心肌细胞闰盘由黏着连接、桥粒与缝隙连接三种结构组成，它们的跨膜蛋白分别是N-cadherin (N-cad)、desmoglein-2 (DSG2)与connexin 43(Cx43)。本文旨在研究大鼠心肌在出生后的发育过程中，这三种蛋白之间两两共定位的特征。用组织免疫荧光染色法观测出生后1天(P1, postnatal day 1)、P7、P14、P28、P90大鼠左室心肌N-cad、DSG2与Cx43的分布与两两之间共定位的动态变化。结果显示，出生1 d心肌细胞，N-cad、DSG2与Cx43在细胞膜呈弥散分布；出生7 d 组N-cad与DSG2在心肌细胞长轴两端集聚，Cx43亦有少量集聚，标示闰盘形成。从14 d到90 d，三种蛋白在闰盘处集聚逐步增多；而在侧面的分布表现出一种相反的趋势：N-cad与DSG2在细胞侧面的分布大幅减少，Cx43虽在细胞侧面的分布降低，但至90 d仍有Cx43分布于细胞侧面。采用体视学方法进行定量分析表明，在出生第1天，N-cad与DSG2总的共定位为33.5%；第7天总共定位升高为38.6%，其中闰盘处共定位占9.4%，细胞侧面共定位为29.2%。从14 d到90 d，随着N-cad与DSG2总共定位增加至65.7%，在闰盘处的共定位亦增加到60.5%，在细胞侧面的共定位却降低至5.2%。N-cad与Cx43的总共定位从1 d的10.3%，逐步增加到90 d的37.1%；在闰盘处的共定位逐步增加，而细胞侧面的共定位保持在5%左右。DSG2与Cx43共定位特征及百分比类似于N-cad与Cx43共定位。N-cad与DSG2共定位百分比明显高于N-cad与Cx43或DSG2与Cx43的共定位。上述结果提示，大鼠心肌在出生后的发育过程中，构成细胞力学连接的N-cad与DSG2先于构成细胞电化学连接的Cx43在闰盘处集聚，即心肌细胞生长首先需形成稳定的力学环境。
[Dynamic assembly of intercalated disc during postnatal development in the rat myocardium.] [Article in Chinese]
Key Laboratory of Aerospace Medicine, Ministry of Education
The intercalated disc (ICD) complex of cardiomyocyte consists of fascia adherens, desmosomes and gap junctions which are mainly constructed by their transmembrane proteins: N-cadherin (N-cad), desmoglein-2 (DSG2) and connexin 43 (Cx43), respectively. The aim of this study was to observe the dynamic changes in colocalization of N-cad, DSG2 and Cx43 with each other in the rat left ventricular myocardium at 1, 7, 14, 28 and 90 day(s) after birth (P1, P7, P14, P28 and P90) using immunofluorescent staining. The results showed that, N-cad, DSG2 and Cx43 located all around the plasma membrane at the P1. These proteins accumulated to the long ends of cardiomyocytes, indicating preliminary formation of the ICD at the P7. The localization of three proteins at the ICD increased progressively, but their lateral localization showed an inverse trend from the P14 to P90. However, Cx43 still kept a certain amount of lateral localization in cardiomyocytes even at the P90 as compared with N-cad and DSG2. Quantitative colocalization of proteins was analyzed by the stereological method. Total percentage of colocalization of N-cad with DSG2 was 33.5% at the P1, and increased to 38.6% at the P7, 9.4% in ICD and 29.2% in lateral side. The total percentage of colocalization of N-cad with DSG2 increased to 65.7% at the P90, ICD colocalization increasing to 60.5% and lateral colocalization decreasing to 5.2%. Total percentage of colocalization of N-cad with Cx43 increased from 10.3% at the P1 to 37.1% at the P90, and only ICD colocalization increased, but lateral colocalization kept about 5%. The colocalization pattern of DSG2 with Cx43 was similar to that of N-cad with Cx43. Total percentage of colocalization of N-cad with DSG2 was higher than those of N-cad or DSG2 with Cx43. The above results suggest that the formation of mechanical junctions at the ICD of cardiomyocyte is prior to that of electrochemistry junctions during postnatal development. In other words, cardiomyocyte growth needs a stable mechanical environment at first.
窦建平，焦 博，圣娟娟，余志斌. 大鼠出生后发育期心肌闰盘装配的动态过程[J]. 生理学报 2014; 66 (5): 569-574.
DOU Jian-Ping. [Dynamic assembly of intercalated disc during postnatal development in the rat myocardium.] [Article in Chinese]. Acta Physiol Sin 2014; 66 (5): 569-574 (in Chinese with English abstract).