A post-transcriptional regulatory switch in polypyrimidine tract-binding proteins reprograms alternative splicing in developing neurons
A post-transcriptional regulatory switch in polypyrimidine tract-binding proteins reprograms alternative splicing in developing neurons
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DOI：
10.1101/gad.1558107
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发表时间：
2007-07-01
影响因子：
10.5
通讯作者：
Black, Douglas L.
中科院分区：
文献类型：
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作者：
Boutz, Paul L.;Stoilov, Peter;Black, Douglas L.
许多后生动物的基因转录表现出神经元特异性剪接模式，但这些剪接事件的发育控制知之甚少。我们发现，一个大组的外显子的剪接是在神经元发育过程中通过两个高度相似的多聚嘧啶道结合蛋白，PTB和nPTB（神经PTB）之间的表达开关重新编程。PTB是一种研究充分的可变剪接调节因子，但nPTB是一种与PTB功能关系密切的蛋白质，其功能尚不清楚。在脑中，nPTB蛋白在有丝分裂后神经元中特异性表达，而PTB仅限于神经元前体细胞（NPC）、神经胶质和其他非神经元细胞。有趣的是，在NPC和其他非神经元细胞中发现了nPTB mRNA转录物，但在这些细胞中，nPTB蛋白表达受到抑制。这种抑制部分是由于PTB诱导的nPTB mRNA的选择性剪接，导致无义介导的衰变（NMD）。然而，我们发现，即使是正确剪接的mRNA不能表达nPTB蛋白时，PTB是存在的，这表明从额外的转录后机制的贡献。PTB控制的nPTB抑制导致脑中相互排斥的表达模式，其中成熟神经元中PTB的丢失允许这些细胞中nPTB的合成。为了研究这种转换的后果，我们使用剪接敏感的微阵列来识别由PTB、nPTB或这两种蛋白质调控的不同外显子组。在神经元分化期间，这些外显子组的剪接如从观察到的PTB和nPTB表达的变化所预测的那样改变。这些数据表明，从PTB到nPTB的转录后开关控制着神经元发育过程中广泛的选择性剪接程序。
Many metazoan gene transcripts exhibit neuron-specific splicing patterns, but the developmental control of these splicing events is poorly understood. We show that the splicing of a large group of exons is reprogrammed during neuronal development by a switch in expression between two highly similar polypyrimidine tract-binding proteins, PTB and nPTB (neural PTB). PTB is a well-studied regulator of alternative splicing, but nPTB is a closely related paralog whose functional relationship to PTB is unknown. In the brain, nPTB protein is specifically expressed in post-mitotic neurons, whereas PTB is restricted to neuronal precursor cells (NPC), glia, and other nonneuronal cells. Interestingly, nPTB mRNA transcripts are found in NPCs and other nonneuronal cells, but in these cells nPTB protein expression is repressed. This repression is due in part to PTB-induced alternative splicing of nPTB mRNA, leading to nonsense-mediated decay (NMD). However, we find that even properly spliced mRNA fails to express nPTB protein when PTB is present, indicating contributions from additional post-transcriptional mechanisms. The PTB-controlled repression of nPTB results in a mutually exclusive pattern of expression in the brain, where the loss of PTB in maturing neurons allows the synthesis of nPTB in these cells. To examine the consequences of this switch, we used splicing-sensitive microarrays to identify different sets of exons regulated by PTB, nPTB, or both proteins. During neuronal differentiation, the splicing of these exon sets is altered as predicted from the observed changes in PTB and nPTB expression. These data show that the post-transcriptional switch from PTB to nPTB controls a widespread alternative splicing program during neuronal development.