ISOFORM-SPECIFIC AMINO-TERMINAL DOMAINS DICTATE DNA-BINDING PROPERTIES OF ROR-ALPHA, A NOVEL FAMILY OF ORPHAN HORMONE NUCLEAR RECEPTORS
ISOFORM-SPECIFIC AMINO-TERMINAL DOMAINS DICTATE DNA-BINDING PROPERTIES OF ROR-ALPHA, A NOVEL FAMILY OF ORPHAN HORMONE NUCLEAR RECEPTORS
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DOI：
10.1101/gad.8.5.538
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发表时间：
1994-03-01
影响因子：
10.5
通讯作者：
OTULAKOWSKI, G
中科院分区：
文献类型：
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作者：
GIGUERE, V;TINI, M;OTULAKOWSKI, G
与视黄酸受体相关的类固醇激素核受体超家族的新成员的三种亚型已经被鉴定。三种亚型，称为ROR α 1，ROR α 2和ROR α 3，共享共同的DNA和推定的配体结合结构域，但其特征在于通过替代RNA加工产生的不同的氨基末端结构域。编码ROR α 2同种型氨基末端结构域的功能重要亚区的外显子位于细胞色素c加工假基因的相对链上。使用体外合成的蛋白质的结合位点选择揭示了ROR α 1和ROR α 2同种型将DNA作为单体结合到激素应答元件，所述激素应答元件由在半位点核心基序PuGGTCA（RORE）之前的6-bp AT富集序列组成。然而，ROR α 1和ROR α 2显示出不同的结合特异性：ROR α 1结合并组成性激活大的RORE亚群的转录，而ROR α 2以严格的特异性识别RORE并显示较弱的转录活性。每个亚型的差异DNA结合活性映射到其各自的氨基末端结构域。尽管氨基末端结构域的截短降低了ROR α 1结合DNA的能力，但类似的缺失使ROR α 2结合特异性松弛至ROR α 1所显示的特异性。值得注意的是，ROR α 1的整个氨基末端区域的转移或ROR α 2的氨基末端缺失赋予RORE对异源受体的结合特异性。这些结果表明，氨基末端结构域和锌指区协同工作，赋予高亲和力和特异性的DNA结合特性的ROR亚型，并提出了一种新的策略来控制核受体的DNA结合活性。
Three isoforms of a novel member of the steroid hormone nuclear receptor superfamily related to the retinoic acid receptors have been identified. The three isoforms, referred to as ROR alpha 1, ROR alpha 2, and ROR alpha 3, share common DNA- and putative ligand-binding domains but are characterized by distinct amino-terminal domains generated by alternative RNA processing. An exon encoding a functionally important subregion of the amino-terminal domain of the ROR alpha 2 isoform resides on the opposite strand of a cytochrome c-processed pseudogene. Binding site selection using in vitro-synthesized proteins reveals that the ROR alpha 1 and ROR alpha 2 isoforms bind DNA as monomers to hormone response elements composed of a 6-bp AT-rich sequence preceding a half-site core motif PuGGTCA (RORE). However, ROR alpha 1 and ROR alpha 2 display different binding specificities: ROR alpha 1 binds to and constitutively activates transcription from a large subset of ROREs, whereas ROR alpha 2 recognizes ROREs with strict specificity and displays weaker transcriptional activity. The differential DNA-binding activity of each isoform maps to their respective amino-terminal domains. Whereas truncation of the amino-terminal domain diminishes the ability of ROR alpha 1 to bind DNA, a similar deletion relaxes ROR alpha 2-binding specificity to that displayed by ROR alpha 1. Remarkably, transfer of the entire amino-terminal region of ROR alpha 1 or amino-terminal deletion of ROR alpha 2 confers RORE-binding specificities to heterologous receptors. These results demonstrate that the amino-terminal domain and the zinc finger region work in concert to confer high affinity and specific DNA-binding properties to the ROR isoforms and suggest a novel strategy to control DNA-binding activity of nuclear receptors.