A role of protein kinase C mu in signalling from the human adenosine A1 receptor to the nucleus.
1 Stimulation of adenosine A(1) receptors produced a stimulation of c-fos promoter-regulated gene transcription in Chinese hamster ovary (CHO)-A1 cells expressing the human A(1) receptor. Gene transcription was monitored using a luciferase-based reporter gene (pGL3). 2 This response to the A(1) receptor agonist N(6)-cyclopentyladenosine (CPA) was sensitive to inhibition by pertussis toxin, the MEK-1 inhibitor PD 98059 and by the phosphatidylinositol-3-kinase inhibitors wortmannin and LY 294002. The response was also completely abolished by the protein kinase C (PKC) inhibitor Ro-31-8220. 3 Several isoforms of PKC can be detected in CHO-A1 cells (alpha, delta, epsilon, micro, iota, zeta), but only PKC alpha, PKC delta and PKC were downregulated by prolonged treatment with phorbol ester. The c-fos-regulated luciferase response to A(1) agonists was not, however, inhibited by 24 h pretreatment with the phorbol esters phorbol 12,13-dibutyrate (PDBu). This observation, together with the fact that a significant attenuation (40%) of the c-fos-luciferase response to PDBu and A(1) agonist was produced by low concentrations of the PKC inhibitor Gö 6976 suggests a role for PKC micro. 4 Stimulation of CHO-A1 cells with CPA stimulated the activation of endogenous PKC micro as measured by autophosphorylation. This was rapid, occurred within 1-2 min, but returned to basal levels after 30 min. Furthermore, transient expression of a constitutively active form of PKC micro resulted in a significant increase in c-fos-regulated gene expression. 5 Taken together, these data suggest that PKC micro plays an important role in the ability of the adenosine A(1) receptor to signal to the nucleus.
Hill
Kathryn J
KJ
Institute of Cell Signalling, Medical School, Queen's Medical Centre, Nottingham NG7 2UH.
Webber
Anne C
AC
Hill
Stephen J
SJ
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D002467:Cell Nucleus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D016762:Genes, fos; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000502:physiology*; D011493:Protein Kinase C / Q000737:chemistry / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000235:genetics; D043682:Receptor, Adenosine A1 / Q000187:drug effects* / Q000235:genetics*; D014158:Transcription, Genetic
D007527:Isoenzymes; D016760:Proto-Oncogene Proteins c-fos; D043682:Receptor, Adenosine A1; C058394:2-chloro-N(6)cyclopentyladenosine; D008156:Luciferases; C089212:protein kinase D; D011493:Protein Kinase C; D000241:Adenosine