A Sub-Element in PRE enhances nuclear export of intronless mRNAs by recruiting the TREX complex via ZC3H18.
Bottom Line: We found that PRE drastically enhances the cytoplasmic accumulation of cDNA transcripts independent of any viral protein.Together, our data indicate that SEP1 enhances mRNA export by recruiting TREX via ZC3H18.The new mRNA export factors that we identified might be involved in cap- and splicing-dependent TREX recruitment to cellular mRNAs.
Affiliation: Shanghai Key Laboratory of Molecular Andrology, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.Show MeSH
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Mentions: Previous studies suggested that PRE enhances the expression of intronless reporter mRNAs by promoting nuclear export (18). To determine the role of PRE in promoting nuclear export of intronless mRNAs, we constructed β-globin reporter plasmids with PRE inserted in the sense (cG-PRE) or anti-sense direction (cG-rPRE) at the 3′ end of the open reading frame (Figure 1A). These constructs, as well as wild-type β-globin (wG) and its cDNA counterpart (cG), were transfected into HeLa cells, and nucleocytoplasmic distribution of these mRNAs was determined using FISH (Figure 1B). As expected, 24 h after transfection, the wG mRNA mainly accumulated in the cytoplasm, whereas the cG mRNA was mostly retained in the nucleus (Figure 1B, wG and cG). Significantly, the cG-PRE mRNA was largely detected in the cytoplasm. In contrast, the cG-rPRE mRNA was mainly nuclear (Figure 1B). These results indicate that PRE enhances the cytoplasmic accumulation of the cG mRNA. To test whether PRE also enhances cytoplasmic accumulation of other intronless mRNAs, we next used Smad reporter constructs. When PRE was inserted at the 3′ end, the Smad cDNA transcript (cS) that was otherwise retained in the nucleus was accumulated in the cytoplasm to the similar extent to the spliced Smad mRNA (wS) (Supplementary Figure S1). Thus, our data indicate that the role of PRE in enhancing nuclear export of cDNA transcripts is general.
Affiliation: Shanghai Key Laboratory of Molecular Andrology, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.