G16-mediated activation of nuclear factor kappaB by the adenosine A1 receptor involves c-Src, protein kinase C, and ERK signaling.
The G(i)-linked adenosine A1 receptor has been shown to mediate anti-inflammatory actions, possibly via modulation of the transcription factor nuclear factor-kappaB (NFkappaB). Here we demonstrate that an adenosine A1 agonist, N(6)-cyclohexyladenosine (CHA), activated IKKalpha/beta phosphorylation through PTX-insensitive G proteins in human lymphoblastoma Reh cells. To delineate the mechanism of action, different PTX-insensitive G proteins were expressed in human embryonic kidney 293 cells. Only Galpha(16) supported the CHA-induced IKK phosphorylation and NFkappaB-driven luciferase activity in time-dependent, dose-dependent, and PTX-insensitive manners. Gbetagamma subunits also modulated IKK/NFkappaB, as indicated by the stimulatory actions of Gbeta(1)gamma(2) and the abrogation of CHA-induced response by transducin. The participation of phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II in CHA-induced IKK/NFkappaB activation were demonstrated by employing specific inhibitors and dominant-negative mutants. Inhibition of c-Src and numerous intermediates along the extracellular signal-regulated (ERK) kinase cascade including Ras, Raf-1 kinase, and MEK1/2 abolished the CHA-induced IKK/NFkappaB activation. Although c-Jun N-terminal kinase and p38 MAPK were also activated by CHA, they were not required for the IKK/NFkappaB regulation. Similar results were obtained using Reh cells. These data suggest that the G(16)-mediated activation of IKK/NFkappaB by CHA required a complex signaling network composed of multiple intermediates.
Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Andrew M F
AM
Liu
Yung H
YH
Wong
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D045744:Cell Line, Tumor; D003513:Cycloheximide / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D005799:Genes, Dominant; D017930:Genes, Reporter; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D051550:I-kappa B Kinase; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D054799:Phospholipase C beta; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D043682:Receptor, Adenosine A1 / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D015293:Transducin / Q000378:metabolism; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D019061:src-Family Kinases
D018076:DNA, Complementary; D007527:Isoenzymes; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D043682:Receptor, Adenosine A1; C027513:N(6)-cyclohexyladenosine; D003513:Cycloheximide; D008156:Luciferases; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D011493:Protein Kinase C; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D054799:Phospholipase C beta; C112631:G protein alpha 16; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D015293:Transducin; D000241:Adenosine