Activation of protein kinase A and atypical protein kinase C by A(2A) adenosine receptors antagonizes apoptosis due to serum deprivation in PC12 cells.
We found in the present study that stimulation of A(2A) adenosine receptors (A(2A)-R) prevents apoptosis in PC12 cells. This A(2A)-protective effect was blocked by protein kinase A (PKA) inhibitors and was not observed in a PKA-deficient PC12 variant. Stimulation of PKA also prevented apoptosis, suggesting that PKA is required for the protective effect of A(2A)-R. A general PKC inhibitor, but not down-regulation of conventional and novel PKCs, readily blocked the protective effect of A(2A)-R stimulation and PKA activation, suggesting that atypical PKCs (aPKCs) serve a critical role downstream of PKA. Consistent with this hypothesis, stimulation of A(2A)-R or PKA enhanced nuclear aPKC activity. In addition, the A(2A)-protective effect was blocked by a specific inhibitor of one aPKC, PKCzeta, whereas overexpression of a dominant-positive PKCzeta enhanced survival. In contrast, inhibitors of MAP kinase and phosphatidylinositol 3-kinase did not modulate the A(2A)-protective effect. Dominant-negative Akt also did not alter the A(2A)-protective effect, whereas it significantly reduced the protective action of nerve growth factor. Collectively, these data suggest that aPKCs can function downstream of PKA to mediate the A(2A)-R-promoted survival of PC12 cells. Furthermore, the results indicate that different extracellular stimuli can employ distinct signaling pathways to protect against apoptosis induced by the same insult.
Huang
N K
NK
Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan, Republic of China.
Lin
Y W
YW
Huang
C L
CL
Messing
R O
RO
Chern
Y
Y
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D002867:Chromones / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004396:Coloring Agents / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005799:Genes, Dominant; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D016716:PC12 Cells; D010627:Phenethylamines / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D015398:Signal Transduction; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection
D002867:Chromones; D004396:Coloring Agents; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D009025:Morpholines; D010627:Phenethylamines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1; D013778:Tetrazolium Salts; D013844:Thiazoles; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D005576:Colforsin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; C022616:thiazolyl blue; D000241:Adenosine