Crossovers trigger a remodeling of meiotic chromosome axis composition that is linked to two-step loss of sister chromatid cohesion
Crossovers trigger a remodeling of meiotic chromosome axis composition that is linked to two-step loss of sister chromatid cohesion
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DOI：
10.1101/gad.1694108
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发表时间：
2008-10-15
影响因子：
10.5
通讯作者：
Villeneuve, Anne M.
中科院分区：
文献类型：
--
作者：
Martinez-Perez, Enrique;Schvarzstein, Mara;Villeneuve, Anne M.
减数分裂期间同源染色体的分离取决于交叉产生的连锁（交叉）以及后期 I 选择性释放姐妹染色单体凝聚力的子集。在秀丽隐杆线虫减数分裂期间，每个染色体对形成单个交叉，并且该事件的位置决定哪些染色体区域将在后期 I 经历凝聚力释放。在这里，我们通过揭示大规模的模型来深入了解这种耦合的基础。由交叉引发的染色体轴组成的区域变化。我们表明，在粗线期晚期，轴向元件成分 HTP-1 和 HTP-2 以交叉依赖性方式从稍后将针对后期 I 内聚释放的区域中去除。我们证明了交叉和 HTP-1/2 耗尽区域之间位置和数量的对应性，并提供了 HTP-1/2 耗尽边界标记交叉位点的证据。在 htp-1 突变体中，二价二价体缺乏正常的不对称特征，并且姐妹染色单体的内聚力在减数分裂过程中过早丧失。我们得出的结论是，HTP-1 是将交叉与后期二价分化联系起来的机制的核心，并定义了在减数分裂 II 之前内聚力将受到保护的域。此外，我们还讨论了响应交叉的 HTP-1/2 去除模式与交叉干扰现象之间的相似之处。
Segregation of homologous chromosomes during meiosis depends on linkages ( chiasmata) created by crossovers and on selective release of a subset of sister chromatid cohesion at anaphase I. During Caenorhabditis elegans meiosis, each chromosome pair forms a single crossover, and the position of this event determines which chromosomal regions will undergo cohesion release at anaphase I. Here we provide insight into the basis of this coupling by uncovering a large-scale regional change in chromosome axis composition that is triggered by crossovers. We show that axial element components HTP-1 and HTP-2 are removed during late pachytene, in a crossover-dependent manner, from the regions that will later be targeted for anaphase I cohesion release. We demonstrate correspondence in position and number between chiasmata and HTP-1/2-depleted regions and provide evidence that HTP-1/2 depletion boundaries mark crossover sites. In htp-1 mutants, diakinesis bivalents lack normal asymmetrical features, and sister chromatid cohesion is prematurely lost during the meiotic divisions. We conclude that HTP-1 is central to the mechanism linking crossovers with late-prophase bivalent differentiation and defines the domains where cohesion will be protected until meiosis II. Further, we discuss parallels between the pattern of HTP-1/2 removal in response to crossovers and the phenomenon of crossover interference.