辅助生殖技术对人胎盘DNA甲基化水平的影响

Effects of assisted reproductive technology on the level of DNA methylation in human placenta

目的探究辅助生殖技术(ART)助孕对单胎足月分娩新生儿的胎盘及胎盘总DNA甲基化水平和甲基化相关基因表达的影响。方法选择2016年6月—2016年12月期间单胎足月分娩的患者,ART子代为ART组,自然妊娠子代为对照组,两组按孕妇年龄、孕周等进行配对后,比较两组胎盘质量、新生儿体质量、胎盘效率。采用酶联免疫吸附测定法(ELISA)测定胎盘总DNA的甲基化水平,采用实时定量聚合酶链式反应(RT-q PCR)方法检测胎盘甲基转移酶(DNA methyltransferase,DNMT)家族和去甲基化酶(ten-eleven translocation,TET)家族的m RNA表达水平。结果 (1)ART组新生儿体质量[(3 650.50±393.84)g]、胎盘重量[(633.05±98.58)g]显著增加,且高于对照组[(3 339.50±377.01)g,(563.00±85.60)g](P<0.05)。(2)ART组胎盘总DNA甲基化水平(1.22%±0.45%)显著低于对照组(2.08%±0.98%)(P<0.05)。(3)ART组DNMT3B、TET1、TET2、TET3的m RNA相对表达量分别为4.61±1.06、4.66±1.06、4.99±1.09、4.92±1.13,显著高于对照组(1.23±0.55、1.27±0.56、1.47±0.50、1.41±0.61)(P<0.05),DNMT1、DNMT3A的表达水平无统计学差异(P>0.05)。结论 ART会导致人类妊娠晚期胎盘过度生长,总DNA甲基化水平降低,DNMT3B、TET1、TET2、TET3表达上调可能是导致胎盘DNA甲基化水平降低的机制。

Objective To explore whether assisted reproductive technology （ART） affects the infant body weight, the placental weight, ratio of infant/placental weight, the mean DNA methylation level and the expression level of DNA methyltransferase （DNMT） family and ten-elevenlranslocation （TET） family. Methods The infant weight, placental weight, ratio of infant/placental weight were compared between 35 singleton full-term neonates derived from ART-born （ART group） and 36 singleton full-term neonates derived from naturally-born （negative control group, NC group）. To avoid the effects of age factors, 20 placentas were selected from each group to detect the mean DNA methylation level by ELISA and the expressions of DNMT family （DNMT1, DNMT3A, DNMT3B） and TET family （TET1, TET2, TET3） by RT-qPCR. Results The infant weight [（3 650.50±393.84） g] and placental weight [（633.05± 98.58） g] were significantly increased in ART group compared with NC group [（3 339.50± 377.01） g, （ 563.00 ± 85.60 ） g ]. The mean DNA methylation level of placenta in ART group （ 1.22 % ±0.45 % ） was significantly lower than that in NC group （2.08%± 0.98%）. The mRNA expression levels ofDNM73B, TET1, TET2, TET3 were up-regulated in ART group （4.61 ± 1.06, 4.66±1.06, 4.99±1.09, 4.92±1.13） compared with control group （1.23±0.55, 1.27± 0.56, 1.47 ± 0.50, 1.41± 0.61） （P〈0.05）, though there were no significant differences in the mRNA expression lever of DNMT1 and DNMT3A. Condusion ART can lead to the overgrowth of placenta in the late stage of human pregnancy and a low level of DNA methylation in the placenta, which may due to the up-regulated expression level ofDNMT3B, TET1, TET2, TET3.