Post-transcriptional mechanisms of gene regulation in cardiac cell growth and development

 描述（由申请人提供）：对于许多基因，稳态mRNA水平不能准确反映其翻译成蛋白质的程度。在心肌肥厚过程中影响单个mRNA翻译的因素知之甚少。我们的目的是确定胞质多聚腺苷酸结合蛋白C1（PABPC 1）作为一种新的调节心脏肥大的功能。PABPC 1选择性地结合大多数真核生物mRNA的3 '-poly（A）尾序列，并且对于它们的整体翻译和周转至关重要。我们证明，PABPC 1蛋白水平在小鼠和人类出生后心脏发育过程中的转录后抑制。重要的是，PABPC 1蛋白水平在心肌肥大过程中增加，我们发现PABPC 1耗竭的小鼠心肌细胞对病理性肥大有抵抗力。为了直接测试PABPC 1在心肌肥大中的作用，我们开发了四环素诱导的和心脏特异性PABPC 1转基因小鼠模型。此外，我们证明了Pabpc 1 mRNA的poly（A）尾长度在心脏发育过程中减少，这与其与多聚核糖体的关联减少和翻译不良一致。更重要的是，我们在成年小鼠和人类心脏中发现了其他稳定的、不同的含有短poly（A）尾的mRNA的群体。本提案的具体目的是：（1）确定控制PABPC 1细胞类型特异性表达的机制;（2）确定PABPC 1在心肌细胞肥大生长中的需求;（3）确定PABPC 1在调节心脏中poly（A）尾长和其靶mRNA翻译控制中的作用。我们将使用分子、生物化学、转基因和高通量测序方法的组合来解决这些重要问题。 公共卫生的相关性：这一提议将建立一种新的基因调控机制，其基础是poly（A）尾长的调节变化影响心脏mRNA亚组的翻译效率。本项目还将剖析poly（A）结合蛋白在刺激心脏肥大中的功能作用，心脏肥大是一种与许多心脏疾病有关的疾病。成功完成拟议的研究将产生对基因调控的未探索机制的详细了解，并将为治疗影响数百万美国人的心脏肥大及其相关病理开辟令人兴奋的新治疗机会。

 DESCRIPTION (provided by applicant): For many genes, steady state mRNA levels provide an inaccurate reflection of the extent to which they are translated into proteins. The factors influencing the translation of individual mRNAs during cardiac hypertrophy are poorly understood. Our objective is to determine the function of the cytosolic polyA-binding protein C1 (PABPC1) as a novel regulator of cardiac hypertrophy. PABPC1 selectively binds to the 3'- poly(A) tail sequence of most eukaryotic mRNAs and is critical for their overall translation and turnover. We demonstrate that PABPC1 protein levels in mice and humans are post-transcriptionally suppressed during postnatal heart development. Importantly, PABPC1 protein levels increase during cardiac hypertrophy, and we show that PABPC1 depleted mouse cardiac myocytes are resistant to pathologic hypertrophy. To directly test the role of PABPC1 in cardiac hypertrophy, we have developed a tetracycline-inducible and cardiac-specific PABPC1 transgenic mouse model. Further, we demonstrate that the poly(A) tail length of Pabpc1 mRNAs decreases during heart development, which is consistent with its reduced association with polysomes and poor translation. More significantly, we have discovered other stable, distinct, populations of short poly(A) tail containing mRNAs in adult hearts of mice and humans. The Specific Aims of this proposal are to: (1) Identify mechanism(s) that control cell-type specific expression of PABPC1; (2) Determine the requirement of PABPC1 in hypertrophic growth of cardiac cells; and (3) Determine the role of PABPC1 in modulating the poly(A) tail length and translation control of its target mRNAs in heart. We will use a combination of molecular, biochemical, transgenic and high-throughput sequencing approaches to address these important questions. PUBLIC HEALTH RELVANCE: This proposal will establish a new gene regulatory mechanism based on regulated changes in poly(A) tail length influencing the efficiency with which subset of cardiac mRNAs are translated. This project will also dissect the functional role of a poly(A) binding protein in stimulation of cardiac hypertrophy, a condition that is involved in number of heart diseases. Successful completion of the proposed research will produce detailed understanding of an unexplored mechanism of gene regulation and will open exciting new therapeutic opportunities to treat cardiac hypertrophy and its associated pathologies that affect millions of Americans.