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首页> 外文期刊>Molecular and Cellular Biology >Loss of Cell Cycle Checkpoint Control in Drosophila Rfc4 Mutants
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Loss of Cell Cycle Checkpoint Control in Drosophila Rfc4 Mutants

机译:果蝇Rfc4突变体中细胞周期检查点控制的丢失。

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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 twoDmRfc4 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.
机译:果蝇果蝇Rfc4 DmRfc4 )基因的两个等位基因编码复制因子C(RFC)复合体的亚基4,在有丝分裂染色体的凝聚和凝缩中引起显着缺陷。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的出现,表现为早熟的染色体凝缩状或早熟的姐妹染色单体分离图。尽管DmRFC4蛋白位于所有复制核中,但它从染色质中分散在有丝分裂中。因此,有丝分裂缺陷似乎不是RFC4在染色体结构中直接作用的结果。我们还表明,这两个 DmRfc4 等位基因中的有丝分裂缺陷是响应DNA复制抑制或染色体损坏而异常检查点控制的结果。由于动线粒体附着检查点可操作,因此并非所有监视功能在这些突变体中都受到损害。有趣的是,经常在两个等位基因中观察到较严重的中期延迟,这表明随后的染色体分离可能受到抑制。这是RFC的第4个亚基在任何生物体中进行检查点控制的第一个证明,我们的发现另外强调了RFC参与多细胞真核生物检查点控制的保守性质。

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