公開ラボセミナー
A trilogy of “Star Wars” in RNAi and new adventure on a fear screen
Qinghua Liu（UT Southwestern Medical Center, 筑波大学WPI-IIIS）
2015年09月25日(金) 17：00-18：00 理学部3号館326号室
The catalytic engine of RNA interference (RNAi) is the RNA-induced silencing complex (RISC), in which single-stranded siRNA guides Argonaute 2 (Ago2) endoRNase to catalyze sequence-specific cleavage of complementary mRNA. In Drosophila melanogaster, assembly of RISC consists of two steps: RISC loading and RISC activation. First, the RISC loading complex (RLC) recruits duplex siRNA to Ago2 to form inactive pre-RISC. Second, Ago2 nicks the passenger strand of duplex siRNA into a 9-nt and 12-nt fragments, which are then degraded by C3PO to convert pre-RISC into active RISC. Previously, we identified Dicer-2(Dcr-2)-R2D2 complex as core RLC components that functions as a gateway for siRNA entry into RISC. We reconstituted a basal level of RISC activity using recombinant Dcr-2-R2D2 and Ago2 proteins, and used this system to identify C3PO as a key RISC activator. Recently, we identified the missing factor of the RLC as TATA-binding protein associated factor 11 (TAF11) by genetic screen. We defined the molecular composition of the RLC and showed that TAF11 tetramer facilitates Dcr-2-R2D2 tetramerization to enhance siRNA binding and RISC loading activities. Furthermore, I will discuss our forward genetic mouse screen to understand the molecular bases of fear and fear/anxiety disorders.
