Genome-wide analysis of epicardial gene expression in E11.5 mouse hearts

Identification of epicardium-enriched genes in the embryonic heart. The epicardium encapsulates the heart and functions as a source of multipotent progenitor cells and paracrine factors essential for cardiac development and repair. Injury of the adult heart results in re-activation of a developmental gene program in the epicardium, but the transcriptional basis of epicardial gene expression has not been delineated. We established a mouse embryonic heart organ culture and gene expression system that facilitated the identification of epicardial enhancers activated during heart development and injury. Epicardial activation of these enhancers depends on a combinatorial transcriptional code centered on CCAAT/enhancer binding protein (C/EBP) transcription factors. Disruption of C/EBP signaling in the adult epicardium reduced injury-induced neutrophil infiltration and improved cardiac function. These findings reveal a transcriptional basis for epicardial activation and heart injury, providing a platform for enhancing cardiac regeneration. Total RNA obtained from lacZ-positive epicardial cells isolated from the E11.5 Tcf21lacZ hearts compared to total dissociated heart cells胚胎心脏心外膜富集基因（epicardium-enriched genes）的鉴定。心外膜（epicardium）包裹心脏，作为多能祖细胞（multipotent progenitor cells）与旁分泌因子的来源，而这些因子对心脏发育与修复至关重要。成年心脏损伤可重新激活心外膜中的发育基因程序，但目前尚未阐明心外膜基因表达的转录调控基础。本研究建立了小鼠胚胎心脏器官培养与基因表达系统，该系统可助力鉴定心脏发育与损伤过程中激活的心外膜增强子。这些增强子在心外膜中的激活依赖于以CCAAT/增强子结合蛋白（CCAAT/enhancer binding protein, C/EBP）家族转录因子为核心的组合式转录调控密码。成年心外膜中C/EBP信号通路的阻断可减少损伤诱导的中性粒细胞浸润，并改善心脏功能。本研究结果阐明了心外膜激活与心脏损伤的转录调控基础，为增强心脏再生提供了研究平台。将从E11.5阶段Tcf21lacZ小鼠心脏中分离得到的lacZ阳性心外膜细胞所提取的总RNA，与完全解离的心脏细胞总RNA进行对比。