DHCR24通过调控P53信号网络改善血管内皮细胞衰老

Senescence of vascular endothelial cells (VECs) is one of the key mechanisms underlying the occurrence and development of vascular aging and age-related diseases...Our previous studies found that endothelial senescence was accompanied by a series of phenotype and function changes, including down-regulation of the gene expression of 24-dehydrocholesterol reductase (DHCR24). Incubation of cells with young plasma could restore a younger phenotype and up-regulate the gene expression of DHCR24 in senescent VECs, while transient silencing of DHCR24 in young VECs resulted accelerated cell senescence, accompanied with significantly increased P53 protein expression. Therefore, we inferred that DHCR24 could delay VEC senescence through repressing the P53 signaling network...In this project, we intend to examine the regulatory effects of DHCR24 on P53 through in vitro study using VECs with individual or double knockout of genes DHCR24 and P53, explore the molecular mechanisms underlying regulation of cell senescence by the DHCR24/P53 axis through their downstream effectors including P21 and Akt, and in vivo verify our hypothesis by using DHCR24+/- transgene mice with Adeno-associated virus...We hope this study could serve as a theoretical basis for a more comprehensive understanding of vascular aging, and for prevention and delay the occurrence and development of vascular aging and age-related diseases.

血管内皮细胞（VEC）的衰老是血管衰老和增龄相关疾病发生发展的核心机制之一。我们前期的研究发现VEC的衰老过程伴随着一系列表型和功能的改变，包括24胆固醇脱氢酶（DHCR24）基因表达水平的下降；年轻血浆的干预能够延缓细胞的衰老，并显著上调DHCR24基因在衰老VEC中的表达。在年轻VEC内敲低DHCR24可加速细胞的衰老，并显著增加细胞内P53蛋白的水平。因此，我们推测DHCR24可能通过调节P53来发挥延缓VEC衰老的作用。在本课题中，我们拟通过创建在VEC内单敲和双敲DHCR24/P53基因的模型来验证P53在DHCR24改善VEC衰老中的作用；探究DHCR24/P53信号轴通过下游P21、Akt分子调控VEC衰老中的具体机制；并利用DHCR24+/-转基因小鼠结合腺相关病毒活体注射技术进行在体水平验证，为更全面地理解血管衰老，开发延缓或逆转血管衰老的治疗策略提供新的思路和理论依据。

血管内皮细胞（vascular endothelial cell,VEC）衰老是血管衰老及增龄性血管疾病的始动环节。前期研究发现应用人年轻血浆干预能够上调衰老VEC上DHCR24的表达并改善细胞衰老状态。本研究旨在明确DHCR24参与调控VEC衰老的作用及机制。.细胞水平及在体水平证实DHCR24在VEC衰老过程中表达量降低，在年轻VEC上沉默DHCR24加速VEC衰老，而在年老VEC上过表达DHCR24改善VEC衰老表型，明确了DHCR24对VEC衰老具有保护性作用（表现为减少半乳糖苷酶染色阳性细胞比例，上调衰老保护蛋白SIRT1的表达，改善细胞周期停滞，提高细胞增殖能力，维持细胞通透完整性），此现象在构建的DHCR24内皮细胞条件性基因敲除小鼠上得到验证（表现为内皮细胞舒张功能受损，衰老保护蛋白SIRT1表达下调，细胞周期相关蛋白表达上调，增殖能力下降）。.机制探究发现DHCR24可通过改变其催化底物链甾醇（desmosterol）含量进而参与VEC衰老(外源性添加desmosterol加速VEC衰老表型)，通过调节ROS/eNOS信号通路改善内皮功能，通过激活ERK信号通路调控细胞周期与增殖。另一方面细胞衰老是复制性衰老和应激性衰老共同作用的结果。为此我们在应用多柔比星构建的VEC应激性衰老模型中，探究了DHCR24通过p-H2AX/p-ATM/p-P53轴改善DNA损伤，延缓VEC衰老的作用。.衰老的VEC出现功能失调（增殖修复能力受损、通透性改变，呈现衰老相关炎性分泌表型），损伤血管屏障的完整性及抗炎、抗血小板聚集的特性，进而参与血管衰老及增龄性血管疾病的发生发展。寻找VEC衰老的相关靶点及发现可行的干预措施具有重要意义，DHCR24是胆固醇代谢的调节酶，调脂药对其表达具有调节作用，因此本研究为将DHCR24作为防治血管内皮细胞衰老及增龄性血管疾病新靶点提供一定理论基础。