König A, Bruckner-Tuderman L
Department of Dermatology, University Hospital Zurich, Switzerland.
J Cell Biol. 1992 May;117(3):679-85. doi: 10.1083/jcb.117.3.679.
Collagen VII, the major component of cutaneous anchoring fibrils is expressed at a low level by normal human keratinocytes and fibroblasts in vitro. In cocultures of these two cell types, signals from fibroblasts enhance expression of collagen VII by keratinocytes and vice versa. In this study, the effects of a possible mediator of such a stimulation, transforming growth factor-beta (TGF-beta), were investigated. Its effect on the expression and deposition of the highly insoluble collagen VII was assessed in a semiquantitative manner by a newly developed enzyme-linked immunoassay which is based on immunoblotting. In keratinocyte monocultures, 0.5-20 ng/ml of TGF-beta 2 induced a dose-dependent stimulation of collagen VII expression as measured per microgram of DNA. The maximal enhancement was about sevenfold compared to controls. The effect of TGF-beta 2 was observed already after 12 h, with a steady increase at least up to 3 d. As previous studies have implicated, untreated cocultures of keratinocytes and fibroblasts exhibited a higher basic level of collagen VII expression, which could be further stimulated about twofold by TGF-beta 2. Fibroblasts alone synthesized very minor quantities of collagen VII and could be only weakly stimulated by TGF-beta 2. This growth factor seems a specific enhancer of collagen VII since the expression of laminin, collagen IV, as well as total protein was increased to a much lesser extent. Our data suggest that TGF-beta may be an important mediator of epithelial-mesenchymal interactions and may regulate the synthesis of the anchoring fibrils at the skin basement membrane zone.
VII型胶原蛋白是皮肤锚定原纤维的主要成分，正常人角质形成细胞和成纤维细胞在体外对其表达水平较低。在这两种细胞类型的共培养中，来自成纤维细胞的信号增强角质形成细胞中VII型胶原蛋白的表达，反之亦然。在本研究中，对这种刺激的一种可能介质——转化生长因子-β（TGF-β）的作用进行了研究。通过一种基于免疫印迹的新开发的酶联免疫测定法，以半定量方式评估了其对高度不溶性VII型胶原蛋白表达和沉积的影响。在角质形成细胞单培养中，0.5-20 ng/ml的TGF-β2以每微克DNA测量诱导了VII型胶原蛋白表达的剂量依赖性刺激。与对照组相比，最大增强约为7倍。TGF-β2的作用在12小时后就已观察到，至少持续增加到3天。如先前研究所暗示的，角质形成细胞和成纤维细胞的未处理共培养物表现出较高的VII型胶原蛋白表达基础水平，TGF-β2可使其进一步刺激约两倍。单独的成纤维细胞合成的VII型胶原蛋白量非常少，并且仅能被TGF-β2微弱刺激。这种生长因子似乎是VII型胶原蛋白的特异性增强剂，因为层粘连蛋白、IV型胶原蛋白以及总蛋白的表达增加程度要小得多。我们的数据表明，TGF-β可能是上皮-间充质相互作用的重要介质，并可能调节皮肤基底膜区锚定原纤维的合成。
