Widespread changes in protein synthesis in duced by microRNAs (Nature, 2008, 455:58-63)

報告日期: 2008/12/23
報告時間: 15:10/16:00
報告學生: Rasmani Hazra
講評老師: 謝達斌


Widespread changes in protein synthesis induced by microRNAs


Matthias Selbach, Björn Schwanhässer, Nadine Thierfelder, Zhuo Fang, Raya Khanin & Nikolaus Rajewsky


Nature 455, 58-63 (2008)


Speaker: Rasmani Hazra

Commentator: Prof. Shieh, Dar-Bin

Date: 23rd December’ 08

Place: Room No. 602

Time: 15:10 – 16:00



MicroRNAs (miRNAs), which are approximately 21-nucleotide-long RNA regulates gene expression either by inhibiting translation or by inducing degradation of target messenger RNAs.  However, it is still unknown how this affects the proteome. The authors used a new proteomic approach by introducing miRNAs into cultured cells and measure their effects on protein level using pSILAC (pulse stable isotope labeling with amino acids in cell culture). This method labels protein with heavy-isotope forms of amino acids during translation. Mass spectrometry is then used to detect the labeled proteins, and to quantify changes in their abundance. The effect of various miRNAs was investigated and observed that individual miRNAs caused the repression of hundreds of proteins. The author also identified specific feature of mRNAs as having a major causative role in protein downregulation by miRNA, a 7–8-nucleotide sequence in the 3′ untranslated region that is complementary to the seed region of the corresponding miRNA. This seed complementary sequence is the only significantly enriched sequence across the repressed proteins, although some proteins without this sequence in their transcripts are also repressed. It shows that individual miRNAs can have an effect on global protein expression, and that protein repression is likely to be mediated by a seed-complementary region in the corresponding mRNA. Finally, the emerging picture is that miRNAs do not have just a small number of mRNA targets - they function at the transcriptional and translational level to subtly modulate the proteome.




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