TRF2媒介の染色体末端保護のための2段階メカニズム
Keiji Okamoto1, Cristina Bartocci, Iliana Ouzounov
1Laboratory of Chromosome Biology and Genomic Stability, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
Nature
|February 8, 2013
まとめ
テロメアタンパク質TRF2 (TERF2) は,染色体の末端を保護するために2段階のメカニズムを使用しています. まずATMの活性化を阻害し,その後下流のDNA損傷シグナリングを抑制し,融合を防ぐ.
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
- 細胞生物学 細胞生物学
背景:
- 哺乳類のテロメアは染色体の末端にあり,シェルテリン複合体によって保護されています.
- TRF2 (TERF2) はシェルテリンの内部で,ATMの活性化を阻害し,染色体のエンドツーエンドの融合を防止して,末端の保護に不可欠です.
研究 の 目的:
- マウス細胞における染色体末端の保護に不可欠なTRF2の分子特性を特定する.
- TRF2媒介のテロメア末端保護のメカニズムを解明する.
主な方法:
- マウスの胚性線維芽細胞でTRF2の分子特性を研究した.
- ATMの活性化とDNAダメージ応答 (DDR) 信号伝達の下流を阻害するTRF2の役割を分析した.
- TRF2媒介末端保護におけるRNF168,BRCC3,UBR5の関与を調査した.
主要な成果:
- TRF2の二分化ドメインは,DDRの初期段階であるATMの活性化を阻害するために必要である.
- TRF2は独立して,E3ユビキチンリガゼRNF168.8.を調節することによって,ダウンストリームDDRシグナリングを抑制します.
- BRCC3とUBR5によるRNF168の抑制は,染色体の端から端への融合を防ぐのに十分である.
結論:
- TRF2は,テロメア末端の保護のために2段階のメカニズムを使用しています.
- このメカニズムは,DDRタンパク質が,損傷を起こす修復を開始することなく,テロメアにどのように存在できるかを説明します.
- TRF2の機能には,ATMの初期活性化と下流信号伝達の抑制のための明確なステップが含まれています.
関連する概念動画
Telomeres and Telomerase
In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded DNA.
DNA Damage can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
Replication in Eukaryotes
In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before cell division, so there are many proteins that fulfill specialized roles in the replication process. Replication occurs in three phases: initiation, elongation, and termination, and ends with two complete sets of chromosomes in the nucleus.
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...
DNA Damage Can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...


