Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
Differentiation. 2011 Jun;81(5):307-14. doi: 10.1016/j.diff.2011.03.004. Epub 2011 Apr 17.
Organogenesis involves a series of dynamic morphogenesis and remodeling processes. Since feathers exhibit complex forms, we have been using the feather as a model to analyze how molecular pathways and cellular events are used. While several major molecular pathways have been studied, the roles of matrix degrading proteases and inhibitors in feather morphogenesis are unknown. Here we addressed this knowledge gap by studying the temporal and spatial expression of proteases and inhibitors in developing feathers using mammalian antibodies that cross react with chicken proteins. We also investigated the effect of protease inhibitors on feather development employing an in vitro feather bud culture system. The results show that antibodies specific for mammalian MMP2 and TIMP2 stained positive in both feather epithelium and mesenchyme. The staining co-localized in structures of E10-E13 developing feathers. Interestingly, MMP2 and TIMP2 exhibited a complementary staining pattern in developing E15 and E20 feathers and in maturing feather filaments. Although they exhibited a slight delay in feather bud development, similar patterns of MMP2 and TIMP2 staining were observed in in vitro culture explants. The broad spectrum pharmacological inhibitors AG3340 and BB103 (MMP inhibitors) but not Aprotinin (a plasmin inhibitor) showed a reversible effect on epithelium invagination and feather bud elongation. TIMP2, a physiological inhibitor to MMPs, exhibited a similar effect. Markers of feather morphogenesis showed that MMP activity was required for both epithelium invagination and mesenchymal cell proliferation. Inhibition of MMP activity led to an overall delay in the expression of molecules that regulate either early feather bud growth and/or differentiation and thereby produced abnormal buds with incomplete follicle formation. This work demonstrates that MMPs and their inhibitors are not only important in injury repair, but also in development tissue remodeling as demonstrated here for the formation of feather follicles.
组织发生涉及一系列动态形态发生和重塑过程。由于羽毛表现出复杂的形态，我们一直将羽毛作为模型来分析分子途径和细胞事件如何被利用。虽然已经研究了几个主要的分子途径，但基质降解蛋白酶和抑制剂在羽毛形态发生中的作用尚不清楚。在这里，我们通过使用与鸡蛋白发生交叉反应的哺乳动物抗体来研究发育中的羽毛中蛋白酶和抑制剂的时空表达，从而填补了这一知识空白。我们还通过体外羽毛芽培养系统研究了蛋白酶抑制剂对羽毛发育的影响。结果表明，针对哺乳动物 MMP2 和 TIMP2 的抗体在羽毛上皮和间充质中均呈阳性染色。染色与 E10-E13 发育中的羽毛的结构共定位。有趣的是，MMP2 和 TIMP2 在发育中的 E15 和 E20 羽毛和成熟的羽毛纤维中表现出互补的染色模式。尽管在羽毛芽发育中它们表现出轻微的延迟，但在体外培养外植体中观察到 MMP2 和 TIMP2 的染色模式相似。广谱药理学抑制剂 AG3340 和 BB103（MMP 抑制剂）而不是 Aprotinin（纤溶酶抑制剂）对上皮内陷和羽毛芽伸长表现出可逆作用。MMPs 的生理抑制剂 TIMP2 也表现出类似的效果。羽毛形态发生的标志物表明 MMP 活性对于上皮内陷和间充质细胞增殖都是必需的。MMP 活性的抑制导致调节早期羽毛芽生长和/或分化的分子的表达整体延迟，从而产生具有不完全滤泡形成的异常芽。这项工作表明，MMP 及其抑制剂不仅在损伤修复中很重要，而且在组织重塑发育中也很重要，正如这里所示，它们在羽毛滤泡的形成中起作用。
