Je-Hyun Yoon1,7,*, Myung Hyun Jo2,7, Elizabeth J.F. White3, Supriyo De1, Markus Hafner4, Beth E. Zucconi3, Kotb Abdelmohsen1, Jennifer L. Martindale1, Xiaoling Yang1, William H. Wood III1, Yu Mi Shin5, Ji-Joon Song5, Thomas Tuschl6, Kevin G. Becker1, Gerald M. Wilson3, Sungchul Hohng2,* and Myriam Gorospe1
1Laboratory of Genetics, National Institute on Aging-Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA;
2Department of Physics and Astronomy, Institute of Applied Physics, National Center for Creative Research Initiatives, Seoul National University, Seoul 151-747, Korea;
3Department of Biochemistry and Molecular Biology, Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA;
4Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases-Intramural Research Program, National Institutes of Health, Bethesda, Maryland 20892, USA;
5Cancer Metastasis Control Center, Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-338, Korea; 6Howard Hughes Medical Institute, Laboratory of RNA Molecular Biology, Rockefeller University, New York, New York 10065, USA
7 These authors contributed equally to this work.
Eukaryotic gene expression is tightly regulated post-transcriptionally by RNA-binding proteins (RBPs) and microRNAs. The RBP AU-rich-binding factor 1 (AUF1) isoform p37 was found to have high affinity for the microRNA let-7b in vitro (Kd = ∼6 nM) in cells. Ribonucleoprotein immunoprecipitation, in vitro association, and single-molecule-binding analyses revealed that AUF1 promoted let-7b loading onto Argonaute 2 (AGO2), the catalytic component of the RNA-induced silencing complex (RISC). In turn, AGO2-let-7 triggered target mRNA decay. Our findings uncover a novel mechanism by which AUF1 binding and transfer of microRNA let-7 to AGO2 facilitates let-7-elicited gene silencing.
Keywords : Argonaute, RISC, hnRNP D, microRNA, ribonucleoprotein complex