PROPERTIES AND LOCALIZATION OF DNA METHYLTRANSFERASE IN PREIMPLANTATION MOUSE EMBRYOS - IMPLICATIONS FOR GENOMIC IMPRINTING
PROPERTIES AND LOCALIZATION OF DNA METHYLTRANSFERASE IN PREIMPLANTATION MOUSE EMBRYOS - IMPLICATIONS FOR GENOMIC IMPRINTING
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DOI：
10.1101/gad.6.12b.2536
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发表时间：
1992-12-01
影响因子：
10.5
通讯作者：
BESTOR, TH
中科院分区：
文献类型：
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作者：
CARLSON, LL;PAGE, AW;BESTOR, TH
植入前小鼠胚胎含有非常高水平的DNA甲基转移酶活性。我们在这里表明，在早期胚胎中的DNA甲基转移酶（DNA MTase）的形式不同于在其他细胞和组织中发现的形式，在凝胶电泳上的迁移率略高。在整个着床前发育过程中，发现DNA MTase水平非常高，尽管已知细胞核DNA中的5-甲基胞嘧啶（m5C）水平在同一时期大幅下降。用DNA MTase特异性抗体染色的小鼠胚胎的共聚焦激光扫描显微镜显示DNA MTase分布的显著发育调节变化。从卵母细胞期到四细胞期，大多数DNA MTase集中在外周细胞质中，细胞核中不含可检测到的DNA MTase。在四细胞和八细胞胚胎中，DNA MTase见于细胞质颗粒;在八细胞胚胎中，DNA MTase也大量存在于细胞核中。囊胚细胞核染色微弱，而细胞质颗粒仍然突出。巧合的是，在DNA中m5C水平下降最快的发育阶段，DNA MTase在细胞核中的水平最高。因此，植入前胚胎中甲基化模式的变化被认为是在未鉴定的调控因子而不是DNA MTase本身的控制下;这些调控因子可能是包含Ssm-1和Imp-1基因产物的组的成员，它们参与基因组印记的调控。
Preimplantation mouse embryos contain very high levels of DNA methyltransferase activity. We show here that the form of DNA methyltransferase (DNA MTase) in early embryos differs from the form found in other cells and tissues by a slightly higher mobility on gel electrophoresis. Levels of DNA MTase were found to be very high throughout preimplantation development even though levels of 5-methylcytosine (m5C) in nuclear DNA are known to undergo a substantial decline in the same period. Confocal laser scanning microscopy of mouse embryos stained with DNA MTase-specific antibodies showed striking developmentally regulated changes in the distribution of DNA MTase. From the oocyte stage to the four-cell-stage, most DNA MTase was concentrated in peripheral cytoplasm, and nuclei did not contain detectable DNA MTase. In four- and eight-cell embryos, DNA MTase was seen in cytoplasmic granules; and in eight-cell embryos, DNA MTase was also present in large amounts in nuclei. Nuclei of blastocysts stained only faintly, whereas the cytoplasmic granules remained prominent. Paradoxically, DNA MTase was found to.be at its highest levels in nuclei at a developmental stage where levels of m5C in DNA are decreasing most rapidly. Changes in methylation patterns in preimplantation embryos are therefore proposed to be under the control of unidentified regulatory factors rather than DNA MTase itself; these regulatory factors could be members of the group that contains the products of the Ssm-1 and Imp-1 genes, which are involved in the regulation of genomic imprinting.