SHRECは,ヘテロクロマティック・トランスクリプション・サイレンシングのためのエフェクター・コンプレックスです
Tomoyasu Sugiyama1, Hugh P Cam, Rie Sugiyama
1Laboratory of Molecular Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Cell
|February 10, 2007
まとめ
新しいタンパク質複合体SHRECは,分裂酵母ヘテロクロマチンの転写遺伝子静止を媒介する. この複合体は,ニュクレオソームの位置を調節し,遺伝子サイレンシングに不可欠な高級染色体構造を確立します.
科学分野:
- エピジェネティクス エピジェネティクス
- 分子生物学は分子生物学である.
- クロマチンの生物学
背景:
- ヘテロクロマチンは伝統的に転写遺伝子サイレンシング (TGS) と関連付けられています.
- 分裂酵母における最近の発見は,ヘテロクロマチンにおけるRNAi媒介の転写後の遺伝子静止 (PTGS) の役割を示唆し,TGSの優位性に異議を唱える.
- ヘテロクロマティックTGSの基礎となる正確な分子機構は,まだ完全に理解されていません.
研究 の 目的:
- 分裂酵母におけるヘテロクロマティック転写遺伝子サイレンシングを担う分子機構を特定し,特徴づけること.
- ヘテロクロマチンにおけるTGSを媒介するエフェクター複合体の構成と機能を明らかにする.
- クロマチン組織におけるこの複合体の募集メカニズムと規制作用を調査する.
主な方法:
- 分裂酵母からのタンパク質複合体の生化学的浄化と特徴付け.
- 遺伝子サイレンシングにおける特定されたタンパク質の機能を評価するための遺伝子分析.
- 複合分布を決定するクロマチンの免疫プレシピテーションと局所化研究.
- 核粒子の位置測量と,より高次元の染色体構造の分析.
主要な成果:
- SHREC (サイレンシング・ハブ・アンド・レギュレータリー・コンプレックス) を,ヘテロクロマティックTGSを媒介する多酵素エフェクター複合体として識別.
- SHRECは,ヘテロクロマチン領域に分布した4つのコア (Clr1,Clr2,Clr3,Mit1) を含む.
- SHRECは,TGSを確立するためにヒストン脱エチラゼ (Clr3) とクロマチンリモデレータ (Mit1) の活動を活用し,より高いレベルのクロマチンの組み立てのための核細胞の位置づけを調節します.
- SHRECは,Ccq1/Taz1およびRNAi機構を通じてテロメアに,Swi6/HP1依存メカニズムを通じてユークロマティックサイトに誘導されます.
結論:
- SHRECは,分裂酵母ヘテロクロマチンの転写遺伝子静止のための重要なエフェクター複合体です.
- ニュクレオソームの位置調節を含む複合体の活動は,機能的なヘテロクロマチンの確立に不可欠です.
- SHRECは,異なるゲノム領域におけるその局所化と機能を確保するために,異なる採用経路を統合しています.
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関連する概念動画
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...
02:36RNA Polymerase II Accessory Proteins
Proteins that regulate transcription can do so either via direct contact with RNA Polymerase or through indirect interactions facilitated by adaptors, mediators, histone-modifying proteins, and nucleosome remodelers. Direct interactions to activate transcription is seen in bacteria as well as in some eukaryotic genes. In these cases, upstream activation sequences are adjacent to the promoters, and the activator proteins interact directly with the transcriptional machinery. For example, in...
02:04Co-activators and Co-repressors
Gene transcription is regulated by the synergistic action of several proteins that form a complex at a gene regulatory site. This is observed in eukaryotes, where the regulation of gene expression is a complex process. Regulatory proteins in eukaryotes can broadly be classified into two types – regulators that bind directly to specific DNA sequences and co-regulators that associate with regulatory proteins but cannot directly bind to the DNA. These co-regulators are further divided into...
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...
02:04Co-activators and Co-repressors
Gene transcription is regulated by the synergistic action of several proteins that form a complex at a gene regulatory site. This is observed in eukaryotes, where the regulation of gene expression is a complex process. Regulatory proteins in eukaryotes can broadly be classified into two types – regulators that bind directly to specific DNA sequences and co-regulators that associate with regulatory proteins but cannot directly bind to the DNA. These co-regulators are further divided into...
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...