The Role of CENP-V in Mammalian Meiosis

在体细胞中，W. Earnshaw表明，动粒蛋白CENP-V参与染色体压实、染色体乘客复合物（CPC）的定位和稳定性、粘着蛋白保护剂SGO 1在着丝粒处的稳定缔合、着丝粒粘着、中期板对齐和适当的染色体分离。然而，CENP-V很少被描述：只有两个关于这种蛋白质的报道，并且没有关于CENP-V在减数分裂中的报道，尽管上面列出的染色体特性对于减数分裂至关重要。我们观察到CENP-V在小鼠精母细胞和卵母细胞中的表达及其在染色体上的特异性定位，并在着丝粒和臂间异染色质中富集。染色体联会和CENP-V的存在相关，CENP-V在未联会的X/Y染色质中基本上不存在，并且它持续存在于去联会双线期染色体上。这表明CENP-V与突触相关。最近，我们获得了一种小鼠品系，其特征是精母细胞特异性缺乏CENP-V，这导致了一种剧烈的表型：染色体轴，联会复合体（SC）的消失。在CENP-V低的细胞中，轴缩短，出现碎片或未突触。基于我们强有力的支持性初步数据，我们的假设是CENP-V在哺乳动物减数分裂过程中起一个或几个重要作用。我们进一步假设，涉及CENP-V的过程在精母细胞和卵母细胞之间部分不同。后者是基于我们的观察，在精母细胞CENP-V是专门排除在X/Y染色质。初步分析表明，CENP-V是必不可少的突触相关的染色体轴的维护。我们将分析这一作用。是否CENP-V是需要适当的粘连蛋白协会的染色体，适当的着丝粒的凝聚力和分离，CPC的招聘，进一步的问题要解决考虑之间的关系，在体细胞中的粘连蛋白，着丝粒，CPC和CENP-V。确定CENP-V在精母细胞和卵母细胞染色体上的特异性定位，以及在减数分裂过程中与诊断蛋白的共定位;确定精母细胞中CENP-V的蛋白质相互作用伴侣; 3.研究CENP-V在小鼠卵母细胞和精母细胞中的体内功能，包括与粘附素的关系。有了这个程序，我们希望解开完全未知的，但显然在哺乳动物减数分裂的CENP-V的核心作用。

In somatic cells the group of W. Earnshaw showed that kinetochore protein CENP-V is involved in chromosome compaction, localization and stability of the chromosomal passenger complex (CPC), stable association of the cohesin protector SGO1 at centromeres, centromeric cohesion, metaphase plate alignment and proper chromosome segregation. However, CENP-V is very little described: there are only two reports on this protein, and nothing has been reported on CENP-V in meiosis, despite the central importance of the above listed chromosome properties for meiosis. We observed expression of CENP-V in mouse spermatocytes and oocytes and its specific chromosomal localization with enrichment at the pericentric heterochromatin and centromeres. Chromosome synapsis and presence of CENP-V correlate, CENP-V is largely absent from the unsynapsed X/Y chromatin, and it persists on desynapsing diplotene chromosomes. This suggest an association of CENP-V with synapsis. Most recently we obtained a mouse strain featuring spermatocyte-specific deficiency in CENP-V, which causes a drastic phenotype: the disappearance of the chromosome axes, the synaptonemal complexes (SCs). In cells with low CENP-V, the axes are shortened and appear either fragmented or unsynapsed. Based on our strongly supportive preliminary data, our hypothesis is that CENP-V plays one or several important roles during mammalian meiosis. We further hypothesize that the processes involving CENP-V partially differ between spermatocytes and oocytes. The latter is based on our observations that in spermatocytes CENP-V is specifically excluded from the X/Y chromatin. The initial analysis suggests that CENP-V is essential for synapsis-associated maintenance of chromosomal axes. This role will be analyzed. Whether CENP-V is required for proper cohesin association to chromosomes, proper centromere cohesion and segregation, CPC recruitment, are further questions to be addressed considering the relationship in somatic cells between cohesin, centromeres, CPC and CENP-V. Our specific aims are: 1. To determine the specific localization of CENP-V on spermatocyte and oocyte chromosomes and co-localization with diagnostic proteins throughout meiosis; 2. To define protein interaction partners of CENP-V in spermatocytes; 3. To decipher the function(s) in vivo of CENP-V, including the relationship to cohesin, in mouse oocytes and spermatocytes. With this program we expect to unravel the entirely unknown, yet apparently central role of CENP-V in mammalian meiosis.