Nicotinic ACh receptor α7 inhibits PDGF-induced migration of vascular smooth muscle cells by activating mitochondrial deacetylase sirtuin 3

Background and Purpose PDGF-BB is an angiogenic factor involved in cardiovascular diseases. Here, we investigated the possible effects of activation of the nicotinic ACh receptor alpha 7 subtype (alpha 7nAChR) on PDGF-BB-induced proliferation and migration in vascular smooth muscle cells (VSMCs). Experimental Approach PNU-282987, a selective alpha 7nAChR pharmacological agonist, was used to activate alpha 7nAChR. The influences of alpha 7nAChR activation on PDGF-BB-induced proliferation and migration, as well as the phosphorylation of focal adhesion kinase (FAK)/Src, a pro-migration signalling pathway, were determined in VSMCs. A variety of biochemical assays were applied to explore the underlying molecular mechanisms. Key Results PDGF-BB induced pronounced migration and proliferation of VSMCs. Activation of alpha 7nAChRs by PNU-282987 blocked PDGF-BB-induced migration but not proliferation in wild-type (WT) VSMCs, whereas this effect was absent in alpha 7nAChR-knockout VSMCs. Accordingly, PNU-282987 attenuated PDGF-BB-induced phosphorylation of FAK(Tyr397) and Src(Tyr416) in WT VSMCs. Mechanistically, PNU-282987 suppressed PDGF-BB-induced oxidative stress, as demonstrated by the alterations in ROS, H2O2 content, superoxide anion and total antioxidant activity. A sirtuin 3 (SIRT3) inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine or shRNA-mediated SIRT3 knockdown abolished the inhibitory effect of PNU-282987. PNU-282987 did not modulate SIRT3 protein expression but enhanced mitochondrial SIRT3 deacetylase activity. In line with this action, PNU-282987 enhanced the deacetylation of mitochondrial FoxO3. Lastly, PNU-282987 corrected the PDGF-BB-induced mitochondrial dysfunction by increasing mitochondrial citrate synthase activity, ATP content and nicotinamide adenine dinucleotide pool. Conclusions Pharmacological activation of alpha 7nAChRs inhibits PDGF-BB-induced VSMC migration by activating the mitochondrial deacetylase SIRT3, implying an important role for alpha 7nAChRs in mitochondria biology and PDGF-related diseases. Linked Articles This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit