Heat shock factor 4 regulates the expression of HSP25 and alpha B-crystallin by associating with DEXD/H-box RNA helicase UAP56
Heat shock factor 4 regulates the expression of HSP25 and alpha B-crystallin by associating with DEXD/H-box RNA helicase UAP56
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热休克因子 4 通过与 DEXD/H-box RNA 解旋酶 UAP56 结合调节 HSP25 和 α B-晶状体蛋白的表达
DOI：
10.1007/s12192-017-0865-y
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发表时间：
2018-07-01
影响因子：
3.8
通讯作者：
Hu, Yanzhong
中科院分区：
文献类型：
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作者：
Cui, Xiukun;Han, Wenxiu;Hu, Yanzhong
热休克因子4控制小的热休克蛋白（例如，HSP 25、α B-晶状体蛋白和r-晶状体蛋白），其在调节透镜蛋白质稳态中起重要作用。然而，HSF 4介导的转录的分子机制仍不清楚。利用酵母双杂交技术，我们发现HSF 4与ATP依赖的DEXD/H-box RNA解旋酶UAP 56相互作用，并通过GST-pull down实验进一步证实了它们在透镜上皮细胞系中的相互作用。UAP 56是前mRNA剪接和成熟mRNA核输出的重要调节因子。免疫荧光检测显示HSF 4和UBA 56共定位于透镜上皮细胞核内。异位UAP 56上调HSF 4调控的HSP 25和α B-crystallin蛋白的表达，而通过shRNA敲低UAP 56则逆转了这一作用，而且UAP 56与HSP 25和α B-crystallin mRNA相互作用，促进其向细胞核的输出，而不影响其总的mRNA表达水平。在透镜组织中，UAP 56和HSF 4均在透镜纤维细胞的同一核中表达，并且它们的表达水平随着纤维细胞成熟而同时降低。综上所述，这些数据表明UAP 56是HSF 4的一种新的调节剂，并且可能上调HSF 4的下游mRNA成熟和核输出。
Heat shock factor 4 controls the transcription of small heat shock proteins (e.g., HSP25, alpha B-cyrstallin, and r-crystallin), that play important roles in modulating lens proteostasis. However, the molecular mechanism underlying HSF4-mediated transcription is still unclear. Using yeast two hybrid, we found that HSF4 interacts with the ATP-dependent DEXD/H-box RNA helicase UAP56, and their interaction in lens epithelial cell line was further confirmed by GST-pull down assay. UAP56 is a vital regulator of pre-mRNA splicing and mature mRNA nuclear export. The immunofluorescence assay showed that HSF4 and UBA56 co-localize with each other in the nucleus of lens epithelial cells. Ectopic UAP56 upregulated HSF4-controlled HSP25 and alpha B-crystallin proteins expression, while knocking down UAP56 by shRNA reversed it. Moreover, UAP56 interacts with and facilitates the nuclear exportation of HSP25 and alpha B-crystallin mRNA without impacting their total mRNA expression level. In lens tissues, both UAP56 and HSF4 are expressed in the same nucleus of lens fiber cells, and their expression levels are simultaneously reduced with fiber cell maturation. Taken together, these data suggested that UAP56 is a novel regulator of HSF4 and might upregulate HSF4’s downstream mRNA maturation and nuclear exportation.