FBS Colloquia No.364RNA Biofunction Laboratory
| Seminar or Lecture |
Identification of RNA Helicases Involved in the Maturation of Spliceosomal U snRNA Ichiro Taniguchi [Specially Appointed Assistant Professor, RNA Biofunction Laboratory] Temperature-dependent phosphorylation of CLK1 regulates the functional switching of nuclear stress bodies Tsuyoshi Ueno [Graduate Student (D4/D5), RNA Biofunction Laboratory] |
|---|---|
| Date and Time | 10 Sep. 2024 (Tue), 12:15～13:00 |
| Place | 2F Seminar Room, BioSystems Building |
| Language | Japanese |
| Contact |
Tomohiro Yamazaki (Specially Appointed Associate Professor) |
Identification of RNA Helicases Involved in the Maturation of Spliceosomal U snRNA
RNA helicases are involved in RNA biogenesis in an ATP-dependent manner. Although many RNA helicases unwind RNA structures and/or remove proteins from RNA, some can load their interacting proteins onto RNA. Here, we developed an in vitro strategy to identify ATP-dependent factors involved in the export of spliceosomal uridine-rich small nuclear RNA (U snRNA). We identified UAP56/DDX39B, a component of the mRNA export complex known as the transcription-export (TREX) complex, as the factor that stimulates the RNA binding of PHAX, an adapter protein for U snRNA export. ALYREF, another TREX component, acted as a bridge between PHAX and UAP56/DDX39B. We also showed that UAP56/DDX39B and ALYREF participate in U snRNA export through a mechanism distinct from that of mRNA export. This study describes a novel aspect of the TREX components in U snRNP biogenesis and highlights the loading activity of RNA helicases.
Temperature-dependent phosphorylation of CLK1 regulates the functional switching of nuclear stress bodies
Nuclear stress bodies (nSBs) are membraneless organelles formed upon thermal stress in primate cells. nSBs are built on HSATIII long non-cording RNAs with >100 kinds of RNA binding proteins such as SR-rich splicing factors (SRSFs) and their modifier proteins such as CLK1 SRSF kinase. Our recent reports revealed that nSBs regulate splicing of >400 pre-mRNAs during thermal stress recovery. As one of the underlying mechanisms, nSBs sequestrates SRSFs that were dephosphorylated during thermal stress. Once the temperature returns to normal, CLK1 specifically localizes to nSBs and rapidly rephosphorylates SRSFs concentrated within nSBs. Therefore, nSBs function as “the reaction crucible” for SRSF phosphorylation under the restricted temperature condition, and the temperature-dependent localization of CLK1 is a pivotal step of the crucible function. Therefore, we aimed to elucidate the molecular mechanism of the temperature-dependent CLK1 localization to nSBs, and we found that the temperature-dependent shift of CLK1 phosphorylation states is essential for its proper localization to nSBs and the crucible function of nSBs.
