Poly(A)-specific ribonuclease regulates the processing of small-subunit rRNAs in human cells

Hideaki Ishikawa, Harunori Yoshikawa, Keiichi Izumikawa, Yutaka Miura, Masato Taoka, Yuko Nobe, Yoshio Yamauchi, Hiroshi Nakayama, Richard J. Simpson, Toshiaki Isobe, Nobuhiro Takahashi (Lead / Corresponding author)

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    Ribosome biogenesis occurs successively in the nucleolus, nucleoplasm, and cytoplasm. Maturation of the ribosomal small subunit is completed in the cytoplasm by incorporation of a particular class of ribosomal proteins and final cleavage of 18S-E pre-rRNA (18S-E). Here, we show that poly(A)-specific ribonuclease (PARN) participates in steps leading to 18S-E maturation in human cells. We found PARN as a novel component of the pre-40S particle pulled down with the pre-ribosome factor LTV1 or Bystin. Reverse pull-down analysis revealed that PARN is a constitutive component of the Bystin-associated pre-40S particle. Knockdown of PARN or exogenous expression of an enzyme-dead PARN mutant (D28A) accumulated 18S-E in both the cytoplasm and nucleus. Moreover, expression of D28A accumulated 18S-E in Bystin-associated pre-40S particles, suggesting that the enzymatic activity of PARN is necessary for the release of 18S-E from Bystin-associated pre-40S particles. Finally, RNase H-based fragmentation analysis and 3'-sequence analysis of 18S-E species present in cells expressing wild-type PARN or D28A suggested that PARN degrades the extended regions encompassing nucleotides 5-44 at the 3' end of mature 18S rRNA. Our results reveal a novel role for PARN in ribosome biogenesis in human cells.

    Original languageEnglish
    Pages (from-to)3437-3447
    Number of pages11
    JournalNucleic Acids Research
    Issue number6
    Early online date24 Nov 2016
    Publication statusPublished - 7 Apr 2017

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