Strong aggregation and increased toxicity of polyleucine over polyglutamine stretches in mammalian cells
Strong aggregation and increased toxicity of polyleucine over polyglutamine stretches in mammalian cells
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DOI：
10.1093/hmg/11.13.1487
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发表时间：
2002-06-15
影响因子：
3.5
通讯作者：
van Ommen, GJB
中科院分区：
文献类型：
--
作者：
Dorsman, JC;Pepers, B;van Ommen, GJB
某些蛋白质中谷氨酰胺 (Gln) 重复序列的扩展超过特定的临界大小会产生易于聚集的蛋白质，从而导致神经退行性疾病，例如亨廷顿病。然而，具有长亲水性聚谷氨酰胺重复序列的蛋白质在自然界中比具有长同质其他氨基酸重复序列（例如疏水性 (Ala)(n) 和 (Leu)(n)）的蛋白质更常见。为了探索这一发现，比较了混合 DNA 重复序列编码的聚谷氨酰胺和聚亮氨酸在哺乳动物细胞中表达的影响。结果发现，聚亮氨酸的毒性明显高于聚谷氨酰胺。此外，我们利用两种互补的生化测定表明，多亮氨酸片段显示出高度的聚集倾向，并且单克隆抗体 1C2 也可以检测多亮氨酸片段，该抗体特异性识别扩展的致病性和易于聚集的谷氨酰胺重复序列。总之，这些结果表明，聚谷氨酰胺片段实际上具有相对较好的耐受性，并且大自然可能对编码长疏水性均聚氨基酸片段（例如聚亮氨酸）的DNA片段进行更强烈的选择，这可能是由于它们具有强烈的聚集倾向。与这一观点相一致的是，越来越多的疾病被发现与疏水性氨基酸片段的扩张有关，包括眼咽肌营养不良症（OPMD），其与疏水性聚丙氨酸片段的扩张有关。
Expansion of a Glutamine (Gln) repeat above a specific critical size in certain proteins gives rise to aggregation-prone proteins that cause neurodegenerative disorders, such as Huntington's disease. However, proteins with long hydrophillic polyglutamine repeats are more frequently found in nature than proteins with long homogeneous repeats of other amino acids, such as hydrophobic (Ala)(n) and (Leu)(n). To explore this finding, the effects of expression in mammalian cells of polyglutamine and polyleucine encoded by mixed DNA repeats were compared. It was found that polyleucine is significantly more toxic than polyglutamine. In addition, we show that polyleucine stretches display a high propensity for aggregation utilizing two complementary biochemical assays and that polyleucine stretches can also be detected by the monoclonal antibody 1C2, which specifically recognizes expanded pathogenic and aggregation-prone glutamine repeats. Together, these results suggest that polyglutamine stretches are in fact relatively well tolerated and that nature may select more strongly against DNA stretches that encode long hydrophobic homopolymeric amino acid stretches, such as polyleucine - possibly owing to their strong propensity for aggregation. In keeping with this notion, an increasing number of diseases are found to be associated with expansion of stretches of hydrophobic amino acids, including oculopharyngeal muscular dystrophy (OPMD), which is associated with expansion of a hydrophobic polyalanine stretch.