Analysis of Genome Operating Systems for Immune Network by Polycomb Group Genes.

Polycomb组（PcG）基因产物在哺乳动物细胞核中形成蛋白质复合物，其有助于维持靶基因的染色质沉默。在哺乳动物PcG同源物中，通过对敲除/Tg小鼠的分析，已经阐明mel-18调节细胞周期进程、细胞死亡或衰老。其产物参与Polycomb蛋白复合物，在细胞核中呈斑点状分布，我们描述了mel-18缺陷小鼠胸腺T淋巴细胞发育的缺陷意味着mel-18的参与，18在维持未成熟淋巴细胞中的作用，通过控制一些定型和存活因子的表达来调节其存活，包括bcl-2家族亚组。因此，我们想提出我们的结果作为调节机制，以控制淋巴细胞发育中的增殖和细胞死亡之间的平衡，特别是DN 1级分的ETP细胞和DN 3级分的小细胞（E细胞），就在通过染色质沉默Polycomb蛋白复合物的不稳定性对未成熟胸腺细胞进行β选择之前。

The Polycomb group (PcG) genes products form protein complexes in mammalian cell nuclei that contribute to maintain chromatin silencing of target genes. Among mammalian PcG homologues, mel-18 has been elucidated to regulate cell cycle progression, cell death, or senescence through analyses of knockout/Tg mice. Its product participatesin Polycomb protein complexes, whose existences in cell nuclei are displayed speckled distributions, overlapped with heterochromatin areas in immunohistochemical examinations.We describe that the defect in thymic T-lymphocyte development of mel-18 deficient mice implies the involvement of mel-18 in the maintenance of immature lymphocyte by regulating their survival via controlling the expression of some commitment and survival factors including subgroup of bcl-2 family. Therefore we would like to propose our results as the regulation mechanisms to control the balance between proliferation and cell death in lymphocyte development, especially ETP cell of DN1 fraction and small cell (E cell) of DN3 fraction just before the beta-selection of immature thymocyte by destabilization of chromatin silencing Polycomb protein complex.