Topoisomerase inhibitors unsilence the dormant allele of Ube3a in neurons.
Topoisomerase inhibitors unsilence the dormant allele of Ube3a in neurons.
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DOI：
10.1038/nature10726
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发表时间：
2011-12-21
期刊：
影响因子：
64.8
通讯作者：
Philpot, Benjamin D.
中科院分区：
文献类型：
--
作者：
Huang, Hsien-Sung;Allen, John A.;Mabb, Angela M.;King, Ian F.;Miriyala, Jayalakshmi;Taylor-Blake, Bonnie;Sciaky, Noah;Dutton, J. Walter, Jr.;Lee, Hyeong-Min;Chen, Xin;Jin, Jian;Bridges, Arlene S.;Zylka, Mark J.;Roth, Bryan L.;Philpot, Benjamin D.
Angelman综合征是一种由母体泛素蛋白连接酶E3a(Ube3a)等位基因缺失或突变引起的严重神经发育障碍。在神经元中，父亲的Ube3a等位基因是完整的，但在表观遗传上是沉默的，这增加了通过激活这种沉默的等位基因来恢复功能的UBE3A蛋白来治疗Angelman综合征的可能性。通过对小鼠原代皮层神经元进行无偏倚的高含量筛选，我们鉴定了12种拓扑异构酶I抑制剂和4种拓扑异构酶II抑制剂，它们能解除父系Ube3a等位基因的沉默。这些药物包括拓扑替康、伊立替康、依托泊苷和右氧氟沙星(ICRF-187)。在纳摩尔浓度下，拓扑替康上调了母体Ube3a缺失小鼠神经元中催化活性的UBE3A。Topotecan伴随着Ube3a反义转录本的表达下调，该反义转录本与Ube3a的父系拷贝重叠。这些结果表明，Topotecan通过减少印记的反义RNA的转录来沉默顺式基因中的Ube3a。在体内给药时，Topotecan在神经系统的几个区域，包括海马区、新皮质、纹状体、小脑和脊髓中的神经元，不会使父亲的Ube3a等位基因沉默。在停止拓扑替康治疗后，父亲的Ube3a在一组脊髓神经元中的表达至少在12周内保持高水平，这表明短暂的拓扑异构酶抑制可以对基因表达产生持久的影响。虽然潜在的靶外效应仍有待研究，但我们的发现建议了一种在Angelman综合征患者中重新激活Ube3a功能但处于休眠状态的等位基因的治疗策略。
Angelman syndrome is a severe neurodevelopmental disorder caused by deletion or mutation of the maternal allele of the ubiquitin protein ligase E3A (Ube3a). In neurons, the paternal allele of Ube3a is intact but epigenetically silenced, raising the possibility that Angelman syndrome could be treated by activating this silenced allele to restore functional UBE3A protein. Using an unbiased, high-content screen in primary cortical neurons from mice, we identified twelve topoisomerase I inhibitors and four topoisomerase II inhibitors that unsilence the paternal Ube3a allele. These drugs included topotecan, irinotecan, etoposide, and dexrazoxane (ICRF-187). At nanomolar concentrations, topotecan upregulated catalytically active UBE3A in neurons from maternal Ube3a-null mice. Topotecan concomitantly downregulated expression of the Ube3a antisense transcript that overlaps the paternal copy of Ube3a. These results suggest that topotecan unsilences Ube3a in cis by reducing transcription of an imprinted antisense RNA. When administered in vivo, topotecan unsilenced the paternal Ube3a allele in several regions of the nervous system, including neurons in the hippocampus, neocortex, striatum, cerebellum and spinal cord. Paternal expression of Ube3a remained elevated in a subset of spinal cord neurons for at least twelve weeks after cessation of topotecan treatment, suggesting transient topoisomerase inhibition can have enduring effects on gene expression. While potential off-target effects remain to be investigated, our findings suggest a therapeutic strategy for reactivating the functional but dormant allele of Ube3a in patients with Angelman syndrome.
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影响因子：
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