Young Blanche B, Zhang Guiyun, Koch Manuel, Birk David E
Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
J Cell Biochem. 2002;87(2):208-20. doi: 10.1002/jcb.10290.
Corneal transparency depends on the architecture of the stromal extracellular matrix, including fibril diameter, packing, and lamellar organization. The roles of collagen types XII and XIV in regulation of corneal fibrillogenesis and development were examined. The temporal and spatial expression patterns were analyzed using semi-quantitative RT-PCR, in situ hybridization, Western analysis, and immunohistochemistry. Expression of types XII and XIV collagens in cornea development demonstrated that type XII collagen mRNA levels are constant throughout development (10D-adult) while type XIV mRNA is highest in early embryonic stages (10D-14D), decreasing significantly by hatching. The spatial expression patterns of types XII and XIV collagens demonstrated a homogeneous signal in the stroma for type XIV collagen, while type XII collagen shows segregation to the sub-epithelial and sub-endothelial stroma during embryonic stages. The type XII collagen in the anterior stroma was an epithelial product during development while fibroblasts contributed in the adult. Type XIV collagen expression was highest early in development and was absent by hatching. Both types XII and type XIV collagen have different isoforms generated by alternative splicing that may alter specific interactions important in fibrillogenesis, fibril-fibril interactions, and higher order matrix assembly. Analysis of these splice variants demonstrated that the long XII mRNA levels were constant throughout development, while the short XII NC3 mRNA levels peaked early (12D) followed by a decrease. Both type XIV collagen NC1 splice variants are highest during early stages (12D-14D) decreasing by 17D of development. These data suggest type XII collagen may have a role in development of stromal architecture and maintenance of fibril organization, while type XIV collagen may have a role in regulation of fibrillogenesis.
角膜透明度取决于基质细胞外基质的结构，包括纤维直径、排列和板层组织。研究了Ⅻ型和ⅩⅣ型胶原在角膜纤维生成和发育调控中的作用。使用半定量逆转录聚合酶链反应、原位杂交、蛋白质免疫印迹分析和免疫组织化学分析了其时空表达模式。Ⅻ型和ⅩⅣ型胶原在角膜发育中的表达表明，Ⅻ型胶原信使核糖核酸水平在整个发育过程（10天龄至成年）中保持恒定，而ⅩⅣ型信使核糖核酸在胚胎早期阶段（10天龄至14天龄）最高，孵化时显著下降。Ⅻ型和ⅩⅣ型胶原的空间表达模式显示，ⅩⅣ型胶原在基质中呈均匀信号，而Ⅻ型胶原在胚胎阶段则定位于上皮下和内皮下层基质。发育过程中，前基质中的Ⅻ型胶原是上皮细胞产物，而成体中则由成纤维细胞产生。ⅩⅣ型胶原表达在发育早期最高，孵化时消失。Ⅻ型和ⅩⅣ型胶原均有通过可变剪接产生的不同异构体，这可能会改变在纤维生成、纤维-纤维相互作用和高阶基质组装中重要的特定相互作用。对这些剪接变体的分析表明，长Ⅻ型信使核糖核酸水平在整个发育过程中保持恒定，而短Ⅻ型非胶原3信使核糖核酸水平在早期（12天龄）达到峰值，随后下降。两种ⅩⅣ型胶原非胶原1剪接变体在早期阶段（12天龄至14天龄）最高，发育至17天龄时下降。这些数据表明，Ⅻ型胶原可能在基质结构发育和纤维组织维持中起作用，而ⅩⅣ型胶原可能在纤维生成调控中起作用。
