Cell-specific alternative splicing modulates myriad cell functions and is disrupted in disease. The mechanisms governing alternative splicing are known for relatively few genes and typically focus on RNA splicing factors. In sensory neurons, cell-specific alternative splicing of the presynaptic Ca_V channel Cacna1b gene modulates opioid sensitivity. How this splicing is regulated is unknown. We find that cell and exon -specific DNA hypomethylation permits CTCF binding, the master regulator of mammalian chromatin structure, which, in turn, controls splicing in a DRG-derived cell line. In vivo, hypomethylation of an alternative exon specifically in nociceptors, likely permits CTCF binding and expression of Ca_V2.2 channel isoforms with increased opioid sensitivity in mice. Following nerve injury, exon methylation is increased, and splicing is disrupted. Our studies define the molecular mechanisms of cell-specific alternative splicing of a functionally validated exon in normal and disease states – and reveal a potential target for the treatment of chronic pain.

中文翻译：

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神经元中的细胞特异性外显子甲基化和CTCF结合调节钙离子通道的剪接和功能

细胞特异性的可变剪接可调节多种细胞功能，并破坏疾病。控制替代剪接的机制对于相对较少的基因是已知的，并且通常集中在RNA剪接因子上。在感觉神经元中，突触前Ca _V通道Cacna1b基因的细胞特异性选择性剪接调节阿片样物质的敏感性。该拼接的调控方式尚不清楚。我们发现细胞和外显子特异的DNA低甲基化允许CTCF结合，这是哺乳动物染色质结构的主要调节剂，继而控制着DRG衍生的细胞系中的剪接。在体内，另一种外显子在伤害感受器中的甲基化不足，可能允许CTCF结合并表达Ca _V在小鼠中具有增加的阿片样物质敏感性的2.2通道亚型。神经损伤后，外显子甲基化增加，剪接被破坏。我们的研究确定了功能正常的外显子在正常和疾病状态下的细胞特异性替代剪接的分子机制，并揭示了治疗慢性疼痛的潜在靶点。