Essential sequence of the N-terminal cytoplasmic localization-related domain of huntingtin and its effect on huntingtin aggregates  

作　　者：YAN YaPing PENG DanTao TIAN Jun CHI JingWei TAN JieQiong YIN XinZhen PU JiaLi XIA Kun ZHANG BaoRong 

机构地区：[1]Department of Neurology, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310009, China [2]Department of Neurology, Beijing Hospital, Ministry of Health, Beijing 100730, China [3]State Key Laboratory of Medical Genetics of China, Changsha 410008, China

出　　处：《Science China(Life Sciences)》2011年第4期342-350,共9页中国科学（生命科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.30770761 and 30971000)

摘　　要：Huntington＇s disease （HD） is caused by abnormal CAG repeat expansion in the 5＇-end of the Huntingtin （HTT） gene. In addition to the canonical C-terminal full-length huntingtin （htt） nuclear export signal, a cytoplasmic localization-related domain （CLRD） in the N-terminus of htt has recently been reported. Here, we analyzed this domain by introducing deletion and substitution mutations in a truncated N-terminal htt protein and subsequently monitored htt expression, aggregation and subcellular localization by immunocytochemistry and Western blot analysis. We demonstrated that Htt1-17 was the essential sequence for htt cytoplasmic localization. We also found that the subcellular distribution of htt was altered when Htt1_17 was mutated to contain amino acids of different charges, suggesting a structural requirement of Htt1-17 for the cytoplasmic localization of htt. Deletion of the first three amino acids did not affect its association with mitochondria. We observed that defective cytoplasmic localization resulted in a reduction of total htt aggregates and increased nuclear aggregates, indicating that the subcellular distribution of the protein might influence the aggregation process. These studies provide new insight into the molecular mechanism of htt aggregation in HD.Huntington's disease(HD) is caused by abnormal CAG repeat expansion in the 5′-end of the Huntingtin(HTT) gene.In addition to the canonical C-terminal full-length huntingtin(htt) nuclear export signal,a cytoplasmic localization-related domain(CLRD) in the N-terminus of htt has recently been reported.Here,we analyzed this domain by introducing deletion and substitution mutations in a truncated N-terminal htt protein and subsequently monitored htt expression,aggregation and subcellular localization by immunocytochemistry and Western blot analysis.We demonstrated that Htt4-17 was the essential sequence for htt cytoplasmic localization.We also found that the subcellular distribution of htt was altered when Htt1-17 was mutated to contain amino acids of different charges,suggesting a structural requirement of Htt1-17 for the cytoplasmic localization of htt. Deletion of the first three amino acids did not affect its association with mitochondria.We observed that defective cytoplasmic localization resulted in a reduction of total htt aggregates and increased nuclear aggregates,indicating that the subcellular distribution of the protein might influence the aggregation process.These studies provide new insight into the molecular mechanism of htt aggregation in HD.

关 键 词：HUNTINGTIN AGGREGATES cytoplasmic localization related domain mitochondria POLYGLUTAMINE 

分 类 号：Q75[生物学—分子生物学] S512.1[农业科学—作物学]