Nuclear toxicity of Huntington disease protein

亨廷顿病蛋白的核毒性

• 批准号: 7751900
• 负责人: XIAO-JIANG LI
• 金额: $ 33.09万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2011-02-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7751900
• 关键词: Affect; Aging; Aging-Related Process; Binding; Binding Sites; Brain; Cell Nucleus; Cells; Chimeric Proteins; Complex; Corpus striatum structure; Cytoplasm; Cytoplasmic Protein; Development; Diffuse; Disease; Disease Progression; Gene Expression; Glutamine; Huntington Disease; Hypoxanthine Phosphoribosyltransferase; Immunoprecipitation; Lead; Mass Spectrum Analysis; Molecular Chaperones; Mus; N-terminal; Nerve Degeneration; Neurologic; Neurons; Nuclear; Nuclear Export; Nuclear Pore; Pore Proteins; Proteins; Proteolysis; Testing; Therapeutic; Toxic effect; Ubiquitination; age related; aged; cell type; human Huntingtin protein; interest; multicatalytic endopeptidase complex; mutant; neuropathology; polyglutamine; transcription factor

Nuclear accumulation of polyglutarhine (polyQ) disease proteins is a common pathological feature of polyQ diseases, which contributes to altered gene expression and neuropathology. In Huntington disease (HD), N- terminal fragments of the disease protein huntingtin (htt) contain an expanded polyQ tract (>38 glutamines) and accumulate in the nucleus in aged neuronal cells, though these fragments do not have known nuclear localization sequences. Prior studies show that expanded polyQ can also cause a small cytoplasmic protein, hypoxanthine-guanine-phosphoribosyltransferase (HPRT), to accumulate in the nucleus even when this protein is tagged with nuclear export sequences. We found that N-terminal htt binds to the nuclear pore protein Tpr, which is involved in nuclear export, and that the binding is decreased by polyQ expansion or aggregation. We hypothesize that small N-terminal htt fragments generated by proteolysis are able to shuttle between the cytoplasm and nucleus. The nuclear export of N-terminal htt is facilitated by its interaction with Tpr. PolyQ misfolding and aggregation reduces the interaction of htt with Tpr and the nuclear export ofhtt. All these could also lead to abnormal interactions of mutant htt with transcription factors. To test these hypotheses, we propose three aims in this application. In Aim-1, we will identify the binding sites in htt and Tpr for their interaction. Wewill study whether polyQ misfolding, ubiquitination, or SUMOylation modulates this interaction to alter intranuclear accumulation of htt.In Aim-2, we will study whether the nuclear capacity to remove misfolded htt is decreased in neurons and whether this decrease results from impaired function of the proteasome or chaperones, which then leads to the selective nuclear accumulation of mutant htt in neurons. In Aim-3, we will use immunoprecipitation and mass spectrometry to identify transcription factors whose interactions with mutant htt in HD mouse brains are associated with disease progression and/or selective neurodegeneration. Understanding the molecularmechanism for the nuclear accumulation of mutant htt in HD-affected neurons will help develop a therapeutic strategy to treat HD.

聚谷氨酰胺 (polyQ) 疾病蛋白的核积聚是 PolyQ 的常见病理特征 疾病，这会导致基因表达和神经病理学的改变。在亨廷顿病 (HD) 中，N- 疾病蛋白亨廷顿蛋白 (htt) 的末端片段包含扩展的 PolyQ 束（>38 个谷氨酰胺） 并在衰老的神经元细胞的细胞核中积累，尽管这些碎片没有已知的核 定位序列。先前的研究表明，扩展的polyQ也可以导致细胞质蛋白的减少， 次黄嘌呤鸟嘌呤磷酸核糖基转移酶（HPRT），即使在这种情况下也会在细胞核中积累 蛋白质带有核输出序列标记。我们发现N端htt与核孔结合 蛋白质 Tpr，参与核输出，并且通过 polyQ 扩展或减少结合 聚合。我们假设蛋白水解产生的小 N 端 htt 片段能够穿梭 细胞质和细胞核之间。 N 端 htt 的核输出是通过其与 Tpr。 PolyQ 错误折叠和聚集减少了 htt 与 Tpr 的相互作用以及 htt 的核输出。 所有这些也可能导致突变htt与转录因子的异常相互作用。为了测试这些 假设，我们在此应用中提出了三个目标。在Aim-1中，我们将识别htt和中的结合位点 Tpr 他们的互动。我们将研究polyQ错误折叠、泛素化或SUMO化是否会调节 这种相互作用改变 htt 的核内积累。在 Aim-2 中，我们将研究核容量是否 去除错误折叠的 htt 在神经元中减少，这种减少是否是由于功能受损造成的 蛋白酶体或分子伴侣，然后导致突变体 htt 在核中选择性积累 神经元。在 Aim-3 中，我们将使用免疫沉淀和质谱来鉴定转录因子 其与 HD 小鼠大脑中突变 htt 的相互作用与疾病进展和/或 选择性神经变性。了解核积累的分子机制 受 HD 影响的神经元中的突变 htt 将有助于开发治疗 HD 的治疗策略。