circLSMs 对Cathepsin D降解光老化皮肤晚期糖基化终末产物的调控作用及机制研究

Photoaging has increasingly received high interest of research for its close relationship with immunologic and inflammatory dermatoses, and potential carcinogenicity. The accumulation of advanced glycation end products (AGEs) is one of its most important pathological features. AGEs used to be believed to resist degradation. However, foreign studies and our research have found that AGEs can be internalized by fibroblasts, and degraded by lysosomal proteases and others. Recently, cathepsin D (CatD) has been confirmed to be the key protease to degrade AGEs in our laboratory, but its expression is decreased in photoaged skin. Moreover, we have found that circLSMs (circular RNA) and their sponged miR-27a and miR-23a are closely correlated with CatD expression and autophagy. Nevertheless, whether they regulate CatD expression and CatD-mediated AGEs degradation is not yet clarified. This research will investigate whether circLSMs regulate CatD expression and affect AGEs accumulation in photoaged skin through sponging miR-27a and or miR-23a, with the methods of dual luciferase reporter gene assay, miRNA poll down, three-dimensional cell culture, and so on. The results will not only reveal the pathogenesis of AGEs accumulation in photoaging, but also provide a new target for the prevention and treatment of photoaging.

皮肤光老化与日光相关免疫性和炎症性皮肤病密切相关，并可导致皮肤肿瘤，故一直为研究热点。晚期糖基化终末产物（AGEs）堆积是其最重要的病理特征之一。既往认为AGEs极难降解，但国外和我们的研究均发现其可被成纤维细胞内吞，并被溶酶体蛋白酶等降解。我们最近的研究不仅证实Cathepsin D(CatD)是降解光老化皮肤AGEs的关键酶及其在光老化皮肤表达降低，还发现环状RNA circLSMs及其对应的海绵吸附miR-23a和miR-27a与CatD表达及自噬密切相关，但它们是否调控CatD表达及其介导的AGEs降解还不清楚。本研究拟采用双荧光素酶报告基因检测、miRNA poll down、三维细胞培养等方法，阐明circLSMs通过海绵吸附miR-23a和或miR-27a调控CatD表达及干预光老化皮肤AGEs堆积。研究结果不仅揭示光老化皮肤AGEs堆积机制，而且可为光老化防治提供新靶点。

皮肤光老化不仅影响人外貌, 而且与日光相关免疫性和炎症性皮肤病密切相关，并可导致皮肤肿瘤。晚期糖基化终末产物（AGEs）堆积是光老化最重要的病理特征之一，在光老化形成过程中的多个环节起重要作用。既往认为AGEs极难降解，但目前发现其可被成纤维细胞内吞，并被溶酶体蛋白酶等降解。环状RNA（circRNA）是最近发现具有基因调控功能的非线性非编码RNA。由于circRNA比线性非编码RNA更耐核酸酶水解、更加稳定，其在光老化中作用和机制备受关注。我们研究了组织蛋白酶D（CatD）对光老化成纤维细胞吞入胞内AGEs降解的调控作用、光老化对成纤维细胞自噬影响以及circIGF2BP3对光老化成纤维细胞CatD表达和活性、自噬及其降解吞入胞内AGEs的影响，发现CatD是皮肤成纤维细胞内AGEs降解的关键酶并对光老化皮肤AGEs的堆积起着重要调控作用，证明了UVA诱导的光老化通过下调溶酶体CatD、B、L表达以及降低溶酶体的酸性抑制细胞自噬，揭示并验证了circIGF2BP3可调控光老化皮肤成纤维细胞自噬水平、CatD表达和活性以及胞内AGEs降解，为进一步干预光老化皮肤AGEs 堆积打下了理论基础。本研究结果从新的角度阐明了光老化的机制，不仅为深入研究皮肤光老化的机制奠定基础，且可据此开发基于circRNA的更好的小分子药物用于光老化及相关皮肤病的预防和治疗，有着重要的理论和应用价值。