title: Methylation status of DJ-1 in leukocyte DNA of Parkinson's disease patients.
abstract: BACKGROUND
  DJ-1 has been thought as a candidate biomarker for Parkinson's disease (PD). It was found reduced in PD brains, CSF and saliva, although there were conflicting results. How DJ-1 expression may be regulated is not clear. Recently, blood-based DNA methylation represents a highly promising biomarker for PD by regulating the causative gene expression. Thus, in this study, we try to explore whether blood-based DNA methylation of DJ-1 could be used as a biomarker to differentiate PD patients from normal control (NC), and whether DNA methylation could regulate DJ-1 expression in a SH-SY5Y cell model.
  
  
  METHODS
  Forty PD patients and 40 NC were recruited in this study. DNA was extracted from peripheral blood leukocytes (PBLs). Methylation status of two CpG islands (CpG1 and CpG2) in promoter region of DJ-1 was explored by bisulfite specific PCR-based sequencing method. Methylation inhibitor 5-Aza-dC was used to treat SH-SY5Y cell line, DJ-1 level was detected in both mRNA and protein level.
  
  
  RESULTS
  CpG sites in these two CpG islands (CpG1 and CpG2) of DJ-1 were unmethylated in both PD and NC group. In SH-SY5Y cell model treated by methylation inhibitor, there was no significant change of DJ-1 expression in either mRNA level or protein level.
  
  
  CONCLUSIONS
  Our results indicated that DNA methylation inhibitor didn't alter DJ-1 gene expression in SH-SY5Y cell model, and DNA methylation of DJ-1 promoter region in PBLs level might not be an efficient biomarker for PD patients.
authors.affiliation: Department of Neurology, and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025 China.
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Department of Neurology, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200011 China.
authors.forename: Li
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Neurology, and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025 China.
authors.forename: Dunhui
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Neurology, and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025 China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Neurology, and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025 China.
authors.forename: Jianqing
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Neurology, and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025 China.|Parkinson's Disease Center, Beijing Institute for Brain Disorders, Beijing, 100069 China.
authors.forename: Shengdi
authors.initials: S
authors.lastname: Chen
keywords: DJ-1; DNA methylation; Parkinson’s disease; Peripheral blood leukocytes