LIM-homeo domain transcription factor, Lhx2, is involved in transcriptional control of brain-specific promoter/exon 1f of the
LIM-homeo domain transcription factor, Lhx2, is involved in transcriptional control of brain-specific promoter/exon 1f of the
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LIM-同源结构域转录因子 Lhx2 参与大脑特异性启动子/外显子 1f 的转录控制
DOI：
10.1111/j.1365-2826.2012.02356.x
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
H.
中科院分区：
文献类型：
--
作者：
Honda;S.-I.;Kozako;T.;Shimeno;H.
神经甾体雌激素已被认为在多种生殖行为中发挥重要作用。芳香化酶是雌激素合成中的关键酶，定位于特定脑区的神经核团中，并受发育调节，在围产期短暂表达高峰。分析芳香酶基因的脑特异性启动子，旨在确定有助于解释时空表达的转录控制机制。我们以前报道过，一个202 bp的序列，这是上游的转录起始位点，是必不可少的基础转录活性。脑特异性外显子1的上游202 bp区域包含至少三种类型的顺式作用元件：aro‐AI（Arom‐Aα）、aro‐AII（Arom‐Aβ）和aro‐B（Arom‐B）。为了鉴定这些作用元件的结合蛋白，使用小鼠胎儿cDNA文库对这些作用元件序列进行酵母单杂交筛选。Lhx 2是一种LIM同源结构域蛋白，被鉴定为aro B结合蛋白之一。使用凝胶迁移试验进一步证实了该鉴定，该试验证明了核蛋白与aro B元件与典型Lhx 2-结合元件的结合竞争。此外，用抗Lhx 2抗体进行的染色质免疫沉淀试验表明，Lhx 2在体内与aro B位点结合。脑特异性启动子的报告基因测定证明Lhx 2依赖性启动子活性增加。此外，原代培养的胎儿神经元中芳香化酶mRNA的时间依赖性增加被小干扰RNA介导的Lhx 2表达敲低所抑制。这些结果表明Lhx 2参与啮齿动物脑中芳香化酶的转录调节。
Neurosteroidal oestrogen has been proposed to play important roles in a variety of reproductive behaviours. Aromatase, a key enzyme in oestrogen synthesis, is localised in neural nuclei of specific brain regions and is developmentally regulated, with a transient expression peak at the perinatal period. The brain‐specific promoter of the aromatase gene was analysed aiming to determine the transcriptional control mechanisms that could help explain the spatiotemporal expression. We previously reported that a 202‐bp sequence, which is upstream from the transcriptional initiation site, is essential for the basal transcriptional activity. The 202‐bp upstream region of brain‐specific exon 1 comprises at least three types ofcis‐acting elements: aro‐AI (Arom‐Aα), aro‐AII (Arom‐Aβ) and aro‐B (Arom‐B). To identify the binding proteins for thecis‐acting elements, a yeast one‐hybrid screen was performed with thesecis‐element sequences using a mouse foetal cDNA library. Lhx2, a LIM‐homeodomain protein, was identified as one of the aro‐B binding proteins. The identification was further confirmed using the gel shift assay, which demonstrated binding competition of nuclear proteins to the aro‐B element with a typical Lhx2‐binding element. In addition, a chromatin immunoprecipitation assay with an anti‐Lhx2 antibody demonstrated that Lhx2 bound to the aro‐B sitein vivo. A reporter assay of the brain‐specific promoter demonstrated increased Lhx2‐dependent promoter activity. Furthermore, the time‐dependent increase in aromatase mRNA in primary cultured foetal neurones was suppressed by an small‐interfering RNA‐mediated knockdown of Lhx2 expression. These results show that Lhx2 is involved in the transcriptional regulation of aromatase in the rodent brain.