Differential regulation of HIF-1α isoforms in murine macrophages by TLR4 and adenosine A2A receptor agonists

Autor: Dmitry Lukashev, Samuel Leibovich, Madhuri Ramanathan, Wenting Luo, Michail V. Sitkovsky, Balázs Csóka, György Haskó
Rok vydání: 2009
Předmět:
Lipopolysaccharides
Vascular Endothelial Growth Factor A
Agonist
Gene isoform
Adenosine
Adenosine A2 Receptor Agonists
medicine.drug_class
Immunology
Adenosine-5'-(N-ethylcarboxamide)
Biology
Transfection
Mice
Mice
Congenic
Genes
Reporter
Nitriles
Phenethylamines
Purinergic P1 Receptor Agonists
medicine
Transcriptional regulation
Animals
Protein Isoforms
Immunology and Allergy
RNA
Messenger
Sulfones
Cells
Cultured
Luciferases
Renilla
Regulation of gene expression
Triazines
NF-kappa B
Cell Biology
Triazoles
Hypoxia-Inducible Factor 1
alpha Subunit
NFKB1
Molecular biology
Adenosine A2 Receptor Antagonists
Receptors
Signal Transduction
& Genes
Mice
Inbred C57BL
Toll-Like Receptor 4
Drug Combinations
Gene Expression Regulation
Macrophages
Peritoneal
TLR4
Female
Protein stabilization
medicine.drug
Zdroj: Journal of Leukocyte Biology. 86:681-689
ISSN: 1938-3673
0741-5400
Popis: Up-regulation of adenosine A2A receptors (A2ARs) and the HIF-1αl. 1 isoform plays an important role in the switch of macrophages from an inflammatory (M1) to an angiogenic (M2-like) phenotype. Adenosine A2AR and TLR agonists synergize to induce an “angiogenic switch” in macrophages, down-regulating TNF-α and up-regulating VEGF expression. This switch involves transcriptional regulation of VEGF by HIF-1, transcriptional induction of HIF-1α by LPS (TLR4 agonist), and A2AR-dependent post-transcriptional regulation of HIF-1α stability. Murine HIF-1α is expressed as two mRNA isoforms: HIF-1αI.1 and -I.2, which contain alternative first exons and promoters. HIF-1αI.2 is expressed ubiquitously, and HIF-1αI.1 is tissue-specific. We investigated the regulation of these isoforms in macrophages by TLR4 and A2AR agonists. HIF-1αI.1 is induced strongly compared with HIF-1αI.2 upon costimulation with LPS and A2AR agonists (NECA or CGS21680). In unstimulated cells, the I.1 isoform constituted ∼4% of HIF-1α transcripts; in LPS and NECA- or CGS21680-treated macrophages, this level was ∼15%, indicating a substantial contribution of HIF-1αI.1 to total HIF-1α expression. The promoters of both isoforms were induced by LPS but not enhanced further by NECA, suggesting A2AR-mediated post-transcriptional regulation. LPS/NECA-induced expression of HIF-1αI.1 was down-regulated by Bay 11-7085 (NF-κB inhibitor) and ZM241385 (A2AR antagonist). Although VEGF and IL-10 expression by HIF-1αI.1−/− macrophages was equivalent to that of wild-type macrophages, TNF-α, MIP-1α, IL-6, IL-12p40, and IL-1β expression was significantly greater, suggesting a role for HIF-1αI.1 in modulating expression of these cytokines. A2AR expression in unstimulated macrophages was low but was induced rapidly by LPS in a NF-κB-dependent manner. LPS-induced expression of A2ARs and HIF-1α and A2AR-dependent HIF-1α mRNA and protein stabilization provide mechanisms for the synergistic effects of LPS and A2AR agonists on macrophage VEGF expression.
Databáze: OpenAIRE
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