Characterization of nuclear bodies built on RNA

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06493
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 43010:Molecular biology-related
• Research Institution: Ritsumeikan University
• Principal Investigator: Mannen Taro 立命館大学, 生命科学部, 助教 (50535763)
• Co-Investigator(Kenkyū-buntansha): 八谷 如美 地方独立行政法人東京都立産業技術研究センター, 開発本部開発第二部バイオ応用技術グループ, 主任研究員 (30408075)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 液液相分離 / 核内RNA顆粒 / がん / プロテオミクス

Outline of Final Research Achievements

The mammalian cell nucleus is a highly organized organelle which contains membraneless structures referred to as nuclear bodies (NBs). Some NBs carry specific RNA types that play architectural roles in their formation. Here we show the presence of two types of RNase-sensitive DBC1 nuclear body (DNB) in HCT116 cells and Sam68 nuclear body (SNB) in HeLa cells, which exhibit phase-separated features and are constructed out of RNA polymerase I or II transcripts in a cell type-specific manner. We identified additional protein components present in DNB by immunoprecipitation-mass spectrometry, some of which (DBC1 and HNRNPL) are required for DNB formation. The rescue experiment using the truncated HNRNPL mutants revealed that two RNA-binding domains and intrinsically disordered regions of HNRNPL play significant roles in DNB formation possibly via both RNA-protein and protein-protein interactions. Moreover, the intrinsically disordered regions of HNRNPL promote in vitro droplet formation.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

近年、膜を持たない細胞内構造体が液-液相分離という現象よって形成されていることが明らかになってきた。最近では、この現象がクロマチン形成や転写活性化機構に関与すること、さらには天然変性領域のアミノ酸変異による相分離異常が神経変性疾患と関連していることも明らかになってきている。本研究では、膜を持たない細胞内構造体の中でも、がん細胞でRNAを骨格に形成される2つの核内構造体Sam68 nuclear body (SNB)とDBC1 nuclear body (DNB)の構成因子や骨格となるRNAの同定をおこない、構造体の形成機構を明らかにした。