Transcriptional down-regulation of MARCKS gene expression in immortalized hippocampal cells by lithium.
Transcriptional down-regulation of MARCKS gene expression in immortalized hippocampal cells by lithium.
复制标题
锂对永生化海马细胞中 MARCKS 基因表达的转录下调。
DOI：
10.1046/j.1471-4159.2001.00631.x
复制
发表时间：
2001
影响因子：
4.7
通讯作者：
Lenox,RH
中科院分区：
文献类型：
--
作者：
Wang,L;Liu,X;Lenox,RH
小鼠富含肉豆蔻酰化丙氨酸的 C 激酶底物 (MARCKS) 的基因 (Macs) 编码蛋白激酶 C 的一种重要底物，该底物与肌动蛋白膜可塑性和细胞骨架重组中需要信号依赖性变化的过程有关。我们之前已经证明，长期暴露于临床相关浓度（1 mm）的锂后，MARCKS 蛋白在大鼠海马和永生化海马细胞系（HN33.dw）中显着下调。我们目前的研究已经检查了转录和转录后事件，这些事件可能是培养海马细胞模型系统中锂诱导的 MARCKS 蛋白下调的基础。发现 HN33.dw 细胞长期接触锂后，MARCKS mRNA 和蛋白质表达同时下调。尽管在锂存在的情况下，MARCKS mRNA 的稳定性保持不变，但核径流测定表明，在用锂处理 7 天的细胞中，新生 MARCKS mRNA 的转录显着降低（约 50%）。用小鼠克隆的 Macs 启动子 (993-bp) 瞬时转染 HN33.dw 细胞表明，在慢性（7-10 天）而不是亚急性（24 小时）锂暴露后，Macs 启动子活性减弱到相同程度。发现Macspromoter的抑制依赖于相对于翻译起始位点-993-bp和-713-bp之间的280-bp启动子区域的存在，表明该区域是Macspromoter (LRR)的潜在锂响应区域。缺乏LRR的突变启动子不仅对长期锂暴露没有反应，而且启动子活性显着降低，这表明长期锂暴露抑制了与启动子结合的激活剂的转录活性。综上所述，我们的数据表明 Macs 基因的转录抑制是锂诱导永生化海马细胞中 MARCKS 表达下调的基础。
The gene (Macs) for the mouse myristoylated alanine‐rich C kinasesubstrate (MARCKS) encodes a prominent substrate for protein kinase C that has been implicated in processes requiring signal dependent changes in actin‐membrane plasticity and cytoskeletal restructuring. We have previously demonstrated that MARCKS protein is significantly down‐regulated in rat hippocampus and in an immortalized hippocampal cell line (HN33.dw) following long‐term exposure to lithium at clinically relevant concentrations (1 mm). Our current studies have examined transcriptional and post‐transcriptional events that may underlie the lithium‐induced down‐regulation of MARCKS protein in the cultured hippocampal cell model system. MARCKS mRNA and protein expression were found to be concomitantly down‐regulated following exposure of the HN33.dw cells to chronic lithium. Whereas the stability of MARCKS mRNA remained unchanged in the presence of lithium, nuclear run‐off assay indicated that the transcription of nascent MARCKS mRNA was significantly reduced (≈50%) in the cells that had been treated with lithium for 7 days. Transient transfection of HN33.dw cells with a mouse clonedMacspromoter (993‐bp) showed that theMacspromoter activity was attenuated to the same extent after chronic (7–10 days), but not subacute (24 h), lithium exposure. The inhibition of theMacspromoter was found to be dependent upon the presence of a 280‐bp promoter region between −993‐bp and −713‐bp relative to the translation start site, suggesting that this region is a potential lithium‐responsive region ofMacspromoter (LRR). Mutant promoter lacking the LRR not only did not respond to chronic lithium exposure but also had significantly reduced promoter activity, suggesting that chronic lithium exposure represses the transcriptional activity of activator(s) bound to the promoter. Taken together, our data indicate that transcriptional inhibition of theMacsgene underlies the lithium‐induced down‐regulation of MARCKS expression in the immortalized hippocampal cells.