Polypyrimidine tract-binding protein is critical for the turnover and subcellular distribution of CD40 ligand mRNA in CD4+ T cells.
Polypyrimidine tract-binding protein is critical for the turnover and subcellular distribution of CD40 ligand mRNA in CD4+ T cells.
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DOI：
10.4049/jimmunol.1003236
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发表时间：
2011-02-15
期刊：
影响因子：
--
通讯作者：
Covey LR
中科院分区：
文献类型：
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作者：
Matus-Nicodemos R;Vavassori S;Castro-Faix M;Valentin-Acevedo A;Singh K;Marcelli V;Covey LR
CD40配体（CD40L或CD154）在转录后水平受激活诱导过程的调节，该过程在T细胞激活的延长时间内产生高度稳定的转录物。转录物稳定性由含有多聚嘧啶片段结合蛋白（PTB）的复合物（复合物I和II）介导，该复合物与3′非翻译区（3′UTR）内的三个相邻的富含CU的序列结合。为了评估PTB在CD40 L mRNA表达和分布中的作用，在原代T细胞和T细胞系中使用shRNA靶向PTB，所述T细胞系重现了受调节的CD40 L mRNA衰减的稳定期。PTB敲低导致mRNA稳定性显著降低，导致CD40 L表面表达降低。PTB对于CD40 L mRNA在细胞核和细胞质之间以及在细胞质中在胞质溶胶和翻译多聚核糖体之间的适当分布也是至关重要的。PTB特异性RNP复合物的活化诱导形成仅在细胞质而非细胞核PTB中观察到，表明由细胞定位定义的蛋白质的功能差异。最后，我们观察到细胞质和细胞核PTB亚型相对于彼此差异修饰，并且细胞质PTB的变化与活化诱导的磷酸化一致。总之，这项工作表明，明显修饰的PTB通过以下方式在多个步骤调节CD40 L表达：1）将CD40 L mRNA保留在细胞核中，2）在活化后期直接调节mRNA稳定性，3）形成优先与翻译核糖体缔合的核糖核复合物，从而导致CD40 L蛋白水平提高。
CD40 ligand (CD40L or CD154) is regulated at the posttranscriptional level by an activation-induced process that results in a highly stable transcript at extended times of T cell activation. Transcript stability is mediated by polypyrimidine tract-binding protein (PTB)-containing complexes (Complex I and II) that bind to three adjacent CU-rich sequences within the 3′ untranslated region (3′UTR). To assess the role of PTB in the expression and distribution of CD40L mRNA, PTB was targeted using shRNA in both primary T cells and a T cell line that recapitulates the stability phase of regulated CD40L mRNA decay. PTB knockdown resulted in a marked decrease in the mRNA stability that resulted in lowered CD40L surface expression. PTB was also critical for appropriate distribution of CD40L mRNA between the nucleus and cytoplasm and in the cytoplasm between the cytosol and the translating polysomes. The activation-induced formation of PTB-specific RNP complexes was observed only with cytoplasmic and not nuclear PTB indicating functional differences in the protein defined by cellular localization. Finally, we observed that cytoplasmic and nuclear PTB isoforms were differentially modified relative to each other and that the changes in cytoplasmic PTB were consistent with activation-induced phosphorylation. Together this work suggests that distinctly modified PTB regulates CD40L expression at multiple steps by 1) retaining CD40L mRNA in the nucleus, 2) directly regulating mRNA stability at late times of activation and 3) forming a ribonuclear complex that preferentially associates with translating ribosomes thus leading to an enhanced level of CD40L protein.
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影响因子：
5.3
作者：
Hamilton, BJ;Genin, A;Rigby, WFC
通讯作者：
Rigby, WFC
影响因子：
4.8
作者：
Hamilton, B. JoNell;Wang, Xiao-Wei;Rigby, William F. C.
通讯作者：
Rigby, William F. C.
影响因子：
56.9
作者：
KRUYS, V;MARINX, O;HUEZ, G
通讯作者：
HUEZ, G
影响因子：
8.7
作者：
Elgueta R;Benson MJ;de Vries VC;Wasiuk A;Guo Y;Noelle RJ
通讯作者：
Noelle RJ
影响因子：
30.5
作者：
通讯作者：
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