8 renal carcinoma cells and in vivo conditional Vhl-deficient mice models. Moreover, we generated chimeric HIF1/2 transcription factors to study the contribution of the HIF1α and HIF2α DNA binding/heterodimerization and transactivation domains to HIF target specificity. We show that the induction of HIF1α-dependent genes in WT8 cells, such as CAIX (CAR9) and BNIP3, requires both halves of HIF, whereas the HIF2α transactivation domain is more relevant for the induction of HIF2 target genes like the amino acid carrier SLC7A5. The HIF selectivity for some genes in WT8 cells is conserved in Vhl-deficient lung and liver tissue, whereas other genes like Glut1 (Slc2a1) behave distinctly in these tissues. Therefore the relative contribution of the DNA binding/heterodimerization and transactivation domains for HIF target selectivity can be different when comparing HIF1α or HIF2α isoforms, and that HIF target gene specificity is conserved in human and mouse cells for some of the genes analyzed.

The role of iron and 2-oxoglutarate oxygenases in signalling

2003 ◽  
Vol 31 (3) ◽  
pp. 510-515 ◽  
Author(s):  
K.S. Hewitson ◽  
L.A. McNeill ◽  
J.M. Elkins ◽  
C.J. Schofield
Keyword(s):  
Transcriptional Activation ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Response ◽  
Transactivation Domain ◽  
Von Hippel Lindau ◽  
Helix Loop Helix ◽  
Hypoxic Conditions ◽  
Tumour Suppressor Protein ◽  
Dependent Modification

Sensing of ambient dioxygen levels and appropriate feedback mechanisms are essential processes for all multicellular organisms. In animals, moderate hypoxia causes an increase in the transcription levels of specific genes, including those encoding vascular endothelial growth factor and erythropoietin. The hypoxic response is mediated by hypoxia-inducible factor (HIF), an αβ heterodimeric transcription factor in which both the HIF subunits are members of the basic helix–loop–helix PAS (PER-ARNT-SIM) domain family. Under hypoxic conditions, levels of HIFα rise, allowing dimerization with HIFβ and initiating transcriptional activation. Two types of dioxygen-dependent modification to HIFα have been identified, both of which inhibit the transcriptional response. Firstly, HIFα undergoes trans-4-hydroxylation at two conserved proline residues that enable its recognition by the von Hippel-Lindau tumour-suppressor protein. Subsequent ubiquitinylation, mediated by an ubiquitin ligase complex, targets HIFα for degradation. Secondly, hydroxylation of an asparagine residue in the C-terminal transactivation domain of HIFα directly prevents its interaction with the co-activator p300. Hydroxylation of HIFα is catalysed by enzymes of the iron(II)- and 2-oxoglutarate-dependent dioxygenase family. In humans, three prolyl hydroxylase isoenzymes (PHD1–3) and an asparagine hydroxylase [factor inhibiting HIF (FIH)] have been identified. The role of 2-oxoglutarate oxygenases in the hypoxic and other signalling pathways is discussed.

scholarly journals Acetylation-Mediated Transcriptional Activation of the ETS Protein ER81 by p300, P/CAF, and HER2/Neu

2003 ◽  
Vol 23 (17) ◽  
pp. 6243-6254 ◽  
Author(s):  
Apollina Goel ◽  
Ralf Janknecht
Keyword(s):  
Protein Kinase ◽  
Transcriptional Activation ◽  
Binding Activity ◽  
Tumor Formation ◽  
Mitogen Activated Protein Kinase ◽  
Transactivation Domain ◽  
Dna Binding Activity ◽  
Mitogen Activated Protein

ABSTRACT The regulated expression of the ETS transcription factor ER81 is a prerequisite for normal development, and its dysregulation contributes to neoplasia. Here, we demonstrate that ER81 is acetylated by two coactivators/acetyltransferases, p300 and p300- and CBP-associated factor (P/CAF) in vitro and in vivo. Whereas p300 acetylates two lysine residues (K33 and K116) within the ER81 N-terminal transactivation domain, P/CAF targets only K116. Acetylation of ER81 not only enhances its ability to transactivate but also increases its DNA binding activity and in vivo half-life. Furthermore, oncogenic HER2/Neu, which induces phosphorylation and thereby activation of ER81, was less able to activate acetylation-deficient ER81 mutants, indicating that both acetyltransferase and protein kinase-specific regulatory mechanisms control ER81 activity. Importantly, HER2/Neu overexpression stimulates the ability of p300 to acetylate ER81, likely by inducing phosphorylation of p300 through the Ras→Raf→mitogen-activated protein kinase pathway. This represents a novel mechanism by which oncogenic HER2/Neu, Ras, or Raf may promote tumor formation by enhancing acetylation not only of ER81 but also of other downstream effector transcription factors as well as histones.

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 ADR1-Mediated Transcriptional Activation Requires the Presence of an Intact TFIID Complex

1998 ◽  
Vol 18 (10) ◽  
pp. 5861-5867 ◽  
Author(s):  
Philip B. Komarnitsky ◽  
Edward R. Klebanow ◽  
P. Anthony Weil ◽  
Clyde L. Denis
Keyword(s):  
Transcriptional Activation ◽  
Yeast Cells ◽  
Binding Studies ◽  
Whole Cell ◽  
Transactivation Domains ◽  
Cell Extracts ◽  
Genes Expression ◽  
Tfiid Complex

ABSTRACT The yeast transcriptional activator ADR1, which is required forADH2 and other genes’ expression, contains four transactivation domains (TADs). While previous studies have shown that these TADs act through GCN5 and ADA2, and presumably TFIIB, other factors are likely to be involved in ADR1 function. In this study, we addressed the question of whether TFIID is also required for ADR1 action. In vitro binding studies indicated that TADI of ADR1 was able to retain TAFII90 from yeast extracts and TADII could retain TBP and TAFII130/145. TADIV, however, was capable of retaining multiple TAFIIs, suggesting that TADIV was binding TFIID from yeast whole-cell extracts. The ability of TADIV truncation derivatives to interact with TFIID correlated with their transcription activation potential in vivo. In addition, the ability of LexA-ADR1-TADIV to activate transcription in vivo was compromised by a mutation in TAFII130/145. ADR1 was found to associate in vivo with TFIID in that immunoprecipitation of either TAFII90 or TBP from yeast whole-cell extracts specifically coimmunoprecipitated ADR1. Most importantly, depletion of TAFII90 from yeast cells dramatically reducedADH2 derepression. These results indicate that ADR1 physically associates with TFIID and that its ability to activate transcription requires an intact TFIID complex.

scholarly journals Meloxicam, a Selective COX-2 Inhibitor, Mediates Hypoxia-Inducible Factor- (HIF-) 1α Signaling in Hepatocellular Carcinoma

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yinghong Zhou ◽  
Xiaofeng Dong ◽  
Peng Xiu ◽  
Xin Wang ◽  
Jianrong Yang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Transcriptional Activation ◽  
Mitochondrial Membrane ◽  
Hypoxia Inducible Factor ◽  
Luciferase Assay ◽  
Cox 2

Hepatocellular carcinoma (HCC) is regarded as a leading cause of cancer-related deaths, and its progression is associated with hypoxia and the induction of hypoxia-inducible factor (HIF). Meloxicam, a selective cyclooxygenase-2 (COX-2) inhibitor, induces cell death in various malignancies. However, the underlying mechanism remains to be elucidated in HCC, especially under hypoxic conditions. The alteration of COX-2 and HIF-1α oncogenicity was evaluated in HCC specimens by tissue microarray. Cell viability, angiogenesis assays, and xenografted nude mice were used to evaluate the effects of meloxicam, along with flow cytometry to detect the cell cycle, apoptosis, and mitochondrial membrane potential (ΔΨm) of HCC. qRT-PCR, Western blotting, immunofluorescence, immunohistochemistry, luciferase assay, and RNAi were carried out to determine the HIF-1α signaling affected by meloxicam. In this study, we showed that meloxicam exerts antiproliferative and antiangiogenesis efficacy in vitro and in vivo and causes disruption of mitochondrial membrane potential (ΔΨm), thus leading to caspase-dependent apoptosis under hypoxic environments. Exposure to meloxicam significantly reduced HIF-1α transcriptional activation and expression through sequestering it in the cytoplasm and accelerating degradation via increasing the von Hippel-Lindau tumor suppressor protein (pVHL) in HCC. These data demonstrated that inhibition of HIF-1α by meloxicam could suppress angiogenesis and enhance apoptosis of HCC cells. This discovery highlights that COX-2 specific inhibitors may be a promising therapy in the treatment of HCC.

scholarly journals Three functional classes of transcriptional activation domain.

1996 ◽  
Vol 16 (5) ◽  
pp. 2044-2055 ◽  
Author(s):  
J Blau ◽  
H Xiao ◽  
S McCracken ◽  
P O'Hare ◽  
J Greenblatt ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Type I ◽  
Rnase Protection ◽  
Activation Domains ◽  
Transcriptional Activation Domain ◽  
Transactivation Domains ◽  
Functional Classes

We have studied the abilities of different transactivation domains to stimulate the initiation and elongation (postinitiation) steps of RNA polymerase II transcription in vivo. Nuclear run-on and RNase protection analyses revealed three classes of activation domains: Sp1 and CTF stimulated initiation (type I); human immunodeficiency virus type 1 Tat fused to a DNA binding domain stimulated predominantly elongation (type IIA); and VP16, p53, and E2F1 stimulated both initiation and elongation (type IIB). A quadruple point mutation of VP16 converted it from a type IIB to a type I activator. Type I and type IIA activators synergized with one another but not with type IIB activators. This observation implies that synergy can result from the concerted action of factors stimulating two different steps in transcription: initiation and elongation. The functional differences between activators may be explained by the different contacts they make with general transcription factors. In support of this idea, we found a correlation between the abilities of activators, including Tat, to stimulate elongation and their abilities to bind TFIIH.

Ankyrin repeats-containing cofactors interact with ADA3 and modulate its co-activator function

2008 ◽  
Vol 413 (2) ◽  
pp. 349-357 ◽  
Author(s):  
Chia-Wei Li ◽  
Gia Khanh Dinh ◽  
Aihua Zhang ◽  
J. Don Chen
Keyword(s):  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Histone Deacetylases ◽  
Binding Protein ◽  
Camp Response Element Binding ◽  
Transactivation Domain ◽  
Ankyrin Repeats ◽  
Camp Response Element ◽  
Element Binding Protein

ANCO (ankyrin repeats-containing cofactor)-1 and ANCO-2 are a family of unique transcriptional co-regulators with dual properties: they interact with both the co-activators and the co-repressors [Zhang, Yeung, Li, Tsai, Dinh, Wu, Li and Chen (2004) J. Biol. Chem. 279, 33799–33805]. Specifically, ANCO-1 is thought to recruit HDACs (histone deacetylases) to the p160 co-activator to repress transcriptional activation by nuclear receptors. In the present study, we provide new evidence to suggest further that ANCO-1 and ANCO-2 also interact with the co-activator ADA3 (alteration/deficiency in activation 3). The interaction occurs between the conserved C-terminal domain of ANCO-1 and the N-terminal transactivation domain of ADA3. Several subunits of the P/CAF {p300/CBP [CREB (cAMP-response-element-binding protein)-binding protein]-associated factor} complex, including ADA3, ADA2α/β and P/CAF, showed co-localization with ANCO-1 nuclear dots, indicating an in vivo association of ANCO-1 with the P/CAF complex. Furthermore, a transient reporter assay revealed that both ANCO-1 and ANCO-2 repress ADA3-mediated transcriptional co-activation on nuclear receptors, whereas ANCO-1 stimulated p53-mediated transactivation. These data suggest that ADA3 is a newly identified target of the ANCO proteins, which may modulate co-activator function in a transcription-factor-specific manner.

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.

scholarly journals Carboxyl-Terminal Transactivation Activity of Hypoxia-Inducible Factor 1α Is Governed by a von Hippel-Lindau Protein-Independent, Hydroxylation-Regulated Association with p300/CBP

2002 ◽  
Vol 22 (9) ◽  
pp. 2984-2992 ◽  
Author(s):  
Nianli Sang ◽  
Jie Fang ◽  
Vickram Srinivas ◽  
Irene Leshchinsky ◽  
Jaime Caro
Keyword(s):  
Hypoxia Inducible Factor ◽  
Adaptation To Hypoxia ◽  
Physical Interaction ◽  
Prolyl Hydroxylases ◽  
Von Hippel Lindau ◽  
Hypoxia Inducible Factor 1 ◽  
Transactivation Activity ◽  
Oxygen Homeostasis ◽  
Stimulation Of

ABSTRACT Hypoxia-inducible factor 1 complex (HIF-1) plays a pivotal role in oxygen homeostasis and adaptation to hypoxia. Its function is controlled by both the protein stability and the transactivation activity of its alpha subunit, HIF-1α. Hydroxylation of at least two prolyl residues in the oxygen-dependent degradation domain of HIF-1α regulates its interaction with the von Hippel-Lindau protein (VHL) that targets HIF-1α for ubiquitination and proteasomal degradation. Several prolyl hydroxylases have been found to specifically hydroxylate HIF-1α. In this report, we investigated possible roles of VHL and hydroxylases in the regulation of the transactivation activity of the C-terminal activating domain (CAD) of HIF-1α. We demonstrate that regulation of the transactivation activity of HIF-1α CAD also involves hydroxylase activity but does not require functional VHL. In addition, stimulation of the CAD activity by a hydoxylase inhibitor, hypoxia, and desferrioxamine was severely blocked by the adenoviral oncoprotein E1A but not by an E1A mutant defective in targeting p300/CBP. We further demonstrate that a hydroxylase inhibitor, hypoxia, and desferrioxamine promote the functional and physical interaction between HIF-1α CAD and p300/CBP in vivo. Taken together, our data provide evidence that hypoxia-regulated stabilization and transcriptional stimulation of HIF-1α function are regulated through partially overlapping but distinguishable pathways.

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