中国组织工程研究2012，Vol.16Issue(20)：3773-3778,6.
变异亨廷顿蛋白对CBP组蛋白乙酰化酶活性及其蛋白表达的影响
Effect of mutant huntingtin on the expression levels and histone acetyltransferase activity of CREB-binding protein
摘要
Abstract
BACKGROUND: Studies addressing the role of CREB-binding protein (CBP) in the pathogenesis of Huntington's disease are mainly concentrated in the inhibitory effect of aggregate formation on CBP.OBJECTIVE: To investigate the effect of mutant huntingtin (htt) on the histone acetyltransferase (HAT) activity and expression levels of CBP in the cell model of Huntington's disease.METHODS: Neuronal phaeochromocytoma rat PC12 cells, stably inducible for GFP-tagged HD exon 1 with either 23 (normal) or 74 (expanded) glutamines (N-htt-Q23 or -Q74), driven by a doxycycline (dox)-dependent Tet-On promoter were used. N-htt expression was observed via immunofluorescence microscopy. The HAT activities of endogenous CBP were determined via a histone H4 acetylation assay with immunoprecipitated CBP. CBP protein levels were observed via Western blot. The effect of specific proteasome inhibitor on CBP protein level was investigated by adding MG-132. CBP mRNA levels were detected by Lightcycler PCR.RESULTS AND CONCLUSION: Cells expressing N-htt-Q74 started to form visible aggregates 1 day after dox induction in a small percentage of cells (< 1%), while after 6 days aggregates were present in about 90% of cells. In contrast, N-htt-Q23 distributed evenly throughout the cells and did not form aggregates. Expression of soluble N-htt-Q74 already inhibited the HAT activity of CBP, the inhibitory effect was exacerbated by aggregate formation of N-htt-Q74, while N-htt-Q23 did not affect CBP HAT activity. Expression of soluble N-htt-Q74 already reduced CBP protein levels; the level of CBP was dramatically decreased after 6 days, while N-htt-Q23 did not affect the levels of CBP protein. Neither N-htt-Q74 nor -Q23 affected CBP mRNA levels. The proteasome inhibitor MG-132 partly restored CBP protein levels by affecting protein degradation in the cells expressing N-htt-Q74. The results indicated that decrement of CBP HAT activity and its protein level play important roles in the molecular pathogenesis HD. Aside from aggregated mutant N-htt, soluble mutant N-htt already represses CBP HAT activity and CBP level, providing theoretical evidence for administration of CBP and histone deacetylase inhibitor in the treatment of Huntington's disease in the early stages.关键词
亨廷顿舞蹈病/CREB结合蛋白/蛋白酶体抑制剂/变异亨廷顿蛋白/组蛋白乙酰化酶分类
医药卫生引用本文复制引用
丛树艳,张威,王亚,邵华,冯娟..变异亨廷顿蛋白对CBP组蛋白乙酰化酶活性及其蛋白表达的影响[J].中国组织工程研究,2012,16(20):3773-3778,6.基金项目
国家自然科学基金资助项目(30971017) （30971017）
辽宁省博士启动基金(20080526)项目. （20080526）
