Objective By detecting the variation of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) DNA methylation in preeclampsia-like mouse models generated by different ways, to explore the roles of multifactor and multiple pathways in preeclampsia pathogenesis on molecular basis. Methods Established preeclampsia-like mouse models in different ways and divided into groups as follows: (1) Nw-nitro-L-arginine-methyl ester (L-NAME) group: wild-type pregnant mouse received subcutaneous injection of L-NAME;(2) lipopolysaccharide (LPS) group:wild-type pregnant mouse received intraperitoneal injection of LPS; (3) apolipoprotein C-Ⅲ (ApoC3) group: ApoC3 transgenic pregnant mouse with dysregulated lipid metabolism received subcutaneous injection of L-NAME;(4)β2 glycoprotein I (β-2GPI) group:wild-type pregnant mouse received subcutaneous injection ofβ-2GPI. According to the first injection time (on day 3, 11, 16 respectively), the L-NAME, LPS and ApoC3 groups were further subdivided into:pre-implantation (PI) experimental stage, early gestation (EG) experimental stage, and late gestation (LG) experimental stage.β-2GPI group was only injected before implantation. LCHAD gene methylation levels in placental were detected in different experimental stage. Normal saline control groups were set within wild-type and ApoC3 transgenic pregnant mice simultaneously. Results (1) CG sites in LCHAD DNA:45 CG sites were detected in the range of 728 bp before LCHAD gene transcription start site, the 5, 12, 13, 14, 15, 16, 19, 24, 25, 27, 28, 29, 30, 31, 32, 34, 35, 43 CG sites were complex sites which contained two or more CG sequences, others were single site which contained one CG sequence. The 3, 5, 6, 11, 13, 14, 18, 28 sites in L-NAME, LPS, ApoC3 and β-2GPI groups showed different high levels of methylation; the 16, 25, 31, 42, 44 sites showed different low levels of methylation; other 32 sites were unmethylated. (2) Comparison of LCHAD gene methylation between different groups:the methylation levels of LCAHD gene at 3, 11, 13, 14, 18 sites in L-NAME, LPS, ApoC3 andβ-2GPI groups were significantly higher than those in the normal saline control group (P<0.05); and the methylation levels of 42, 44 sites in these groups were significantly lower than those in the normal saline control group (P<0.05). (3) Methylation of LCHAD gene at the same site between different experimental stages: ① The 3, 11, 18 sites of EG experimental stage was significantly lower than PI and LG experimental stage in L-NAME group (P<0.05);the 3, 11, 18 sites of PI experimental stage was significantly lower than EG and LG experimental stage in LPS group (P<0.05);these sites of PI experimental stage was significantly higher than EG and LG experimental stages in ApoC3 group (P<0.05).②The methylation of site 5 in L-NAME and LPS groups were significantly higher than that of the normal saline control group (P<0.05), and the LG experimental stages were significantly higher than other stages, but in ApoC3 group , only PI and EG stages were significantly higher than the normal saline control group (P<0.05).③At site 6 in L-NAME group which showed high methylation level was significantly higher than the same site in other groups which showed low methylation level (P<0.05).④At 13, 14 sites, earlier preeclampsia onset caused a lower methylation level in L-NAME group, but PI experimental stage was significantly higher than EG and LG experimental stages in LPS group (P<0.05), EG experimental stage was significantly higher than PI and LG experimental stages in ApoC3 group (P<0.05). ⑤ At site 28, earlier preeclampsia onset caused a higher methylation level in L-NAME group, but PI experimental stage was significantly lower than EG and LG experimental stages in LPS group (P<0.05), EG experimental stage was significantly higher than PI and LG experimental stages in ApoC3 group (P<0.05).⑥The 16, 25, 31 sites in ApoC3 group were significantly higher than other groups (P<0.05). ⑦ At site 42 in β-2GPI group was unmethylated, but it in other groups showed low methylation level, the methylation level of site 42 inβ-2GPI group was significantly lower than that in other groups (P<0.05). Conclusions The methylation of 6 and 42 CG sites may be related to LCHAD gene expression in placenta of L-NAME and β-2GPI induced preeclampsia-like models respectively;LCHAD gene expression and DNA methylation may not have obviouscorrelation in LPS and ApoC3 induced preeclampsia-like models. Differences exist in LCHAD DNA methylation in preeclampsia-like models generated by different ways, revealed a molecular basis to expand our understanding of the multi-factorial pathogenesis of preeclampsia.%目的 通过检测不同诱发途径建立的子痫前期模型孕鼠胎盘组织中长链脂肪酸β氧化关键酶长链-3-羟酰基辅酶A脱氢酶(LCHAD)基因位点甲基化程度的差异,探讨多因素和多通路在子痫前期病理机制中的分子实验基础.方法 按不同途径建立子痫前期孕鼠模型并分组如下:(1)左硝基精氨酸甲酯(L-NAME)组:给予孕鼠皮下注射L-NAME的方法建模;(2)脂多糖(LPS)组:给予孕鼠腹腔注射LPS的方法建模;(3)载脂蛋白C3(ApoC3)组:给予存在脂代谢障碍的孕鼠皮下注射L-NAME的方法建模型;(4)β2糖蛋白Ⅰ(β-2GPI)组:给予孕鼠皮下注射β-2GPI不完全弗氏佐剂的方法建模.根据建模时间对L-NAME组、LPS组及ApoC3组孕鼠于妊娠第3、11、16天分别定为胚胎植入前期、子痫前期早发期和晚发期3个不同实验阶段,β-2GPI组孕鼠仅有植入前期,对不同实验阶段的孕鼠胎盘LCHAD基因位点的甲基化水平进行检测.同时设生理盐水对照组,以及应用ApoC3高表达转基因孕鼠作为对照的转基因对照组.结果 (1)各组孕鼠LCHAD基因发生甲基化的位点:在LCHAD基因转录起始位点上游728 bp的范围内,共发现存在45个CG位点,其中LCHAD基因CG-5、12、13、14、15、16、19、24、25、27、28、29、30、31、32、34、35、43为含有2个及以上CG序列的复合位点,其他位点为仅含有1个CG序列的单一位点.L-NAME组、LPS组、ApoC3组和β-2GPI组孕鼠均有13个LCHAD基因位点发生甲基化改变,其中,LCHAD基因CG-3、5、6、11、13、14、18、28位点呈不同程度的高甲基化状态;LCHAD基因CG-16、25、31、42、44位点呈不同程度的低甲基化状态;其余32个位点无甲基化改变.(2)各组孕鼠胎盘LCHAD基因位点甲基化水平比较:L-NAME组、LPS组、ApoC3组、β-2GPI组和转基因对照组孕鼠胎盘LCHAD基因CG-3、11、13、14、18位点的甲基化水平显著高于生理盐水对照组,分别比较,差异均有统计学意义(P<0.05);而LCHAD基因CG-42、44位点的甲基化水平显著低于生理盐水对照组,分别比较,差异有统计学意义(P<0.05).(3)各组孕鼠LCHAD基因相同位点的甲基化水平比较:①L-NAME组孕鼠早发期LCHAD基因CG-3、11、18位点的甲基化水平显著低于植入前期及晚发期,LPS组孕鼠植入前期显著低于早发期及晚发期;而ApoC3组孕鼠植入前显著高于早发期及晚发期,分别比较,差异均有统计学意义(P<0.05).②L-NAME组、LPS组不同实验阶段孕鼠LCHAD基因CG-5位点甲基化水平均显著高于生理盐水对照组,而ApoC3组仅植入前及早发期高于生理盐水对照组,分别比较,差异均有统计学意义(P<0.05).③L-NAME组孕鼠不同实验阶段LCHAD基因CG-6位点甲基化水平显著高于其他各组,分别比较,差异均有统计学意义(P<0.05).④L-NAME组孕鼠LCHAD基因CG-13、14位点甲基化水平在植入前、早发期、晚发期呈逐渐升高趋势,LPS组孕鼠在植入前显著高于早发期、晚发期,而ApoC3组孕鼠早发期的甲基化水平最高,分别比较,差异均有统计学意义(P<0.05).⑤L-NAME组孕鼠LCHAD基因CG-28位点甲基化水平在植入前、早发期、晚发期呈逐渐降低趋势,LPS组孕鼠早发期、晚发期甲基化水平高于植入前期,ApoC3组孕鼠早发期甲基化水平最高,分别比较,差异均有统计学意义(P<0.05).⑥ApoC3组孕鼠LCHAD基因CG-16、25、31位点甲基化水平显著高于其他各组,分别比较,差异均有统计学意义(P<0.05).⑦β-2GPI组孕鼠LCHAD基因CG-42位点未检测到甲基化,而其他各组CG-42位点呈低甲基化状态,β-2GPI组与其他各组的CG-42位点甲基化水平比较,差异均有统计学意义(P<0.05).结论 LCHAD基因CG-6、42位点甲基化可能分别与L-NAME、β-2GPI诱导的子痫前期孕鼠胎盘中LCHAD基因表达变化相关;LCHAD基因表达和甲基化在LPS和ApoC3转基因孕鼠中未见明显联系.不同诱发途径的子痫前期孕鼠LCHAD甲基化水平和表达存在的差异,进一步揭示了多因素和多通路在子痫前期发病机制中的分子实验基础.
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