Mulleners Otto J, van der Maarel Lieve E, Christoffels Vincent M, Jensen Bjarke
Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, Amsterdam, The Netherlands.
Ann N Y Acad Sci. 2025 Mar;1545(1):76-90. doi: 10.1111/nyas.15296. Epub 2025 Feb 11.
A poorly understood, major event in heart evolution is the convergent prioritization in mammals and birds of compact myocardium over trabecular myocardium. Compact myocardium is thought to facilitate the greater cardiac outputs that distinguish endothermic mammals and birds from ectotherms, but the underlying mechanism remains unclear. We used transcriptomics to investigate whether the compact layer myocardium is intrinsically different from that of the trabecular layer. In the embryonic mouse heart, spatial transcriptomics revealed that 3% of detected genes were differentially expressed between trabecular and compact myocardium. In the adult, this analysis yielded only 0.2% differentially expressed genes. Additionally, the transcriptomes of both embryonic trabecular and compact myocardium greatly differed from those of the adult myocardium. Reanalysis of available single-cell transcriptomes showed relationships between human embryonic and adult trabecular and compact myocardium similar to those in mice. Analysis of new and published transcriptomes from adult zebra finch, zebrafish, and tuna revealed few differentially expressed genes (<0.6%) and no conservation between species. We conclude that the transcriptional states of developing trabecular and compact myocardium do not persist into adulthood. In adult hearts, the compact layer myocardium is not intrinsically different from that of the trabecular layer despite the overt morphological differences.
心脏进化过程中一个尚未被充分理解的重大事件是，在哺乳动物和鸟类中，致密心肌相对于小梁心肌出现了趋同的优先发展趋势。致密心肌被认为有助于实现更高的心输出量，这是恒温哺乳动物和鸟类区别于变温动物的特征之一，但其潜在机制仍不清楚。我们利用转录组学来研究致密层心肌与小梁层心肌在本质上是否存在差异。在胚胎期小鼠心脏中，空间转录组学显示，在小梁心肌和致密心肌之间，3%的检测基因存在差异表达。在成体中，该分析仅产生了0.2%的差异表达基因。此外，胚胎期小梁心肌和致密心肌的转录组与成体心肌的转录组有很大差异。对现有单细胞转录组的重新分析表明，人类胚胎期和成体小梁心肌与致密心肌之间的关系与小鼠相似。对成年斑胸草雀、斑马鱼和金枪鱼的新转录组和已发表转录组的分析显示，差异表达基因很少（<0.6%），且物种间不存在保守性。我们得出结论，发育中的小梁心肌和致密心肌的转录状态不会持续到成年期。在成体心脏中，尽管致密层心肌与小梁层心肌在形态上存在明显差异，但在本质上并无不同。
