AU-rich-element-dependent translation repression requires the cooperation of tristetraprolin and RCK/P54.
AU-rich elements (AREs), residing in the 3' untranslated region (UTR) of many labile mRNAs, are important cis-acting elements that modulate the stability of these mRNAs by collaborating with trans-acting factors such as tristetraprolin (TTP). AREs also regulate translation, but the underlying mechanism is not fully understood. Here we examined the function and mechanism of TTP in ARE-mRNA translation. Through a luciferase-based reporter system, we used knockdown, overexpression, and tethering assays in 293T cells to demonstrate that TTP represses ARE reporter mRNA translation. Polyribosome fractionation experiments showed that TTP shifts target mRNAs to lighter fractions. In murine RAW264.7 macrophages, knocking down TTP produces significantly more tumor necrosis factor alpha (TNF-α) than the control, while the corresponding mRNA level has a marginal change. Furthermore, knockdown of TTP increases the rate of biosynthesis of TNF-α, suggesting that TTP can exert effects at translational levels. Finally, we demonstrate that the general translational repressor RCK may cooperate with TTP to regulate ARE-mRNA translation. Collectively, our studies reveal a novel function of TTP in repressing ARE-mRNA translation and that RCK is a functional partner of TTP in promoting TTP-mediated translational repression.
Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Graduate School of Chinese Academy of Sciences & Shanghai Jiao-Tong University School of Medicine, Shanghai, China.
Mei-Yan
MY
Qi
Zhi-Zhang
ZZ
Wang
Zhuo
Z
Zhang
Qin
Q
Shao
An
A
Zeng
Xiang-Qi
XQ
Li
Wen-Qing
WQ
Li
Chen
C
Wang
Fu-Ju
FJ
Tian
Qing
Q
Li
Jun
J
Zou
Yong-Wen
YW
Qin
Gary
G
Brewer
Shuang
S
Huang
Qing
Q
Jing
D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002460:Cell Line; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D051816:Tristetraprolin / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D020413:3' Untranslated Regions; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D051816:Tristetraprolin; D014409:Tumor Necrosis Factor-alpha; C490616:Ddx6 protein, mouse; C094683:DDX6 protein, human; D053487:DEAD-box RNA Helicases