Flowchart: Preparation: A2A

Text Box: IL-1beta Text Box: TNF-apha


Parkison Disease

Text Box: A2AText Box: A3A

Text Box: Vegf 





J Immunol. 2006 Nov 15;177(10):7173-83.Click here to read  Links

IL-1beta and TNF-alpha regulation of the adenosine receptor (A2A) expression: differential requirement for NF-kappaB binding to the proximal promoter.

     Morello S, Ito K, Yamamura S, Lee KY, Jazrawi E, Desouza P, Barnes P, Cicala C, Adcock IM.

Airways Disease Section, NHLI Imperial College London, London, United Kingdom.

Adenosine is a potent endogenous regulator of airway inflammation that acts through specific receptor subtypes that can either cause constriction (A1R, A2BR, and A3R) or relaxation (A2AR) of the airways. We therefore examined the effects of key inflammatory mediators on the expression of the A2AR in a lung epithelial cell line (A549). IL-1beta and TNF-alpha increased the expression of the A2AR gene at the mRNA and protein levels. In contrast, LPS had no effect on A2AR gene expression. IL-1beta and TNF-alpha rapidly activated p50 and p65, but not C-Rel, RelB, or p52, and both IL-1beta- and TNF-alpha-stimulated A2AR expression was inhibited by the IkappaB kinase 2 inhibitor AS602868 in a concentration-dependent manner. Using chromatin immunoprecipitation assays, we demonstrate that IL-1beta can enhance p65 association with putative kappaB binding sites in the A2AR promoter in a temporal manner. In contrast, TNF-alpha failed to enhance p65 binding to these putative sites. Functionally, the two most 5' kappaB sites were important for IL-1beta-, but not TNF-alpha-, induced A2AR promoter reporter gene activity. Finally, neither TNF-alpha nor Il-1beta had any effect on A2AR mRNA transcript degradation. These results directly implicate a major role for NF-kappaB in the regulation of A2AR gene transcription by IL-1beta and TNF-alpha but suggest that the effects of TNF-alpha on A2AR gene transcription are not mediated through the proximal promoter.

PMID: 17082635 [PubMed - in process]

Mol Biol Cell. 2006 Oct 25; [Epub ahead of print]Click here to read  Links

Synergistic Up-Regulation of Vascular Endothelial Growth Factor (VEGF) Expression in Macrophages by Adenosine A2A Receptor Agonists and Endotoxin Involves Transcriptional Regulation via the Hypoxia Response Element (HRE) in the VEGF Promoter.

     Ramanathan M, Pinhal-Enfield G, Hao I, Leibovich SJ.

Department of Cell Biology and Molecular Medicine and The Cardiovascular Research Institute, New Jersey Medical School, University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ 07103.

Monitoring Editor: Richard Assoian Macrophages are an important source of VEGF. Adenosine A2A receptor (A2AR) agonists with Toll-like receptor (TLR) 2, 4, 7, and 9 agonists synergistically induce macrophage VEGF expression. We show here using VEGF promoter-luciferase reporter constructs that the TLR4 agonist Escherichia coli LPS and the A2AR agonists NECA and CGS21680 synergistically augment VEGF transcription in macrophages, and that the HRE in the VEGF promoter is essential for this transcription. We examined whether LPS and/or NECA induce HIF-1alpha expression. HIF-1alpha mRNA levels were increased in LPS-treated macrophages in an NF-kappaB-dependent manner; NECA strongly increased these levels in an A2AR-dependent manner. LPS induced luciferase expression from a HIF-1alpha promoter-luciferase construct in an A2AR-independent manner. Further stimulation with NECA did not increase HIF-1alpha promoter activity, indicating that the A2AR-dependent increase in HIF-1alpha mRNA is post-transcriptional. LPS/NECA treatment also increased HIF-1alpha protein and DNA binding levels. Deletion of putative NF-kappaB-binding sites from the VEGF promoter did not affect LPS/NECA-induced VEGF promoter activity, suggesting that NF-kappaB is not directly involved in VEGF transcription. Taken together, these data indicate that LPS/NECA-induced VEGF expression involves transcriptional regulation of the VEGF promoter by HIF-1alpha through the HRE. HIF-1alpha is transcriptionally induced by LPS, and post-transcriptionally up-regulated in an A2AR-dependent manner.

PMID: 17065555 [PubMed - as supplied by publisher