Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 295, Issue 2, Pages 390-402Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA119.011617
Keywords
microRNA (miRNA); RNA binding protein; post-transcriptional regulation; polyadenylation; hepatocyte; miRNA metabolism
Categories
Funding
- Ministry of Education, Culture, Sports, Science, and Technology of Japan (MEXT)
- Japan Society for the Promotion of Science (JSPS)
- Japan Agency for Medical Research and Development (AMED)
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MicroRNA-122 (miR-122) is highly expressed in hepatocytes, where it plays an important role in regulating cholesterol and fatty acid metabolism, and it is also a host factor required for hepatitis C virus replication. miR-122 is selectively stabilized by 3? adenylation mediated by the cytoplasmic poly(A) polymerase GLD-2 (also known as PAPD4 or TENT2). However, it is unclear how GLD-2 specifically stabilizes miR-122. Here, we show that QKI7 KH domain-containing RNA binding (QKI-7), one of three isoforms of the QKI proteins, which are members of the signal transduction and activation of RNA (STAR) family of RNA-binding proteins, is involved in miR-122 stabilization. QKI down-regulation specifically decreased the steady-state level of mature miR-122, but did not affect the pre-miR-122 level. We also found that QKI-7 uses its C-terminal region to interact with GLD-2 and its QUA2 domain to associate with the RNA-induced silencing complex protein Argonaute 2 (Ago2), indicating that the GLD-2?QKI-7 interaction recruits GLD-2 to Ago2. QKI-7 exhibited specific affinity to miR-122 and significantly promoted GLD-2?mediated 3? adenylation of miR-122 in vitro. Taken together, our findings indicate that miR-122 binds Ago2?interacting QKI-7, which recruits GLD-2 for 3? adenylation and stabilization of miR-122.
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