转录因子Foxp1在压力超负荷致心室重构中的作用和机制研究

Cardiac remodeling, hypertrophy or fibrosis, is a mechanism to compensate for increased cardiac work load, that is, after myocardial infarction or upon pressure overload. However, in the long run it is a prevailing risk factor for the development of heart failure. During pathological remodeling processes leading to heart failure, decompensate cardiomyocyte hypertrophy and caridac fibrosis are apparent. Despite the critical importance of cardiac remodeling in cardiovascular disease, our limited understanding impedes the development of potential therapies that effectively target the cell types and their pathological contribution to disease progression..Transcription factor Foxp1 ubiquitously expresses in cardiovascular system and is crucial for cardiac development, and cell lineage-specific regulation of Fgf ligand expression in endothelial cells and Nkx2.5 expression in cardiomyocytes coordinates the balance of cardiomyocyte proliferation and differentiation, which is crucial for cardiac development. High level of Foxp1 is also found in the heart of heart failure patients. This study uses the conditional knockout Foxp1 mice to investigate the cell specific role of Foxp1 in cardiac remodeling and dysfunction, more severely heart failure..Our preliminary data shows that endothelial cell or cardiomyocyte specific deletion of Foxp1 aggravates TAC pressure overload induced cardiac hypertrophy and interstitial fibrosis, worsens the cardiac dysfunction. Gene expression profile by RNA sequencing shows that endothelial loss of Foxp1 increases expression of ET-1 and IL-β, thus we hypothesize that endothelial Foxp1 might regulate cardiac hypertrophy, fibroblast proliferation and secretion of extracellular matrix protein through ET-1 and IL-β signaling pathway. FoxP1 was reported to interact with and inhibit Nfat3 transcriptional activity which negatively regulated cardiac hypertrophyby. Our qPCR shows that loss of Foxp1 in cardiomyocytes lead to up-regulation of TGF-βR1/2 and Nfat3 expression. It is well known that TGF-β/TGF-βR1/2 signaling tightly regulates cardiac remodeling, thus we hypothesize that cardiomyocyte Foxp1 may control cardiac remodeling via TGF-β/TGF-βR1/2 signaling..Molecular biology methods ChIP and lucifereous reporter assay will be used to confirm the Foxp1 downstream target genes in cardiac remodeling. The cell-specific viral vectors targeted for knockdown of foxp1 downstream target genes in endothelial cells or cardiomyocytes will be constructed to observe whether change of these genes can rescue the aggravated cardiac remodeling and dysfunction by cell-specific deletion of Foxp1 in vitro cell culture and in vivo mouse experiments. This study will help us understand the molecular mechanisms of cell-specific deletion of Foxp1 in cardiac remodeling and development of heart failure, and cell-specific adeno- or adeno-associated viral gene target knockdown or ectopic expression will block the progression of cardiac hypertrophy and interstitial fibrosis, which further improve the cardiac dysfunction, providing the experimental evidence for prevention and treatment of heart failure.

转录因子Foxp1在心脏发育中起关键作用，心衰病人心脏Foxp1表达增加，我们实验发现血管内皮和心肌细胞Foxp1缺失加剧压力超负荷致心肌肥厚、间质纤维化和心功能障碍。有报导ET-1、IL-1β和TGF-βR1/2在心肌肥厚和心脏纤维化中起重要作用，心肌细胞Foxp1通过抑制Nfat3减少心肌肥大，我们RNA测序和定量PCR证实心肌细胞和血管内皮细胞Foxp1缺失分别上调TGF-βR1/2和ET-1及IL-1β，提出细胞特异性Foxp1通过不同信号通路调控心室重构。ChIP和启动子报告系统将证实Foxp1下游靶基因，通过条件性Foxp1基因敲除小鼠，辅以靶基因功能拮抗剂或基因沉默的离体细胞和在体小鼠实验探索Foxp1调节心室重构分子机制；构建细胞靶向基因调控腺相关病毒，观察改变特定细胞Foxp1或其下游靶基因表达是否改善心室重构和心功能障碍，寻找防治心衰发生发展的新靶点。

Foxp1广泛表达在心血管系统组织细胞中，在心脏发育中起关键作用。既往研究表明心衰患者心肌细胞Foxp1表达显著上调，我们的前期研究结果显示内皮Foxp1缺失加重血管紧张素II微量注射泵皮下埋植模型及主动脉弓缩窄术（TAC）压力超负荷所致心肌肥大和心肌间质纤维化以及心脏功能障碍，提示Foxp1在心衰发生发展和心室重构中具有重要的调控作用。.我们揭示了内皮转录因子Foxp1通过TGFβ信号旁分泌作用调控成纤维细胞增殖和转化为活化的肌成纤维细胞并分泌大量细胞外基质参与心脏纤维化以及通过TGFβ-ET1信号通路作用参与心肌细胞肥大的调控，从而解释了Foxp1参与压力后负荷所致心肌重构中的机制。并且由于TGFβ全身性作用过于广泛，TGFβ抑制剂全身性用药会带来一系列严重的副作用。因此我们进一步探索了铁磁性RGD-多肽纳米材料作为载体成功将TGFβ1小干扰RNA（siRNA）靶向导入内皮细胞，成功实现了内皮细胞靶向性基因调控。并进一步证实了RGD-多肽纳米材料介导的血管内皮特异性抑制TGFβ1能够逆转Foxp1敲除所致加重的心功能障碍和心脏重构。.在后续研究中，我们进一步发现临床常用降脂药物辛伐他汀通过内皮细胞KLF2-Foxp1通路间接或直接通过KLF2转录调控抑制TGFβ信号，从而参与压力后符合所致心室重构保护作用的新机制，并为今后他汀药物在心力衰竭防治中的应用提供新思路。.在本项目的资助下，本项目揭示了内皮细胞Foxp1调控压力后负荷所致心室重构的作用和机制，并利用铁磁性RGD纳米材料内皮细胞靶向基因调控干预病理性心室重构的新策略。以及揭示他汀通过内皮细胞KLF2-Foxp1通路干预心室重构的新机制。相关研究内容在国际心血管领域权威期刊发表，共发表受本项目资助SCI论文9篇，申请专利1项，在国际国内会议进行学术报告8次，培养博士后2人、博士1人、硕士1人，达到项目预期，顺利完成项目计划。

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