Association of type XII collagen with regions of increased stability and keratocyte density in the cornea
Association of type XII collagen with regions of increased stability and keratocyte density in the cornea
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DOI：
10.1006/exer.2002.2058
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发表时间：
2002-12-01
影响因子：
3.4
通讯作者：
Birk, DE
中科院分区：
文献类型：
--
作者：
Marchant, JK;Zhang, GY;Birk, DE
禽类前角膜具有几个不同的细胞和细胞外区域，包括上皮基底层、鲍曼层和将鲍曼层与基质分开的界面基质。这些独特的区域在生化、物理和形态上有所不同，但都含有 XII 型胶原蛋白。此前，这些界面区域中的几个区域的胶原原纤维已被证明对热变性和酶变性是稳定的。我们推断 XII 型胶原蛋白（一种原纤维相关胶原蛋白）将是赋予这种稳定特性的良好候选者。本文描述的研究旨在定位 XII 型胶原并评估其在界面基质 (IM) 中的作用。使用与短和长 XII 型胶原亚型反应以及与长亚型特异性反应的抗体，我们证明短亚型存在于鲍曼层以及位于鲍曼层和基质之间的相关界面基质中。原位杂交分析表明上皮细胞和内皮细胞均合成 XII 型胶原蛋白。然而，体外细胞培养分析表明，除了上皮细胞合成之外，基质成纤维细胞还能够合成 XII 型胶原蛋白。在高温下进行的免疫荧光分析表明，XII 型胶原蛋白在鲍曼层中具有热稳定性，但在前界面基质或后弹力层中则不然。此外，我们观察到，前部细胞外基质发育过程中 XII 型胶原的分布与鲍曼层深处界面基质中角膜细胞密度的升高精确相关。我们证明这种细胞密度是发育调节的，并不是由细胞增殖的局部增加引起的。这些数据表明鲍曼层和前界面基质具有独特的生化和形态学特性。 XII 型胶原蛋白在鲍曼层中具有热稳定性，并且作为 I 型胶原原纤维的表面成分，可能有助于该区域原纤维的稳定性。 XII 型和 I 型胶原在相邻的界面基质中都不稳定，这表明鲍曼层和 IM 之间可能存在 I-XII 型胶原原纤维组织的差异。 (C) 2002 Elsevier Science Ltd. 保留所有权利。
The anterior avian cornea possesses several distinct cellular and extracellular regions including the epithelial basal lamina, Bowman's layer and the interfacial matrix that separates Bowman's layer from the stroma. These unique regions differ biochemically, physically and morphologically but all contain type XII collagen. Previously, the collagen fibrils of several of these interfacial regions were shown to be stable to thermal and enzymatic denaturation. We reasoned that type XII collagen, a fibril-associated collagen, would be a good candidate to confer such stabilizing properties. The studies described herein were performed to localize type XII collagen and to assess its role in the interfacial matrices (IM). Using antibodies that react with both the short and long type XII collagen isoforms and that react specifically with the long isoform, we demonstrate that it is the short isoform that is present in Bowman's layer and the associated interfacial matrix lying between Bowman's and the stroma proper. In situ hybridization analyses demonstrate that both the epithelial and endothelial cells synthesize type XII collagen. In vitro cell culture analyses, however, demonstrate that in addition to epithelial cell synthesis, the stromal fibroblasts are capable of synthesizing type XII collagen as well. Immunofluorescence analyses performed at elevated temperature demonstrate that type XII collagen is thermally stable in Bowman's layer, but not in the anterior interfacial matrix or Descemet's layer. In addition, we observed that the distribution of type XII collagen during the development of the anterior extracellular matrices correlates precisely with an elevated density of keratocytes populating the interfacial matrix just deep to Bowman's layer. We show that this cellular density is developmentally regulated and does not arise from a localized increase in cell proliferation. These data demonstrate that Bowman's layer and the anterior interfacial matrix have unique biochemical and morphologic properties. Type XII collagen is thermally stable in Bowman's layer and, as a surface component of type I collagen fibrils, may contribute to the stability of the fibrils in this region. Neither type XII nor type I collagen is stable in the adjacent interfacial matrix, suggesting that differences in the type I-XII collagen fibril organization may exist between Bowman's layer and IM. (C) 2002 Elsevier Science Ltd. All rights reserved.