Tobacco Smoking Increases Methylation of Polypyrimidine Tract Binding Protein 1 Promoter in Intracranial Aneurysms.

Zhepei Wang,Jikuang Zhao,Xiang Gao,Zhiqin Lin,Cameron Lenahan,Jie Sun,Shengjun Zhou,Yi Huang,Sheng Nie,Gao Chen

doi:10.3389/fnagi.2021.688179

Abstract

DNA methylation at the gene promoter region is reportedly involved in the development of intracranial aneurysm (IA). This study aims to investigate the methylation levels of polypyrimidine tract-binding protein 1 (PTBP1) in IA, as well as its potential to predict IA. Forty-eight patients with IA and 48 age- and sex-matched healthy controls were recruited into this study. Methylation levels of CpG sites were determined via bisulfite pyrosequencing. The PTBP1 levels in the blood were determined using a real-time quantitative reverse transcription-polymerase chain reaction test. Significant differences were found between IAs and controls in CpG1 (p = 0.001), CpG2 (p < 0.001), CpG3 (p = 0.037), CpG4 (p = 0.003), CpG5 (p = 0.006), CpG6 (p = 0.02), and mean methylation (p < 0.001). The mRNA level of PTBP1 in the blood was much lower in IAs compared with controls (p = 0.002), and the PTBP1 expression was significantly associated with DNA methylation promoter levels in individuals (r = −0.73, p < 0.0001). In addition, stratification analysis comparing smokers and non-smokers revealed that tobacco smokers had significantly higher levels of DNA methylation in PTBP1 than non-smokers (p = 0.002). However, no statistical difference in PTBP1 methylation was found between ruptured and unruptured IA groups (p > 0.05). The ROC analyses of curves revealed that PTBP1 methylation may be a predictor of IA regardless of sex (both sexes, area under curve (AUC) = 0.78, p < 0.0001; male, AUC = 0.76, p = 0.002; female, AUC = 0.79, p < 0.0001). These findings suggest that long-term tobacco smoke exposure led to DNA methylation in the promoter region of the PTBP1 gene, which further decreased PTBP1 gene expression and participated in the pathogenesis of IA. The methylation of PTBP1 may be a potential predictive marker for the occurrence of IA.

Highlights

An intracranial aneurysm (IA) is a cystic pathological dilatation of the intracranial arteries
No significant differences were observed between the two groups regarding clinical data, such as age, sex, hypertension, diabetes, drinking, smoking, TG, total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) (p > 0.05)
Six CpG dinucleotides in the promoter region of the polypyrimidine tract-binding protein 1 (PTBP1) gene were selected to measure DNA methylation levels (Figure 1)

Summary

Introduction

An intracranial aneurysm (IA) is a cystic pathological dilatation of the intracranial arteries. Previous studies have demonstrated that hemodynamic stress, vascular risk factors (i.e., hypertension, hyperlipidemia, arteriosclerosis, and smoking), and genetic susceptibility play an important role in the formation of IA (Kassam et al, 2004; Frosen et al, 2012, 2013). DNA methylation is a common epigenetic modification that regulates gene expression by recruiting proteins involved in gene repression or by inhibiting the binding of transcription factors to DNA (Moore et al, 2013). Tobacco smoking was a risk factor for cerebrovascular disease, including IA, which participated in the process of arterial vascular disease through epigenetic regulation of DNA methylation (Siemelink et al, 2018). Another study suggested that DNA methylation played an important role in the development of IA, involving the regulation of immune and inflammatory responses, cell functions, and cell signal transduction (Yu et al, 2017)

Objectives

Methods

Results

Discussion

Conclusion