过渡的同源染色体配对标志着X无活化开始
Na Xu1, Chia-Lun Tsai, Jeannie T Lee
1Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School Boston, MA 02114, USA.
Science (New York, N.Y.)
|January 21, 2006
概括
哺乳动物X无活化涉及X-X染色体配对,由Xite和Tix介导. 这种配对确保了相互排斥的沉默,用于女性的剂量补偿.
科学领域:
- 遗传学 是一个遗传学.
- 表观遗传学 在表观遗传学中,表观遗传学是指表观遗传学.
- 分子生物学分子生物学
背景情况:
- 哺乳动物X无活化使XX雌性和XY雄性之间的X染色体基因剂量相等.
- 通过Xite,Tix和Xist在cis中调节X无活化,但相互排斥的沉默的跨作用机制尚不清楚.
研究的目的:
- 研究染色体间通信在调节X无活化选择中的作用.
- 为了确定Xite和Tsix是否在转换中起作用,以确保相互排斥的X染色体沉默.
主要方法:
- 使用染色体构造捕获技术分析X-X和X-自体相互作用.
- 对Xite和Tix loci进行基因操纵,以评估它们对配对和无活化的影响.
- 观察了外宫X-自体组对对内生X-X对和无活化启动的作用.
主要成果:
- X染色体之间的染色体间配对在X无活化开始时暂时发生,特别是在X无活化中心.
- 删除Xite和Tsix会破坏X-X配对和计数/选择过程.
- 自体插入Xite和Tsix诱导X-自体组对,抑制内源X-X对并阻止X无活化.
结论:
- 染色体间配对是X染色体在不活化过程中之间沟通的关键机制.
- 克西特和Tsix在cis和trans中运行,以调节X-X配对,计数和相互排斥的选择.
- Tsix和Xite可能通过X-X配对相互作用来控制X无活化的启动.
相关概念视频
01:34Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
01:58X-Inactivation
The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.
03:17Inheritance of Chromatin Structures
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
01:58X-inactivation
The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
01:30Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...