ヒストンH2A.ZとDNAメチレーションは,相互に敵対するクロマチンのマークです
Daniel Zilberman1, Devin Coleman-Derr, Tracy Ballinger
1University of California, 211 Koshland Hall, Berkeley, California 94720, USA. daniel.zilberman@nature.berkely.edu
Nature
|September 26, 2008
まとめ
DNAメチル化は,通常,遺伝子の活性を促進するヒストン変種H2A.Zを除外することによって,遺伝子を静止させます. この研究は,クロマチンの構造と遺伝子発現の調節において,DNAメチル化とH2A.Zの間の重要な相互作用を明らかにしています.
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.
- 植物科学 植物科学について
背景:
- ユカリオットクロマチンの組織は,遺伝子調節のためのDNAメチル化とヒストンの改変に依存しています.
- DNAメチル化は通常,転写を沈黙させ,ヒストンの変異種H2A.Zは遺伝子活動を促進する.
- 転写調節におけるDNAメチル化とH2A.Zの相互作用は十分に理解されていません.
研究 の 目的:
- アラビドプシス・タリアナのDNAメチル化とH2A.Z堆積との関係を調査する.
- DNAメチル化とH2A.Zが遺伝子転写とクロマチンの構造に影響を与えるメカニズムを解明する.
主な方法:
- 野生型および変異種アラビドプシス・タリアナのDNAメチル化領域におけるH2A.Z占有量の分析.
- DNAメチルトランスフェラーゼMET1とSwr1複合体のサブユニットPIE1における突然変異がDNAメチル化とH2A.Z堆積に及ぼす影響を調査する.
- エピジェネティック変異と遺伝子発現の全ゲノム分析.
主要な成果:
- アラビドプシス・タライアナのDNAメチル化の領域は,H2A.Zが定量的に不足している.
- H2A.Z排除は,活性的に転写された遺伝子とトランポゾン内のメチル化部位で発生します.
- MET1とPIE1の変異は,DNAメチル化とH2A.Z堆積の相互調節を示し,PIE1の変異は全ゲノムにわたる超メチル化につながる.
結論:
- DNAメチル化は,H2A.Zをクロマチンから積極的に排除することによって,遺伝子サイレンスに寄与する.
- H2A.Zは保護因子として作用し,DNAメチル化を防止し,転写能力を維持します.
- この研究は,DNAメチル化とH2A.Z.との間の敵対的な相互作用を含む新種のエピジェネティック調節メカニズムを発見した.
関連する概念動画
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.
Spreading of Chromatin Modifications
The histone proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are methylation, acetylation, phosphorylation, and ubiquitination of lysine amino acids in the histone H3 tail region. These histone modifications have specific meaning for the cell. Hence, they are called "histone code". The protein complex involved in histone modification is termed as "reader-writer" complex.
Writers
The writer is an enzyme that can...
Writers
The writer is an enzyme that can...
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...
DNA Helicases
DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
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...
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...


