DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals
DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals
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DOI：
10.1523/jneurosci.21-03-00788.2001
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发表时间：
2001-02-01
影响因子：
5.3
通讯作者：
Jaenisch, R
中科院分区：
文献类型：
--
作者：
Fan, GP;Beard, C;Jaenisch, R
DNA甲基转移酶1(Dnmt1)是DNA胞嘧啶甲基化的维持酶，在胚胎发育和出生后的中枢神经系统中高水平表达。由于缺乏Dnmt1的胚胎在原肠形成时死亡，因此无法利用该突变来研究Dnmt1在神经系统发育和功能中的作用。因此，我们使用cre/loxP系统来产生条件突变，这些突变在第12天胚胎的神经母细胞或出生后动物的有丝分裂后神经元中缺乏DNMT1。Dnmt1基因的条件性缺失导致Dnmt1蛋白迅速耗尽，表明有丝分裂后神经元中的酶迅速翻转。有丝分裂后神经元中DNMT1缺乏既不影响全局DNA甲基化水平，也不影响出生后生命中细胞的存活。相反，有丝分裂的CNS前体细胞中Dnmt1缺乏导致子代细胞DNA低甲基化。大脑中含有95%低甲基化细胞的突变胚胎出生后立即死于呼吸窘迫，而含有30%低甲基化中枢神经系统细胞的马赛克动物可以存活到成年。然而，这些突变细胞在出生后3周内就从大脑中迅速消除。因此，低甲基化的中枢神经系统神经元在功能上受到损害，并在出生后阶段被筛选出来。
DNA methyltransferase 1 (Dnmt1), the maintenance enzyme for DNA cytosine methylation, is expressed at high levels in the CNS during embryogenesis and after birth. Because embryos deficient for Dnmt1 die at gastrulation, the role of Dnmt1 in the development and function of the nervous system could not be studied by using this mutation. We therefore used the cre/loxP system to produce conditional mutants that lack Dnmt1 in neuroblasts of embryonic day 12 embryos or in postmitotic neurons of the postnatal animal. Conditional deletion of the Dnmt1 gene resulted in rapid depletion of Dnmt1 proteins, indicating that the enzyme in postmitotic neurons turns over quickly. Dnmt1 deficiency in postmitotic neurons neither affected levels of global DNA methylation nor influenced cell survival during postnatal life. In contrast, Dnmt1 deficiency in mitotic CNS precursor cells resulted in DNA hypomethylation in daughter cells. Whereas mutant embryos carrying 95% hypomethylated cells in the brain died immediately after birth because of respiratory distress, mosaic animals with 30% hypomethylated CNS cells were viable into adulthood. However, these mutant cells were eliminated quickly from the brain within 3 weeks of postnatal life. Thus, hypomethylated CNS neurons were impaired functionally and were selected against at postnatal stages.