AU-Rich-Element-Dependent Translation Repression Requires the Cooperation of Tristetraprolin and RCK/P54

Abstract

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-␣) than the control, while the corresponding mRNA level has a marginal change. Furthermore, knockdown of TTP increases the rate of biosynthesis of TNF-␣, 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.

Recruitment of the 4EHP-GYF2 cap-binding complex to tetraproline motifs of tristetraprolin promotes repression and degradation of mRNAs with AU-rich elements

“…In addition to activating mRNA degradation, TTP has been demonstrated to promote translation repression, which TTP recruits 4EHP-GYF2 to repress ARE-mRNAs www.rnajournal.org 377 might be the predominant mechanism of TTP-mediated repression in some conditions (Qi et al 2012;Schott et al 2014). 4EHP was recently reported to stimulate translation repression mediated by TTP (Tao and Gao 2015), which is consistent with the reported function of Drosophila 4EHP and the mammalian 4EHP-GYF2 complex in translation repression (Cho et al 2005;Morita et al 2012).…”

“…In addition to activation of mRNA decay, TTP also promotes translation repression, which appears to be the dominant mechanism of repression by TTP under certain conditions (Schott et al 2014). The helicase DDX6 (also called Rck/p54) was recently implicated in translation repression by TTP (Qi et al 2012), but the specific mechanism of TTP-mediated translation repression has remained poorly understood.…”

Emerging complexity of the HuD/ELAVl4 gene; implications for neuronal development, function, and dysfunction

“…Transcription enhancement (Davis-Smyth et al 1996) Alternative splicing (Min et al 1997) Destabilization (Chen et al 2001;Gherzi et al 2004) Cytoplasmic transport (Snee et al 2002) Tristetraprolin (TTP) Transcription repression (Liang et al 2009;Schichl et al 2009) Destabilization (Carballo et al 1998) Translation repression (Pfeiffer and Brooks 2012;Qi et al 2012;Tiedje et al 2012) Butyrate-response factor-1 (BRF1) 3 ′ End processing inhibition (Desroches-Castan et al 2011) Destabilization (Stoecklin et al 2002) TINO/Mex3D/RKHD1 Destabilization (Donnini et al 2004) Polyadenylate-binding proteininteracting protein 2 (PAIP2)…”

Tristetraprolin Recruits Eukaryotic Initiation Factor 4E2 To Repress Translation of AU-Rich Element-Containing mRNAs

“…It has been reported elsewhere that TTP associates with polysomes (15,16) and that a TTP-interacting protein, cullin 4B, promotes the loading of TTP-associated TNF-␣ mRNA complex onto polysomes (17). Recently, Qi et al reported that TTP inhibits the translation of TNF-␣ in an ARE-dependent manner and the RNA helicase RCK is involved in this process (18). In addition, Tiedje et al reported that TTP represses the translation of TNF-␣ through competing with HuR to bind to ARE (19).…”

“…RNA was reverse transcribed in a 20-l reaction mixture [1 to 5 g RNA, 1 g oligo(dT) 18 , 10 mM deoxynucleoside triphosphates (dNTPs), Tris-HCl (pH 8.3), 75 mM KCl, 3 mM MgCl 2 , 5 mM DTT, 1 l RT]. The cDNA levels were measured by SYBR green real-time PCR in the Rotor-Gene 6000 system (Corbett Life Science).…”