在无意义介导的mRNA衰变过程中,Upf1酸化触发了转化抑制
Olaf Isken1, Yoon Ki Kim, Nao Hosoda
1Department of Biochemistry and Biophysics, School of Medicine and Dentistry, 601 Elmwood Avenue, Box 712, University of Rochester, Rochester, NY 14642, USA.
Cell
|April 22, 2008
概括
无意中介的mRNA衰变 (NMD) 涉及化Upf1抑制翻译启动因子eIF3. 这阻止了进一步的翻译,标记了转录的退化.
科学领域:
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
- 在RNA生物学,RNA生物学.
背景情况:
- 无意中介的mRNA衰变 (NMD) 是一种监测途径,通过过早停止编码子降解异常的mRNA.
- 在一轮先驱翻译过程中,NMD通常需要在外子结合复合体 (EJC) 上游进行翻译终结.
- 由EJC相关激酶的Upf1酸化是NMD激活的一个关键事件.
研究的目的:
- 阐明在NMD中光-Upf1功能的分子机制.
- 研究-Upf1与翻译启动因子之间的相互作用.
- 了解转化抑制如何与NMD.中的mRNA降解相结合.
主要方法:
- 生物化学测试用于研究蛋白质与蛋白质相互作用.
- 使用哺乳动物细胞提取物进行体外翻译试验.
- 对NMD向和非向转录的mRNA衰变率的分析.
- 调查eIF3和CRPV IRES在NMD中的作用.
主要成果:
- -Upf1与翻译启动因子eIF3.3直接相互作用.
- -Upf1抑制了依赖eIF3.3的80S翻译启动复合物的形成.
- 对于通过CrPV IRES独立于eIF3启动翻译的转录,NMD的效率降低了.
- 这确定了一个关键步骤,即翻译抑制在mRNA降解之前.
结论:
- -Upf1通过抑制eIF3.3来作为翻译启动的抑制剂.
- 这种抑制将先驱翻译复合体转化为翻译抑制的RNP,促进NMD.
- 这些发现揭示了一个保存的机制,将翻译抑制与NMD.中的mRNA衰变联系在一起.
相关概念视频
Chromatin 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...
Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
Nonsense-mediated mRNA Decay
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Nonsense-mediated mRNA Decay
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Regulation of Expression at Multiple Steps
The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the addition of a...
Transcriptional Regulation: Riboswitches
Riboswitches are RNA elements that regulate gene expression by altering their secondary structures in response to specific effector molecules. These elements, located in the leader regions of certain mRNAs, act as transcriptional regulators by toggling between alternative conformations to control downstream gene expression. Riboswitch-mediated regulation is a precise mechanism for modulating biosynthetic pathways, as exemplified by the riboflavin biosynthesis pathway in Bacillus...


