Bird, R. J., Baillie, G. S. and Yarwood, S. J. (2010) Interaction with receptor for activated C-kinase 1 (RACK1) sensitizes the phosphodiesterase PDE4D5 towards hydrolysis of cAMP and activation by protein kinase C. Biochemical Journal, 432(1), pp. 207-216. (doi: 10.1042/BJ20101010)
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Publisher's URL: http://dx.doi.org/10.1042/BJ20101010
Abstract
We have previously identified the PKC (protein kinase C)-anchoring protein RACK1 (receptor for activated C-kinase 1), as a specific binding partner for the cAMP-specific phosphodiesterase PDE4D5, suggesting a potential site for cross-talk between the PKC and cAMP signalling pathways. In the present study we found that elevation of intracellular cAMP, with the β2-adrenoceptor agonist isoproterenol (isoprenaline), led to activation of PDE4 enzymes in the particulate and soluble fractions of HEK (human embryonic kidney)-293 cells. In contrast activation of PDE4D5, with isoproterenol and the PKC activator PMA, was restricted to the particulate fraction, where it interacts with RACK1; however, RACK1 is dispensable for anchoring PDE4D5 to the particulate fraction. Kinetic studies demonstrated that RACK1 alters the conformation of particulate-associated PDE4D5 so that it more readily interacts with its substrate cAMP and with rolipram, a PDE4 inhibitor that specifically targets the active site of the enzyme. Interaction with RACK1 was also essential for PKC-dependent and ERK (extracellular-signal-regulated kinase)-independent phosphorylation (on Ser<sup>126</sup>), and activation of PDE4D5 in response to PMA and isoproterenol, both of which trigger the recruitment of PKCα to RACK1. Together these results reveal novel signalling cross-talk, whereby RACK1 mediates PKC-dependent activation of PDE4D5 in the particulate fraction of HEK-293 cells in response to elevations in intracellular cAMP.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Baillie, Professor George and Yarwood, Dr Stephen |
| Authors: | Bird, R. J., Baillie, G. S., and Yarwood, S. J. |
| College/School: | College of Medical Veterinary and Life Sciences > School of Molecular Biosciences |
| Journal Name: | Biochemical Journal |
| Publisher: | Portland Press Ltd. |
| ISSN: | 0264-6021 |
| ISSN (Online): | 1470-8728 |
| Published Online: | 25 October 2010 |
| Copyright Holders: | Copyright © 2010 The Authors |
| First Published: | First published in Biochemical Journal 432(1):207-216 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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