lncRNA家族T-UCR调控心肌肥厚的分子机制研究

Cardiac hypertrophy is the pivotal pathological event in the development of heart failure. The better understanding of the underlying molecular mechanisms of cardiac hypertrophy will contribute to the development of the treatment for heart failure. However, most of the current studies investigating the molecular mechanisms of cardiac hypertrophy have focused on coding genes. It remains unclear whether non-coding RNAs, especially T-UCRs (transcribed ultra-conserved regions) which are highly conserved in the lncRNAs (long non-coding RNA) family, are involved in pathological cardiac hypertrophy. By using lncRNA microarray, we discovered that the mice with aortic banding (AB) showed altered expressions of 31 T-UCRs (fold change >1.5, p<0.05) compared to those of Sham group and the alterations of uc.452 and uc.323 are the most significant. These results suggest that T-UCR, especially uc.452 and uc.323, may be involved in the regulation of cardiac hypertrophy. Therefore, in the present study, we aim to further investigate the effects of uc.452 and uc.323 on cardiac hypertrophy and the underlying molecular mechanisms in vitro and in vivo by adenovirus transfection as well as conditional transgenic mice. The results will reveal a new mechanism regulating cardiac hypertrophy with focus on lncRNA and will provide proofs for the treatment of heart failure.

心肌肥厚是心衰发生发展的核心环节，对其分子机制的研究有助于心衰的治疗。然而，目前心肌肥厚的机制研究多集中在蛋白编码基因领域，在非编码RNA、尤其是长链非编码RNA（lncRNA）领域的研究极度缺乏，并且lncRNA家族中较保守的T-UCR与心肌肥厚的关系尚无报道。我们的lncRNA芯片结果显示：在压力过负荷诱导的心肌肥厚中，T-UCR的表达谱发生明显改变，表达变化大于1.5倍的T-UCR 共有31个，以uc.452和uc.323的改变最为显著，提示T-UCR（尤其是uc.452和uc.323）可能参与调控心肌肥厚。为深入研究T-UCR对心肌肥厚的作用，本研究以uc.452和uc.323为研究对象，利用腺病毒转染技术和构建心脏条件性转基因小鼠，从体外和体内实验深入探讨uc.452和uc.323对心肌肥厚的调控作用及其分子机制，旨在完善心肌肥厚发生发展的分子机制研究，为治疗心衰提供理论依据。

T-UCRs是一类转录超保守区域（UCRs）转录而成一种特殊类型的长链非编码RNA，它在人、小鼠和大鼠中序列完一致。本研究探讨了T-UCRs对心肌肥厚的调控作用。首先，我们通过主动脉缩窄诱导的心肌肥厚模型结合基因芯片，筛选出了在心肌肥厚过程中显著下调的基因uc.323。进一步通过体内外研究表明，uc.323对苯肾上腺素诱导的心肌细胞肥厚具有保护作用。此外，我们发现mTOR1参与了苯肾上腺素诱导uc.323下调以及uc.323介导的心肌细胞肥厚的病理生理过程。后续通过基因芯片的mRNA表达分析，我们进一步定位了uc.323可能作用的靶基因（CPT1b）。随后，通过染色质免疫沉淀证明EZH2可能通过H3K27me3（组蛋白H3的赖氨酸27的三甲基化）与CPT1b启动子结合，诱导CPT1b下调。在进一步的动物实验中，我们发现uc.323缺失可导致心肌肥厚的发生。因此，我们的研究结果表明uc.323是一种保守的T-UCR，并可能通过与EZH2的相互作用调节CPT1b的转录从而抑制心肌肥厚。