Loss of cell cycle checkpoint control in Drosophila Rfc4 mutants
Loss of cell cycle checkpoint control in Drosophila Rfc4 mutants
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DOI：
10.1128/mcb.21.15.5156-5168.2001
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发表时间：
2001-08-01
影响因子：
5.3
通讯作者：
Heck, MMS
中科院分区：
文献类型：
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作者：
Krause, SA;Loupart, ML;Heck, MMS
黑腹果蝇Rfc 4（DmRfc 4）基因编码复制因子C（RFC）复合物的亚基4，其两个等位基因导致有丝分裂染色体凝聚和凝聚的显著缺陷。这些突变产生的幼虫表型与DNA复制中的作用一致，但也导致有丝分裂染色体缺陷，表现为过早的染色体浓缩样或早熟的姐妹染色单体分离图。虽然DmRFC 4蛋白定位于所有复制的细胞核，但它在有丝分裂中从染色质分散。因此，有丝分裂缺陷似乎不是RFC 4在染色体结构中的直接作用的结果。我们还表明，在这两个DmRfc4等位基因的有丝分裂缺陷的异常检查点控制响应DNA复制抑制或染色体损伤的结果。在这些突变体中，并非所有的监视功能都受到损害，因为动粒附着检查点是有效的。有趣的是，两个等位基因中较严重的一个经常观察到中期延迟，表明随后的染色体分离可能受到抑制。这是第一次证明RFC亚基4在任何生物体中的检查点控制中发挥作用，我们的研究结果还强调了RFC参与多细胞真核生物检查点控制的保守性。
Two alleles of the Drosophila melanogaster Rfc4 (DmRfc4) gene, which encodes subunit 4 of the replication factor C (RFC) complex, cause striking defects in mitotic chromosome cohesion and condensation. These mutations produce larval phenotypes consistent with a role in DNA replication but also result in mitotic chromosomal defects appearing either as premature chromosome condensation-like or precocious sister chromatid separation figures. Though the DmRFC4 protein localizes to all replicating nuclei, it is dispersed from chromatin in mitosis. Thus the mitotic defects appear not to be the result of a direct role for RFC4 in chromosome structure. We also show that the mitotic defects in these two DmRfc4 alleles are the result of aberrant checkpoint control in response to DNA replication inhibition or damage to chromosomes. Not all surveillance function is compromised in these mutants, as the kinetochore attachment checkpoint is operative. Intriguingly, metaphase delay is frequently observed with the more severe of the two alleles, indicating that subsequent chromosome segregation may be inhibited. This is the first demonstration that subunit 4 of RFC functions in checkpoint control in any organism, and our findings additionally emphasize the conserved nature of RFC's involvement in checkpoint control in multicellular eukaryotes.