Utoh R, Asahina K, Suzuki K, Kotani K, Obara M, Yoshizato K
Developmental Biology Laboratory, Hiroshima University, Higashihiroshima, Japan.
Dev Growth Differ. 2000 Dec;42(6):571-80. doi: 10.1046/j.1440-169x.2000.00543.x.
We investigated the cellular mechanism of formation of subepidermal thick bundles of collagen (collagen lamella) during larval development of the bullfrog, Rana catesbeiana, using cDNA of alpha1(I) collagen as a probe. The originally bilayered larval epidermis contains basal skein cells and apical cells, and the collagen lamella is directly attached to the basement membrane. The basal skein cells above the collagen lamella and fibroblasts beneath it intensively expressed the alpha1(I) gene. As the skin developed, suprabasal skein cells ceased expression of the gene. Concomitantly, the fibroblasts started to outwardly migrate, penetrated into the lamella and formed connective tissue between the epidermis and the lamella. These fibroblasts intensively expressed the gene. As the connective tissue developed, the basal skein cells ceased to express the gene and were replaced by larval basal cells that did not express the gene. These dynamic changes took place first in a lateral region of the body skin and proceeded to all other regions except the tail. Isolated cultured skein cells expressed the gene and extracellularly deposited its protein as the type I collagen fibrils. Thus, it is concluded that anuran larval epidermal cells can autonomously and intrinsically synthesize type I collagen.
我们以α1（I）型胶原蛋白的cDNA为探针，研究了牛蛙（Rana catesbeiana）幼体发育过程中表皮下厚胶原束（胶原板层）形成的细胞机制。最初的双层幼体表皮包含基底细丝细胞和顶端细胞，胶原板层直接附着于基底膜。胶原板层上方的基底细丝细胞和其下方的成纤维细胞强烈表达α1（I）基因。随着皮肤发育，基底上层的细丝细胞停止该基因的表达。与此同时，成纤维细胞开始向外迁移，侵入板层并在表皮和板层之间形成结缔组织。这些成纤维细胞强烈表达该基因。随着结缔组织的发育，基底细丝细胞停止表达该基因，并被不表达该基因的幼体基底细胞所取代。这些动态变化首先发生在身体皮肤的外侧区域，然后除尾部外扩展到所有其他区域。分离培养的细丝细胞表达该基因，并在细胞外沉积其作为I型胶原纤维的蛋白质。因此，可以得出结论，无尾两栖类幼体表皮细胞能够自主且内在地合成I型胶原蛋白。
