Leptin Gene Expression in Human Preadipocytes Is Switched on by Maturation-induced Demethylation of Distinct CpGs in Its Proximal Promoter

Abstract

The peptide hormone leptin plays a major role in the regulation of energy intake and expenditure and is predominantly expressed in mature adipocytes but not in preadipocytes. Using bisulfite genomic sequencing, we found that 32 CpGs, distributed within a 317-bp sequence of the proximal leptin promoter, were highly methylated in human preadipocytes (73.4% ؎ 9.0%). During maturation toward terminally differentiated adipocytes, this promoter region was extremely demethylated (9.4% ؎ 4.4%). CpG methylation-dependent transcriptional activity of the promoter fragment was determined in transfection experiments using a set of 5-truncated mock-, HhaI-, and SssI-methylated promoter-reporter constructs. Whereas the methylated CpG within the CCAAT/enhancer-binding protein ␣ recognition site down-regulated reporter expression, methylated CpGs proximal to the TATA motif and/or in a further upstream region abrogated promoter activity completely. These distinct promoter CpG sequences were found unmethylated in leptin-expressing mature adipocytes. As evidenced by electrophoretic mobility shift assays, nuclear protein complexes were specifically formed on methylated oligonucleotide probes corresponding to the dedicated promoter sequences, indicating that methyl-CpG binding proteins participate in transcriptional repression and regulation of the human leptin gene.

RETRACTED ARTICLE: Mechanism of leptin expression in breast cancer cells: role of hypoxia-inducible factor-1α

“…Consequently, we investigated whether insulin and hypoxia-mimetic agents might regulate the expression of the leptin gene in this cell context. The human leptin gene promoter is B3000 long and contains several regulatory motifs, including AP2, SP-1, CREB, C/EBP, GRE, CRE elements (Mason et al, 1998;Ahima and Flier, 2000;Melzner et al, 2002;Meissner et al, 2003). Most importantly, the promoter contains eight hypoxia-responsive elements (HRE) with the minimal core sequence 5 0 -RCGTG-3 0 that can recruit hypoxia-inducible factor (HIF) (Grosfeld et al, 2002;Meissner et al, 2003).…”

Duration of breastfeeding and gender are associated with methylation of the LEPTIN gene in very young children

“…Lower methylation of LEP leads to increased expression and higher concentrations of leptin, which is illustrated by our finding of an increased leptin concentration with lower methylation of LEP. This is supported by the functional effect of methylation on leptin levels (7,12). The association between the duration of breastfeeding and LEP methylation is intriguing.…”

“…The CpG sites studied in the LEP promoter show similar methylation in peripheral blood and adipocytes in vivo. Furthermore, methylation in adipocytes influences LEP expression in vitro (7,12). However, measurements of LEP mRNA have revealed that especially in children LEP is differentially expressed depending on the adipose region (34).…”

“…In human preadipocytes, leptin is not expressed owing to hypermethylation of the LEP promoter. When the preadipocytes mature, the gene is switched on through demethylation (12). Differences in methylation of the LEP promoter influence LEP expression in vitro, which suggests a functional effect of methylation on leptin levels (7).…”

Developmental programming of the metabolic syndrome - critical windows for intervention

“…Twin studies show that DNA methylation and histone acetylation patterns diverged more strongly in older twin pairs with more marked life history differences [117] . It has been shown that the promoter in the leptin gene is subject to epigenetic programming and leptin gene expression can be modulated by DNA methylation [127][128][129] . Recent studies report that impaired glucose tolerance during pregnancy is associated with adaptations in leptin gene DNA methylation although the functional significance of these changes is not yet clear [130] .…”