Characterization of a subset of the basic-helix-loop-helix-PAS superfamily that interacts with components of the dioxin signaling pathway
Characterization of a subset of the basic-helix-loop-helix-PAS superfamily that interacts with components of the dioxin signaling pathway
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DOI：
10.1074/jbc.272.13.8581
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发表时间：
1997-03-28
影响因子：
4.8
通讯作者：
Bradfield, CA
中科院分区：
文献类型：
--
作者：
Hogenesch, JB;Chan, WK;Bradfield, CA
为了更好地了解2,3,7,8-四氯二苯并-对二恶英的毒性机制，我们采用了人类表达序列标签的迭代搜索，以鉴定与Ah受体（AHR）或Ah受体核转运体（ARNT）相互作用的新型碱性-螺旋-环-螺旋- pas （bHLH-PAS）蛋白。我们描述了五个新的“PAS超家族成员”，或MOPs 1-5，它们在大小和结构组织上与AHR和ARNT相似。MOPs 1-4具有n端bHLH和PAS结构域和c端可变区。MOP5含有特征PAS结构域和可变C端；cDNA可能包含bHLH结构域，但整个开放阅读框尚未完成。共免疫沉淀研究、酵母双杂交分析和瞬时转染实验表明，MOP1和MOP2与ARNT二聚体，并且这些复合物在体内对特定的DNA增强子序列具有转录活性。在体外发现MOP3与AHR相关，但在体内没有。这一观察结果，再加上MOP3与90kda热休克蛋白形成了比人类AHR更紧密的联系，表明MOP3可能是一种条件活性bHLH-PAS蛋白，需要一种未知配体的激活。AHR、MOP1和MOP2 mrna的表达谱，再加上它们作为一个共同的二聚体伴侣共享ARNT的观察，表明MOP1和MOP2介导的细胞通路可能影响或响应二恶英信号通路。
In an effort to better understand the mechanism of toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin, we employed an iterative search of human expressed sequence tags to identify novel basic-helix-loop-helix-PAS (bHLH-PAS) proteins that interact with either the Ah receptor (AHR) or the Ah receptor nuclear translocator (ARNT). We characterized five new ''members of the PAS superfamily,'' or MOPs 1-5, that are similar in size and structural organization to the AHR and ARNT. MOPs 1-4 have N-terminal bHLH and PAS domains and C-terminal variable regions. MOP5 contained the characteristic PAS domain and a variable C terminus; it is possible that the cDNA contains a bHLH domain, but the entire open reading frame has yet to be completed. Coimmunoprecipitation studies, yeast two-hybrid analysis, and transient transfection experiments demonstrated that MOP1 and MOP2 dimerize with ARNT and that these complexes are transcriptionally active at defined DNA enhancer sequences in vivo. MOP3 was found to associate with the AHR in vitro but not in vivo. This observation, coupled with the fact that MOP3 formed tighter associations with the 90-kDa heat shock protein than the human AHR, suggests that MOP3 may be a conditionally active bHLH-PAS protein that requires activation by an unknown ligand. The expression profiles of the AHR, MOP1, and MOP2 mRNAs, coupled with the observation that they all share ARNT as a common dimeric partner, suggests that the cellular pathways mediated by MOP1 and MOP2 may influence or respond to the dioxin signaling pathway.