The RecQ helicase AtRECQ4A is required to remove inter-chromosomal telomeric connections that arise during meiotic recombination in Arabidopsis
The RecQ helicase AtRECQ4A is required to remove inter-chromosomal telomeric connections that arise during meiotic recombination in Arabidopsis
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DOI：
10.1111/j.1365-313x.2010.04438.x
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发表时间：
2011-02-01
期刊：
影响因子：
7.2
通讯作者：
Franklin, F. Christopher H.
中科院分区：
文献类型：
--
作者：
Higgins, James D.;Ferdous, Maheen;Franklin, F. Christopher H.
RecQ解旋酶是一组保守的蛋白质，在维持基因组完整性中发挥作用。在酿酒酵母（芽殖酵母）中，在不存在RecQ解旋酶Sgs1的情况下，减数分裂重组增加。在这里，我们研究了潜在的减数分裂的作用，Sgs1同源AtRECQ4A和密切相关的AtRECQ4B。这两种蛋白质已被证明在体细胞重组过程中发挥作用，但到目前为止，它们在减数分裂中的作用尚未研究。AtRECQ4A和AtRECQ4B均在生殖组织中表达。虽然免疫定位研究表明，AtRECQ4A与重组中间体，我们发现没有证据表明，其损失或AtRECQ4B有一个显着的影响减数分裂交换，这表明与其他RECQ家族成员的功能冗余。然而，花粉生活力下降Atrecq4A，导致在降低生育力，虽然这是不是在Atrecq4B的情况。细胞学分析显示，在中期I，Atrecq4A中非同源染色体的端粒之间存在染色质桥，在某些情况下，在后期I伴有染色体断裂。桥需要端粒重复序列，并依赖于减数分裂重组。免疫定位证实了协会AtRECQ4A与端粒在前期I，我们建议使重组依赖性端粒协会的解散。因此，这项研究已经确定了一个迄今为止未知的作用RECQ解旋酶家族的成员在减数分裂过程中，有助于维持染色体的完整性。由于端粒结构通常是保守的，这些关联似乎可能出现在其他物种的减数分裂过程中，在那里它们也必须被去除。
P>RecQ helicases are a conserved group of proteins with a role in the maintenance of genome integrity. In Saccharomyces cerevisiae (budding yeast), meiotic recombination is increased in the absence of the RecQ helicase Sgs1. Here we investigated the potential meiotic role of the Sgs1 homologue AtRECQ4A and the closely related AtRECQ4B. Both proteins have been shown to function during recombination in somatic cells, but so far their meiotic role has not been investigated. Both AtRECQ4A and AtRECQ4B were expressed in reproductive tissues. Although immunolocalization studies showed that AtRECQ4A associates with recombination intermediates, we found no evidence that its loss or that of AtRECQ4B had a significant effect on meiotic cross-overs, suggesting functional redundancy with other RECQ family members. Nevertheless, pollen viability decreased in Atrecq4A, resulting in a reduction in fertility, although this was not the case in Atrecq4B. Cytological analysis revealed chromatin bridges between the telomeres of non-homologous chromosomes in Atrecq4A at metaphase I, in some instances accompanied by chromosome fragmentation at anaphase I. The bridges required telomeric repeats and were dependent on meiotic recombination. Immunolocalization confirmed the association of AtRECQ4A with the telomeres during prophase I, which we propose enables dissolution of recombination-dependent telomeric associations. Thus, this study has identified a hitherto unknown role for a member of the RECQ helicase family during meiosis that contributes to the maintenance of chromosome integrity. As telomere structure is generally conserved, it seems likely that these associations may arise during meiosis in other species, where they must also be removed.