p16INK4a-pRb通路及其相关表观遗传调控在人真皮干细胞自我更新与衰老中的作用

Skin-derived precursors (SKPs) are multipotent progenitor cells with properties of dermal stem cells. SKPs play important roles in the homeostasis and wound repair of human skin, which make them promising in skin tissue engineering. Besides, their ability to differentiate into a broad panel of cell types endows them with the therapeutic potential even in other tissues. However, in-vitro expansion of SKPs is defective and people so far know very little about their self-renewal regulation, which definitely hampers their application in regenerative medicine. Our previous work showed that after separation from their physiological microenvironment, human foreskin-derived SKPs quickly senesced and lost their self-renewal ability, which resulted in the failure of their long-term expansion.Our results also imply that p16INK4a pathway may play a critical role in this process. Based on this discovery, the present study is to investigate in detail the role of .p16INK4a pathway in SKP senescence and aging regulation, both in vitro and in vivo. We also propose to explore the functions and regulation mechanisms of p16INK4a related PcG proteins in SKP self-renewal and aging. Our study will not only promote the practice of SKPs in medicine, but also help people learn more about skin aging in order to fight against it.

皮肤来源前体细胞（SKPs）是一类具有真皮干细胞特性的多潜能细胞，在皮肤正常生理功能维持与损伤修复中发挥关键作用,对于皮肤创伤修复和组织工程皮肤的构建具有重要意义。但人们对SKPs的自我更新缺乏研究，SKPs在体外无法大量扩增，给SKPs的深入研究和应用造成极大障碍。本实验室在前期工作中首次发现人SKPs离开其体内微环境后将迅速发生细胞衰老现象，前期结果提示p16INK4a-pRb通路可能在其中发挥关键作用。本课题将在前期发现的基础上，进一步详细研究p16INK4-pRb信号通路在SKPs体内外衰老调控中的具体作用，深入挖掘染色质修饰因子PcG蛋白参与p16INK4a表达和活性调节以及真皮干细胞衰老调控的具体机制，并探索其与皮肤衰老的联系。我们的研究将有助于全面了解真皮干细胞的调控机制，对认识和对抗皮肤衰老具有积极意义，对发展真皮干细胞应用于皮肤组织工程与再生医学治疗也将起到推动作用。

皮肤来源前体细胞（SKPs）是一类具有真皮干细胞特性的多潜能细胞，在皮肤正常生理功能维持与损伤修复中发挥关键作用，对于皮肤创伤修复和组织工程皮肤的构建具有重要意义。但人们对人SKPs 的自我更新缺乏研究，人SKPs 在体外无法大量扩增，给SKPs 的深入研究和应用造成极大障碍。本实验室前期的研究发现人SKPs在体外迅速发生衰老从而无法长期维持其自我更新。本项目以细胞衰老关键调控信号p16INK4a相关通路在SKPs衰老中的作用为切入点，拟深入探究人SKPs衰老与自我更新的调控机制。本项目在建立了稳定的人SKPs体外衰老模型后对人SKPs的衰老进行了详细的表型研究与基因表达分析。我们发现人SKPs的衰老表型及其基因表达模式与经典的细胞衰老存在诸多差异。随后的实验发现细胞衰老经典调控通路p53通路与p16INK4a通路在人SKPs衰老中发挥的作用有限。进一步深入的表达与功能实验发现Akt-FOXO3-p27KIP1/p15INK4b信号通路对人SKPs的体外衰老起关键的调控作用。操控该通路关键因子的表达或活性能改变人SKPs衰老的进程，延长SKPs在体外自我更新的时间。同时，我们利用三维水凝胶支架培养体系模拟人SKPs在体内的微环境，有效地抑制了人SKPs的衰老并增强其自我更新能力。此外，我们还建立了SKPs的裸鼠移植模型，为研究SKPs的体内功能与衰老情况奠定了基础。本项目为成体干细胞的衰老与自我更新研究提供了全新的视野，也为SKPs这种极易获取的干细胞在体外的大量扩增提供了新思路与方法，促进了SKPs在再生医学中的应用。