Analysis of the role of keratinocyte Stat3 using the epithelia-specific gene ablation technology.

我们在角蛋白5启动子下使用Cre-loxP系统建立了角化细胞特异性Stat3破坏小鼠，以研究Stat3在角化细胞内所需信号传导中的作用，因为种系Stat3基因的消融会导致早期胚胎致死。虽然被stat3破坏的小鼠出生正常，皮肤没有变化，但发现伤口愈合大大迟缓，第二毛周期缺失。体外迁移实验显示，生长因子介导的细胞迁移在stat3破坏的角质形成细胞中明显受损，而它们的增殖反应完好无损。这些结果表明，角化细胞中的Stat3对于皮肤形态发生是必不可少的，但对于皮肤重塑（包括伤口愈合和第二毛发周期的进展）是必不可少的，这一过程需要角化细胞的迁移。有趣的是，与对照组小鼠相比，局部应用PMA或拔毛可诱导Stat3破坏小鼠的生长。此外，我们发现stat3干扰的角质形成细胞在PKC激活后在体外迁移。鉴于生长过程需要角化细胞迁移，这些结果表明，至少有两种不同的基于角化细胞迁移的生长过程，stat3依赖和独立的途径。有趣的是，这两种信号通路都需要PI3K激活。因此，我们利用角化细胞特异性stat3破坏小鼠，阐明了参与毛发循环的信号通路及其串扰。

We have established keratinocyte-specific Stat3-disrupted mice by using Cre-loxP system under the keratin 5 promoter in order to Investigate the role of Stat3 in signaling required within keratinocytes, since germline ablation of Stat3 gene resulted in early embryonic lethality. Although Stat3-disrupted mice were born normal and no alteration in the skin was found, It was found that wound healing was greatly retarded and the second hair cycle was absent. In vitro migration assay revealed that growth factor-mediated cell migration was markedly impaired in Stat3-disrupted keratinocytes, while their proliferative responses were Intact. These results indicated that Stat3 in keratinocytes was dispensable for skin morphogenesis, but essential for the skin remodeling including wound healing and the progression of the second hair cycle, the processes which required keratinocyte migration. Interestingly, anagen of Stat3- disrupted mice was Induced by topical application of PMA or hair plucking compared to control mice. Furthermore, we found that Stat3-disrupted keratinocytes migrated in vitro upon PKC activation. Given that anagen process required keratinocyte migration, these results suggested that there were at least two distinct pathways for anagen progression based on keratinocyte migration, Stat3-dependent and independent pathways. Interestingly, both signal pathways required PI3K activation. Thus we elucidated signaling pathways and their crosstalks that are Involved in hair cycling using keratinocyte-specific Stat3-disrupted mice.