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When the Tail Wags the Dog: Phosphodiesterase 4D7 Regulation of a cAMP‐signalosome Located at the Rear of Migrating Smooth Muscle Cells Regulates Localized RhoA/ROCK Signaling and Tail Retraction During Migration
Author(s) -
Maurice Donald H,
Truong Tammy,
Wudwud Alie
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.990.7
Subject(s) - phosphodiesterase , gene isoform , microbiology and biotechnology , rhoa , vascular smooth muscle , cyclic adenosine monophosphate , intracellular , biology , phosphodiesterase 3 , chemistry , medicine , signal transduction , endocrinology , biochemistry , gene , enzyme , smooth muscle , receptor
Inhibiting the maladaptive migration of human arterial smooth muscle cells (HASMCs) in injured blood vessels may help reduce the development of intimal lesions in vascular diseases, including atherosclerosis or restenosis. Agents that act to increase intracellular levels of cyclic adenosine monophosphate (cAMP) impact numerous individual events involved in coordinating HASMC migration. Signaling via cAMP is ubiquitous and dynamic, and requires control through signaling termination mechanisms. cAMP Phosphodiesterase (PDE) enzymes catalyze the hydrolysis of cAMP and are critical in the control of cAMP signaling, most specifically when they regulate cAMP levels within numerous discrete subcellular domains. Through spatial restriction, these enzymes are thought to allow cAMP‐elevating agents to selectively regulate numerous distinct responses. The PDE4D gene family plays a dominant role in cAMP hydrolysis in HASMCs. Considerable interest exists in the idea that the unique N‐terminal domains of the numerous distinct PDE4D isoform variants promotes their spatial restriction in cells, and that this is coordinated through selective interactions of these PDE4Ds with other proteins. This study examined the targeting of individual PDE4D isoforms in HASMCs through the overexpression of GFP constructs containing the unique N‐terminal domains of the PDE4D isoforms (NT‐PDE4D/GFP) known to be expressed endogenously in these cells (PDE4D8, 9, 5, 7). Although transient over‐expression of NT/PDE4D8‐GFP, NT/PDE4D9‐GFP or NT/PDE4D5‐GFP did not significantly impact HASMC morphology or migration character or speed, over‐expression of NT/PDE4D7‐GFP was observed to alter HASMC morphology of migrating HASMCs as well as their migratory velocity. By combining these observations with the effects of selective siRNA‐mediated knockdown of PDE4D7, we established that PDE4D7 is involved in controlling rear retraction in migrating HASMCs. We show that altering PDE4D7 targeting and expression in these cells affects rear retraction largely through its ability to impact RhoA‐ROCK signaling. We also report that PDE4D7 interacts with AKAP5, PKA and EPAC1 in migrating and immotile HASMCs. Our results suggest a functional role for localized PDE4D7 activity in regulating cAMP‐mediated rear retraction in migrating HASMCs, and identify PDE4D7 as a potential therapeutic target in controlling HASMC migration. Support or Funding Information Canadian Institutes of Health Sciences