DNA demethylation-dependent enhancement of toll-like receptor-2 gene expression in cystic fibrosis epithelial cells involves SP1-activated transcription.
BACKGROUND
The clinical course of cystic fibrosis (CF) is characterized by recurrent pulmonary infections and chronic inflammation. We have recently shown that decreased methylation of the toll-like receptor-2 (TLR2) promoter leads to an apparent CF-related up-regulation of TLR2. This up-regulation could be responsible, in part, for the CF-associated enhanced proinflammatory responses to various bacterial products in epithelial cells. However, the molecular mechanisms underlying DNA hypomethylation-dependent enhancement of TLR2 expression in CF cells remain unknown.


RESULTS
The present study indicates that there is a specific CpG region (CpG#18-20), adjacent to the SP1 binding site that is significantly hypomethylated in several CF epithelial cell lines. These CpGs encompass a minimal promoter region required for basal TLR2 expression, and suggests that CpG#18-20 methylation regulates TLR2 expression in epithelial cells. Furthermore, reporter gene analysis indicated that the SP1 binding site is involved in the methylation-dependent regulation of the TLR2 promoter. Inhibition of SP1 with mithramycin A decreased TLR2 expression in both CF and 5-azacytidine-treated non-CF epithelial cells. Moreover, even though SP1 binding was not affected by CpG methylation, SP1-dependent transcription was abolished by CpG methylation.


CONCLUSIONS
This report implicates SP1 as a critical component of DNA demethylation-dependent up-regulation of TLR2 expression in CF epithelial cells.
Furuta
Takashi
T
Department of Molecular Medicine, Graduate School of Pharmaceutical Science, Global COE Cell Fate Regulation Research and Education Unit, Kumamoto University, Kumamoto 862-0973, Japan. furutakashi@molmed730.com
Shuto
Tsuyoshi
T
Shimasaki
Shogo
S
Ohira
Yuko
Y
Suico
Mary Ann
MA
Gruenert
Dieter C
DC
Kai
Hirofumi
H
D001665:Binding Sites; D002460:Cell Line; D018899:CpG Islands; D003550:Cystic Fibrosis / Q000235:genetics* / Q000473:pathology*; D019175:DNA Methylation; D004847:Epithelial Cells; D005786:Gene Expression Regulation; D006801:Humans; D008954:Models, Biological; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000235:genetics*; D014158:Transcription, Genetic
D016329:Sp1 Transcription Factor; D051195:Toll-Like Receptor 2