Li Chang You, Chu Jia You, Yu Jian Kun, Huang Xiao Qin, Liu Xiao Juan, Shi Li, Che Yan Chun, Xie Jiu Yong
Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming 650118, China.
Cell Res. 2004 Dec;14(6):473-9. doi: 10.1038/sj.cr.7290250.
The splicing of many alternative exons in the precursor messenger RNA (pre-mRNA) is regulated by extracellular factors but the underlying molecular bases remain unclear. Here we report the differential regulation of Bcl-x pre-mRNA splicing by extracellular factors and their distinct requirements for pre-mRNA elements. In K562 leukemia cells, treatment with interleukin-6 (IL-6) or granulocyte-macrophage colony stimulating factor (GM-CSF) reduced the proportion of the Bcl-xL variant mRNA while treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) had no effect. In U251 glioma cells, however, TPA efficiently increased the Bcl-xL level. These regulations were also seen for a transfected splicing reporter mini-gene. Further analyses of deletion mutants indicate that nucleotides 1-176 on the downstream intron are required for the IL-6 effect, whereas additional nucleotides 177-284 are essential for the GM-CSF effects. As for the TPA effect, only nucleotides 1-76 are required in the downstream intron, Thus UK-6, GM-CSF and TPA differentially regulate Bcl-x splicing and require specific intronic pre-mRNA sequences for their respective effects.
前体信使核糖核酸（pre-mRNA）中许多可变外显子的剪接受细胞外因子调控，但其潜在分子基础仍不清楚。在此，我们报道细胞外因子对Bcl-x pre-mRNA剪接的差异调控及其对pre-mRNA元件的不同要求。在K562白血病细胞中，用白细胞介素-6（IL-6）或粒细胞-巨噬细胞集落刺激因子（GM-CSF）处理可降低Bcl-xL变异体mRNA的比例，而用12-O-十四酰佛波醇-13-乙酸酯（TPA）处理则无影响。然而，在U251胶质瘤细胞中，TPA能有效提高Bcl-xL水平。转染的剪接报告小基因也出现了这些调控现象。对缺失突变体的进一步分析表明，下游内含子上的核苷酸1-176是IL-6发挥作用所必需的，而额外的核苷酸177-284对GM-CSF的作用至关重要。至于TPA的作用，下游内含子中仅需核苷酸1-76。因此，IL-6、GM-CSF和TPA对Bcl-x剪接有差异调控作用，且各自的作用需要特定的内含子pre-mRNA序列。
