Neuronal AKAP150 coordinates PKA and Epac-mediated PKB/Akt phosphorylation.
In diverse neuronal processes ranging from neuronal survival to synaptic plasticity cyclic adenosine monophosphate (cAMP)-dependent signaling is tightly connected with the protein kinase B (PKB)/Akt pathway but the precise nature of this connection remains unknown. In the current study we investigated the effect of two mainstream pathways initiated by cAMP, cAMP-dependent protein kinase (PKA) and exchange proteins directly activated by cAMP (Epac1 and Epac2) on PKB/Akt phosphorylation in primary cortical neurons and HT-4 cells. We demonstrate that PKA activation leads to a reduction of PKB/Akt phosphorylation, whereas activation of Epac has the opposite effect. This effect of Epac on PKB/Akt phosphorylation was mediated by Rap activation. The increase in PKB/Akt phosphorylation after Epac activation could be blocked by pretreatment with Epac2 siRNA and to a somewhat smaller extent by Epac1 siRNA. PKA, PKB/Akt and Epac were all shown to establish complexes with neuronal A-kinase anchoring protein150 (AKAP150). Interestingly, activation of Epac increased phosphorylation of PKB/Akt complexed to AKAP150. From experiments using PKA-binding deficient AKAP150 and peptides disrupting PKA anchoring to AKAPs, we conclude that AKAP150 acts as a key regulator in the two cAMP pathways to control PKB/Akt phosphorylation.
Department of Molecular Neurobiology, University of Groningen, 9750 AA, Haren, The Netherlands. i.m.nijholt@rug.nl
Ingrid M
IM
Nijholt
Amalia M
AM
Dolga
Anghelus
A
Ostroveanu
Paul G M
PG
Luiten
Martina
M
Schmidt
Ulrich L M
UL
Eisel
D054758:A Kinase Anchor Proteins / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*
D054758:A Kinase Anchor Proteins; C520665:Akap5 protein, mouse; D002352:Carrier Proteins; C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; C486707:Rapgef4 protein, mouse; D000242:Cyclic AMP; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases