Fukunaga Ryuya
Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, 521A Physiology Building, Baltimore, MD, 21205, USA.
Biochem Biophys Res Commun. 2018 Apr 15;498(4):1022-1027. doi: 10.1016/j.bbrc.2018.03.108. Epub 2018 Mar 16.
Drosophila Dicer-2 processes RNA substrates into short interfering RNAs (siRNAs). Loquacious-PD (Loqs-PD), a dsRNA-binding protein that associates with Dicer-2, is required for processing of a subset of RNA substrates including hairpin RNAs into siRNAs. Inorganic phosphate-a small molecule present in all cell types-inhibits Dicer-2 from processing precursor of microRNAs (pre-miRNAs), which are processed by Dicer-1. Whether or how Loqs-PD modulates the inhibitory effect of inorganic phosphate on Dicer-2 processing of RNA substrates is unknown. To address this question, I performed in vitro hairpin RNA processing assay with Dicer-2 in the presence or absence of Loqs-PD and/or inorganic phosphate. I found that inorganic phosphate inhibits Dicer-2 alone, but not Dicer-2 + Loqs-PD, from processing blunt-end hairpin RNAs into siRNAs. Thus, Loqs-PD removes the inhibitory effect of inorganic phosphate on Dicer-2 processing of blunt-end hairpin RNAs, allowing siRNA production in the presence of inorganic phosphate.
果蝇Dicer-2将RNA底物加工成小干扰RNA（siRNA）。Loquacious-PD（Loqs-PD）是一种与Dicer-2相关的双链RNA结合蛋白，它是将包括发夹RNA在内的一部分RNA底物加工成siRNA所必需的。无机磷酸盐——一种存在于所有细胞类型中的小分子——会抑制Dicer-2对微小RNA前体（pre-miRNA）的加工，而pre-miRNA是由Dicer-1加工的。Loqs-PD是否以及如何调节无机磷酸盐对Dicer-2加工RNA底物的抑制作用尚不清楚。为了解决这个问题，我在有或没有Loqs-PD和/或无机磷酸盐的情况下，用Dicer-2进行了体外发夹RNA加工试验。我发现无机磷酸盐单独抑制Dicer-2将平端发夹RNA加工成siRNA，但不抑制Dicer-2 + Loqs-PD。因此，Loqs-PD消除了无机磷酸盐对Dicer-2加工平端发夹RNA的抑制作用，使得在有无机磷酸盐的情况下能够产生siRNA。
