The HUS1B promoter is hypomethylated in the placentas of low-birth-weight infants

• The promoter of the HUS1B gene was highly methylated in human placentas.
• The promoter of the HUS1B gene was hypomethylated in three of 86 placentas from LBW infants.
• The HUS1B expression was induced by hypomethylation of the gene promoter in trophoblastic cell lines.

Aberrant DNA methylation is associated with a range of human disorders. To identify differences in DNA methylation of gene promoters between placentas of low-birth-weight (LBW) and normal-birth-weight (NBW) infants, we screened 8091 genes for aberrant methylation in placentas using microarray-based integrated analysis of methylation by isoschizomers (MIAMI). Seven candidate genes for hypomethylation in the placentas of LBW infants were selected. Among these candidates, COBRA analyses suggested that the HUS1B gene was hypomethylated in some of the placentas. Quantitative methylation analyses by bisulfite-pyrosequencing indicated that the promoter region of the gene was hypomethylated in three of the 86 placentas analyzed. The HUS1B promoter was highly methylated in two cell lines derived from trophoblastic cells. Gene expression increased when the promoter was demethylated by 5Aza-dC treatment. This suggests that hypomethylation of HUS1B alters gene expression in the placenta and that this dysregulated gene expression may contribute to the pathogenesis of LBW by affecting placental functions involved in fetal growth.