Kapila Y L, Kapila S, Johnson P W
Department of Stomatology, University of California San Francisco, USA.
Matrix Biol. 1996 Sep;15(4):251-61. doi: 10.1016/s0945-053x(96)90116-x.
Fragments of the matrix molecule fibronectin (FN) have been shown to modulate tissue remodeling activity by inducing matrix metalloproteinases (MMPs) in synovial fibroblasts. These molecules could contribute to the tissue degradation that occurs during periodontal disease if they also modulate the expression of proteinases in cells of the periodontal ligament (PDL). We tested the hypothesis that FN and specific FN fragments induce the expression of specific proteinases in PDL cells. Using substrate zymograms, reverse zymograms and Western immunoblots, we found that PDL cells constitutively express 72 kDa gelatinase, urokinase-type plasminogen activator (uPA) and at least three inhibitors whose molecular masses correspond to those of the tissue inhibitors of metalloproteinases (TIMPs). A fourth, previously uncharacterized, proteinase inhibitor of approximately 22 kDa was also observed in some cell isolates. PDL cells, when exposed to a 120 kDa proteolytic FN fragment containing the cell-binding domain, were induced to express collagenase and stromelysin and also demonstrated an increased secretion of the serine proteinase uPA. Expression of collagenase increased with increasing concentrations (0.001 microM-1 microM) of the 120 kDa FN fragment. This fragment also induced the expression of a 20 kDa inhibitor, but not of the higher-molecular-mass inhibitors, in PDL cells. The observed alterations in proteinases were associated specifically with the 120 kDa FN fragment, since similar responses were not seen when PDL cells were exposed to either a 60 kDa heparin-binding FN fragment or a 45 kDa collagen/gelatin-binding FN fragment. PDL cells exposed to intact FN did not express the proteinases induced by the 120 kDa fragment but did express 92 kDa gelatinase and the 20 kDa proteinase inhibitor. These data suggest that FN and specific FN fragments can differentially induce the expression of proteinases in PDL cells. Thus, functional regions of FN may modulate many of the functions of PDL cells that contribute to periodontal disease, wound healing and maintenance of extracellular matrix in periodontal tissues.
基质分子纤连蛋白（FN）片段已被证明可通过诱导滑膜成纤维细胞中的基质金属蛋白酶（MMPs）来调节组织重塑活性。如果这些分子也能调节牙周韧带（PDL）细胞中蛋白酶的表达，那么它们可能会导致牙周疾病期间发生的组织降解。我们验证了FN和特定FN片段可诱导PDL细胞中特定蛋白酶表达的假说。通过底物酶谱、反向酶谱和Western免疫印迹，我们发现PDL细胞组成性表达72 kDa明胶酶、尿激酶型纤溶酶原激活剂（uPA）以及至少三种分子量与金属蛋白酶组织抑制剂（TIMPs）相对应的抑制剂。在一些细胞分离物中还观察到一种分子量约为22 kDa的第四种蛋白酶抑制剂，此前未对其进行过描述。当PDL细胞暴露于含有细胞结合域的120 kDa FN蛋白水解片段时，会被诱导表达胶原酶和基质溶解素，并且丝氨酸蛋白酶uPA的分泌也会增加。胶原酶的表达随着120 kDa FN片段浓度的增加（0.001 microM - 1 microM）而增加。该片段还在PDL细胞中诱导了一种20 kDa抑制剂的表达，但未诱导高分子量抑制剂的表达。观察到的蛋白酶变化与120 kDa FN片段特异性相关，因为当PDL细胞暴露于60 kDa肝素结合FN片段或45 kDa胶原/明胶结合FN片段时，未观察到类似的反应。暴露于完整FN的PDL细胞不表达由120 kDa片段诱导的蛋白酶，但表达92 kDa明胶酶和20 kDa蛋白酶抑制剂。这些数据表明，FN和特定FN片段可差异诱导PDL细胞中蛋白酶的表达。因此，FN的功能区域可能会调节PDL细胞的许多功能，这些功能有助于牙周疾病、伤口愈合以及牙周组织细胞外基质的维持。
