Complex regulation of the transactivation function of hypoxia-inducible factor-1 alpha by direct interaction with two distinct domains of the CREB-binding protein/p300.

Abstract

Activation of transcription in response to low oxygen tension is mediated by the hypoxia-inducible factor-1 (HIF-1). HIF-1 is a heterodimer of two proteins: aryl hydrocarbon receptor nuclear translocator and the oxygen-regulated HIF-1 alpha. The C-terminal activation domain of HIF-1 alpha has been shown to interact with cysteine/histidine-rich region 1 (CH1) of the coactivator CBP/p300 in a hypoxia-dependent manner. However, HIF forms lacking C-terminal activation domain (naturally occurring or genetically engineered) are still able to activate transcription of target genes in hypoxia. Here, we demonstrate that the N-terminal activation domain (N-TAD) of HIF-1 alpha interacts with endogenous CBP and that this interaction facilitates its transactivation function. Our results show that interaction of HIF-1 alpha N-TAD with CBP/p300 is mediated by the CH3 region of CBP known to interact with, among other factors, p53. Using fluorescence resonance energy transfer experiments, we demonstrate that N-TAD interacts with CH3 in vivo. Coimmunoprecipitation assays using endogenous proteins showed that immunoprecipitation of CBP in hypoxia results in the recovery of a larger fraction of HIF-1 alpha than of p53. Chromatin immunoprecipitation demonstrated that at 1% O(2) CBP is recruited to a HIF-1 alpha but not to a p53 target gene. Upon activation of both pathways, lower levels of chromatin-associated CBP were detected at either target gene promoter. These results identify CBP as the coactivator directly interacting with HIF-1 alpha N-TAD and mediating the transactivation function of this domain. Thus, we suggest that in hypoxia HIF-1 alpha is a major CBP-interacting transcription factor that may compete with other CBP-dependent factors, including p53, for limiting amounts of this coactivator, underscoring the complexity in the regulation of gene expression by HIF-1 alpha.

• Authors: Jorge L Ruas, Utta Berchner-Pfannschmidt, Sohail Malik, Katarina Gradin, Joachim Fandrey, Robert G Roeder, Teresa Pereira, Lorenz Poellinger
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 285 Issue 4 Pg. 2601-9 (Jan 22 2010) ISSN: 1083-351X [Electronic] United States
• PMID: 19880525 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Chelating Agents
• HIF1A protein, human
• Hypoxia-Inducible Factor 1, alpha Subunit
• Tumor Suppressor Protein p53
• Histidine
• 2,2'-Dipyridyl
• E1A-Associated p300 Protein
• p300-CBP Transcription Factors
• Cysteine

Topics

• 2,2'-Dipyridyl (pharmacology)
• Cell Line
• Chelating Agents (pharmacology)
• Cysteine (metabolism)
• E1A-Associated p300 Protein (chemistry, metabolism)
• HeLa Cells
• Histidine (metabolism)
• Humans
• Hypoxia (metabolism, physiopathology)
• Hypoxia-Inducible Factor 1, alpha Subunit (chemistry, genetics, metabolism)
• Kidney (cytology)
• Mutagenesis
• Protein Interaction Domains and Motifs (drug effects, physiology)
• Protein Structure, Tertiary
• Transcriptional Activation (physiology)
• Tumor Suppressor Protein p53 (metabolism)
• p300-CBP Transcription Factors (chemistry, metabolism)