Truncated N-terminal huntingtin fragment with expanded-polyglutamine (htt552-100Q) suppresses brain-derived neurotrophic factor transcription in astrocytes.
Truncated N-terminal huntingtin fragment with expanded-polyglutamine (htt552-100Q) suppresses brain-derived neurotrophic factor transcription in astrocytes.
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DOI：
10.1093/abbs/gmr125
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发表时间：
2012-03
影响因子：
3.7
通讯作者：
Lin-hui Wang;Fang Lin;Jin Wang;Jun-chao Wu;Rong Han;Lujia Zhu;Guoxing Zhang;M. Difiglia;Zhenghong Qin
中科院分区：
文献类型：
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作者：
Lin-hui Wang;Fang Lin;Jin Wang;Jun-chao Wu;Rong Han;Lujia Zhu;Guoxing Zhang;M. Difiglia;Zhenghong Qin
虽然亨廷顿蛋白（htt）可以在许多位点被半胱天冬酶、钙蛋白酶和N-乙酰基蛋白酶切割，但氨基酸（aa）552被定义为在人亨廷顿病（HD）脑中体内切割的优选位点。迄今为止，野生型htt N端片段1-552 aa（htt 552）的正常功能和突变型htt 552的病理作用仍不清楚。虽然突变型htt（mhtt）也在星形胶质细胞中表达，但mhtt是否以及如何通过星形胶质细胞在HD中促进神经退行性变仍然是未知的。本研究利用腺病毒载体在大鼠原代皮层星形胶质细胞中表达野生型htt 552（htt 552 - 18 Q）及其突变体（htt 552 - 100 Q），建立胶质细胞HD模型，研究htt 552对脑源性神经营养因子（BDNF）转录的影响。酶联免疫吸附试验结果显示，表达htt 552 - 100 Q的星形胶质细胞条件培养液中BDNF水平降低。实时荧光定量聚合酶链反应结果表明，HTT 552 - 100 Q能减少BDNF III和IV的转录，从而抑制BDNF的转录。免疫荧光结果显示，HTT 552 - 100 Q形成的聚集体包埋了转录因子cAMP反应元件结合蛋白和刺激蛋白1，这可能是导致BDNF转录减少的原因。这些结果表明，mhtt 552减少BDNF在星形胶质细胞的转录，这可能有助于在HD的神经功能障碍。
Although huntingtin (htt) can be cleaved at many sites by caspases, calpains, and aspartyl proteases, amino acid (aa) 552 was defined as a preferred site for cleavage in human Huntington disease (HD) brains in vivo. To date, the normal function of wild-type N-terminal htt fragment 1-552 aa (htt552) and its pathological roles of mutant htt552 are still unknown. Although mutant htt (mhtt) is also expressed in astrocytes, whether and how mhtt contributes to the neurodegeneration through astrocytes in HD remains largely unknown. In this study, a glia HD model, using an adenoviral vector to express wild-type htt552 (htt552-18Q) and its mutation (htt552-100Q) in rat primary cortical astrocytes, was generated to investigate the influence of htt552 on the transcription of brain-derived neurotrophic factor (BDNF). Results from enzyme linked immunosorbent assay showed that the level of BDNF in astrocyte-conditioned medium was decreased in the astrocytes expressing htt552-100Q. Quantitative real-time polymerase chain reaction demonstrated that htt552-100Q reduced the transcripts of the BDNF III and IV, hence, repressed the transcription of BDNF. Furthermore, immunofluorescence showed that aggregates formed by htt552-100Q entrapped transcription factors cAMP-response element-binding protein and stimulatory protein 1, which might account for the reduction of BDNF transcription. These findings suggest that mhtt552 reduces BDNF transcription in astrocytes, which might contribute to the neuronal dysfunction in HD.