Ogawa E, Saito Y, Harada M, Kamitani S, Kuwahara K, Miyamoto Y, Ishikawa M, Hamanaka I, Kajiyama N, Takahashi N, Nakagawa O, Masuda I, Kishimoto I, Nakao K
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
J Mol Cell Cardiol. 2000 May;32(5):765-76. doi: 10.1006/jmcc.2000.1119.
Cardiac hypertrophy involves the accumulation of extracellular matrix proteins, such as fibronectin, leading to increasing myocardial stiffness, ventricular dysfunction and heart failure. To better understand the possible role of extracellular matrix-evoked intracellular signalling in ventricular myocytes, we investigated the effect of fibronectin on myocyte hypertrophic responses using cell culture models. Cell size in myocytes cultured on fibronectin-coated dishes was three times larger than that grown on non-coated dishes. However, the number of cells on fibronectin-coated dishes was not changed throughout the experiment. Protein synthesis was significantly increased by fibronectin, as were synthesis of atrial and brain natriuretic peptides. Fibronectin also elicited actin reorganization, co-localization of beta 1 integrin and vinculin, formation of focal adhesions and tyrosine phosphorylation of focal adhesion kinase in myocytes. These fibronectin-mediated effects were inhibited in a dose-dependent manner by GRGDSP, a competitive antagonist of the fibronectin receptors; GRGDSP had no effect on cell number or viability. Blocking antibody for beta 1 and beta 3 integrin significantly suppressed fibronectin-induced secretion of natriuretic peptides. Myocyte hypertrophy was observed in myocyte-nonmyocyte co-culture that reflects more closely the myocyte environment in vivo. GRGDSP may also suppress the myocyte hypertrophic response in the co-culture. These findings demonstrate that the interaction of fibronectin and RGD-dependent integrins is involved in the hypertrophic responses of myocyte in vitro, and suggest that extracellular matrix proteins such as fibronectin are not merely passive adhesive molecules but are active participants in processes leading to myocyte hypertrophy.
心肌肥大涉及细胞外基质蛋白（如纤连蛋白）的积累，导致心肌僵硬度增加、心室功能障碍和心力衰竭。为了更好地理解细胞外基质引发的细胞内信号传导在心室肌细胞中的可能作用，我们使用细胞培养模型研究了纤连蛋白对心肌细胞肥大反应的影响。在纤连蛋白包被的培养皿上培养的心肌细胞的大小是在未包被的培养皿上生长的细胞大小的三倍。然而，在整个实验过程中，纤连蛋白包被的培养皿上的细胞数量没有变化。纤连蛋白显著增加了蛋白质合成，心房钠尿肽和脑钠尿肽的合成也增加了。纤连蛋白还引起了肌动蛋白重排、β1整合素与纽蛋白的共定位、粘着斑的形成以及心肌细胞中粘着斑激酶的酪氨酸磷酸化。这些纤连蛋白介导的效应被纤连蛋白受体的竞争性拮抗剂GRGDSP以剂量依赖性方式抑制；GRGDSP对细胞数量或活力没有影响。β1和β3整合素的阻断抗体显著抑制了纤连蛋白诱导的钠尿肽分泌。在心肌细胞 - 非心肌细胞共培养中观察到了心肌细胞肥大，这更紧密地反映了体内的心肌细胞环境。GRGDSP也可能抑制共培养中的心肌细胞肥大反应。这些发现表明纤连蛋白与RGD依赖性整合素的相互作用参与了体外心肌细胞的肥大反应，并表明纤连蛋白等细胞外基质蛋白不仅是被动的粘附分子，而且是导致心肌细胞肥大过程中的积极参与者。
