Li W E I, Waldo K, Linask K L, Chen T, Wessels A, Parmacek M S, Kirby M L, Lo C W
Biology Department, Goddard Laboratories, University of Pennsylvania, Philadelphia, PA, USA.
Development. 2002 Apr;129(8):2031-42. doi: 10.1242/dev.129.8.2031.
Connexin43 knockout mice die neonatally from conotruncal heart malformation and outflow obstruction. Previous studies have indicated the involvement of neural crest perturbations in these cardiac anomalies. We provide evidence for the involvement of another extracardiac cell population, the proepicardial cells. These cells give rise to the vascular smooth muscle cells of the coronary arteries and cardiac fibroblasts in the heart. We have observed the abnormal presence of fibroblast and vascular smooth muscle cells in the infundibular pouches of the connexin43 knockout mouse heart. In addition, the connexin43 knockout mice exhibit a variety of coronary artery patterning defects previously described for neural crest-ablated chick embryos, such as anomalous origin of the coronary arteries, absent left or right coronary artery, and accessory coronary arteries. However, we show that proepicardial cells also express connexin43 gap junctions abundantly. The proepicardial cells are functionally well coupled, and this coupling is significantly reduced with the loss of connexin43 function. Further analysis revealed an elevation in the speed of cell locomotion and cell proliferation rate in the connexin43-deficient proepicardial cells. A parallel analysis of proepicardial cells in transgenic mice with dominant negative inhibition of connexin43 targeted only to neural crest cells showed none of these coupling, proliferation or migration changes. These mice exhibit outflow obstruction, but no infundibular pouches. Together these findings indicate an important role for connexin43 in coronary artery patterning, a role that probably involves the proepicardial and cardiac neural crest cells. We discuss the potential involvement of connexin43 in human cardiovascular anomalies involving the coronary arteries.
连接蛋白43基因敲除小鼠在出生时死于圆锥动脉干心脏畸形和流出道梗阻。先前的研究表明神经嵴扰动与这些心脏异常有关。我们提供了另一种心外细胞群即心外膜前体细胞参与其中的证据。这些细胞产生冠状动脉的血管平滑肌细胞和心脏中的心脏成纤维细胞。我们在连接蛋白43基因敲除小鼠心脏的漏斗囊中观察到成纤维细胞和血管平滑肌细胞的异常存在。此外，连接蛋白43基因敲除小鼠表现出先前在神经嵴消融的鸡胚中描述的各种冠状动脉形态缺陷，如冠状动脉起源异常、左冠状动脉或右冠状动脉缺失以及副冠状动脉。然而，我们发现心外膜前体细胞也大量表达连接蛋白43间隙连接。心外膜前体细胞在功能上耦合良好，而这种耦合随着连接蛋白43功能的丧失而显著降低。进一步分析显示，连接蛋白43缺陷的心外膜前体细胞的细胞运动速度和细胞增殖率升高。对仅针对神经嵴细胞进行连接蛋白43显性负抑制的转基因小鼠的心外膜前体细胞进行的平行分析显示，这些小鼠没有出现耦合、增殖或迁移变化。这些小鼠表现出流出道梗阻，但没有漏斗囊。这些发现共同表明连接蛋白43在冠状动脉形态形成中起重要作用，这一作用可能涉及心外膜前体细胞和心脏神经嵴细胞。我们讨论了连接蛋白43在涉及冠状动脉的人类心血管异常中的潜在作用。
