Nicotine facilitates VSMC dysfunction through a miR-200b/RhoGDIA/cytoskeleton module

Dongli Liang,Meisheng Shang,Zhaoxia Wang,Wangjie Xu,Zhongdong Qiao,Zhiqiang Yan,Shangwei Hou,Lianyun Wang

doi:10.1038/srep43798

Abstract

Nicotine can induce the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs). We have previously shown that cytoskeletal proteins and RhoGDIA, a negative regulator of the Rho GTPase pathway, are involved in the nicotine-induced dysfunction of VSMCs. Here, we found that nicotine can activate the Rho GTPase pathway and induce the synthesis of the cytoskeletal proteins in VSMCs through the activation of intracellular downstream signaling pathways, including targets such as MYPT1, PAK1 and PI3K/AKT. Upon nicotine treatment, the mRNA level of RhoGDIA is increased but protein level is decreased both in vitro and in vivo, which suggested a mechanism of post-translational regulation. By the dual luciferase reporter assay, we identified the microRNA-200b (miR-200b) as a modulator of the behavioural changes of VSMCs in response to nicotine through targeting RhoGDIA directly. Introducing miR-200b inhibitors into cultured VSMCs significantly attenuated cell proliferation and migration. Additionally, we found that hypomethylation in the CpG island shore region of miR-200b was responsible for the nicotine-induced miR-200b up-regulation in VSMCs. The study demonstrates that nicotine facilitates VSMC dysfunction through a miR-200b/RhoGDIA/cytoskeleton module through the hypomethylation of miR-200b promoter and suggests that epigenetic modifications may play an important role in the pathological progression.

Highlights

Cigarette smoke is a complex mixture of more than 4000 chemicals and cigarette smoking is considered to be a major risk factor for the development of cardiovascular diseases[1,2] such as atherosclerosis and hypertension
This result indicates that the Rho GTPase pathway is involved in the change of F-actin expression induced by nicotine
There was an obvious activation of the Rho GTPase pathway and the downstream signaling pathway in vascular smooth muscle cells (VSMCs) and both α-BtX and Y27632 could substantially inhibit this increased activation. These results indicate that treatment with nicotine can activate the Rho GTPase pathway and induce the synthesis of the cytoskeletal proteins (α-actin, β-actin, F-actin, MLC, p-MLC, desmin, calponin and caldesmon) in VSMCs through the activation of intracellular downstream signaling pathways, including targets such as myosin phosphatase target subunit-1 (MYPT1), p21-activated kinase-1 (PAK1) and PI3K/AKT

Summary

Introduction

Cigarette smoke is a complex mixture of more than 4000 chemicals and cigarette smoking is considered to be a major risk factor for the development of cardiovascular diseases[1,2] such as atherosclerosis and hypertension. The pathological changes induced by nicotine in VSMCs are very likely to be associated with the Rho GTPase family, which plays a central role in many diverse biological processes such as actin cytoskeleton organization, microtubule dynamics, gene transcription and cell cycle progression[13]. Recent studies have shown that various functions in VSMCs are finely regulated by miRNAs18, including miR-143/miR-14519,20, miR-2121, miR-3122 and miR-221/ miR-22223,24 It has not been reported whether miRNAs are involved in the nicotine-induced dysfunction of VSMCs. In addition, miRNAs play a critical role in regulating RhoGDIA in several diseases[25], the mechanism by which RhoGDIA is regulated by miRNAs in VSMCs after nicotine exposure is not well defined. In the current study, we investigated whether RhoGDIA is involved in promoting migration and proliferation of VSMCs in response to nicotine exposure and we sought to determine the mechanism underlying nicotine-induced deregulation of RhoGDIA

Methods

Results

Conclusion