Expanded-polyglutamine huntingtin protein suppresses the secretion and production of a chemokine (CCL5/RANTES) by astrocytes
Expanded-polyglutamine huntingtin protein suppresses the secretion and production of a chemokine (CCL5/RANTES) by astrocytes
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DOI：
10.1523/jneurosci.0116-08.2008
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发表时间：
2008-03-26
影响因子：
5.3
通讯作者：
Chern, Yijuang
中科院分区：
文献类型：
--
作者：
Chou, Szu-Yi;Weng, Ju-Yun;Chern, Yijuang
亨廷顿病 (HD) 是一种遗传性神经系统疾病，由 HD 基因中的 CAG 重复序列扩展引起，该基因编码一种名为亨廷顿蛋白 (Htt) 的蛋白质。由此产生的突变亨廷顿蛋白 (mHtt) 在神经元中形成聚集体并导致神经元功能障碍。在星形胶质细胞（最大的脑细胞群体）中，mHtt 也存在。我们在此报道，从 R6/2 小鼠（HD 小鼠模型）星形胶质细胞收集的星形胶质细胞条件培养基（ACM）导致初级皮层神经元生长不太成熟的神经突，迁移更慢，并且在去极化后表现出比野生型（WT）ACM 中维持的钙流入更低。使用细胞因子抗体阵列和 ELISA 测定，我们证明 R6/2 星形胶质细胞释放的趋化因子 [趋化因子（C-C 基序）配体 5 (CCL5)/调节正常 T 细胞表达和分泌的激活 (RANTES)] 的量远少于 WT 星形胶质细胞。当皮层神经元用指定的 ACM 处理时，补充重组 CCL5/RANTES 改善了 HD-ACM 引起的神经元缺陷，而使用抗 CCL5/RANTES 抗体从 WT-ACM 中去除 CCL5/RANTES 则模拟了 HD-ACM 引起的效果。定量 PCR 和启动子分析表明，mHtt 通过降低核因子 kappa B-p65 的可用性来阻碍 CCL5/RANTES 启动子的激活，从而降低 CCL5/RANTES 的转录水平。此外，ELISA 测定和免疫细胞化学染色显示 mHtt 在 R6/2 星形胶质细胞内保留了残留的 CCL5/RANTES。与上述发现一致，在两种 HD 小鼠模型[R6/2 和 Hdh((CAG)150)] 和人类 HD 患者的大脑中也观察到胞质 CCL5/RANTES 水平升高。这些发现表明 mHtt 阻碍星形胶质细胞的一项主要营养功能，这可能导致 HD 的神经元功能障碍。
Huntington's disease (HD) is a hereditary neurological disease caused by expended CAG repeats in the HD gene, which codes for a protein called Huntingtin ( Htt). The resultant mutant Huntingtin (mHtt) forms aggregates in neurons and causes neuronal dysfunction. In astrocytes, the largest population of brain cells, mHtt also exists. We report herein that astrocyte-conditioned medium (ACM) collected from astrocytes of R6/2 mice ( a mouse model of HD) caused primary cortical neurons to grow less-mature neurites, migrate more slowly, and exhibit lower calcium influx after depolarization than those maintained in wild-type (WT) ACM. Using a cytokine antibody array and ELISA assays, we demonstrated that the amount of a chemokine [chemokine (C-C motif) ligand 5 (CCL5)/regulated on activation normal T cell expressed and secreted ( RANTES)] released by R6/2 astrocytes was much less than that by WT astrocytes. When cortical neurons were treated with the indicated ACM, supplementation with recombinant CCL5/RANTES ameliorated the neuronal deficiency caused by HD-ACM, whereas removing CCL5/RANTES from WT-ACM using an anti-CCL5/RANTES antibody mimicked the effects evoked by HD-ACM. Quantitative PCR and promoter analyses demonstrated that mHtt hindered the activation of the CCL5/RANTES promoter by reducing the availability of nuclear factor kappa B-p65 and, hence, reduced the transcript level of CCL5/RANTES. Moreover, ELISA assays and immunocytochemical staining revealed that mHtt retained the residual CCL5/RANTES inside R6/2 astrocytes. In line with the above findings, elevated cytosolic CCL5/RANTES levels were also observed in the brains of two mouse models of HD[R6/2 and Hdh((CAG)150)] and human HD patients. These findings suggest that mHtt hinders one major trophic function of astrocytes which might contribute to the neuronal dysfunction of HD.