Department of Neurology, Washington University, Saint Louis, Missouri, USA.
Sean M. Healey & AMG Center for ALS, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.
Ann Clin Transl Neurol. 2023 Jun;10(6):1012-1024. doi: 10.1002/acn3.51784. Epub 2023 Apr 29.
Accumulation of misfolded superoxide dismutase-1 (SOD1) is a pathological hallmark of SOD1-related amyotrophic lateral sclerosis (ALS) and is observed in sporadic ALS where its role in pathogenesis is controversial. Understanding in vivo protein kinetics may clarify how SOD1 influences neurodegeneration and inform optimal dosing for therapies that lower SOD1 transcripts.
We employed stable isotope labeling paired with mass spectrometry to evaluate in vivo protein kinetics and concentration of soluble SOD1 in cerebrospinal fluid (CSF) of SOD1 mutation carriers, sporadic ALS participants and controls. A deaminated SOD1 peptide, SDGPVKV, that correlates with protein stability was also measured.
In participants with heterozygous SOD1 mutations, known to cause rapidly progressive ALS, mutant SOD1 protein exhibited ~twofold faster turnover and ~ 16-fold lower concentration compared to wild-type SOD1 protein. SDGPVKV levels were increased in SOD1 carriers relative to controls. Thus, SOD1 mutations impact protein kinetics and stability. We applied this approach to sporadic ALS participants and found that SOD1 turnover, concentration, and SDGPVKV levels are not significantly different compared to controls.
These results highlight the ability of stable isotope labeling approaches and peptide deamidation to discern the influence of disease mutations on protein kinetics and stability and support implementation of this method to optimize clinical trial design of gene and molecular therapies for neurological disorders.
Clinicaltrials.gov: NCT03449212.
错误折叠的超氧化物歧化酶 1（SOD1）的积累是 SOD1 相关肌萎缩侧索硬化症（ALS）的病理标志，在散发性 ALS 中也观察到了这种现象，但其在发病机制中的作用存在争议。了解体内蛋白质动力学可能有助于阐明 SOD1 如何影响神经退行性变，并为降低 SOD1 转录本的治疗方法提供最佳剂量。
我们采用稳定同位素标记与质谱联用的方法，评估 SOD1 突变携带者、散发性 ALS 参与者和对照组脑脊液（CSF）中可溶性 SOD1 的体内蛋白质动力学和浓度。还测量了与蛋白质稳定性相关的脱氨 SOD1 肽 SDGPVKV。
在已知导致进行性肌萎缩侧索硬化症的杂合 SOD1 突变参与者中，突变型 SOD1 蛋白的周转率比野生型 SOD1 蛋白快约两倍，浓度低约 16 倍。SOD1 携带者的 SDGPVKV 水平高于对照组。因此，SOD1 突变会影响蛋白质的周转率和稳定性。我们将这种方法应用于散发性 ALS 参与者，发现与对照组相比，SOD1 的周转率、浓度和 SDGPVKV 水平没有显著差异。
这些结果突出了稳定同位素标记方法和肽脱酰胺作用的能力，可以辨别疾病突变对蛋白质动力学和稳定性的影响，并支持实施这种方法来优化神经疾病基因和分子治疗的临床试验设计。
Clinicaltrials.gov：NCT03449212。
