Xiao Jingbo, Marugan Juan J, Zheng Wei, Titus Steve, Southall Noel, Cherry Jonathan J, Evans Matthew, Androphy Elliot J, Austin Christopher P
NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850
Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, LRB 328, Worcester, Massachusetts 01605
Spinal Muscular Atrophy (SMA) is an autosomal recessive disorder affecting the selective degeneration of survival motor neuron (SMN) in the spinal cord due to the deletion or mutations of the survival motor neuron gene 1 (SMN1). However, the human genome includes a second nearly identical gene called SMN2 which functionally differs from SMN1 by a critical nucleotide C to T transition residing in exon 7. Although SMN2 is able to produce a small portion of full length SMN protein, the majority of SMN2 RNAs undergo alternative splicing and produce truncated, proteolytically unstable SMN variants that are not able to replace the function of full length SMN protein. Therefore, increasing overall SMN production through up-regulation of SMN2 expression or through the variation of splicing rate has been postulated to be one of the potential therapeutic strategies for SMA. In this report, we detail the discovery of ML200 (CID 46907676) as a novel arylpiperidine-based small molecule modulator of SMN protein production. ML200 had an AC50 of 31nM and gave 576% increase in fold induction of SMN promoter in the reporter assay. ML200 was confirmed by western blot analysis and gem count assay using SMA patient fibroblasts at low nanomolar range (37 nM). The structure property relationships (SPR) including microsomal stability, cell permeability and full time oral dosing in vivo pharmacokinetic studies were also investigated to address ADME properties. We anticipate that ML200 may serve as a useful lead for exploring the therapeutic benefits of SMN protein induction in SMA animal models, and ultimately in human clinical trials.
脊髓性肌萎缩症（SMA）是一种常染色体隐性疾病，由于生存运动神经元基因1（SMN1）的缺失或突变，影响脊髓中生存运动神经元（SMN）的选择性退化。然而，人类基因组包含另一个几乎相同的基因，称为SMN2，其在功能上与SMN1的区别在于外显子7中关键的核苷酸C到T的转变。尽管SMN2能够产生一小部分全长SMN蛋白，但大多数SMN2 RNA会发生可变剪接，并产生截短的、蛋白水解不稳定的SMN变体，这些变体无法替代全长SMN蛋白的功能。因此，通过上调SMN2表达或改变剪接率来增加整体SMN产量，被认为是SMA潜在的治疗策略之一。在本报告中，我们详细介绍了ML200（CID 46907676）作为一种新型的基于芳基哌啶的小分子SMN蛋白产生调节剂的发现。在报告基因测定中，ML200的AC50为31nM，SMN启动子的诱导倍数增加了576%。在低纳摩尔范围（37 nM）使用SMA患者成纤维细胞通过蛋白质免疫印迹分析和基因计数测定法对ML200进行了确认。还研究了包括微粒体稳定性、细胞通透性和体内药代动力学研究中的全时口服给药在内的结构性质关系（SPR），以解决药物代谢动力学性质。我们预计，ML200可能作为一个有用的先导物，用于探索在SMA动物模型中诱导SMN蛋白的治疗益处，并最终用于人类临床试验。
