Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-1 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
Mol Cell. 2014 Jul 17;55(2):186-98. doi: 10.1016/j.molcel.2014.05.022. Epub 2014 Jun 19.
It has been proposed that Ataxin-2, a member of the like-Sm (LSm) protein family, participates in the regulation of RNA metabolism through interaction with PABPC1. However, the exact biological mechanism and in vivo targets remain unknown. Here, we report that Ataxin-2 binds directly to RNAs in a PABPC1-independent manner. High-throughput sequencing of Ataxin-2-bound RNAs prepared by PAR-CLIP revealed that Ataxin-2 binds predominantly to uridine-rich elements, including well-characterized cis-regulatory AU-rich elements, in the 3' UTRs of target mRNAs. Gene expression analysis after Ataxin-2 depletion or overexpression revealed that Ataxin-2 stabilizes target mRNAs and increases the abundance of the corresponding proteins. A tethering assay demonstrated that Ataxin-2 elicits this effect by direct interaction with mRNAs. We also found that disease-associated polyglutamine expansion downregulates the physiological activity of Ataxin-2. These findings suggest that Ataxin-2 is an RNA-binding protein that targets cis-regulatory elements in 3' UTRs to stabilize a subset of mRNAs and increase protein expression.
现已提出，一种属于 LSm 蛋白家族的 Ataxin-2 通过与 PABPC1 的相互作用参与 RNA 代谢的调节。然而，确切的生物学机制和体内靶标仍然未知。在这里，我们报告 Ataxin-2 以不依赖于 PABPC1 的方式直接与 RNA 结合。通过 PAR-CLIP 制备的 Ataxin-2 结合 RNA 的高通量测序表明，Ataxin-2 主要与富含尿嘧啶的元件结合，包括靶 mRNA 3'UTR 中已充分表征的顺式调控 AU 富含元件。Ataxin-2 耗尽或过表达后的基因表达分析表明，Ataxin-2 稳定靶 mRNA 并增加相应蛋白的丰度。系绳测定表明，Ataxin-2 通过与 mRNA 的直接相互作用产生这种效应。我们还发现，与疾病相关的多聚谷氨酰胺扩展会下调 Ataxin-2 的生理活性。这些发现表明，Ataxin-2 是一种 RNA 结合蛋白，可靶向 3'UTR 中的顺式调控元件，以稳定一组特定的 mRNA 并增加蛋白表达。
