增生性瘢痕中DDR1调控PTEN在成纤维细胞增殖中的作用研究

Hyperplastic scar (HS) is a common complication secondary to trauma of the skin, severe trouble plastic and burn surgery. Fibroblasts (FBs) excessive proliferation and activation and secretion of ECM are the important reasons for the formation of the HS. We found that there is a high expression and the high level of phosphorylation of DDR1 collagen receptors in the HS tissue, the activation of the latter can promote Akt phosphorylation and FBs proliferation and activation. However the mechanism of DDR1 induced Akt pathway activation is still unclear. PTEN is one of the upstream regulatory molecules of Akt. We found that the expression of PTEN in HS tissue and the primary culture FBs significantly lower than that of in normal skin. Thus we speculate on the formation of the HS, PTEN may participate in the DDR1-dependent Akt activation. However the regulation function of PTEN expression by DDR1 need to be further confirmed, the details of the molecular mechanisms also need further exploration. Therefore, this study proposed on the basis of previous work, using the primary culture, gene transfection, virus packaging, RNA interference, luciferase report gene and confocal laser technology by in vitro and in vivo experiments, explicit the function and molecular mechanism of PTEN in DDR1-Akt pathway and the process of FBs excessive proliferation, lay a foundation for clarifying the mechanism of HS formation.

增生性瘢痕（HS）是继发于皮肤创伤后的常见并发症。成纤维细胞（FBs）过度增殖活化及分泌ECM是导致HS形成的重要原因。我们发现①HS组织中存在一种高表达且高磷酸化的胶原受体DDR1，后者的活化能够促进Akt的磷酸化修饰以及FBs的增殖和活化；②Akt上游调控分子PTEN在HS组织及原代FBs中表达显著低于正常皮肤。大量文献提示，PTEN对Akt具有负性调控作用。因此我们推测在HS形成时，PTEN可能参与了DDR1依赖的Akt激活。然而DDR1对PTEN表达的调控作用需要进一步确认，DDR1-PTEN-Akt通路在HS形成中发挥的作用有待深入探索。因此，本研究拟在前期工作的基础上，利用原代培养、基因转染、病毒包装、RNA干扰、双荧光素酶报告基因、激光共聚焦等技术，通过体外和体内实验，明确PTEN在DDR1-Akt通路及FBs过度增殖中的作用及分子机制，为阐明HS发生机制奠定基础。

成纤维细胞(FBs)过度增殖及向肌成纤维细胞(MFBs)分化被认为是增生性瘢痕(HS)形成的主要原因，因此抑制瘢痕组织中FBs活化是HS防治的重要策略之一。本研究中我们发现在人瘢痕组织中存在一种高表达和高磷酸化的酪氨酸激酶受体——盘状蛋白结构域受体1 (DDR1)，其在胶原蛋白的诱导下能够发生磷酸化修饰。在体外实验中，我们证实了磷酸化的DDR1能够促进FBs增殖及向MFBs方向大量分化。深入研究中，我们发现DDR1磷酸化能够诱导核因子NF-κB p65亚基入核进而阻遏抑癌基因PTEN表达，这一发现解释了胶原受体DDR1促进FBs活化的原因。我们也观察到在人HS临床标本中存在DDR1和PTEN表达水平负相关的现象，即DDR1上调的同时伴有PTEN的下调。这一现象即支持了前期细胞水平的发现，也提示了二者在HS病理进程中的临床价值。在兔耳增生性瘢痕治疗过程中，我们发现DDR1抑制剂可显著改善瘢痕的增生。这些结果表明DDR1/NF-κB/PTEN通路可能是胶原诱导FBs活化及HS形成的关键因素，DDR1有望成为HS治疗过程中潜在的新靶点。