在酵母菌中核素依赖基因表达和沉默的染色体景观
J J Wyrick1, F C Holstege, E G Jennings
1Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
Nature
|December 10, 1999
概括
基因组因子有助于基因沉默,特别是在酵母端粒,以Sir-独立的方式. 核缩会对全球基因表达产生影响,对端粒-近端基因产生特定影响.
科学领域:
- 分子生物学分子生物学
- 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.
背景情况:
- 细胞基因组组织成核体,这些核体通常抑制基因表达.
- 酵母中的端粒异色素表现出由静音信息调节器 (SIR) 复合体和Rap1.1介导的基因沉默.
- 核细胞和沉默因子在全球基因调节中的确切作用仍然是研究领域.
研究的目的:
- 研究核细胞和沉默因子对酵母菌全球基因表达的影响.
- 为了确定组织素对端粒沉默的贡献.
- 阐明基因特异性与基因组的一般抑制作用.
主要方法:
- 利用酵母中的高密度阵列来研究基因表达.
- 枯竭的核细胞组组质,特别是组质H4.
- 评估了沉默因子耗尽的影响.
主要成果:
- 降低素H4水平改变了25%的酵母基因的表达 (15%增加,10%减少).
- 端粒邻近基因显示,端粒的去压力高达20千基,超过已知的Sir蛋白结合范围.
- 基因组体枯竭对大多数 (75%) 酵母基因的表达影响很小.
结论:
- 基因组蛋白在端粒沉默中扮演着重要的角色,独立于SIR复合体.
- 核细胞体在已确定的沉默因子结合部位之外的端粒中促进基因抑制.
- 基因调节中的基因素的功能是上下文依赖的,在端粒区域之外表现出基因特异性的作用.
相关概念视频
Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Chromatin Position Affects Gene Expression
Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the nucleus greatly influences access to genetic information. Generally, the nucleus' periphery is considered transcriptionally repressive, while the cell's interior is considered a transcriptionally active area.
Topologically Associated Domains (TADs)
The 3-dimensional positioning of chromatin in the nucleus influences the timing and level of...
Topologically Associated Domains (TADs)
The 3-dimensional positioning of chromatin in the nucleus influences the timing and level of...
Eukaryotic Transcription Inhibitors
Certain biochemical processes, such as embryonic development and cell growth regulation, depend on the repression of specific genes. DNA binding proteins known as eukaryotic transcription inhibitors regulate the repression of gene expression in eukaryotes. The presence of these inhibitors at the required location and time in the cell is triggered by the presence of hormones and additional signals from other cells.
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Heterochromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Epigenetic Regulation
Epigenetic changes alter the physical structure of the DNA without changing the genetic sequence and often regulate whether genes are turned on or off. This regulation ensures that each cell produces only proteins necessary for its function. For example, proteins that promote bone growth are not produced in muscle cells. Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.
X-chromosome...
X-chromosome...


