Drosophila rhino encodes a female-specific chromo-domain protein that affects chromosome structure and egg polarity.
Drosophila rhino encodes a female-specific chromo-domain protein that affects chromosome structure and egg polarity.
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发表时间：
2001-11
期刊：
影响因子：
3.3
通讯作者：
Alison M. Volpe;H. Horowitz;C. Grafer;Stephen M. Jackson;C. Berg
中科院分区：
文献类型：
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作者：
Alison M. Volpe;H. Horowitz;C. Grafer;Stephen M. Jackson;C. Berg
在这里，我们描述了我们对Rhino的分析，Rhino是一种异染色质蛋白1（HP1）亚家族的新成员。Rhino （rhi）仅在雌性中表达，主要在种系中表达，从而提供了一个新的工具来解剖色域蛋白在发育中的作用。rhi突变破坏蛋壳和胚胎模式，并在多倍体染色体的特定阶段重组中阻止护士细胞核，这是一种称为“五团”的有丝分裂状态。这些可见的染色体结构改变不会通过改变关键模式基因的转录来影响极性。gurken （grk）、oskar （osk）、bicoid （bcd）和decapentapletic （dpp）转录本的表达水平正常，bcd和dpp mrna的出现略有延迟。然而，grk和osk转录本的错误定位表明，在卵发生的中期，微管重组存在缺陷，并决定了轴向极性。这种缺陷可能是由于早期阶段的异常Grk/Egfr信号，因为rhi突变延迟了日耳曼和早期卵室中Grk蛋白的合成。此外，Grk蛋白在6-10期卵室内质网附近的大的肌动蛋白笼泡中积累。我们提出两个假设来解释这些结果。首先，Rhi可能在卵子发生中发挥双重作用，在独特的内复制周期5结束时独立调节哺乳细胞的染色体压实，并抑制抑制Grk合成的基因的转录。因此，功能丧失突变在5 blob阶段阻止了护理细胞染色体重组，延迟了Grk蛋白的产生或加工，导致轴向图型缺陷。其次，Rhi可能调节乳母细胞和卵母细胞的染色体压实。功能缺失突变在五团阶段阻断护士细胞核转移，激活卵母细胞中的检查点控制，从而阻止Grk合成和/或抑制细胞骨架功能。这些功能可能涉及Rhi与染色体的直接结合，也可能涉及对控制这些过程的途径的间接影响。
Here we describe our analyses of Rhino, a novel member of the Heterochromatin Protein 1(HP1) subfamily of chromo box proteins. rhino (rhi) is expressed only in females and chiefly in the germline, thus providing a new tool to dissect the role of chromo-domain proteins in development. Mutations in rhi disrupt eggshell and embryonic patterning and arrest nurse cell nuclei during a stage-specific reorganization of their polyploid chromosomes, a mitotic-like state called the "five-blob" stage. These visible alterations in chromosome structure do not affect polarity by altering transcription of key patterning genes. Expression levels of gurken (grk), oskar (osk), bicoid (bcd), and decapentaplegic (dpp) transcripts are normal, with a slight delay in the appearance of bcd and dpp mRNAs. Mislocalization of grk and osk transcripts, however, suggests a defect in the microtubule reorganization that occurs during the middle stages of oogenesis and determines axial polarity. This defect likely results from aberrant Grk/Egfr signaling at earlier stages, since rhi mutations delay synthesis of Grk protein in germaria and early egg chambers. In addition, Grk protein accumulates in large, actin-caged vesicles near the endoplasmic reticulum of stages 6-10 egg chambers. We propose two hypotheses to explain these results. First, Rhi may play dual roles in oogenesis, independently regulating chromosome compaction in nurse cells at the end of the unique endoreplication cycle 5 and repressing transcription of genes that inhibit Grk synthesis. Thus, loss-of-function mutations arrest nurse cell chromosome reorganization at the five-blob stage and delay production or processing of Grk protein, leading to axial patterning defects. Second, Rhi may regulate chromosome compaction in both nurse cells and oocyte. Loss-of-function mutations block nurse cell nuclear transitions at the five-blob stage and activate checkpoint controls in the oocyte that arrest Grk synthesis and/or inhibit cytoskeletal functions. These functions may involve direct binding of Rhi to chromosomes or may involve indirect effects on pathways controlling these processes.