circRNA TET2调控STAT3影响角质形成细胞再上皮化在糖尿病皮肤伤口愈合中的机制研究

Skin keratinocytes play a critical role in diabetic wound healing. Our previous work has demonstrated that advanced glycation end products (AGEs) could affect keratinocytes re-epithelization and diabetic dermopathy development, the lower expression of circRNA TET2 in keratinocytes. Further experiments suggest that circRNA TET2 can binding to STAT3 protein via RNA pull-down. Therefore, we speculate that circRNA TET2 can improve STAT3 nuclear exclusion and increased its transcriptional activity, the binding of STAT3 and miR-125b in nucleus competitively inhibits miR-125b to regulate Sp1, leading to the binding of Sp1 to MMP-9 promoter and inhibiting the expression of MMP-9. By further using RNA pull-down and dual-luciferase reporter gene assay to investigate interplay between circRNA TET2 and STAT3, the present study was to explore the molecular mechanisms responsible for skin keratinocytes re-epithelization in the development of diabetic wound healing. This research may shed new lights into the role of circRNA in diabetic dermopathy, and provide clues for developing effective diabetic ulcers therapeutic strategies.

角质形成细胞在糖尿病创面愈合中起关键作用。我们前期研究已证明糖基化终末产物(AGEs)通过抑制角质形成细胞再上皮化影响创面愈合，而该过程中皮肤角质形成细胞低表达circRNA TET2；进一步RNA pull-down实验表明circRNA TET2可结合蛋白STAT3。基于此，我们提出circRNA TET2促进糖尿病皮肤角质形成细胞再上皮化的可能机制：circRNA TET2通过影响STAT3核内聚集，STAT3与miR-125b结合后竞争性抑制miR-125b对Sp1调控，导致Sp1与MMP-9启动子结合减少抑制MMP-9表达，最终促进皮肤角质形成细胞再上皮化。本项目拟进一步采用 RNA pull-down、双荧光素酶报告基因、RIP等方法，旨在获得circRNA TET2调控STAT3参与糖尿病皮肤角质形成细胞再上皮化的可靠证据，并探讨这一事件对糖尿病皮肤创面愈合的重要性和意义。

角质形成细胞在糖尿病创面愈合中起关键作用。近年来，研究显示环状RNA（circular RNA, circRNA）与表观遗传、基因表达调控和疾病发生有非常密切的关系，其参与调节细胞增殖、分化和凋亡等生物学过程，而在糖尿病皮肤病变中尚未有研究。在我们前期研究已证明在糖尿病患者皮肤组织中低表达circRNA TET2；进一步在角质形成细胞中行RNA pull-down实验表明circRNA TET2可结合蛋白STAT3。我们进一步研究circRNA TET2在糖尿病皮肤角质形成细胞再上皮化中的机制：高糖作用下，角质形成细胞中circRNA TET2低表达；过表达circRNA TET2后角质形成细胞增殖、迁移能力增加，与STAT3、miRNA125b、Sp1表达有相关性；RIP发现角质形成细胞中STAT3可钩取circRNA TET2，双荧光素酶报告基因证实STAT3、Sp1均为miRNA125b靶基因；上调circRNA TET2通过抑制STAT3核内聚集，STAT3与miRNA 125b结合减少，解除竞争性抑制miR-125b对Sp1的调控，导致Sp1对MMP-9启动子调控减弱MMP-9表达减少，最终促进皮肤角质形成细胞再上皮化。获得circRNA TET2调控STAT3参与糖尿病皮肤角质形成细胞再上皮化的可靠证据，对糖尿病皮肤创面愈合有重要的意义。