Department of Internal Medicine II, University of Ulm, Albert-Einstein-Allee 23, Ulm 89081, Germany; Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
Molecular Cardiology, Department of Internal Medicine II, University of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
J Mol Cell Cardiol. 2021 Jun;155:25-35. doi: 10.1016/j.yjmcc.2021.01.006. Epub 2021 Feb 5.
Genome-wide association studies identified Spen as a putative modifier of cardiac function, however, the precise function of Spen in the cardiovascular system is not known yet. Here, we analyzed for the first time the in vivo role of Spen in zebrafish and found that targeted Spen inactivation led to progressive impairment of cardiac function in the zebrafish embryo. In addition to diminished cardiac contractile force, Spen-deficient zebrafish embryos developed bradycardia, atrioventricular block and heart chamber fibrillation. Assessment of cardiac-specific transcriptional profiles identified Connexin 43 (Cx43), a cardiac gap junction protein and crucial regulator of cardiomyocyte-to-cardiomyocyte communication, to be significantly diminished in Spen-deficient zebrafish embryos. Similar to the situation in Spen-deficient embryos, Morpholino-mediated knockdown of cx43 in zebrafish resulted in cardiac contractile dysfunction, bradycardia, atrioventricular block and fibrillation of the cardiac chambers. Furthermore, ectopic overexpression of cx43 in Spen deficient embryos led to the reconstitution of cardiac contractile function and suppression of cardiac arrhythmia. Additionally, sensitizing experiments by simultaneously injecting sub-phenotypic concentrations of spen- and cx43-Morpholinos into zebrafish embryos resulted in pathological supra-additive effects. In summary, our findings highlight a crucial role of Spen in controlling cx43 expression and demonstrate the Spen-Cx43 axis to be a vital regulatory cascade that is indispensable for proper heart function in vivo.
全基因组关联研究鉴定出 Spen 是心脏功能的一个假定修饰因子，然而，Spen 在心血管系统中的精确功能尚不清楚。在这里，我们首次分析了 Spen 在斑马鱼体内的作用，发现靶向 Spen 失活导致斑马鱼胚胎心脏功能进行性受损。除了心肌收缩力下降外，Spen 缺陷型斑马鱼胚胎还出现心动过缓、房室传导阻滞和心腔纤维颤动。对心脏特异性转录谱的评估发现，连接蛋白 43（Cx43），一种心脏缝隙连接蛋白，是心肌细胞间通讯的关键调节因子，在 Spen 缺陷型斑马鱼胚胎中显著减少。与 Spen 缺陷型胚胎的情况类似，Morpholino 介导的 cx43 在斑马鱼中的敲低导致心肌收缩功能障碍、心动过缓、房室传导阻滞和心腔纤维颤动。此外，cx43 在 Spen 缺陷型胚胎中的异位过表达导致心肌收缩功能的重建和心律失常的抑制。此外，通过同时向斑马鱼胚胎注射亚表型浓度的 spen 和 cx43-Morpholinos 进行敏感实验，导致病理性超加性效应。总之，我们的研究结果强调了 Spen 在控制 cx43 表达中的关键作用，并证明了 Spen-Cx43 轴是一个至关重要的调节级联，对于体内正常心脏功能是不可或缺的。
