Short RNA Molecules with High Binding Affinity to the KH Motif of A-Kinase Anchoring Protein 1 (AKAP1): Implications for the Regulation of Steroidogenesis
Short RNA Molecules with High Binding Affinity to the KH Motif of A-Kinase Anchoring Protein 1 (AKAP1): Implications for the Regulation of Steroidogenesis
复制标题
DOI：
10.1210/me.2012-1123
复制
发表时间：
2012-12-01
影响因子：
--
通讯作者：
Stocco, Douglas M.
中科院分区：
文献类型：
--
作者：
Grozdanov, Petar N.;Stocco, Douglas M.
类固醇生成急性调节蛋白（STAR）是类固醇生成组织中急性类固醇激素生物合成的关键调控蛋白之一。在转录水平上对STAR产生的急性调控主要是通过camp依赖机制实现的，这一机制已经得到了很好的理解。然而，关于STAR合成的转录后调控，特别是影响STAR mRNA离开细胞核后命运的因素知之甚少。在这里，我们发现Star mRNA的3'-未翻译区在体外与线粒体支架a激酶锚定蛋白1 （AKAP1）的异质核核糖核蛋白k同源（KH）基序相互作用，通过emsa测量具有中等亲和力。在这些条件下，模仿特定丝氨酸上KH基序磷酸化状态的突变要么不改变，要么对蛋白质- rna结合产生负面影响。经体外筛选证实，AKAP1的KH基序结合具有稳定发夹结构的富含嘧啶的短RNA分子。在二丁基camp刺激的人体内类固醇源性肾上腺皮质癌细胞系中，AKAP1也与STAR mRNA相互作用。因此，我们提出了一种模型，其中AKAP1将Star mRNA锚定在线粒体上，从而稳定了该细胞器上的翻译复合体，这种情况可能会影响Star的产生和类固醇的形成。此外，我们认为AKAP1的最后216个氨基酸残基可能通过与rna诱导的沉默复合体，特别是argonaute 2蛋白相互作用，参与了STAR和其他核编码线粒体mrna的降解。（分子内分泌学26:2104-2117,2012）
One of the key regulators of acute steroid hormone biosynthesis in steroidogenic tissues is the steroidogenic acute regulatory (STAR) protein. Acute regulation of STAR production on the transcriptional level is mainly achieved through a cAMP-dependent mechanism, which is well understood. However, less is known about the posttranscriptional regulation of STAR synthesis, specifically the factors influencing the destiny of the Star mRNA after it leaves the nucleus. Here, we show that the 3'-untranslated region of Star mRNA interacts with the heterogeneous nuclear ribonucleoprotein K-homology (KH) motif of the mitochondrial scaffold A-kinase anchoring protein 1 (AKAP1) in vitro with a moderate affinity as measured by EMSAs. A mutation that mimics the phosphorylation state of the KH motif at a specific serine either did not alter, or had a negative impact on, protein-RNA binding under these conditions. The KH motif of AKAP1 binds short pyrimidine-rich RNA molecules with a stable hairpin structure as demonstrated by in vitro selection. AKAP1 also interacts with STAR mRNA in a dibutyryl-cAMP-stimulated human steroidogenic adrenocortical carcinoma cell line in vivo. Therefore, we propose a model in which AKAP1 anchors Star mRNA at the mitochondria, thus stabilizing the translational complex at this organelle, a situation that might affect STAR production and steroidogenesis. In addition, we suggest that the last 216 amino acid residues of AKAP1 might participate in the degradation of STAR and other nuclear-encoded mitochondrial mRNAs through interaction with a RNA-induced silencing complex, specifically with the argonaute 2 protein. (Molecular Endocrinology 26: 2104-2117, 2012)