Identification of a novel functional deletion variant in the 5'-UTR of the DJ-1 gene
Date
2009-10
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: DJ-1 forms part of the neuronal cellular defence mechanism against oxidative insults, due
to its ability to undergo self-oxidation. Oxidative stress has been implicated in the pathogenesis of central
nervous system damage in different neurodegenerative disorders including Alzheimer's disease and
Parkinson's disease (PD). Various mutations in the DJ-1 (PARK7) gene have been shown to cause the
autosomal recessive form of PD. In the present study South African PD patients were screened for
mutations in DJ-1 and we aimed to investigate the functional significance of a novel 16 bp deletion variant
identified in one patient.
Methods: The possible effect of the deletion on promoter activity was investigated using a Dual-
Luciferase Reporter assay. The DJ-1 5'-UTR region containing the sequence flanking the 16 bp deletion was
cloned into a pGL4.10-Basic luciferase-reporter vector and transfected into HEK293 and BE(2)-M17
neuroblastoma cells. Promoter activity under hydrogen peroxide-induced oxidative stress conditions was
also investigated. Computational (in silico) cis-regulatory analysis of DJ-1 promoter sequence was
performed using the transcription factor-binding site database, TRANSFAC via the PATCH™ and rVISTA
platforms.
Results: A novel 16 bp deletion variant (g.-6_+10del) was identified in DJ-1 which spans the transcription
start site and is situated 93 bp 3' from a Sp1 site. The deletion caused a reduction in luciferase activity of
approximately 47% in HEK293 cells and 60% in BE(2)-M17 cells compared to the wild-type (P < 0.0001),
indicating the importance of the 16 bp sequence in transcription regulation. The activity of both constructs
was up-regulated during oxidative stress. Bioinformatic analysis revealed putative binding sites for three
transcription factors AhR, ARNT, HIF-1 within the 16 bp sequence. The frequency of the g.-6_+10del
variant was determined to be 0.7% in South African PD patients (2 heterozygotes in 148 individuals).
Conclusion: This is the first report of a functional DJ-1 promoter variant, which has the potential to
influence transcript stability or translation efficiency. Further work is necessary to determine the extent
to which the g.-6_+10del variant affects the normal function of the DJ-1 promoter and whether this variant
confers a risk for PD.
Description
Publication of this article was funded by the Stellenbosch University Open Access Fund.
The original publication is available at http://www.biomedcentral.com/bmcmedgenet/
Bibliography.
The original publication is available at http://www.biomedcentral.com/bmcmedgenet/
Bibliography.
Keywords
Nervous system -- Degeneration, Alzheimer's disease, Parkinson's disease, Oxidative stress, Oxidative stress and neurodegenerative diseases
Citation
Keyser, R. J. et al. 2009. Identification of a novel functional deletion variant in the 5'-UTR of the DJ-1 gene. BMC Medical Genetics, 10:105, doi:10.1186/1471-2350-10-105.