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Protein kinase a negatively regulates VEGF-induced AMPK activation by phosphorylating CaMKK2 at serine 495
Spengler, Katrin Zibrova, Darya Woods, Angela Langendorf, Christopher G. Scott, John W. Carling, David Heller, Regine
Spengler, Katrin
Zibrova, Darya
Woods, Angela
Langendorf, Christopher G.
Scott, John W.
Carling, David
Heller, Regine
Abstract
Activation of AMP-activated protein kinase (AMPK) in endothelial cells by vascular endothelial growth factor (VEGF) via the Ca2+/calmodulin-dependent protein kinase kinase 2 (CaMKK2) represents a pro-angiogenic pathway, whose regulation and function is incompletely understood. This study investigates whether the VEGF/AMPK pathway is regulated by cAMP-mediated signalling. We show that cAMP elevation in endothelial cells by forskolin, an activator of the adenylate cyclase, and/or 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterases, triggers protein kinase A (PKA)-mediated phosphorylation of CaMKK2 (serine residues S495, S511) and AMPK (S487). Phosphorylation of CaMKK2 by PKA led to an inhibition of its activity as measured in CaMKK2 immunoprecipitates of forskolin/IBMX-treated cells. This inhibition was linked to phosphorylation of S495, since it was not seen in cells expressing a non-phosphorylatable CaMKK2 S495C mutant. Phosphorylation of S511 alone in these cells was not able to inhibit CaMKK2 activity. Moreover, phosphorylation of AMPK at S487 was not sufficient to inhibit VEGF-induced AMPK activation in cells, in which PKA-mediated CaMKK2 inhibition was prevented by expression of the CaMKK2 S495C mutant. cAMP elevation in endothelial cells reduced basal and VEGF-induced acetyl-CoA carboxylase (ACC) phosphorylation at S79 even if AMPK was not inhibited. Together, this study reveals a novel regulatory mechanism of VEGF-induced AMPK activation by cAMP/PKA, which may explain, in part, inhibitory effects of PKA on angiogenic sprouting and play a role in balancing pro- and anti-angiogenic mechanisms in order to ensure functional angiogenesis.
Keywords
AMPK, CaMKK2, cAMP, protein kinase A, vascular endothelial growth factor
Date
2020
Type
Journal article
Journal
Biochemical Journal
Book
Volume
477
Issue
17
Page Range
3453-3469
Article Number
ACU Department
Mary MacKillop Institute for Health Research
Faculty of Health Sciences
Faculty of Health Sciences
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Relation URI
Source URL
Event URL
Open Access Status
License
All rights reserved
File Access
Controlled