Somatic motor neurons are selectively vulnerable in spinal muscular atrophy (SMA), which is caused by a deficiency of the ubiquitously expressed survival of motor neuron protein. However, some motor neuron groups, including oculomotor and trochlear (ocular), which innervate eye muscles, are for unknown reasons spared. To reveal mechanisms of vulnerability and resistance in SMA, we investigate the transcriptional dynamics in discrete neuronal populations using laser capture microdissection coupled with RNA sequencing (LCM-seq). Using gene correlation network analysis, we reveal a TRP53-mediated stress response that is intrinsic to all somatic motor neurons independent of their vulnerability, but absent in relatively resistant red nucleus and visceral motor neurons. However, the temporal and spatial expression analysis across neuron types shows that the majority of SMA-induced modulations are cell type–specific. Using Gene Ontology and protein network analyses, we show that ocular motor neurons present unique disease-adaptation mechanisms that could explain their resilience. Specifically, ocular motor neurons up-regulate (1) Syt1, Syt5, and Cplx2, which modulate neurotransmitter release; (2) the neuronal survival factors Gdf15, Chl1, and Lif; (3) Aldh4, that protects cells from oxidative stress; and (4) the caspase inhibitor Pak4. Finally, we show that GDF15 can rescue vulnerable human spinal motor neurons from degeneration. This confirms that adaptation mechanisms identified in resilient neurons can be used to reduce susceptibility of vulnerable neurons. In conclusion, this in-depth longitudinal transcriptomics analysis in SMA reveals novel cell type–specific changes that, alone and combined, present compelling targets, including Gdf15, for future gene therapy studies aimed toward preserving vulnerable motor neurons.

中文翻译：

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LCM-seq 揭示了抗性神经元独特的转录适应机制，并确定了脊髓性肌萎缩症的保护途径。


体细胞运动神经元在脊髓性肌萎缩症（SMA）中选择性脆弱，这是由于普遍表达的运动神经元存活蛋白缺陷引起的。然而，一些运动神经元群，包括支配眼部肌肉的动眼神经元和滑车神经元，由于未知的原因却幸免于难。为了揭示 SMA 的脆弱性和抵抗机制，我们使用激光捕获显微切割结合 RNA 测序 (LCM-seq) 研究离散神经元群体的转录动态。使用基因相关网络分析，我们揭示了 TRP53 介导的应激反应，这是所有体运动神经元固有的，与它们的脆弱性无关，但在相对抵抗的红核和内脏运动神经元中不存在。然而，跨神经元类型的时间和空间表达分析表明，大多数 SMA 诱导的调节是细胞类型特异性的。使用基因本体论和蛋白质网络分析，我们表明眼运动神经元呈现出独特的疾病适应机制，可以解释它们的恢复能力。具体而言，眼运动神经元上调 (1) Syt1 、 Syt5和Cplx2 ，从而调节神经递质释放； (2) 神经元存活因子Gdf15、Chl1和Lif ； (3) Aldh4，保护细胞免受氧化应激； (4)半胱天冬酶抑制剂Pak4。最后，我们证明 GDF15 可以挽救脆弱的人类脊髓运动神经元免于退化。这证实了在弹性神经元中发现的适应机制可用于降低脆弱神经元的敏感性。 总之，这种对 SMA 的深入纵向转录组学分析揭示了新的细胞类型特异性变化，这些变化单独或组合，为未来旨在保护脆弱运动神经元的基因治疗研究提供了引人注目的靶点，包括Gdf15 。