Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
Division of Translational Science, National Cancer Center, Goyang-si, Gyeonggi-do 10408, Korea.
Cells. 2019 Mar 7;8(3):220. doi: 10.3390/cells8030220.
Chicken ovalbumin upstream promoter-transcription factor I (COUP-TFI) is an orphan receptor and member of the nuclear receptor superfamily. Among a series of methylene substituted diindolylmethanes (C-DIMs) containing substituted phenyl and heteroaromatic groups, we identified 1,1-bis(3'-indolyl)-1-(4-pyridyl)-methane (DIM-C-Pyr-4) as an activator of COUP-TFI. Structure activity studies with structurally diverse heteroaromatic C-DIMs showed that the pyridyl substituted compound was active and the 4-pyridyl substituent was more potent than the 2- or 3-pyridyl analogs in transactivation assays in breast cancer cells. The DIM-C-Pyr-4 activated chimeric GAL4-COUP-TFI constructs containing full length, C- or N-terminal deletions, and transactivation was inhibited by phosphatidylinositol-3-kinase and protein kinase A inhibitors. However, DIM-C-Pyr-4 also induced transactivation and interactions of COUP-TFI and steroid receptor coactivators-1 and -2 in mammalian two-hybrid assays, and ligand-induced interactions of the C-terminal region of COUP-TFI were not affected by kinase inhibitors. We also showed that DIM-C-Pyr-4 activated COUP-TFI-dependent early growth response 1 (Egr-1) expression and this response primarily involved COUP-TFI interactions with Sp3 and to a lesser extent Sp1 bound to the proximal region of the Egr-1 promoter. Modeling studies showed interactions of DIM-C-Pyr-4 within the ligand binding domain of COUP-TFI. This report is the first to identify a COUP-TFI agonist and demonstrate activation of COUP-TFI-dependent Egr-1 expression.
鸡卵清蛋白上游启动子转录因子 I（COUP-TFI）是一种孤儿受体，属于核受体超家族成员。在一系列含有取代苯基和杂芳基的亚甲基取代二吲哚基甲烷（C-DIM）中，我们鉴定出 1,1-双（3'-吲哚基）-1-（4-吡啶基）-甲烷（DIM-C-Pyr-4）是 COUP-TFI 的激活剂。具有不同结构的杂芳基 C-DIM 的结构活性研究表明，吡啶取代的化合物是活性的，4-吡啶基取代基在乳腺癌细胞中的转激活测定中比 2-或 3-吡啶基类似物更有效。DIM-C-Pyr-4 激活包含全长、C 或 N 末端缺失的嵌合 GAL4-COUP-TFI 构建体，转激活被磷脂酰肌醇-3-激酶和蛋白激酶 A 抑制剂抑制。然而，DIM-C-Pyr-4 还在哺乳动物双杂交测定中诱导 COUP-TFI 和类固醇受体共激活剂-1 和 -2 的转激活和相互作用，并且激酶抑制剂不影响 COUP-TFI 羧基末端区域的配体诱导相互作用。我们还表明，DIM-C-Pyr-4 激活 COUP-TFI 依赖性早期生长反应 1（Egr-1）表达，这种反应主要涉及 COUP-TFI 与 Sp3 的相互作用，并且在较小程度上涉及与 Egr-1 启动子近端区域结合的 Sp1。建模研究表明 DIM-C-Pyr-4 在 COUP-TFI 的配体结合域内的相互作用。本报告首次鉴定出 COUP-TFI 激动剂，并证明激活 COUP-TFI 依赖性 Egr-1 表达。
