Adenosine signaling mediates SUMO-1 modification of IkappaBalpha during hypoxia and reoxygenation.
Small ubiquitin-like modifier 1 (SUMO-1) modification of IkappaBalpha has been described to actively participate in NFkappaB regulation. Following proteosomal degradation of IkappaBalpha, an auto-regulatory loop consisting of transcriptional activation of IkappaBalpha gene and SUMO-1 modification of newly synthesized IkappaBalpha proceeds. The SUMOylated IkappaBalpha form is resistant to signal-induced degradation, consequently halting NFkappaB activation. We describe a mechanistic model by which adenosine (Ado) signaling results in significant accumulation of SUMO-1 modified IkappaBalpha with subsequent attenuation of NFkappaB activation. Using models of hypoxia followed by reoxygenation (H/R), we have documented an H/R cycle-dependent increase in extracellular Ado correlating with increases in the cytoplasmic pool of IkappaBalpha/SUMO-1. We demonstrate a dose-dependent increase in IkappaBalpha/SUMO in cells treated with the general Ado receptor agonist NECA and abolished by Ado receptor antagonists. Experiments in cells exposed to cycles of H/R followed by hypoxia demonstrated differential patterns of SUMOylation and phosphorylation of IkappaBalpha, greatly impacting its proteosomal degradation by the 26 S proteasome. Assays targeting knockdown and overexpression of SUMO-1 demonstrated significant regulation of NFkappaB activation and NFkappaB-mediated gene transcription (interleukin-6). These results were confirmed in vivo using wild type and cd73 null mouse lung tissue. In summary, we present an endogenous mechanism by which cells and tissues acquire anti-inflammatory properties by recruiting a nondegradable form of IkappaBalpha, a major control point for NFkappaB activation via Ado signaling.
Liu
Qian
Q
Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115; Department of Surgery, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
Li
Jing
J
Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115; Laboratory of Stem Cell and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing 400016, China.
Khoury
Joseph
J
Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115.
Colgan
Sean P
SP
Mucosal Inflammation Program, Division of Gastroenterology, University Colorado Health Sciences Center, Denver, Colorado 80220.
Ibla
Juan C
JC
Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115. Electronic address: juan.ibla@childrens.harvard.edu.
D015720:5'-Nucleotidase / Q000235:genetics; D000241:Adenosine / Q000378:metabolism* / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism*; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D008168:Lung / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011014:Pneumonia / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1 / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D020672:I-kappa B Proteins; C508600:IL6 protein, human; D015850:Interleukin-6; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1; D025842:SUMO-1 Protein; D014665:Vasodilator Agents; D000072000:NF-KappaB Inhibitor alpha; D019830:Adenosine-5'-(N-ethylcarboxamide); D015720:5'-Nucleotidase; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000241:Adenosine