Tatsuke Tsuneyuki, Zhu Li, Li Zhiqing, Mitsunobu Hitoshi, Yoshimura Kaito, Mon Hiroaki, Lee Jae Man, Kusakabe Takahiro
Laboratory of Silkworm Science, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, Fukuoka, Japan.
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America.
PLoS One. 2014 Mar 17;9(3):e92313. doi: 10.1371/journal.pone.0092313. eCollection 2014.
Piwi proteins are part of a superfamily of Argonaute proteins, which are one of the core components of the RNA silencing pathway in many eukaryotes. Piwi proteins are thought to repress the transposon expression both transcriptionally and post-transcriptionally. Recently, Drosophila melanogaster Piwi was recently reported to associate with chromatin and to interact directly with the Heterochromatin Protein 1 (HP1a). However, similar interactions have not been reported in other higher eukaryotes. Here we show that silkworm Piwi proteins interact with HP1s in the nucleus. The silkworm, Bombyx mori, has two Piwi proteins, Ago3 and Siwi, and two typical HP1 proteins, HP1a and HP1b. We found that HP1a plays an important role in the interaction between Ago3/Siwi and HP1b in the ovary-derived BmN4 cell line. We also found that Ago3/Siwi regulates the transcription in an HP1-dependent manner. These results suggest that silkworm Piwi proteins function as a chromatin regulator in collaboration with HP1a and HP1b.
Piwi蛋白是Argonaute蛋白超家族的一部分，而Argonaute蛋白是许多真核生物中RNA沉默途径的核心组成部分之一。Piwi蛋白被认为在转录和转录后水平上抑制转座子的表达。最近，有报道称果蝇Piwi与染色质相关，并直接与异染色质蛋白1（HP1a）相互作用。然而，在其他高等真核生物中尚未报道过类似的相互作用。在此，我们表明家蚕Piwi蛋白在细胞核中与HP1蛋白相互作用。家蚕（Bombyx mori）有两种Piwi蛋白，即Ago3和Siwi，以及两种典型的HP1蛋白，即HP1a和HP1b。我们发现，在源自卵巢的BmN4细胞系中，HP1a在Ago3/Siwi与HP1b的相互作用中起重要作用。我们还发现，Ago3/Siwi以HP1依赖的方式调节转录。这些结果表明，家蚕Piwi蛋白与HP1a和HP1b协同作用，作为一种染色质调节因子发挥功能。
