多肽:N-乙酰氨基半乳糖转移酶3调控FGF23参与内皮细胞功能障碍的作用和机制

Polypeptide N-acetylgalactosaminyl transferase 3 (ppGalNAc-T3) is a member of the GalNAc-Ts family. ppGalNAc-T3 selectively directs O-glycosylation of factor fibroblast growth factor 23 (FGF23), which could play a role for processing and secretion of FGF23. Elevated FGF23 has been reported to be associated with endothelium dysfunction. We have previously obsevered that ppGalNAc-T3 contributed to endothelial dysfunction, however, the precise mechanisms of its regulation remain to be determined. The central hypothesis of the current application is that ppGalNAc-T3 mediates glycan-masking of FGF23 and serves as an important test case in the stabilization of FGF23, then regulated endothelium-dependent vasorelaxation by regulating superoxide levels and nitric oxide bioavailability. Comprehensive experimental approaches including in vitro and in vivo techniques will be used (1) to identity molecular mechanisms of ppGalNAc-T3 in endothelial injury; (2) to investigate the function of ppGalNAc-T3 in atherosclerosis process. The study will confirm the role of ppGalNAc-T3 in AS and provided new insights into the genetic regulation of the ppGalNAc-T3 with respect to the pathogenesis of AS.

多肽:N-乙酰氨基半乳糖转移酶3（ppGalNAc-T3）是ppGalNAc-Ts家族成员。已证实ppGalNAc-T3催化FGF23的O-糖基化，影响FGF23的代谢形式和功能，FGF23的异常表达介导内皮细胞功能障碍，在动脉粥样硬化（AS）的发病中起重要作用。申请者前期研究发现ppGalNAc-T3与内皮细胞的损伤有关，但其具体机制不清楚，尚缺乏ppGalNAc-T3参与AS的直接实验证据。据此，我们设想ppGalNAc-T3的糖基化作用影响FGF23的代谢和功能，进而调控内皮细胞中NO的合成及ROS的合成及清除。本课题通过人群样本数据分析、细胞实验和整体动物水平验证，探讨ppGalNAc-T3通过糖基化作用调控FGF23参与内皮细胞功能障碍的分子机制，明确ppGalNAc-T3在AS发生和发展中的作用。本研究将为寻找新的治疗AS的药物靶点提供科学依据。

由动脉粥样硬化（Atherosclerosis，AS）所导致的急性心肌梗死、心绞痛、心脏性猝死、缺血性脑卒中、心力衰竭等心血管疾病已成为全世界第一位死因。血管钙化(Vascular calcification，VC)是心血管不良事件发生风险增加和死亡率升高的独立危险因素。多肽:N-乙酰氨基半乳糖转移酶3（GALNT3）是O-GalNAc糖基转移酶家族成员，越来越多研究证据表明O-GalNAc 糖基化异常与心血管疾病发生相关。本项目研究结果显示，GALNT3具有抗动脉粥样硬化的作用。人群样本分析发现冠心病患者GALNT3表达水平与血清FGF23水平呈负相关；动物实验结果证实GALNT3通过激活PI3K/AKT/eNOS信号通路，抑制内皮细胞损伤，缓解小鼠AS的程度和发展。此外，GALNT3通过调控FGF23活性，抑制WNT/β-catenin信号通路保护高磷诱导的血管钙化；同时，GALNT3通过TNFR1/NF-κB信号通路降低血管平滑肌细胞的氧化应激和凋亡来抑制血管钙化的发生和发展。总之，本项目提供了GALNT3直接参与动脉粥样硬化及其并发症血管钙化的发生和发展的实验证据，为进一步将GALNT3作为新的潜在的动脉粥样硬化治疗靶点提供了理论支持和实验依据。