Elabela/Apelin-APJ轴在调控SIRT6/ku80信号和心脏衰老中的作用及其机制

Aging is a major risk factor of chronic cardiovascular diseases including heart failure in aged people, which is a major public health problem in our country and relates to abmormality of Apelin. Recently, Elabela was identified as a new cardiovascular peptide that activate apelin receptor APJ and implicated in the pathogenesis of heart failure. Our previous study demonstrated that the levels of Apelin is reduced in hearts of aged mice with heart failure (Hypertension 2017), but its roles are still unknown. Based on this, the Apelin or ku80 gene knockout (KO) mice, aged mice with heart failure are used to induce cardiac injury animal models by pressure overload using aortic banding operation (TAC) or by an osmotic minipump with Ang II. In addition, Elabela, Apelin-13, APJ siRNA, and recombinant human SIRT6 are used for in vivo & in vitro intervention experiments on the above-mentioned animal model and cardiomyocytes in order to investigate the regulatory roles and relevant mechanisms of the Elabela-Apelin-APJ axis on oxidative stress, DNA damage and repaire factor, telomere consumption, aging-related microRNAs (miR-122, miR-34a), SA-beta-gal and target signaling (AMPK-mTOR-FoxO3alpha, SIRT6-KU80). Therefore, it has a prospective future and far-reaching significance on the aspects of basic study and clinical practice to to reduce the occurrence of cardiovascular events in patients with heart failure and to provide a scientific basis of the establishing the Elabela-Apelin-APJ axis as new targets for the early prevention of the cardiac senescence, dysfunction and damage.

衰老为心力衰竭等老年人慢性疾病的主要危险因素，与Apelin异常有关。新近发现的Elabela可结合并激活Apelin受体APJ，参与心力衰竭的发病。前期研究中我们证实在老年心衰小鼠心脏组织中Apelin表达下调(Hypertension 2017)，但其作用不明。在此基础上，利用Apelin基因敲除(KO)、早衰老模型ku80KO小鼠及经TAC术诱导老年心衰损伤模型，通过Elabela、Apelin-13、APJ siRNA及重组SIRT6进行体内外干预实验，旨在探讨Elabela/Apelin-APJ轴对心肌氧自由基生成、DNA损伤修复因子、端粒耗损、衰老相关微小RNA(miR-122、miR-34a)、SA-b-gal及靶信号(AMPK-mTOR-FoxO3a、SIRT6-ku80)的影响，为确立Elabela/Apelin-APJ轴作为心脏等器官衰老及心衰损伤早期防治新靶点提供科学依据。

衰老为高血压、冠心病、心力衰竭等老年人慢性疾病的主要危险因素。本项目研究提示，与对照相比，老年高血压合并心力衰竭患者血浆中miRNA-122-5p明显上调，而ELA和APLN水平出现下调，且低血浆ELA水平对心衰患者再住院率等心血管事件有预测价值。与年轻对照小鼠相比，12月龄老龄小鼠心肌ELA、SIRT6和APLN水平下调；高血压大鼠心脏、血管组织中SA-b-gal、ku80、p21、p53、CTGF、TGFb1表达明显上调，ELA、SIRT6、ACE2水平下调。APLN基因缺失进一步导致ACE2表达下调，而p53和CTGF上调。另外，转染rAAV-miR-122-5p过表达后加重SHR高血压大鼠心肌和肾脏纤维化、凋亡和炎症损伤，与APLN、SIRT6、Beclin-1、BNIP3水平下调以及P62、CTGF、TGF-β1增加有关。在原代培养心肌成纤维细胞（CFs）和心肌细胞中，Ang II刺激减少细胞中ELA、SIRT6、AMPK和eNOS磷酸化水平，促进ROS、SA-b-gal及促炎症因子增加。miRNA-122-5p抑制剂和ELA干预治疗可逆转CFs细胞中Ang II介导的促氧化、促凋亡、促炎症及促纤维化作用，伴有DNA损伤修复因子p21、p53和SA-b-gal水平下调。ELA的细胞保护效应可被SIRT6 siRNA所逆转。对缺氧/复氧（HR）刺激的H9c2细胞，Foxp1和Pik3ip1表达均明显上调，Foxp1 siRNA干预明显抑制了H9c2细胞中HR介导的的细胞凋亡、线粒体功能障碍和超氧化物生成增加，主要与激活Pik3ip1/PI3K/Akt/eNOS信号通路有关(Acta Pharm Sin B 2020、J Am Heart Assoc 2019、Circ Res 2020、Hypertension 2021、Front Cardiovasc Med 2021、FASEB J 2021、J Cell Mol Med2020、Eur J Pharmacol 2020、Exp Cell Res 2022）。本项目为ELA-APLN-APLNR受体轴、SIRT6信号和衰老相关miRNAs（miRNA-122、miRNA-34a）调控心脏衰老损伤相关靶基因的新药物设计提供一定的科学依据。