Depinet T W, Zackowski J L, Earnshaw W C, Kaffe S, Sekhon G S, Stallard R, Sullivan B A, Vance G H, Van Dyke D L, Willard H F, Zinn A B, Schwartz S
Department of Genetics and Center for Human Genetics, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, OH 44106-9959, USA.
Hum Mol Genet. 1997 Aug;6(8):1195-204. doi: 10.1093/hmg/6.8.1195.
Recent studies have implicated alpha-satellite DNA as an integral part of the centromere, important for the normal segregation of human chromosomes. To explore the relationship between the normal functioning centromere and alpha-satellite DNA, we have studied eight accessory marker chromosomes in which fluorescence in-situ hybridization could detect neither pancentromeric nor chromosome-specific alpha-satellite DNA. These accessory marker chromosomes were present in the majority of or all cells analyzed and appeared mitotically stable, thereby indicating the presence of a functional centromere. FISH analysis with both chromosome-specific libraries and single-copy YACs, together with microsatellite DNA studies, allowed unequivocal identification of both the origin and structure of these chromosomes. All but one of the marker chromosomes were linear mirror image duplications, and they were present along with either two additional normal chromosomes or with one normal and one deleted chromosome. Indirect immunofluorescence analysis revealed that the centromere protein CENP-B was not present on these markers; however, both CENP-C and CENP-E were present at a position defining a 'neo-centromere'. These studies provide insight into a newly defined class of marker chromosomes that lack detectable alpha-satellite DNA. At least for such marker chromosomes, alpha-satellite DNA at levels detectable by FISH appears unnecessary for chromosome segregation or for the association of CENP-C and CENP-E at a functional centromere.
最近的研究表明，α-卫星DNA是着丝粒的一个组成部分，对人类染色体的正常分离很重要。为了探究正常功能的着丝粒与α-卫星DNA之间的关系，我们研究了八条副标记染色体，在这些染色体中，荧光原位杂交既检测不到全着丝粒α-卫星DNA，也检测不到染色体特异性α-卫星DNA。这些副标记染色体存在于大多数或所有分析的细胞中，并且在有丝分裂过程中表现稳定，从而表明存在功能性着丝粒。使用染色体特异性文库和单拷贝酵母人工染色体（YAC）进行的荧光原位杂交分析，以及微卫星DNA研究，使得能够明确鉴定这些染色体的起源和结构。除了一条标记染色体外，其他所有标记染色体都是线性镜像重复，它们与另外两条正常染色体或一条正常染色体和一条缺失染色体一起出现。间接免疫荧光分析显示，着丝粒蛋白CENP-B在这些标记上不存在；然而，CENP-C和CENP-E都存在于定义“新着丝粒”的位置。这些研究为一类新定义的缺乏可检测α-卫星DNA的标记染色体提供了见解。至少对于此类标记染色体而言，荧光原位杂交可检测水平的α-卫星DNA对于染色体分离或功能性着丝粒处CENP-C和CENP-E的结合似乎并非必要。
