Emerin binding to Btf, a death-promoting transcriptional repressor, is disrupted by a missense mutation that causes Emery-Dreifuss muscular dystrophy
Emerin binding to Btf, a death-promoting transcriptional repressor, is disrupted by a missense mutation that causes Emery-Dreifuss muscular dystrophy
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DOI：
10.1111/j.1432-1033.2004.04007.x
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发表时间：
2004-03-01
期刊：
影响因子：
--
通讯作者：
Hiraoka, Y
中科院分区：
文献类型：
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作者：
Haraguchi, T;Holaska, JM;Hiraoka, Y
功能性艾默林（一种核膜蛋白）的丧失会导致 X 连锁隐性艾默-德莱福斯肌营养不良症。在酵母双杂交筛选中，我们发现 emerin 与 Btf 相互作用，Btf 是一种促死亡转录抑制因子，在骨骼肌中高水平表达。生化分析表明 emerin 与 Btf 结合的平衡亲和力 (K-D) 为 100 nM。利用 emerin 中 21 个聚集的丙氨酸取代突变的集合，将与 Btf 结合所需的残基映射到 emerin 的核纤层蛋白结合域侧翼的两个区域。 emerin 中的两个致病突变 S54F 和 Delta95-99 破坏了与 Btf 的结合。 Delta95-99 突变的信息相对较少，因为该突变还会破坏 emerin 与核纤层蛋白 A 和称为无生殖细胞 (GCL) 的不同转录抑制因子的结合。与此形成鲜明对比的是，通常与屏障自动整合因子、核纤层蛋白 A 和 GCL 结合的 emerin 突变体 S54F，选择性地破坏了 emerin 与 Btf 的结合。我们使用亲和纯化的 Btf 抗体，通过间接免疫荧光法将内源性 Btf 定位在 HeLa 细胞中。在非凋亡 HeLa 细胞中，在整个核内部的点状结构中发现了 Btf。然而，用Fas抗体处理细胞诱导细胞凋亡后3小时内，Btf的分布发生变化，Btf集中在核膜附近的一个明显区域。这些结果表明，Btf 定位受细胞凋亡信号调节，并且 emerin 与 Btf 结合的丧失可能与 Emery-Dreifuss 肌营养不良症中的肌肉萎缩有关。
Loss of functional emerin, a nuclear membrane protein, causes X-linked recessive Emery-Dreifuss muscular dystrophy. In a yeast two-hybrid screen, we found that emerin interacts with Btf, a death-promoting transcriptional repressor, which is expressed at high levels in skeletal muscle. Biochemical analysis showed that emerin binds Btf with an equilibrium affinity (K-D) of 100 nM. Using a collection of 21 clustered alanine-substitution mutations in emerin, the residues required for binding to Btf mapped to two regions of emerin that flank its lamin-binding domain. Two disease-causing mutations in emerin, S54F and Delta95-99, disrupted binding to Btf. The Delta95-99 mutation was relatively uninformative, as this mutation also disrupts emerin binding to lamin A and a different transcription repressor named germ cell-less (GCL). In striking contrast, emerin mutant S54F, which binds normally to barrier-to-autointegration factor, lamin A and GCL, selectively disrupted emerin binding to Btf. We localized endogenous Btf in HeLa cells by indirect immunoflurorescence using affinity-purified antibodies against Btf. In nonapoptotic HeLa cells Btf was found in dot-like structures throughout the nuclear interior. However, within 3 h after treating cells with Fas antibody to induce apoptosis, the distribution of Btf changed, and Btf concentrated in a distinct zone near the nuclear envelope. These results suggest that Btf localization is regulated by apoptotic signals, and that loss of emerin binding to Btf may be relevant to muscle wasting in Emery-Dreifuss muscular dystrophy.