Sasse Philipp, Malan Daniela, Fleischmann Michaela, Roell Wilhelm, Gustafsson Erika, Bostani Toktam, Fan Yun, Kolbe Thomas, Breitbach Martin, Addicks Klaus, Welz Armin, Brem Gottfried, Hescheler Jürgen, Aszodi Attila, Costell Mercedes, Bloch Wilhelm, Fleischmann Bernd K
Institute of Physiology I, Life & Brain Center, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.
Cardiovasc Res. 2008 Dec 1;80(3):435-44. doi: 10.1093/cvr/cvn225. Epub 2008 Aug 10.
Perlecan is a heparansulfate proteoglycan found in basement membranes, cartilage, and several mesenchymal tissues that form during development, tumour growth, and tissue repair. Loss-of-function mutations in the perlecan gene in mice are associated with embryonic lethality caused primarily by cardiac abnormalities probably due to hemopericards. The aim of the present study was to investigate the mechanism underlying the early embryonic lethality and the pathophysiological relevance of perlecan for heart function.
Perlecan-deficient murine embryonic stem cells were used to investigate the myofibrillar network and the electrophysiological properties of single cardiomyocytes. The mechanical stability of the developing perlecan-deficient mouse hearts was analysed by microinjecting fluorescent-labelled dextran. Maturation and formation of basement membranes and cell-cell contacts were investigated by electron microscopy, immunohistochemistry, and western blotting. Sarcomere formation and cellular functional properties were unaffected in perlecan-deficient cardiomyocytes. However, the intraventricular dye injection experiments revealed mechanical instability of the early embryonic mouse heart muscle wall before embryonic day 10.5 (E10.5). Accordingly, perlecan-null embryonic hearts contained lower amounts of the critical basement membrane components, collagen IV and laminins. Furthermore, basement membranes were absent in perlecan-null cardiomoycytes whereas adherens junctions formed and matured around E9.5. Infarcted hearts from perlecan heterozygous mice displayed reduced heart function when compared with wild-type hearts.
We propose that perlecan plays an important role in maintaining the integrity during cardiac development and is important for heart function in the adult heart after injury.
基底膜聚糖是一种硫酸乙酰肝素蛋白聚糖，存在于基底膜、软骨以及发育、肿瘤生长和组织修复过程中形成的几种间充质组织中。小鼠基底膜聚糖基因的功能丧失突变与胚胎致死率相关，主要是由于可能由心包积血导致的心脏异常。本研究的目的是探讨早期胚胎致死率的潜在机制以及基底膜聚糖对心脏功能的病理生理相关性。
利用缺乏基底膜聚糖的小鼠胚胎干细胞研究单个心肌细胞的肌原纤维网络和电生理特性。通过显微注射荧光标记的葡聚糖分析发育中的基底膜聚糖缺陷型小鼠心脏的机械稳定性。通过电子显微镜、免疫组织化学和蛋白质印迹法研究基底膜和细胞间接触的成熟和形成。缺乏基底膜聚糖的心肌细胞中肌节形成和细胞功能特性未受影响。然而，心室内染料注射实验显示，在胚胎第10.5天（E10.5）之前，早期胚胎小鼠心肌壁存在机械不稳定性。因此，缺乏基底膜聚糖的胚胎心脏中关键基底膜成分胶原蛋白IV和层粘连蛋白的含量较低。此外，缺乏基底膜聚糖的心肌细胞中不存在基底膜，而在E9.5左右形成并成熟了黏着连接。与野生型心脏相比，基底膜聚糖杂合小鼠的梗死心脏心脏功能降低。
我们认为基底膜聚糖在心脏发育过程中维持完整性方面起重要作用，并且对成年心脏损伤后的心脏功能也很重要。
