The benzamide M344, a novel histone deacetylase inhibitor, significantly increases SMN2 RNA/protein levels in spinal muscular atrophy cells
The benzamide M344, a novel histone deacetylase inhibitor, significantly increases SMN2 RNA/protein levels in spinal muscular atrophy cells
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DOI：
10.1007/s00439-006-0186-1
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发表时间：
2006-08-01
期刊：
影响因子：
5.3
通讯作者：
Wirth, Brunhilde
中科院分区：
文献类型：
--
作者：
Riessland, Markus;Brichta, Lars;Wirth, Brunhilde
近端脊髓性肌萎缩症（SMA）是一种常见的常染色体隐性遗传神经肌肉疾病，导致一半的婴儿死亡。存活运动神经元1 （SMN1）基因的纯合缺失导致SMA，而SMN2拷贝基因的数量调节疾病的严重程度。由于外显子剪接增强子内的沉默突变，SMN2主要产生缺乏外显子7的选择性剪接转录物，并且与SMN1相同的全长蛋白仅相似于10%。然而，SMN2代表了SMA治疗的一个有希望的靶点。SMN2的正确剪接可以通过剪接因子htra2 - β 1的过表达以及抑制组蛋白去乙酰化酶（hdac）的药物等外源因子有效地恢复。在这里，我们发现新型苯甲酰胺M344，一种HDAC抑制剂，在治疗64小时后，在SMA患者的成纤维细胞中上调SMN2蛋白表达达7倍。此外，M344显著提高了宝石/核的总数以及包含宝石的核的数量。这是迄今为止报道的药物对SMN蛋白水平的最强体外效应。定量RT-PCR显示，Delta 7-SMN2转化为FL-SMN2转录本很可能是由htra2 - β 1水平升高促进的。使用MTT试验对M344的细胞毒性进行研究，发现只有在非常高的浓度下才会对细胞产生毒性作用。总之，M344可以被认为是高效的HDAC抑制剂，在低剂量下具有活性，因此代表了SMA因果治疗的有希望的候选者。
Proximal spinal muscular atrophy (SMA) is a common autosomal recessively inherited neuromuscular disorder causing infant death in half of all patients. Homozygous loss of the survival motor neuron 1 (SMN1) gene causes SMA, whereas the number of the SMN2 copy genes modulates the severity of the disease. Due to a silent mutation within an exonic splicing enhancer, SMN2 mainly produces alternatively spliced transcripts lacking exon 7 and only similar to 10% of a full-length protein identical to SMN1. However, SMN2 represents a promising target for an SMA therapy. The correct splicing of SMN2 can be efficiently restored by over-expression of the splicing factor Htra2-beta 1 as well as by exogenous factors like drugs that inhibit histone deacetylases (HDACs). Here we show that the novel benzamide M344, an HDAC inhibitor, up-regulates SMN2 protein expression in fibroblast cells derived from SMA patients up to 7-fold after 64 h of treatment. Moreover, M344 significantly raises the total number of gems/nucleus as well as the number of nuclei that contain gems. This is the strongest in vitro effect of a drug on the SMN protein level reported so far. The reversion of Delta 7-SMN2 into FL-SMN2 transcripts as demonstrated by quantitative RT-PCR is most likely facilitated by elevated levels of Htra2-beta 1. Investigations of the cytotoxicity of M344 using an MTT assay revealed toxic cell effects only at very high concentrations. In conclusion, M344 can be considered as highly potent HDAC inhibitor which is active at low doses and therefore represents a promising candidate for a causal therapy of SMA.