Ca2+-activated Nucleotidase 1, a Novel Target Gene for the Transcriptional Repressor DREAM (Downstream Regulatory Element Antagonist Modulator), Is Involved in Protein Folding and Degradation
Ca2+-activated Nucleotidase 1, a Novel Target Gene for the Transcriptional Repressor DREAM (Downstream Regulatory Element Antagonist Modulator), Is Involved in Protein Folding and Degradation
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DOI：
10.1074/jbc.m111.304733
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发表时间：
2012-05-25
影响因子：
4.8
通讯作者：
Brini, Marisa
中科院分区：
文献类型：
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作者：
Cali, Tito;Fedrizzi, Laura;Brini, Marisa
DREAM是一种在神经元细胞中高度表达的Ca 2+依赖性转录抑制因子。许多基因已经被确定为其调控的靶点。对表达显性活性DREAM突变体（daDREAM）的转基因小鼠小脑进行的靶向分析显示，Ca 2+激活的核苷酸酶1（CANT 1）的转录量急剧减少，CANT 1是一种内质网（ER）-高尔基体驻留的Ca 2+依赖性核苷二磷酸酶，已被认为在与ER和高尔基体中蛋白质质量控制相关的糖基化反应中发挥作用。CANT 1下调也被发现在神经母细胞瘤SH-SY 5 Y细胞稳定过表达野生型（wt）DREAM或daDREAM，从而提供了一个简单的细胞模型，研究蛋白质成熟途径。脉冲追踪实验表明，CANT 1的下调与蛋白分泌减少和降解速率增加有关。重要的是，wtDREAM或daDREAM的过表达增强了EDEM 1基因的表达，EDEM 1基因编码ER相关降解途径的关键组分，这表明了增强蛋白质降解的替代途径。在神经母细胞瘤克隆中恢复CANT 1水平恢复了表型，从而证实了CANT 1及其基因通过DREAM调控在蛋白质合成和降解控制中的关键作用。
DREAM is a Ca2+-dependent transcriptional repressor highly expressed in neuronal cells. A number of genes have already been identified as the target of its regulation. Targeted analysis performed on cerebella from transgenic mice expressing a dominant active DREAM mutant (daDREAM) showed a drastic reduction of the amount of transcript of Ca2+-activated nucleotidase 1 (CANT1), an endoplasmic reticulum (ER)-Golgi resident Ca2+-dependent nucleoside diphosphatase that has been suggested to have a role in glucosylation reactions related to the quality control of proteins in the ER and the Golgi apparatus. CANT1 down-regulation was also found in neuroblastoma SH-SY5Y cells stably overexpressing wild type (wt) DREAM or daDREAM, thus providing a simple cell model to investigate the protein maturation pathway. Pulse-chase experiments demonstrated that the down-regulation of CANT1 is associated with reduced protein secretion and increased degradation rates. Importantly, overexpression of wtDREAM or daDREAM augmented the expression of the EDEM1 gene, which encodes a key component of the ER-associated degradation pathway, suggesting an alternative pathway to enhanced protein degradation. Restoring CANT1 levels in neuroblastoma clones recovered the phenotype, thus confirming a key role of CANT1, and of the regulation of its gene by DREAM, in the control of protein synthesis and degradation.