Meiotic spindle formation in Drosophila females

描述(申请人提供)：在第一次减数分裂中，由交叉连接的同源染色体与纺锤体微管相互作用，并分离到相反的两极。这一过程中的缺陷会导致受精卵中的非整倍体，并对发育造成严重后果，通常会导致发育中的胚胎死亡。在人类中，非整倍体是导致女性自然流产和不孕的主要原因。如果非整倍体真的存活下来，它们会表现为唐氏症、特纳氏症或克莱菲尔特氏综合症等疾病。在包括人类和苍蝇在内的许多生物中，卵母细胞的减数分裂纺锤体缺乏中心粒和两极经典的微管组织中心。由于中心体及其组成蛋白通常组织两极纺锤体，卵母细胞减数分裂中的纺锤体极组织肯定是通过另一种机制发生的。果蝇卵母细胞是阐明无着丝体纺锤体形成机制的良好系统。Subito是果蝇中人类有丝分裂激动素样蛋白2(MKLP2)的同源物，是雌性减数分裂过程中形成双极纺锤体所必需的。Subito是减数分裂中期中心纺锤体发育所必需的，这种结构可能是在没有中心体的情况下形成两极纺锤体的关键。本研究的目的是：1)分析Subito的结构和功能。这将为这种蛋白质的功能和调控提供洞察力。Ii)描述Subito与乘客蛋白或RAN途径之间的相互作用。这将决定哪些蛋白质与Subito相互作用，以及它们在纺锤体组装中的功能是什么。Iii)确定两极纺锤体形成的时间和染色体的取向。这将测试极间微管和动粒微管的相对重要性，并研究成对的同源染色体如何定位在无着丝体纺锤体上。Iv)分析减数分裂纺锤体组装所需的新基因。这将使用一种相对公正的方法来识别无着丝体纺锤体组装所需的新基因。在第一次减数分裂中，通过将成对的同源染色体分离成配子，染色体数量减少了一半。在人类中，减数分裂错误会导致非整倍体，即精子或卵子中染色体数量的异常，是导致自然流产、女性不孕不育以及唐氏症、特纳氏症或克莱菲尔特氏症等疾病的主要原因。这些研究的目的是了解这些错误是如何发生的。

DESCRIPTION (provided by applicant): During the first meiotic division, homologous chromosomes linked by chiasmata interact with the spindle microtubules and segregate to opposite poles. Defects in this process lead to aneuploidy in the fertilized egg and have serious consequences on development, often resulting in death of the developing embryo. In humans, aneuploidy is a leading cause of spontaneous abortions and infertility in women. If aneuploids do survive, they manifest with diseases such as Down's, Turner's or Klinefelter's syndrome. In many organisms, including humans and flies, the oocyte meiotic spindle lacks centrioles and the classical microtubule-organizing center at the poles. Since the centrosomes and their constituent proteins usually organize bipolar spindles, spindle pole organization in oocyte meiosis must occur by another mechanism. Drosophila melanogaster oocytes are an excellent system to elucidate the mechanisms of acentrosomal spindle formation. Subito is the Drosophila homolog of human Mitotic Kinesin Like Protein 2 (MKLP2) and is required for bipolar spindle formation during female meiosis. Subito is required for the development of the central spindle at meiotic metaphase and this structure may be critical for formation of a bipolar spindle in the absence of centrosomes. The goals of this study are: i) analyze the structure and function of Subito. This will provide insights into how this protein functions and is regulated. ii) characterize the interactions between Subito and the Passenger proteins or the Ran pathway. This will determine which proteins interact with Subito and what is their function in spindle assembly. iii) determine the timing of bipolar spindle formation and chromosomes orientation. This will test the relative importance of interpolar and kinetochore microtubules and investigate how pairs of homologous chromosomes orient on the acentrosomal spindle. iv) analyze new genes required for meiotic spindle assembly. This will identify new genes required for acentrosomal spindle assembly using a relatively unbiased approach. During the first meiotic division, the chromosome number is reduced in half by separating pairs of homologous chromosomes into the gametes. In humans, errors in meiosis lead to aneuploidy, an abnormal number of chromosomes in a sperm or egg, and is the leading cause of spontaneous abortions, infertility in women and diseases such as Down's, Turner's or Klinefelter's syndrome. The objective of these studies is to understand how these errors occur.