Velagapudi Srividya, Miranda Melroy X, Adla Priyanka, Kraler Simon, Mohammed Shafeeq A, Baki Shekhar, Robert Jerome, Rohrer Lucia, Lee Hwan, Jang Hyun-Duk, Obeid Slayman, Tailleux Anne, Staels Bart, Sepuri Naresh Babu V, Paneni Francesco, Gutti Ravi Kumar, von Eckardstein Arnold, Kim Hyo-Soo, Akhmedov Alexander, Camici Giovanni G, Lüscher Thomas F
Center for Molecular Cardiology, University of Zürich, Schlieren Campus, Switzerland.
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Cardiovasc Res. 2025 Jul 14. doi: 10.1093/cvr/cvaf087.
Low-density lipoprotein (LDL)-cholesterol is causally involved in atherosclerotic cardiovascular disease (ASCVD) pathogenesis. Pharmacological activation of the intracellular NAD + -dependent deacetylase Sirtuin-1 (SIRT1) reduces plasma LDL-cholesterol levels by increasing hepatic LDL-receptor (LDLR) expression, which intriguingly associates with atheroprotective effects. Recent studies have identified the presence of SIRT1 in plasma, however, its effects remain elusive. We found that plasma levels of SIRT1 to be decreased in atherosclerotic mice compared with wild-type controls and aimed to investigate the therapeutic potential of systemic SIRT1 restoration on lipid metabolism and plaque burden in atherosclerotic mice and dissect the underlying molecular mechanisms involved.
Twelve-week-old apolipoprotein E-deficient (ApoE-/-) mice fed a high-cholesterol diet (1.25% w/w) were randomized to receive recombinant murine SIRT1(rmSIRT1) (n = 6; 0.3 mg/kg BW i.p.) or vehicle (n = 6; PBS) every third day over 4 weeks. Boosting systemic SIRT1 levels increased hepatic LDLR protein expression, reduced plasma LDL-cholesterol levels and decreased plaque progression in ApoE-/- mice. Yet, rmSIRT1 treatment did not change hepatic proprotein convertase subtilisin/kexin type 9 (PCSK9) expression but notably increased its deacetylated levels. Mechanistically, rmSirt1 directly bound to hepatic PCSK9 thereby promoting PCSK9 deacetylation involving 3 sites, namely Lys243, Lys421, and Lys506, as shown by mass spectrometric analyses. In vitro mutagenesis to triple deacetylation mimetic (3KR) reduced SIRT1-induced PCSK9 activity, as evidenced by increased cellular binding and association of 125I-LDL to hepatic LDLR. Finally, plasma levels of SIRT1 and PCSK9 were assessed at baseline in patients with acute coronary syndromes. In these patients, plasma SIRT1 levels correlated inversely with PCSK9 with high SIRT1 levels conferring a reduced risk of major adverse cardiovascular events (MACE).
SIRT1 directly binds hepatic PCSK9 and decreases its activity by deacetylation, thereby enhancing LDL-cholesterol clearance by hepatic LDLR upregulation. Boosting circulating SIRT1 exerts atheroprotective effects in mice, with high levels associating with improved prognosis in patients with established ASCVD.
低密度脂蛋白（LDL）胆固醇在动脉粥样硬化性心血管疾病（ASCVD）发病机制中起因果作用。细胞内烟酰胺腺嘌呤二核苷酸（NAD⁺）依赖性脱乙酰酶沉默调节蛋白1（SIRT1）的药理学激活通过增加肝脏LDL受体（LDLR）表达来降低血浆LDL胆固醇水平，有趣的是，这与动脉粥样硬化保护作用相关。最近的研究已确定血浆中存在SIRT1，然而，其作用仍不明确。我们发现与野生型对照相比，动脉粥样硬化小鼠血浆中SIRT1水平降低，旨在研究全身恢复SIRT1对动脉粥样硬化小鼠脂质代谢和斑块负荷的治疗潜力，并剖析其中潜在的分子机制。
将12周龄喂食高胆固醇饮食（1.25% w/w）的载脂蛋白E缺陷（ApoE⁻/⁻）小鼠随机分组，每三天接受重组小鼠SIRT1（rmSIRT1）（n = 6；0.3 mg/kg体重，腹腔注射）或溶剂（n = 6；PBS），持续4周。提高全身SIRT1水平可增加肝脏LDLR蛋白表达，降低ApoE⁻/⁻小鼠血浆LDL胆固醇水平并减少斑块进展。然而，rmSIRT1治疗并未改变肝脏前蛋白转化酶枯草溶菌素/kexin 9型（PCSK9）的表达，但显著增加了其去乙酰化水平。从机制上讲，rmSirt1直接与肝脏PCSK9结合，从而促进PCSK9的去乙酰化，质谱分析显示涉及3个位点，即赖氨酸243、赖氨酸421和赖氨酸506。体外诱变至三去乙酰化模拟物（3KR）降低了SIRT1诱导的PCSK9活性，这通过增加细胞结合以及125I-LDL与肝脏LDLR的结合得以证明。最后，在急性冠状动脉综合征患者基线时评估血浆SIRT1和PCSK9水平。在这些患者中，血浆SIRT1水平与PCSK9呈负相关，高SIRT1水平可降低主要不良心血管事件（MACE）风险。
SIRT1直接结合肝脏PCSK9并通过去乙酰化降低其活性，从而通过上调肝脏LDLR增强LDL胆固醇清除。提高循环SIRT1水平在小鼠中发挥动脉粥样硬化保护作用，高水平与已确诊ASCVD患者的预后改善相关。
