RNA silencing identifies PDE4D5 as the functionally relevant cAMP phosphodiesterase interacting with beta arrestin to control the protein kinase A/AKAP79-mediated switching of the beta2-adrenergic receptor to activation of ERK in HEK293B2 cells

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Item Type:	Article
Title:	RNA silencing identifies PDE4D5 as the functionally relevant cAMP phosphodiesterase interacting with beta arrestin to control the protein kinase A/AKAP79-mediated switching of the beta2-adrenergic receptor to activation of ERK in HEK293B2 cells
Creators Name:	Lynch, M.J., Baillie, G.S., Mohamed, A., Li, X., Maisonneuve, C., Klussmann, E., van Heeke, G. and Houslay, M.D.
Abstract:	PDE4B and PDE4D provide >90% of PDE4 cAMP phosphodiesterase activity in human embryonic kidney (HEK293B2) cells. Their selective small interference RNA (siRNA)-mediated knockdown potentiates isoprenaline-stimulated protein kinase A (PKA) activation. Whereas endogenous PDE4D co-immunoprecipitates with beta arrestin, endogenous PDE4B does not, even upon PDE4D knockdown. Ectopic overexpression of PDE4B2 confers co-immunoprecipitation with beta arrestin. Knockdown of PDE4D, but not PDE4B, amplifies isoprenaline-stimulated phosphorylation of the beta2-adrenergic receptor (beta2-AR) by PKA and activation of extracellular signal-regulated kinase (ERK) through G(i). Isoform-selective knockdown identifies PDE4D5 as the functionally important species regulating isoprenaline stimulation of both these processes. Ht31-mediated disruption of the tethering of PKA to AKAP scaffold proteins attenuates isoprenaline activation of ERK, even upon PDE4D knockdown. Selective siRNA-mediated knockdown identifies AKAP79, which is constitutively associated with the beta2-AR, rather than isoprenaline-recruited gravin, as being the functionally relevant AKAP in this process. Isoprenaline-stimulated membrane recruitment of PDE4D is ablated upon beta arrestin knockdown. A mutation that compromises interactions with beta arrestin prevents catalytically inactive PDE4D5 from performing a dominant negative role in potentiating isoprenaline-stimulated ERK activation. Beta arrestin-recruited PDE4D5 desensitizes isoprenaline-stimulated PKA phosphorylation of the beta2-AR and the consequential switching of its signaling to ERK. The ability to observe a cellular phenotype upon PDE4D5 knockdown demonstrates that other PDE4 isoforms, expressed at endogenous levels, are unable to afford rescue in HEK293B2 cells.
Keywords:	3',5'-Cyclic-AMP Phosphodiesterases, Arrestins, Western Blotting, Cell Line, Cyclic AMP-Dependent Protein Kinases, Type 3 Cyclic Nucleotide Phosphodiesterases, Enzyme Activation, Isoenzymes, Mitogen-Activated Protein Kinases, Biological Models, Phosphoric Diester Hydrolases, Precipitin Tests, RNA Interference, Adrenergic beta-2 Receptors
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	280
Number:	39
Page Range:	33178-33189
Date:	30 September 2005
Official Publication:	https://doi.org/10.1074/jbc.M414316200
PubMed:	View item in PubMed

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