Ulrich M M, Janssen A M, Daemen M J, Rappaport L, Samuel J L, Contard F, Smits J F, Cleutjens J P
Cardiovascular Research Institute Maastricht, Department of Pathology, Universiteit Maastricht, Maastricht, The Netherlands.
J Mol Cell Cardiol. 1997 Sep;29(9):2533-43. doi: 10.1006/jmcc.1997.0486.
Fibronectin is a known chemoattractant for several cell types which play a role in the wound healing process, like fibroblasts, endothelial cells and macrophages. In addition, fibronectin generates a scaffold to which other extracellular matrix components can attach. The possible involvement of fibronectin in the wound healing process after myocardial infarction (MI) was investigated by studying the expression of fibronectin isoforms after induction of a MI in the rat. Deposition of plasma (pFN) and cellular fibronectin (cFN) protein was determined immunohistochemically, using monoclonal antibodies specific for cFN and polyclonal anti-human total FN (tFN antibodies). Expression of the mRNAs of total cFN and the embryonic isoforms EIIIA and EIIIB was investigated, using in situ hybridization (ISH). The ratio between EIIIA containing fibronectin (EIIIA+-FN) mRNA and total cFN mRNA was determined using a semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). cFN protein was present from day 4 until day 35 after infarction and was located around the area of infarction, in the epi- and endomyocardium and in the wall of larger vessels. pFN was found in the infarcted cardiomyocytes 1 day after the induction of the MI. From day 4 on pFN protein deposition was found in the border zone of the infarction and in the wall of larger vessels. pFN immunoreactivity remained present at high levels around the area of infarction and in the vessel wall throughout the entire period of investigation (90 days). From day 35 after the infarction pFN protein was detected in cardiomyocytes of the right ventricle and septum. cFN mRNA, determined by in situ hybridization, was present in the border zone of the infarcted area as early as 1 day after MI, and its expression peaked at 4 days after MI. Four days after MI the mRNA's coding for both the embryonic isoforms EIIIA and EIIIB could also be detected in the same area. Because expression of the EIIIA isoform was more abundant than the EIIIB isoform we only determined the percentage of the EIIIIA containing isoform from total FN. EIIIA+ mRNA was elevated 1 day after MI. We conclude that various fibronectin isoforms including the embryonic isoforms accumulate in the heart after MI. This suggests that these isoforms may play a role in the wound healing process in the left ventricle of the infarcted heart.
纤连蛋白是几种细胞类型的已知趋化因子，这些细胞类型在伤口愈合过程中发挥作用，如成纤维细胞、内皮细胞和巨噬细胞。此外，纤连蛋白生成一个支架，其他细胞外基质成分可附着其上。通过研究大鼠心肌梗死（MI）诱导后纤连蛋白异构体的表达，探讨了纤连蛋白在心肌梗死后伤口愈合过程中的可能作用。使用针对细胞纤连蛋白（cFN）的单克隆抗体和多克隆抗人总纤连蛋白（tFN抗体），通过免疫组织化学法测定血浆纤连蛋白（pFN）和细胞纤连蛋白（cFN）蛋白的沉积。使用原位杂交（ISH）研究总cFN和胚胎异构体EIIIA和EIIIB的mRNA表达。使用半定量逆转录聚合酶链反应（RT-PCR）测定含EIIIA纤连蛋白（EIIIA+-FN）mRNA与总cFN mRNA的比率。cFN蛋白在梗死后第4天至第35天存在，位于梗死区域周围、心外膜和心内膜以及较大血管壁中。在MI诱导后1天，在梗死心肌细胞中发现pFN。从第4天起，在梗死边缘区和较大血管壁中发现pFN蛋白沉积。在整个研究期间（90天），梗死区域周围和血管壁中的pFN免疫反应性一直保持在高水平。梗死后第35天，在右心室和室间隔的心肌细胞中检测到pFN蛋白。通过原位杂交测定，cFN mRNA早在MI后1天就存在于梗死区域的边缘区，其表达在MI后4天达到峰值。MI后4天，在同一区域也可检测到编码胚胎异构体EIIIA和EIIIB的mRNA。由于EIIIA异构体的表达比EIIIB异构体更丰富，我们仅测定了总FN中含EIIIIA异构体的百分比。EIIIA+ mRNA在MI后1天升高。我们得出结论，包括胚胎异构体在内的各种纤连蛋白异构体在MI后在心脏中积累。这表明这些异构体可能在梗死心脏左心室的伤口愈合过程中发挥作用。
