The carbohydrate response element binding protein (ChREBP) is a glucose-responsive transcription factor that plays a critical role in glucose-mediated induction of genes involved in hepatic glycolysis and lipogenesis. In response to fluctuating blood glucose levels ChREBP activity is regulated mainly by nucleocytoplasmic shuttling of ChREBP. Under high glucose ChREBP binds to importin α and importin β and translocates into the nucleus to initiate transcription. We have previously shown that the nuclear localization signal site (NLS) for ChREBP is bipartite with the NLS extending from Arg158 to Lys190. Here, we report the 2.5 Å crystal structure of the ChREBP-NLS peptide bound to importin α. The structure revealed that the NLS binding is monopartite, with the amino acid residues K171RRI174 from the ChREBP-NLS interacting with ARM2–ARM5 on importin α. We discovered that importin α also binds to the primary binding site of the 14-3-3 proteins with high affinity, which suggests that both importin α and 14-3-3 are each competing with the other for this broad-binding region (residues 117–196) on ChREBP. We screened a small compound library and identified two novel compounds that inhibit the ChREBP-NLS/importin α interaction, nuclear localization, and transcription activities of ChREBP. These candidate molecules support developing inhibitors of ChREBP that may be useful in treatment of obesity and the associated diseases.

中文翻译：

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Importinα的结构和ChREBP的核定位肽，以及ChREBP-importinα相互作用的小化合物抑制剂。

碳水化合物反应元件结合蛋白（ChREBP）是葡萄糖反应性转录因子，在葡萄糖介导的肝糖酵解和脂肪形成相关基因的诱导中起关键作用。响应于血糖水平的波动，ChREBP活性主要由ChREBP的核质穿梭调节。在高葡萄糖下，ChREBP结合importinα和importinβ并易位进入细胞核以启动转录。我们以前已经表明，ChREBP的核定位信号位点（NLS）是两部分的，并且NLS从Arg158延伸到Lys190。在这里，我们报道了与importinα结合的ChREBP-NLS肽的2.5Å晶体结构。结构表明NLS结合是单部分的，ChREBP-NLS的氨基酸残基K171RRI174与输入α上的ARM2-ARM5相互作用。我们发现importinα还以很高的亲和力与14-3-3蛋白的主要结合位点结合，这表明importinα和14-3-3都彼此竞争这个广泛的结合区域（残基117–196）。我们筛选了一个小的化合物库，并鉴定了两种抑制ChREBP-NLS /重要蛋白α相互作用，核定位和ChREBP转录活性的新型化合物。这些候选分子支持开发的ChREBP抑制剂，可用于治疗肥胖症和相关疾病。这表明importinα和14-3-3都在ChREBP的这个广泛结合区域（残基117-196）相互竞争。我们筛选了一个小的化合物库，并鉴定了两种抑制ChREBP-NLS /重要蛋白α相互作用，核定位和ChREBP转录活性的新型化合物。这些候选分子支持开发的ChREBP抑制剂，可用于治疗肥胖症和相关疾病。这表明importinα和14-3-3都在ChREBP的这个广泛结合区域（残基117-196）相互竞争。我们筛选了一个小的化合物库，并鉴定了两种抑制ChREBP-NLS /重要蛋白α相互作用，核定位和ChREBP转录活性的新型化合物。这些候选分子支持开发的ChREBP抑制剂，可用于治疗肥胖症和相关疾病。