X chromosome inactivation and differentiation occur readily in ES cells doubly-deficient for macroH2A1 and macroH2A2.
X chromosome inactivation and differentiation occur readily in ES cells doubly-deficient for macroH2A1 and macroH2A2.
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DOI：
10.1371/journal.pone.0021512
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Rasmussen TP
中科院分区：
文献类型：
--
作者：
Tanasijevic B;Rasmussen TP
大组蛋白（mh2a）是一种罕见的组蛋白变体，仅存在于脊椎动物的染色质中。在小鼠中，H2afy基因编码两个剪接变体mH2A1.1和mH2A1.2，第二个基因H2afy2编码另外一个mH2A2蛋白。在分化的哺乳动物雌性细胞中，两种mH2A亚型均富集于失活的X染色体（Xi）上，并被纳入发育调节基因的染色质中。为了研究mH2A亚型对X染色体失活（XCI）的功能意义，我们制备了具有稳定整合shRNA结构的雄性和雌性胚胎干细胞（ESC）系，这些shRNA结构同时靶向mH2A1和mH2A2。令人惊讶的是，我们发现缺乏mH2A1和mH2A2的雌性ESCs在分化时很容易执行和维持XCI。此外，男性和女性mh2a缺陷ESCs在多能培养条件下正常增殖，并对几种标准分化程序做出有效反应。我们的结果表明，XCI可以很容易地进行，大大降低了总mH2A含量。
Macrohistones (mH2As) are unusual histone variants found exclusively in vertebrate chromatin. In mice, the H2afy gene encodes two splice variants, mH2A1.1 and mH2A1.2 and a second gene, H2afy2, encodes an additional mH2A2 protein. Both mH2A isoforms have been found enriched on the inactive X chromosome (Xi) in differentiated mammalian female cells, and are incorporated into the chromatin of developmentally-regulated genes. To investigate the functional significance of mH2A isoforms for X chromosome inactivation (XCI), we produced male and female embryonic stem cell (ESC) lines with stably-integrated shRNA constructs that simultaneously target both mH2A1 and mH2A2. Surprisingly, we find that female ESCs deficient for both mH2A1 and mH2A2 readily execute and maintain XCI upon differentiation. Furthermore, male and female mH2A-deficient ESCs proliferate normally under pluripotency culture conditions, and respond to several standard differentiation procedures efficiently. Our results show that XCI can readily proceed with substantially reduced total mH2A content.
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