Gene expression profiling of hypertrophic and failing cardiomyocytes identifies new players in heart failure

Aim - Pathological cardiac remodeling is characterized by cardiomyocyte hypertrophy and fibroblast activation, which can ultimately lead to heart failure (HF). Genome-wide expression analysis on heart tissue has been instrumental for the identification of molecular mechanisms at play. However, these data were based on signals derived from all cardiac cell types. Here we aimed for a more detailed view on molecular changes driving cardiomyocyte hypertrophy and failure to aid in the development of therapies to reverse maladaptive remodeling. Methods and results - Utilizing cardiomyocyte-specific reporter mice exposed to pressure overload by transverse aortic banding (TAB), we obtained gene expression profiles of hypertrophic (one-week TAB) and failing (eight-weeks TAB) cardiomyocytes. We identified subsets of genes differentially regulated and specific for either stage. Among these, we found upregulation of known marker genes for HF, such as Nppb and Myh7. Additionally, we identified a set of genes specifically upregulated in failing cardiomyocytes and that so far have not been studied in HF, including the platelet isoform of phosphofructokinase (PFKP). Human cardiomyocytes subjected to 7-day NE/AngII treatment recapitulated the upregulation of the failure-induced genes indicating conservation. RNA-seq on failing and healthy human hearts confirmed increased expression for several failure-induced genes and allowed for expressional correlation to NPPB/MYH7. Finally, suppression of Pfkp in PE-treated primary cardiomyocytes reduced stress-induced gene expression and hypertrophy, suggesting a role in cardiomyocyte failure. Conclusion - Using cardiomyocyte-specific transcriptomic analysis we identified novel failure-induced genes relevant for human HF, and show that PFKP is a conserved failure-induced gene that can modulate cardiomyocyte stress response. RNA-sequencing on cardiomyocytes from 12 ventricule samples from mice of sham, hypertrophic or failing hearts.

研究目的：病理性心脏重构以心肌细胞（cardiomyocyte）肥大与成纤维细胞激活为核心特征，最终可进展为心力衰竭（heart failure, HF）。既往心脏组织全基因组表达分析曾为解析该过程的分子机制提供了关键支撑，但此类数据均基于所有心脏细胞类型的混合转录信号。本研究旨在更精准地解析驱动心肌细胞肥大与衰竭的分子变化，为开发逆转不良心脏重构的治疗策略提供理论依据。
方法与结果：本研究利用经横向主动脉缩窄术（transverse aortic banding, TAB）构建压力负荷模型的心肌细胞特异性报告基因小鼠，分别获取了造模1周的肥厚型与造模8周的衰竭型心肌细胞的基因表达谱。我们鉴定出了两个疾病阶段特异性的差异调控基因子集，其中包含已知的心力衰竭标志物基因如Nppb与Myh7的上调表达。此外，我们还发现了一组在衰竭型心肌细胞中特异性上调、此前尚未被纳入心力衰竭研究范畴的基因，其中包括磷酸果糖激酶血小板亚型（phosphofructokinase platelet isoform, PFKP）。经7天去甲肾上腺素（NE）/血管紧张素II（AngII）处理的人源心肌细胞可重现该类衰竭诱导基因的上调特征，提示该调控机制具有进化保守性。对衰竭与健康人心脏组织开展的RNA测序（RNA-seq）验证了多个衰竭诱导基因的表达上调，并实现了这些基因与NPPB/MYH7的表达相关性分析。最后，在PE处理的原代心肌细胞中抑制Pfkp的表达，可降低应激诱导的基因表达与心肌细胞肥大程度，提示PFKP在心肌细胞衰竭中发挥正向调控作用。
研究结论：通过心肌细胞特异性转录组分析，我们鉴定出了与人类心力衰竭相关的新型衰竭诱导基因，并证实PFKP是一类进化保守的衰竭诱导基因，可调控心肌细胞的应激应答反应。本研究对来自假手术、心肌肥厚及心力衰竭模型小鼠的12份心室心肌细胞样本开展了RNA测序。