Knockdown of CENH3 in Arabidopsis reduces mitotic divisions and causes sterility by disturbed meiotic chromosome segregation
Knockdown of CENH3 in Arabidopsis reduces mitotic divisions and causes sterility by disturbed meiotic chromosome segregation
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DOI：
10.1111/j.1365-313x.2011.04664.x
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发表时间：
2011-10-01
期刊：
影响因子：
7.2
通讯作者：
Schubert, Ingo
中科院分区：
文献类型：
--
作者：
Lermontova, Inna;Koroleva, Olga;Schubert, Ingo
着丝粒核小体的组蛋白H3变体（CENH 3）对于动粒组装以及真核生物中的染色体分离是必不可少的。决定着丝粒身份、装配和维持着丝粒的机制仍然知之甚少。虽然CENH 3在有丝分裂过程中的作用已经在几种生物中进行了研究，但对其减数分裂功能知之甚少。我们发现，RNAi介导的CENH 3基因敲低在拟南芥中引起侏儒症作为有丝分裂数目减少的结果。剩余的有丝分裂似乎是无差错的。CENH 3 RNAi转化体由于频繁干扰减数分裂染色体分离而具有降低的育性。N-末端截短的EYFP-CENH 3（C）沉积在拟南芥有丝分裂染色体的着丝粒中并在其中起作用，但不能加载到减数分裂核的着丝粒上。因此，N-末端部分显然是在减数分裂期间CENH 3加载所需的。EYFP-CENH 3（C）表达减少内源性CENH 3的量，从而模拟RNAi的作用。内源CENH 3减少和EYFP-CENH 3减数分裂掺入缺乏的结果（C）是由不充分的CENH 3加载到减数分裂染色体的着丝粒、随后染色体的滞后和微核的形成引起的育性降低。
The histone H3 variant (CENH3) of centromeric nucleosomes is essential for kinetochore assembly and thus for chromosome segregation in eukaryotes. The mechanism(s) that determine centromere identity, assembly and maintenance of kinetochores are still poorly understood. Although the role of CENH3 during mitosis has been studied in several organisms, little is known about its meiotic function. We show that RNAi-mediated CENH3 knockdown in Arabidopsis thaliana caused dwarfism as the result of a reduced number of mitotic divisions. The remaining mitotic divisions appeared to be error-free. CENH3 RNAi transformants had reduced fertility because of frequently disturbed meiotic chromosome segregation. N-terminally truncated EYFP-CENH3(C) is deposited to and functional within Arabidopsis centromeres of mitotic chromosomes, but cannot be loaded onto centromeres of meiotic nuclei. Thus the N-terminal part is apparently required for CENH3 loading during meiosis. EYFP-CENH3(C) expression reduces the amount of endogenous CENH3, thus mimicking the effect of RNAi. The consequences of reduced endogenous CENH3 and lack of meiotic incorporation of EYFP-CENH3(C) are reduced fertility caused by insufficient CENH3 loading to the centromeres of meiotic chromosomes, subsequent lagging of chromosomes and formation of micronuclei.