S29-7 THE ROLE OF S-PHASE KINASE-ASSOCIATED PROTEIN-2 (SKP2) IN THE REGULATION OF VASCULAR SMOOTH MUSCLE CELL MIGRATION AND APOPTOSIS IN VITRO AND NEOINTIMAL THICKENING IN VIVO

Vascular remodeling after mechanoinjury largely depends on the migration of smooth muscle cells, an initial key step to wound healing. However, the role of the second messenger system, in particular, the cAMP signal, in regulating such remodeling remains controversial. Exchange protein activated by cAMP (Epac) has been identified as a new target molecule of the cAMP signal, which is independent from PKA. We thus examined whether Epac plays a distinct role from PKA in vascular remodeling. To examine the role of Epac and PKA in migration, we used primary culture smooth muscle cells from both the fetal and adult rat aorta. A cAMP analog selective to PKA, 8-(4-parachlorophenylthio)-cAMP (pCPT-cAMP), decreased cell migration, whereas an Epac-selective analog, 8-pCPT-2′- O-Me-cAMP, enhanced migration. Adenovirus-mediated gene transfer of PKA decreased cell migration, whereas that of Epac1 significantly enhanced cell migration. Striking morphological differences were observed between pCPT-cAMP- and 8-pCPT-2′- O-Me-cAMP-treated aortic smooth muscle cells. Furthermore, overexpression of Epac1 enhanced the development of neointimal formation in fetal rat aortic tissues in organ culture. When the mouse femoral artery was injured mechanically in vivo, we found that the expression of Epac1 was upregulated in vascular smooth muscle cells, whereas that of PKA was downregulated with the progress of neointimal thickening. Our findings suggest that Epac1, in opposition to PKA, increases vascular smooth muscle cell migration. Epac may thus play an important role in advancing vascular remodeling and restenosis upon vascular injury.

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Metformin Suppresses the Progress of Diabetes-Accelerated Atherosclerosis by Inhibition of Vascular Smooth Muscle Cell Migration Through AMPK–Pdlim5 Pathway

Frontiers in Cardiovascular Medicine ◽

10.3389/fcvm.2021.690627 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yi Yan ◽

Ting Li ◽

Zhonghao Li ◽

Mingyuan He ◽

Dejiang Wang ◽

...

Keyword(s):

Smooth Muscle ◽

Cell Migration ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cell ◽

Muscle Cell ◽

Vascular Smooth Muscle Cell ◽

Protective Function ◽

Accelerated Atherosclerosis

Backgrounds: Our previous work revealed that AMP-activated protein kinase (AMPK) activation inhibits vascular smooth muscle cell migration in vitro by phosphorylating PDZ and LIM domain 5 (Pdlim5). As metformin is an AMPK activator, we used a mouse vascular smooth muscle cell (VSMC) line and a Myh11-cre-EGFP mice to investigate whether metformin could inhibit the migration of VSMCs in vitro and in a wire-injury model in vivo. It is recognized that VSMCs contribute to the major composition of atherosclerotic plaques. In order to investigate whether the AMPK–Pdlim5 pathway is involved in the protective function of metformin against atherosclerosis, we utilized ApoE−/− male mice to investigate whether metformin could suppress diabetes-accelerated atherosclerosis by inhibition of VSMC migration via the AMPK–Pdlim5 pathway.Methods: The mouse VSMC cell line was exogenously transfected wild type, phosphomimetic, or unphosphorylatable Pdlim5 mutant before metformin exposure. Myh11-cre-EGFP mice were treated with saline solution or metformin after these were subjected to wire injury in the carotid artery to study whether metformin could inhibit the migration of medial VSMCs into the neo-intima. In order to investigate whether the AMPK–Pdlim5 pathway is involved in the protective function of metformin against atherosclerosis, ApoE−/− male mice were divided randomly into control, streptozocin (STZ), and high-fat diet (HFD)-induced diabetes mellitus; STZ+HFD together with metformin or Pdlim5 mutant carried the adenovirus treatment groups.Results: It was found that metformin could induce the phosphorylation of Pdlim5 and inhibit cell migration as a result. The exogenous expression of phosphomimetic S177D-Pdlim5 inhibits lamellipodia formation and migration in VSMCs. It was also demonstrated that VSMCs contribute to the major composition of injury-induced neointimal lesions, while metformin could alleviate the occlusion of the carotid artery. The data of ApoE−/− mice showed that increased plasma lipids and aggravated vascular smooth muscle cell infiltration into the atherosclerotic lesion in diabetic mice were observed Metformin alleviated diabetes-induced metabolic disorders and atherosclerosis and also reduced VSMC infiltration in atherosclerotic plaques, while the Pdlim5 phospho-abolished mutant that carried adenovirus S177A-Pdlim5 undermines the protective function of metformin.Conclusions: The activation of the AMPK–Pdlim5 pathway by metformin could interrupt the migratory machine of VSMCs and inhibit cell migration in vitro and in vivo. The maintenance of AMPK activity by metformin is beneficial for suppressing diabetes-accelerated atherosclerosis.

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