| Background and Objective:Gene imprinting is a unique mechanism that inactivates one allele of a gene in a parent-of-origin-dependent manner for being imprinted, just one allele gene expressed, called imprinted genes. Imprinted genes show parent of origin specific monoallelic or parental allele-based expression, such that for some genes, it is mainly the maternally inherited allele that is expressed, whereas for other genes, expression occurs mainly from the paternal copy. The silenced genes will be expressed for being activated by the absence of imprinting. The biallelic expressions are called loss of imprinting (LOI). Gene imprint- ing affects the embryonic and fetus growth, cell differentiations and proliferations, psycho- behaviors. LOI can result some genetic diseases and tumors.The imprinted H19 gene, as one of first genes shown to be paternal imprinted, matern- al expressed, mostly considered as a growth regulation gene, is abundantly expressed in embryonic tissues. It involves in the growth and development of embryo and different- tiations of trophoblasts. But the functions on generation regulation are still not to be completely illuminated. It is reported that H19 exists dynamic changes in animal and human pregnancy, but only few articles reported the H19 in trophoblasts. Some scholars considered that pre-eclampsia is a disease together with the disorders of maternal expressed imprinted genes. In Gestational trophpblastic tumors (GTT) with high invasion ability of trophoblasts, H19 is down-regulated. Pre-eclampsia is one of the placenta diseases with decreased trophoblasts invasion ability, H19 may have an association with its morbidity, but still lack of reports on this aspect right now.Using PCR-RFLP (the RsaI polymorphism of H19) methods to investigate the imprinting status of the villi or placenta tissues in different gestation weeks and pre-eclampsia. Further more, using real time PCR methods to detect the H19 RNA levels of the villi tissues in the first trimesters, and placenta tissues in the third trimesters and pre-eclampsia. So to analyse the association of the imprinting status and RNA levels of H19 with normal pregnancy and pre-eclampsia.Materials and Methods:1. 188 villi tissues of the first trimesters(5-9weeks), 54 placenta tissues of the first trimesters(10-12weeks), 50 placenta tissues of the second trimesters, 65 placenta tissues of the third trimesters, 24 placenta tissues of pre-eclampsia, using PCR-RFLP methods to investigate the imprinting status of H19, so to analyse the special-allelic imprinting status.2. 20 villi tissues of the first trimesters, 20 placenta tissues of the third trimesters, 15 placenta tissues of pre-eclampsia, using real time PCR methods to detect the levels of the H19 RNA in those samples.Results:1.87 (46.28%) heterozygotes in 188 villi tissues of the first trimesters (5-9weeks), 24 cases (27.59%) are bialleliccally expressed, while 63 cases (72.41%) are monoallelically expressed. 25(46.29%) heterozygotes in 54 placenta tissues of first trimesters (10-12weeks), 21 (42%) heterozygotes in 50 placenta tissues of the second trimesters, 26 (40%) heterozygotes in 65 placenta tissues of the third trimesters, are exclusively monoallelically expressed.2. 11 (45.83%) heterozygotes in 24 placenta tissues of pre-eclampsia, 5 cases (45.45%) are bialleliccally expressed (LOI). The SBP/DBP levels in bialleliccally expressed patients are higher than monoallelically expressed patients.3. The results of real time PCR show the H19 RNA levels in the villi tissues of the first trimesters are lower than the H19 RNA levels in placenta tissues of the third trimesters.4. The results of real time PCR show there are no changes of the H19 RNA levels between the third trimesters and pre-eclampsia.Conclusion:1. In normal pregnancy, H19 biallelic expression is confined to the placenta until 10 weeks of gestation, after which it becomes exclusively maternal, the paternal imprinting is re-established before 10 weeks of gestation. H19 RNA levels in the villi tissues of the first trimesters are lower than the H19 RNA levels in placenta tissues of the third trimesters. Our observations demonstrate that the imprinting status and expression levels of the imprinted H19 gene are dynamically changed in normal pregnancy, and may be related with the invasion of trophoblasts and maintenance of pregnancy.2. The loss of imprinting of the H19 is found in pre-eclampsia, and related with the blood pressures. It demonstrates that H19 gene may involve the pre-eclampsia, and is highly related with the disease degree, can become a precaution index for pre-eclampsia. |
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