The G(s)-coupled adenosine A(2B) receptor recruits divergent pathways to regulate ERK1/2 and p38.
Adenosine A(2B) receptors have been suggested to influence cell differentiation and proliferation. Human adenosine A(2B) receptors expressed in Chinese hamster ovary cells mediate phosphorylation and activation of the extracellular signal-regulated kinase (ERK1/2). Already low concentrations of agonists such as 5'-N-ethylcarboxamidoadenosine (NECA) are effective. Phosphorylation of the stress-activated protein kinase p38 was also potently induced by NECA (EC(50) 18.5 nM). These NECA-induced effects were mimicked by forskolin and 8-Br-cAMP. Inhibition of cAMP-dependent protein kinase (PKA) using H89 (N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide)) blocked phosphorylation of the cAMP response element-binding protein (CREB) and p38, but did not decrease NECA-induced ERK1/2 phosphorylation. NECA activated the small GTPase Rap1, and this was also not blocked by H89. Inhibition of phosphatidylinositol-3'-kinase (PI3K) by wortmannin inhibited adenosine A(2B) receptor-mediated ERK1/2 phosphorylation and activation of Rap1, without affecting CREB and p38 phosphorylation. A(2B) receptor-stimulated protein kinase B phosphorylation was sensitive to wortmannin, but not to H89. Thus, stimulation of adenosine A(2B) receptors activates both ERK1/2 and p38 via cAMP, but the downstream pathways are markedly different. ERK1/2 activation was dependent on PI3K but not on PKA. p38 activation by NECA was instead independent of PI3K but required cAMP and PKA. The potent activation of both MAPKs suggests a physiological role.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000187:drug effects / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D043704:Receptor, Adenosine A2B; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases; D020827:rap1 GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism
D015124:8-Bromo Cyclic Adenosine Monophosphate; D019830:Adenosine-5'-(N-ethylcarboxamide); D005576:Colforsin; D000242:Cyclic AMP; D017362:Cyclic AMP Response Element-Binding Protein; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D019205:GTP-Binding Protein alpha Subunits, Gs; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D043704:Receptor, Adenosine A2B; D018047:Receptors, Purinergic P1; D048051:p38 Mitogen-Activated Protein Kinases; D020827:rap1 GTP-Binding Proteins