Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine, St. Louis, MO 63110, USA; Genome Engineering and iPSC Center, Washington University School of Medicine, St. Louis, MO 63110, USA.
Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.
Exp Neurol. 2021 May;339:113636. doi: 10.1016/j.expneurol.2021.113636. Epub 2021 Feb 4.
Axonal degeneration contributes to the pathogenesis of many neurodegenerative disorders, motivating efforts to dissect the mechanism of pathological axon loss in order to develop therapies for axonal preservation. SARM1 is a particularly attractive therapeutic target, as it is an inducible NAD cleaving enzyme that is required for axon loss in multiple mouse models of traumatic and degenerative neurological disease. However, it is essential to establish whether SARM1 triggers axon degeneration in human neurons before proceeding with the development of SARM1-directed therapeutics. Here we combine genome engineering with the production of human stem cell-derived neurons to test the role of human SARM1 in traumatic and neurotoxic axon degeneration. We have generated two independent SARM1 knockout human iPSC lines that do not express SARM1 protein upon differentiation into neurons. We have developed a modified sensory neuron differentiation protocol that generates human sensory neurons with high yield and purity. We find that SARM1 is required for axon degeneration in response to both physical trauma and in a cellular model of chemotherapy-induced peripheral neuropathy. Finally, we identify cADPR as a biomarker of SARM1 enzyme activity in both healthy and injured human sensory neurons. These findings are consistent with prior molecular and cellular studies in mouse neurons, and highlight the therapeutic potential of SARM1 inhibition for the prevention and treatment of human neurological disease.
轴突变性是许多神经退行性疾病发病机制的一个重要因素，这促使人们努力解析病理性轴突丢失的机制，以期开发出轴突保护疗法。SARM1 是一个特别有吸引力的治疗靶点，因为它是一种诱导型 NAD 裂解酶，在多种创伤性和退行性神经疾病的小鼠模型中，该酶对于轴突丢失是必需的。然而，在开发针对 SARM1 的治疗方法之前，有必要确定 SARM1 是否会引发人类神经元中的轴突退化。在这里，我们将基因组工程与人类干细胞衍生神经元的产生相结合，以测试人类 SARM1 在创伤性和神经毒性轴突退化中的作用。我们已经生成了两种独立的 SARM1 敲除人 iPSC 系，在分化为神经元时不表达 SARM1 蛋白。我们开发了一种改良的感觉神经元分化方案，该方案可高效且高纯度地产生人类感觉神经元。我们发现 SARM1 对于物理创伤和化学治疗诱导的周围神经病的细胞模型中的轴突退化都是必需的。最后，我们确定了 cADPR 是健康和受损的人类感觉神经元中 SARM1 酶活性的生物标志物。这些发现与先前在小鼠神经元中的分子和细胞研究一致，并强调了 SARM1 抑制在预防和治疗人类神经疾病方面的治疗潜力。
