Implication of adenylyl cyclase 8 in pathological smooth muscle cell migration occurring in rat and human vascular remodelling

Abstract

Recently, we discovered on primary cell cultures that adenylyl cyclase type 8 (AC8) was involved in the transition of rat vascular smooth muscle cells (VSMCs) to an inflammatory phenotype. Here we demonstrate, in human vessels displaying early or advanced atherosclerotic lesions, that: (a) only intimal VSMCs strongly express AC8; and (b) very few AC8-positive VSMCs were detected in the medial layer, either in atherosclerotic or healthy arteries. Furthermore, over-expressing AC8 in primary rat VSMC cultures triggered the recolonization of a wounded zone and similar results were obtained in the presence of mitomycin, a potent inhibitor of proliferation. This phenomenon was prevented by silencing AC8. Indeed, in IL-1 beta-treated cells, AC8 silencing halted migration and decreased the matrix-metalloproteinases 2/9 secretion, known to be involved in VSMC migration. In vivo, we showed: (a) a pronounced up-regulation of AC8 expression in highly migrating VSMCs of the injured rat carotid artery; (b) an undetectable AC8 labelling in re-endothelized vessels where neo-intimal thickening had stopped. From our data, we conclude that AC8 expression appears closely linked to the properties developed by VSMCs in atherosclerosis and post-angioplasty neo-intima formation leading to restenosis. In addition, it reinforces the idea that VSMC responses to their cell environment greatly depend on the AC isoforms expressed and attributes a new role for AC8 in these pathological vascular processes.

The Notch Pathway Attenuates Interleukin 1β (IL1β)-mediated Induction of Adenylyl Cyclase 8 (AC8) Expression during Vascular Smooth Muscle Cell (VSMC) Trans-differentiation

“…A similar tendency was observed for SM22 expression although its expression still seemed low at this time. This was consistent with the completion of neointimal formation usually occurring between 14 and 21 days postinjury when neointimal as well as medial VSMCs regain a differentiated state (15). In accordance with the in vitro findings mentioned above, AC8 expression opposed that of Notch3.…”

“…induces the trans-differentiation of VSMCs and stimulates the expression of AC8 (15). As an initial approach to determine whether there is any correlation between AC8 and Notch expressions in VSMCs, we analyzed their transcript expressions when treated with various concentrations of IL1␤.…”

“…Indeed, AC8 emergence allows maximal secretion of phospholipase A2 type IIA, an inflammatory marker associated with an increased risk of coronary artery disease (14,16); overexpression of AC8 in rat VSMCs triggered the re-colonization of the wounded zone, whereas blocking AC8 in IL1␤-treated cells stopped the IL1␤-induced migration. The cause to effect relationship between AC8 expression and the migratory (but not proliferative) response of the VSMCs translated, in the rat in vivo model of postangioplasty restenosis, into a pronounced transitory up-regulation of AC8 expression in VSMCs migrating to form the intimal layer (15). Of note: in mammals nine AC isoforms have been identified and characterized, each having a discrete tissue distribution and a specific pattern of regulation by G protein subunits, calcium-calmodulin and protein kinases (17); out of any inflammatory context, VSMCs mainly express AC isoforms 3, 5, and 6 (18), which, although all producing cAMP, have different functions and distinct membrane localizations.…”

“…Transformation of VSMCs into inflammatory/migratory cells results in part on the up-regulation of calcium/calmodulin positively regulated adenylyl cyclase isoform 8 (AC8) expression (14,15). Indeed, AC8 emergence allows maximal secretion of phospholipase A2 type IIA, an inflammatory marker associated with an increased risk of coronary artery disease (14,16); overexpression of AC8 in rat VSMCs triggered the re-colonization of the wounded zone, whereas blocking AC8 in IL1␤-treated cells stopped the IL1␤-induced migration.…”

Tollip Negatively Regulates Vascular Smooth Muscle Cell–Mediated Neointima Formation by Suppressing Akt‐Dependent Signaling

“…Moreover, we observed that the regulatory effect of Tollip on VSMC proliferation and differentiation was independent of its secretion, since addition of Tollip antibody did not affect the effect of PDGF‐BB on VSMC (Figure S3). In addition to proliferation and phenotypic switching, the migrating VSMCs participate in the pathogenesis of neointima formation 19. To elucidate the role of Tollip in the migratory property of VSMCs, primary VSMCs derived from Tollip‐KO and Tollip‐TG mice were seeded into a Boyden chamber supplemented with or without PDGF‐BB (20 ng/mL) for 6 hours.…”