Dynamic cytoplasmic anchoring of the transcription factor Bach1 by intracellular hyaluronic acid binding protein IHABP.
Dynamic cytoplasmic anchoring of the transcription factor Bach1 by intracellular hyaluronic acid binding protein IHABP.
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DOI：
10.1093/jb/mvi031
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发表时间：
2005-03
影响因子：
2.7
通讯作者：
Chikara Yamasaki;S. Tashiro;Y. Nishito;T. Sueda;K. Igarashi
中科院分区：
文献类型：
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作者：
Chikara Yamasaki;S. Tashiro;Y. Nishito;T. Sueda;K. Igarashi
Bach1 充当血红素加氧酶-1 (HO-1) 和 β-珠蛋白基因的转录抑制因子。这些基因的增强子区域包含多个 Bach1 可以结合的 Maf 识别元件 (MARE)。先前的研究表明，血红素和镉水平增加会诱导 Bach1 向核输出，导致细胞质积累。通过使用 Bach1 作为诱饵进行酵母两种杂交筛选，我们确定了细胞内透明质酸结合蛋白（IHABP）作为 Bach1 的潜在调节剂。 IHABP 是一种微管相关蛋白，可以调节细胞骨架网络的组织。一系列结构域分析表明，之前参与细胞质积累的 Bach1 区域对于 IHABP 结合是必需的。 IHABP 的 C 末端区域对于 Bach1 结合是必需的。过表达的 Bach1 与 IHABP 共定位于细胞质中，在微管上形成纤维状结构。光漂白后荧光恢复 (FRAP) 分析揭示了活细胞中 Bach1-IHABP 相互作用的动态性质。 Bach1 对 HO-1 报告基因活性的抑制通过共转染 IHABP 以剂量依赖性方式减弱。此外，IHABP的过度表达诱导NIH3T3细胞中内源性HO-1基因的产生。总体结果表明，IHABP 调节 Bach1 的亚细胞定位，以微调 Bach1 靶基因（例如 HO-1）的反式激活。
Bach1 functions as a transcriptional repressor of heme oxygenase-1 (HO-1) and the beta-globin genes. The enhancer regions of these genes contain multiple Maf recognition elements (MAREs) to which Bach1 can bind. Previous studies have shown that increased levels of heme and cadmium induce the nuclear export of Bach1, resulting in cytoplasmic accumulation. By means of a yeast two hybrid screening using Bach1 as bait, we identified the intracellular hyaluronic acid binding protein (IHABP) as a potential regulator of Bach1. IHABP is a microtubule-associated protein that may regulate the organization of the cytoskeletal network. A series of domain analyses revealed that a region of Bach1 previously implicated in cytoplasmic accumulation was necessary for IHABP-binding. A C-terminal region of IHABP was necessary for Bach1-binding. Overexpressed Bach1 colocalized with IHABP in the cytoplasm, forming fiber-like structures on microtubules. Fluorescence recovery after photobleaching (FRAP) analysis revealed a dynamic nature of the Bach1-IHABP interaction in living cells. The repression of HO-1 reporter activity by Bach1 was attenuated by co-transfecting IHABP in a dose-dependent manner. Moreover, the overexpression of IHABP induced the endogenous HO-1 gene in NIH3T3 cells. The overall results suggest that IHABP regulates the subcelluar localization of Bach1 in order to fine-tune transactivation of Bach1 target genes such as HO-1.