mRNA expression and promoter methylation of paternally expressed gene 1 and paternally expressed gene 3 in human placenta of abnormal birth weight fetuses

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WANG Ying(Department of Obstetrics and Gynecology,Shengjing Hospital Affiliated to China Medical University,Shenyang 110004,China)
SONG Wei-wei(Department of Obstetrics and Gynecology,Shengjing Hospital Affiliated to China Medical University,Shenyang 110004,China)
WANG Li-li()
YANG Lin(Department of Obstetrics and Gynecology,Shengjing Hospital Affiliated to China Medical University,Shenyang 110004,China)
Journal Title:
Volume 13, Issue 03, 2010
Key Word:
Birth weight;Methylation;Proteins;Kruppel-like transcription factors;Placenta

Abstract: Objective To study the mRNA expression of two imprinted genes,paternally expressed gene 1(PEG1) and paternally expressed gene 3(PEG3),and their promoter methylation in human placenta of abnormal birth weight(BW)neonates. Methods Placentas were obtained after full term delivery,without any maternal complications during pregnancy,and were divided into 3 groups according to BW:high BW group(n=22,BW≥4000 g),normal BW group(n=14,BW>2500 g and<4000 g)and low BW group(n=24,BW≤2500 g).The mRNA expression of PEG1 and PEG3 were determined by real-time quantitative polymerase chain reaction.Promoter methylation was measured by the bisulfite genomic sequencing method.Results among different groups were compared. Results (1)The mRNA expression of PEGl and PEG3 were 11.66±9.01 and 16.45±10.13 in the high BW group,0.84±0.49 and 0.85±0.67 in the low BW group and 1.10±0.77 and 1.11±0.60 in the normal BW group,respectively.Both genes were significantly up-regulated in the high BW group compared to the normal BW group(P<0.05),but no significant difference was found between the normal and low BW group (P>0.05). (2) The levels of PEG1 promoter methylation were (49. 7± 2. 3) %, (50. 2 ± 2. 1 )% and (50. 3 ± 1.9)% in the high, low and normal BW group (P>0.05), while the levels of PEG3 promoter methylation in the high BW was significantly lower than in the normal BW group [(13.1± 2. 7) % vs (16.2 ±1.8)%, P<0. 05], but no difference was shown between the low BW group (16.7± 3.5)% and the normal BW group (P>0.05). (3)Negative correlation was detected between the expression of PEG:3 and DNA methylation level within the objective fragment of promoter region (r= -0. 963, P<0. 01). Conclusions The up-regulation of PEG1 and PEG3 may be associated with high BW. The reduction of methylation pattern in the promoter region of PEG3 might be involved in the up-regulation of PEG3 and contribute to the mechanism of high BW fetus in turn.

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