ヘテロクロマチンの形成における転写とRNAの干渉
Shiv I S Grewal1, Sarah C R Elgin
1Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. grewals@mail.nih.gov
Nature
|May 25, 2007
まとめ
静音化クロマチン (ヘテロクロマチン) の転写は矛盾しているように見えるが,ヘテロクロマチンを維持するRNA干渉経路には不可欠である. このプロセスは,ヘテロクロマチン内の遺伝子を転写し,小さなRNAを生成することを含む.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- エピジェネティクス エピジェネティクス
背景:
- ヘテロクロマチンは一般的に,転写的に無音であると考えられています.
- しかし,低レベルの転写は,数百の遺伝子を含むヘテロクロマティック領域で起こります.
- RNA干渉 (RNAi) メカニズムはヘテロクロマチン維持に関与しています.
研究 の 目的:
- ヘテロクロマチンにおける転写の役割を調査する.
- ヘテロクロマチンサイレンシングとRNAiにおけるトランスクリプションの要件との間の明らかな矛盾を調和させる.
主な方法:
- ヘテロクロマティック領域における遺伝子発現の分析.
- ヘテロクロマチン維持におけるRNA干渉経路の調査.
- ドロソフィラ・メラノガスターのモデルシステムに関する研究.
主要な成果:
- ヘテロクロマティック領域における低レベルの転写が確認された.
- ヘテロクロマチンにとって重要なRNAの干渉メカニズムが転写に依存することを示した.
- 静音化のためにヘテロクロマティック領域そのものの転写が必要となる症例を特定した.
結論:
- 逆説的に,RNAの干渉によるヘテロクロマチンの維持には,転写が必要である.
- ヘテロクロマティック・トランスクリプションから生成された小型のRNAは,ヘテロクロマチンを標的とし維持する役割を果たします.
- これは,ヘテロクロマチンが純粋に静止されているという伝統的な見解に異議を唱えます.
関連する概念動画
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...
01:01Euchromatin
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...
02:41Chromatin Structure Regulates pre-mRNA Processing
In eukaryotic cells, nascent mRNA transcripts need to undergo many post-transcriptional modifications to reach the cell cytoplasm and translate into functional proteins. For a long time, transcription and pre-mRNA processing were considered two independent events that occur sequentially in the cell. However, it has now been well established that transcription and pre-mRNA processing are two simultaneous processes that are precisely regulated inside the cell.
The chromatin structure, especially...
The chromatin structure, especially...
02:05Duplication of Chromatin Structure
The process of chromosome duplication during cell division requires genome-wide disruption and re-assembly of chromatin. The chromatin structure must be accurately inherited, reassembled, and maintained in the daughter cells to ensure lineage propagation.
The basic unit of the chromatin is the nucleosome, consisting of DNA wrapped around octameric histone proteins and short stretches of linker DNA separating individual nucleosomes. The histone proteins within the nucleosome have their...
The basic unit of the chromatin is the nucleosome, consisting of DNA wrapped around octameric histone proteins and short stretches of linker DNA separating individual nucleosomes. The histone proteins within the nucleosome have their...
02:38Heterochromatin
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...
02:38Heterochromatin
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...