Essential Roles of SETD7 as Transcriptional Activator and Co-regulator of H3K36me in Cardiac Lineage Commitment

Coordinated epigenome alteration is fundamental for cardiac development. However, the precise mechanisms by which epigenetic modifying enzymes regulate cardiac development are still unclear. Here we identify SET domain containing protein 7 (SETD7) as a key regulator of cardiac differentiation. ChIP-seq reveals that SETD7 has distinct groups of target genes and regulates its stage-specific expression during cardiomyocyte differentiation, which is crucial for lineage commitment. We find SETD7 associates with stage-specific co-factors, such as SWI/SNF chromatin remodeling factors during mesodermal formation and transcription factor NKX2-5 in cardiac progenitor differentiation. Cross-analysis of epigenetic modifications shows that SETD7 recognizes and binds with active histone marker H3K36 methylation on gene-body region of its target genes. We further demonstrate SETD7 is required for functional properties of terminally differentiated cardiomyocytes. Together, our results suggest unidentified roles of SETD7 in cardiac lineage commitment and provide new insights into the crosstalk between epigenetic dynamics and epigenetic modifying enzymes. Overall design: RNA-seq (n=8) and ChIP-seq (n=28) of the cardiac differentiation of H7 ESC.表观基因组的协同改变是心脏发育的核心基础。然而，表观遗传修饰酶调控心脏发育的确切分子机制仍未明确。本研究鉴定出含SET结构域蛋白7（SET domain containing protein 7，SETD7）作为心脏分化的关键调控因子。染色质免疫共沉淀测序（ChIP-seq）结果显示，SETD7拥有独特的靶基因集，并在心肌细胞分化过程中调控其靶基因的阶段特异性表达，这对细胞谱系定型至关重要。研究发现，SETD7可与阶段特异性辅因子结合：在中胚层形成阶段结合SWI/SNF染色质重塑因子，在心脏祖细胞分化阶段结合转录因子NKX2-5。表观遗传修饰交叉分析结果表明，SETD7可识别并结合其靶基因基因体区域的活性组蛋白标记H3K36甲基化。本研究进一步证实，SETD7对终末分化心肌细胞的功能特性维持不可或缺。综上，本研究结果揭示了SETD7在心脏谱系定型中尚未被阐明的作用，并为表观遗传动态与表观遗传修饰酶之间的交互调控关系提供了全新视角。实验整体设计：针对H7胚胎干细胞（H7 ESC）的心脏分化过程开展RNA测序（RNA-seq，样本量n=8）与染色质免疫共沉淀测序（ChIP-seq，样本量n=28）。