Investigating the Role of Phosphodiesterase 1C in Vascular Smooth Muscle Cell Migration and Invasion
Phenotypic plasticity of human arterial smooth muscle cells (HASMCs) allows them to transition from a “contractile/quiescent” state, in which they regulate arterial tone and blood pressure, to one in which these cells are more “synthetic/activated”. Synthetic/activated HASMCs are migratory and proliferative, and these capabilities allow them to participate in vasculogenesis during development, as well as post-natal vessel repair. Although several laboratories have investigated the overall inhibitory influence of cAMP-elevating agents on HASMC migration, few have addressed whether cAMP signalling also coordinates HASMC invasion of extracellular matrices, a critical first step in HASMC migration in vivo. Indeed, while several cAMP-elevating agents reduce intimal hyperplasia/hypertrophy in animal models, it is presently unclear whether these effects are due to reduced matrix invasion of these cells or solely to inhibition of their migratory capacity. Previous work conducted by our group and others have identified the critical role of cyclic nucleotide phosphodiesterase 1C (PDE1C) in HASMC migration, proliferation, and extracellular matrix adhesion. Here, we directly tested the hypothesis that cAMP signaling, and specifically PDE1C, influences the ability of activated/synthetic HASMCs to invade matrix in 3-dimensions (3D) and show that this effect is distinct from their migratory actions. Overall, we observed that inhibiting PDE1C activity reduced invasion of 3D collagen matrices by these cells to a greater degree than it did migration in systems not requiring invasion. Using a spheroid model, it was found that either inhibition of PDE1, or the selective silencing of PDE1C, reduced the distance of sprout outgrowth. Of importance in assessing how PDE1C regulates matrix invasion, we investigated whether HASMCs invading collagen matrices generated matrix degrading structures, specifically podosomes. Our data, although preliminary, is consistent with this idea. Similarly, initial success at generating mixed spheroids of human endothelial and SMCs cultures is presented. In these latter experiments, we used telomerase immortalized human aortic endothelial cells (TeloHAECs). This work reports that inhibiting or silencing HASMC PDE1C preferentially impacts invasion over migration of these cells. This aids in bridging the gap between in vitro and in vivo effects of PDE1C, and in HASMC evaluation of its potential as a therapeutic target.
PDE1C, Migration, Invasion, Spheroids, Cyclic Nucleotide Phosphodiesterase, Vascular, Smooth Muscle Cell
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