A Role for the Novel Poly(A) RNA-Binding Protein, ZC3H14, in Breast Cancer

描述（由申请人提供）：仅今年一年，乳腺癌就将夺去大约39，000名美国妇女的生命。因此，揭示乳腺癌发病机制的新分子机制对于填补我们对这种疾病的理解的空白以及每年挽救成千上万妇女的生命至关重要。改变的基因表达是癌症中失调的一个关键点，并且越来越多的证据表明mRNA转录物的转录后加工在确保适当的基因表达中起主要作用。转录后事件由无数RNA结合蛋白（RBP）介导，其中一个关键类别由多聚腺苷酸结合蛋白（Pabs）组成。一种新的CCCH锌指Pab，ZC 3 H14，最近被认为与乳腺肿瘤的雌激素受体（ER）状态有关。尽管ZC 3 H14的分子功能尚不清楚，但芽殖酵母对应物Nab 2是适当控制poly（A）尾长度和mRNA从细胞核输出所必需的，这与关键的细胞因子调控一致。 ZC 3 H14在转录后调节中的作用。虽然ZC 3 H14是一种Pab，但我们的初步数据表明，乳腺癌细胞中特定的mRNA转录物受到ZC 3 H14的调节。ZC 3 H14可能通过另一种识别特定mRNA的RBP实现这种转录特异性，例如人类抗原R（HuR），这是一种与乳腺癌密切相关的富含AU的元件结合蛋白。先前在酵母中的研究证明了Nab 2和Pub 1之间的相互作用（S. cerevisiae HuR直系同源物），其影响靶mRNA转录物的稳定性。在ZC 3 H14和HuR的全基因组分析中，我们鉴定了位于两种蛋白质的候选mRNA靶标的3' UTR内的共有顺式元件以及候选靶标之间的显著重叠的证据。这些数据表明，ZC 3 H14，像HuR，具有特定的mRNA靶点，ZC 3 H14和HuR可能具有功能关系。在该提议中，我们将采用多种方法来测试我们的假设，即ZC 3 H14结合靶mRNA转录物的3' UTR内的特异性顺式元件以调节其稳定性和/或poly（A）尾长度，可能与HuR一致。从长远来看，我们试图提供进一步的洞察力，RBPs在调节基因表达中发挥的作用。在我们的第一个目标中，我们将验证特定的ZC 3 H14靶标，并鉴定这些靶标mRNA中的候选ZC 3 H14调控序列，以评估ZC 3 H14与靶标mRNA结合的转录后后果。在我们的第二个目标中，我们将研究ZC 3 H14和HuR在调节靶mRNA中的功能关系。这项研究将提供深入了解poly（A）RBP的作用，如ZC 3 H14作为转录后调控球员和他们的潜在参与乳腺癌。

DESCRIPTION (provided by applicant): Breast cancer will claim the lives of approximately 39,000 American women this year alone. Uncovering novel molecular mechanisms of breast cancer pathogenesis is therefore critical to fill gaps in our understanding of this disease and to save the lives of thousands of women every year. Altered gene expression is one critical point of dysregulation in cancer and there is increasing evidence that post-transcriptional processing of mRNA transcripts plays a major role in ensuring proper gene expression. Post-transcriptional events are mediated by a myriad of RNA-binding proteins (RBPs), one key class of which is comprised of poly (A) binding proteins (Pabs). A novel CCCH zinc finger Pab, ZC3H14, has recently been linked to the Estrogen Receptor (ER) status of breast tumors. Although the molecular function of ZC3H14 is unknown, the budding yeast counterpart, Nab2, is required for proper control of poly (A) tail length and mRNA export from the nucleus, consistent with a critical role for ZC3H14 in post-transcriptional regulation. Although ZC3H14 is a Pab, our preliminary data suggest that specific mRNA transcripts are modulated by ZC3H14 in breast cancer cells. ZC3H14 may achieve this transcript specificity via another RBP that recognizes specific mRNAs, such as Human Antigen R (HuR), an AU-rich element binding protein already strongly linked to breast cancer. A previous study in yeast demonstrated an interaction between Nab2 and Pub1 (S. cerevisiae HuR ortholog) that influenced the stability of target mRNA transcripts. In a genome-wide analysis of ZC3H14 and HuR, we identified evidence of consensus cis-elements located within the 3' UTR of candidate mRNA targets of the two proteins as well as a significant overlap between candidate targets. These data suggest that ZC3H14, like HuR, has specific mRNA targets, and that ZC3H14 and HuR may have a functional relationship. In this proposal we will employ multiple approaches to test our hypothesis that ZC3H14 binds to specific cis- elements within the 3' UTR of target mRNA transcripts to modulate their stability and/or poly (A) tail length, potentially in concert with HuR. In the long-term, we seek to provide further insight into the role that RBPs play in modulating gene expression. In our first aim, we will validate specific ZC3H14 targets and identify candidate ZC3H14 regulatory sequences in these target mRNAs to assess the post-transcriptional consequence of ZC3H14 binding to target mRNAs. In our second aim, we will examine the functional relationship between ZC3H14 and HuR in modulating target mRNAs. This study will provide insight into the role of poly (A) RBPs such as ZC3H14 as post-transcriptional regulatory players and their potential involvement in breast cancer.