In vivo neuronal subtype-specific targets of Atoh1 (Math1) in dorsal spinal cord.
In vivo neuronal subtype-specific targets of Atoh1 (Math1) in dorsal spinal cord.
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DOI：
10.1523/jneurosci.0445-11.2011
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发表时间：
2011-07-27
期刊：
影响因子：
--
通讯作者：
Johnson JE
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文献类型：
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作者：
Lai HC;Klisch TJ;Roberts R;Zoghbi HY;Johnson JE
神经碱性螺旋-环-螺旋（bHLH）转录因子在调节神经元分化和神经元亚型特化中起着至关重要的作用。由于缺乏体内真正的靶点，这些转录因子如何精确地指导这些过程在很大程度上是未知的。遗传学证据表明，bHLH因子在其共同的分化作用中具有共同的靶点，但在神经元亚型规范中具有独特的靶点。然而，是否存在神经元亚型特异性靶点仍然是一个悬而未决的问题。为了解决这个问题，我们专注于Atoh 1（Math 1），bHLH转录因子，指定不同的神经元亚型的本体感受通路在哺乳动物，包括背中间神经元1（dI 1）人口的发展脊髓。我们确定了独特的转录Atoh 1衍生的谱系使用微阵列分析特定的bHLH分选的人口从小鼠。染色质免疫沉淀测序（ChIP-seq）实验，随后进行增强子报告基因分析，确定了Atoh 1在体内的五个直接神经元亚型特异性靶点及其Atoh 1响应增强子沿着。这些靶点Klf 7、Rab 15、Rassf 4、Selm和Smad 7具有多种功能，从转录因子到内吞作用和信号传导途径的调节剂。只有Rab 15和Selm在几种不同的Atoh 1特异性神经元亚型中表达，包括发育中小脑的外部颗粒细胞（EGL）、内耳的毛细胞和默克尔细胞。我们的工作在分子水平上建立了神经元分化bHLH转录因子具有不同的谱系特异性靶点。
Neural basic helix-loop-helix (bHLH) transcription factors are crucial in regulating the differentiation and neuronal subtype specification of neurons. Precisely how these transcription factors direct such processes is largely unknown due to the lack of bona fide targets in vivo. Genetic evidence suggests that bHLH factors have shared targets in their common differentiation role, but unique targets with respect to their distinct roles in neuronal subtype specification. However, whether neuronal subtype specific targets exist remains an unsolved question. To address this question, we focused on Atoh1 (Math1), a bHLH transcription factor that specifies distinct neuronal subtypes of the proprioceptive pathway in mammals including the dorsal interneuron 1 (dI1) population of the developing spinal cord. We identified transcripts unique to the Atoh1-derived lineage using microarray analyses of specific bHLH-sorted populations from mouse. Chromatin immunoprecipitation-sequencing (ChIP-seq) experiments followed by enhancer reporter analyses identified five direct neuronal subtype specific targets of Atoh1 in vivo along with their Atoh1-responsive enhancers. These targets, Klf7, Rab15, Rassf4, Selm, and Smad7, have diverse functions that range from transcription factors to regulators of endocytosis and signaling pathways. Only Rab15 and Selm are expressed across several different Atoh1-specified neuronal subtypes including external granule cells (EGL) in the developing cerebellum, hair cells of the inner ear, and Merkel cells. Our work establishes on a molecular level that neuronal differentiation bHLH transcription factors have distinct lineage-specific targets.