CLP1 acts as the main RNA kinase in mice

Hiroyuki Fujinami; Hiroshi Shiraishi; Kazumasa Hada; Masanori Inoue; Ikuko Morisaki; Ryoko Higa; Toshitaka Shin; Takashi Kobayashi; Reiko Hanada; Josef M Penninger; Hiromitsu Mimata; Toshikatsu Hanada

doi:10.1016/j.bbrc.2020.02.066

CLP1 acts as the main RNA kinase in mice

Biochem Biophys Res Commun. 2020 Feb 17:S0006-291X(20)30334-X. doi: 10.1016/j.bbrc.2020.02.066. Online ahead of print.

Authors

Affiliations

¹ Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan; Department of Urology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
² Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
³ Department of Infectious Disease Control, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
⁴ Department of Urology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
⁵ Department of Neurophysiology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan.
⁶ IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria; Department of Medical Genetics, Life Science Institute, University of British Columbia, Vancouver, Canada.
⁷ Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, 879-5593, Japan. Electronic address: thanada@oita-u.ac.jp.

PMID: 32081435
DOI: 10.1016/j.bbrc.2020.02.066

Abstract

CLP1 plays an essential role in the protein complex involved in mRNA 3'-end formation and polyadenylation as well as in the tRNA splicing endonuclease (TSEN) complex involved in the splicing of precursor tRNAs. NOL9 localizes in the nucleolus of cells and plays an essential role in ribosomal RNA maturation. Both CLP1 and NOL9 are RNA kinases that phosphorylate the 5' end of RNAs. From the evidence that phosphorylation of the 5' end of a siRNA is essential for its efficient RNA cleavage, it was expected that CLP1 and NOL9 would be corresponding molecules. However, there had been no direct evidence that this is the case. In this study, murine NOL9 showed no apparent RNA kinase activity in cells or even in an RNA kinase assay using recombinant murine NOL9 protein. Although siRNA efficiency was decreased in CLP1 kinase-dead (Clp1^K/K) cells, it was not influenced by NOL9 overexpression. These findings indicate that in mouse cells it is CLP1 that mainly acts to phosphorylate the 5' end of RNAs in the siRNA pathway, with no apparent involvement of NOL9.

Keywords: CLP1; NOL9; RNA kinase; siRNA.