Biochem Biophys Res Commun. 2013 Nov 22;441(3):649-54.
Type V collagen (Col V) molecule, a minor component of kidney connective tissues, was found in adult cornea, and has been considered as a regulatory fibril-forming collagen that emerges into type I collagen to trigger the initiation of Col I fiber assembly. Col V was also found in injured, wound healing tissues or placenta, and was considered as a dysfunctional extracellular matrix (ECM). Reconstituted Col V fibril was characterized as an ECM to detach cells in vitro, and our previous study showed that the reconstituted Col V fibril facilitated the migration of glomerular endothelial cells and induced ECM remodeling, whereas Col V molecules stabilized cells. These facts suggest that not only the structure but also the function of Col V fibril are different from Col V molecule. Recently, Col V molecule has been reported existing in various developing tissues such as bone and lung, but Col V fibril has not been reported yet. In this study, we firstly explored the existence of Col V fibril in metanephroi, and found it distributed in the immature kidney tissues whereas disappeared when the tissues reached mature. It is likely that Col V fibril may form a prototype of pericellular microenvironment and the transient existence of Col V fibril may play a role as the pioneering ECM during metanephric tissue morphogenesis.
V 型胶原（Col V）分子是肾脏结缔组织的次要成分，在成人角膜中被发现，被认为是一种调节性纤维形成胶原，可进入 I 型胶原纤维组装中，从而引发 Col I 纤维组装的启动。Col V 也存在于受伤、愈合中的组织或胎盘组织中，被认为是一种功能失调的细胞外基质（ECM）。重建的 Col V 纤维被特征化为一种 ECM，可在体外分离细胞，我们之前的研究表明，重建的 Col V 纤维促进肾小球内皮细胞的迁移，并诱导 ECM 重塑，而 Col V 分子稳定细胞。这些事实表明，不仅 Col V 纤维的结构而且其功能都与 Col V 分子不同。最近，已经有报道称 Col V 分子存在于骨骼和肺部等各种发育组织中，但尚未有 Col V 纤维的报道。在这项研究中，我们首次探索了 Col V 纤维在肾原基中的存在，并发现其分布在未成熟的肾脏组织中，而当组织成熟时，Col V 纤维消失。可能是 Col V 纤维形成了细胞周围微环境的原型，而 Col V 纤维的短暂存在可能在肾原基组织形态发生过程中充当先驱 ECM 的作用。
