Scappini Erica, Koh Tong-Wey, Martin Negin P, O'Bryan John P
Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA.
Hum Mol Genet. 2007 Aug 1;16(15):1862-71. doi: 10.1093/hmg/ddm134. Epub 2007 Jun 5.
Huntingon's disease is a progressive neurodegenerative disease arising from expansion of a polyglutamine (polyQ) tract in the protein huntingtin (Htt) resulting in aggregation of mutant Htt into nuclear and/or cytosolic inclusions in neurons. Mutant Htt affects multiple processes including protein degradation, transcription, signal transduction, fast axonal transport and endocytosis [reviewed in Ross, C.A. and Poirier, M.A. (2005) Opinion: what is the role of protein aggregation in neurodegeneration? Nat. Rev. Mol. Cell. Biol., 6, 891-898]. Here, we report that the endocytic and signal transduction scaffold intersectin (ITSN) increased aggregate formation by mutant Htt through activation of the c-Jun-NH(2)-terminal kinase (JNK)-MAPK pathway. Conversely, silencing ITSN or inhibiting JNK attenuated aggregate formation. Using a Drosophila model for polyQ repeat disease, we observed that ITSN enhanced polyQ-mediated neurotoxicity. A reciprocal relationship was observed between ITSN and Htt. While ITSN enhanced Htt aggregation and toxicity, Htt, in turn, inhibited the cooperativity between ITSN and the epidermal growth factor receptor signal transduction pathway. Finally, we observed that ITSN overexpression enhanced aggregation of polyQ-expanded androgen receptor (AR) as well as wild-type versions of both Htt and AR suggesting a broader involvement of ITSN in neurodegenerative diseases through destabilization of polyQ-containing proteins.
亨廷顿舞蹈病是一种进行性神经退行性疾病，由亨廷顿蛋白（Htt）中多聚谷氨酰胺（polyQ）序列的扩增引起，导致突变型Htt在神经元中聚集成核内和/或胞质内包涵体。突变型Htt影响多个过程，包括蛋白质降解、转录、信号转导、快速轴突运输和内吞作用[见Ross, C.A.和Poirier, M.A.（2005年）观点：蛋白质聚集在神经退行性变中的作用是什么？《自然评论：分子细胞生物学》，6, 891 - 898]。在此，我们报告内吞和信号转导支架蛋白相交蛋白（ITSN）通过激活c-Jun-NH(2)-末端激酶（JNK）-丝裂原活化蛋白激酶（MAPK）途径增加突变型Htt的聚集体形成。相反，沉默ITSN或抑制JNK可减弱聚集体形成。利用果蝇多聚Q重复疾病模型，我们观察到ITSN增强了多聚Q介导的神经毒性。在ITSN和Htt之间观察到一种相互关系。虽然ITSN增强了Htt的聚集和毒性，但Htt反过来抑制了ITSN与表皮生长因子受体信号转导途径之间的协同作用。最后，我们观察到ITSN过表达增强了多聚Q扩展的雄激素受体（AR）以及Htt和AR野生型版本的聚集，这表明ITSN通过使含多聚Q的蛋白质不稳定而更广泛地参与神经退行性疾病。
