Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
Circ Res. 2013 Aug 2;113(4):399-407. doi: 10.1161/CIRCRESAHA.113.301588. Epub 2013 Jun 6.
To date, there has been no specific marker of the first heart field to facilitate understanding of contributions of the first heart field to cardiac lineages. Cardiac arrhythmia is a leading cause of death, often resulting from abnormalities in the cardiac conduction system (CCS). Understanding origins and identifying markers of CCS lineages are essential steps toward modeling diseases of the CCS and for development of biological pacemakers.
To investigate HCN4 as a marker for the first heart field and for precursors of distinct components of the CCS, and to gain insight into contributions of first and second heart lineages to the CCS.
HCN4CreERT2, -nuclear LacZ, and -H2BGFP mouse lines were generated. HCN4 expression was examined by means of immunostaining with HCN4 antibody and reporter gene expression. Lineage studies were performed using HCN4CreERT2, Isl1Cre, Nkx2.5Cre, and Tbx18Cre, coupled to coimmunostaining with CCS markers. Results demonstrated that, at cardiac crescent stages, HCN4 marks the first heart field, with HCN4CreERT2 allowing assessment of cell fates adopted by first heart field myocytes. Throughout embryonic development, HCN4 expression marked distinct CCS precursors at distinct stages, marking the entire CCS by late fetal stages. We also noted expression of HCN4 in distinct subsets of endothelium at specific developmental stages.
This study provides insight into contributions of first and second heart lineages to the CCS and highlights the potential use of HCN4 in conjunction with other markers for optimization of protocols for generation and isolation of specific conduction system precursors.
迄今为止，尚无特定的第一心区标志物来帮助理解第一心区对心脏谱系的贡献。心律失常是导致死亡的主要原因，通常是由于心脏传导系统（CCS）的异常引起的。了解起源和鉴定 CCS 谱系的标志物是对 CCS 疾病建模以及开发生物起搏器的重要步骤。
研究 HCN4 作为第一心区和 CCS 不同成分前体的标志物，并深入了解第一和第二心区谱系对 CCS 的贡献。
生成了 HCN4CreERT2、-nuclear LacZ 和 -H2BGFP 小鼠品系。通过使用 HCN4 抗体和报告基因表达进行免疫染色来检查 HCN4 的表达。通过 HCN4CreERT2、Isl1Cre、Nkx2.5Cre 和 Tbx18Cre 进行谱系研究，并与 CCS 标志物的共免疫染色相结合。结果表明，在心脏新月形阶段，HCN4 标记第一心区，HCN4CreERT2 允许评估第一心区心肌细胞采用的细胞命运。在整个胚胎发育过程中，HCN4 在不同阶段表达标记不同的 CCS 前体，在晚期胎儿阶段标记整个 CCS。我们还注意到 HCN4 在特定发育阶段的特定内皮细胞亚群中的表达。
本研究深入了解了第一和第二心区谱系对 CCS 的贡献，并强调了 HCN4 与其他标志物结合使用在优化特定传导系统前体的生成和分离方案方面的潜在用途。
