Poly(A)-specific ribonuclease regulates the processing of small-subunit rRNAs in human cells.
Poly(A)-specific ribonuclease regulates the processing of small-subunit rRNAs in human cells.
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DOI：
10.1093/nar/gkw1047
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发表时间：
2017-04-07
影响因子：
14.9
通讯作者：
Takahashi N
中科院分区：
文献类型：
--
作者：
Ishikawa H;Yoshikawa H;Izumikawa K;Miura Y;Taoka M;Nobe Y;Yamauchi Y;Nakayama H;Simpson RJ;Isobe T;Takahashi N
核糖体的生物合成依次发生在核仁、核质和细胞质中。核糖体小亚基的成熟在细胞质中通过掺入特定类别的核糖体蛋白和18 S-E前rRNA（18 S-E）的最终切割而完成。在这里，我们表明，聚（A）特异性核糖核酸酶（PARN）参与步骤，导致18 S-E成熟的人类细胞。我们发现PARN是前核糖体因子LTV 1或Bystin下拉的前40 S颗粒的新组分。反向下拉分析表明，PARN是一个组成部分的Bystin相关的前40 S颗粒。PARN的敲除或酶死亡PARN突变体（D28 A）的外源表达在细胞质和细胞核中积累18 S-E。此外，D28 A的表达在Bystin相关的前40 S颗粒中积累18 S-E，表明PARN的酶活性对于从Bystin相关的前40 S颗粒释放18 S-E是必需的。最后，对表达野生型PARN或D28 A的细胞中存在的18 S-E种类的基于RNase H的片段化分析和3 ′端序列分析表明，PARN降解成熟18 S rRNA的3 ′端处包含核苷酸5-44的延伸区域。我们的研究结果揭示了PARN在人类细胞核糖体生物合成中的新作用。
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.