MicroRNA Inhibition of Translation Initiation in Vitro by Targeting the Cap-Binding Complex eIF4F

• Published in: Science (American Association for the Advancement of Science) Vol. 317; no. 5845; pp. 1764 - 1767
• Main Authors: Mathonnet, Géraldine, Fabian, Marc R, Svitkin, Yuri V, Parsyan, Armen, Huck, Laurent, Murata, Takayuki, Biffo, Stefano, Merrick, William C, Darzynkiewicz, Edward, Pillai, Ramesh S, Filipowicz, Witold, Duchaine, Thomas F, Sonenberg, Nahum
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 21.09.2007; The American Association for the Advancement of Science
• Subjects: Animals; Ascites; Binding sites; Biochemistry; Biological and medical sciences; Carcinoma, Krebs 2; Cell Extracts; Encephalomyocarditis virus - genetics; Eukaryotic Initiation Factor-4F - physiology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - physiology; Genetics; Inhibitor drugs; Luciferases, Renilla - genetics; Messenger RNA; Mice; MicroRNA; MicroRNAs - physiology; Molecular and cellular biology; Molecular biology; Molecular genetics; Nucleotides; Oligonucleotides; Protein Biosynthesis - physiology; Repression; Research universities; Ribonucleic acid; Ribosomes; Ribosomes - metabolism; RNA; RNA Caps - physiology; RNA stability; Rodents; Translation. Translation factors. Protein processing; In vitro translation; RNA interference; Inhibition; Translation initiation; Initiation factor eIF4F; Micro RNA
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1146067

MicroRNAs (miRNAs) play an important role in gene regulatory networks in animals. Yet, the mechanistic details of their function in translation inhibition or messenger RNA (mRNA) destabilization remain controversial. To directly examine the earliest events in this process, we have developed an in vitro translation system using mouse Krebs-2 ascites cell-free extract that exhibits an authentic miRNA response. We show here that translation initiation, specifically the 5' cap recognition process, is repressed by endogenous let-7 miRNAs within the first 15 minutes of mRNA exposure to the extract when no destabilization of the transcript is observed. Our results indicate that inhibition of translation initiation is the earliest molecular event effected by miRNAs. Other mechanisms, such as mRNA degradation, may subsequently consolidate mRNA silencing.