Role of DNA methylation in the regulation of the RANKL-OPG system in human bone

Jesus Delgado-Calle, Carolina Sañudo, Agustín F. Fernández, Raúl García-Renedo, Mario F. Fraga, José A. Riancho

Research output: Contribution to journalArticle

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Abstract

Osteoblasts are specialized cells that form new bone and also indirectly influence bone resorption by producing factors that modulate osteoclast differentiation. Although the methylation of CpG islands plays an important role in the regulation of gene expression, there is still scanty information about its role in human bone. The aim of this study was to investigate the influence of CpG methylation on the transcriptional levels of two osteoblast-derived critical factors in the regulation of osteoclastogenesis: the receptor activator of nuclear factor NFκB ligand (RANKL) and its soluble decoy receptor osteoprotegerin (OPG). Quantitative methylation specific PCR (qMSP) and pyrosequencing analysis in various cell types showed that the methylation of regulatory regions of these genes, in the vicinity of the transcription start sites, repressed gene transcription, whereas an active transcription was associated with low levels of methylation. In addition, treatment with the DNA demethylating agent 5-azadeoxycitidine promoted a 170-fold induction of RANKL and a 20-fold induction of OPG mRNA expression in HEK-293 cells, which showed hypermethylation of the CpG islands and barely expressed RANKL and OPG transcripts at baseline. Transcriptional levels of both genes were also explored in bone tissue samples from patients with hip fractures and hip osteoarthritis. Although RANKL transcript abundance and the RANKL:OPG transcript ratio were significantly higher in patients with fractures than in those with osteoarthritis (RANKL: 0.76 ± 0.23 vs. 0.24 ± 0.08, p = 0.012; RANKL:OPG: 7.66 ± 2.49 vs. 0.92 ± 0.21, p = 0.002), there was no evidence for differential methylation across patient groups. In conclusion, the association between DNA methylation and the repression of RANKL and OPG expression strongly suggests that methylation-dependent mechanisms influence the transcription of these genes, which play a critical role in osteoclastogenesis. However, other mechanisms appear to be involved in the increased RANKL/OPG ratio of patients with osteoporotic fractures.

Original languageEnglish (US)
Pages (from-to)83-91
Number of pages9
JournalEpigenetics : official journal of the DNA Methylation Society
Volume7
Issue number1
DOIs
StatePublished - 2012
Externally publishedYes

Fingerprint

Osteoprotegerin
DNA Methylation
Methylation
Bone and Bones
CpG Islands
Osteoblasts
Osteogenesis
Genes
Hip Osteoarthritis
Osteoporotic Fractures
HEK293 Cells
Nucleic Acid Regulatory Sequences
Transcription Initiation Site
Hip Fractures
Gene Expression Regulation
Osteoclasts
Regulator Genes
Cytoplasmic and Nuclear Receptors
Osteoarthritis
Ligands

Keywords

  • Bone remodeling
  • DNA methylation
  • Osteoblasts
  • Osteoporosis

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research

Cite this

Role of DNA methylation in the regulation of the RANKL-OPG system in human bone. / Delgado-Calle, Jesus; Sañudo, Carolina; Fernández, Agustín F.; García-Renedo, Raúl; Fraga, Mario F.; Riancho, José A.

In: Epigenetics : official journal of the DNA Methylation Society, Vol. 7, No. 1, 2012, p. 83-91.

Research output: Contribution to journalArticle

Delgado-Calle, Jesus ; Sañudo, Carolina ; Fernández, Agustín F. ; García-Renedo, Raúl ; Fraga, Mario F. ; Riancho, José A. / Role of DNA methylation in the regulation of the RANKL-OPG system in human bone. In: Epigenetics : official journal of the DNA Methylation Society. 2012 ; Vol. 7, No. 1. pp. 83-91.
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