Khan Taslima G, Bragazzi Cunha Juliana, Raut Chinmay, Burroughs Michael, Vyas Hitarthi S, Leix Kyle, Goonewardena Sascha N, Smrcka Alan V, Speliotes Elizabeth K, Emmer Brian T
Program in Chemical Biology, University of Michigan, Ann Arbor, MI, USA.
Division of Hospital Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
Atherosclerosis. 2025 Apr;403:119174. doi: 10.1016/j.atherosclerosis.2025.119174. Epub 2025 Mar 22.
An elevated level of lipoprotein(a), or Lp(a), in the bloodstream has been causally linked to the development of atherosclerotic cardiovascular disease and calcific aortic valve stenosis. Steady state levels of circulating lipoproteins are modulated by their rate of clearance, but the identity of the Lp(a) uptake receptor(s) has been controversial.
We performed a genome-scale CRISPR screen to functionally interrogate all potential Lp(a) uptake regulators in HuH7 cells. Screen validation was performed by single gene disruption and overexpression. Direct binding between purified lipoproteins and recombinant protein was tested using biolayer interferometry. An association between human genetic variants and circulating Lp(a) levels was analyzed in the UK Biobank cohort.
The top positive and negative regulators of Lp(a) uptake in our screen were LDLR and MYLIP, encoding the LDL receptor and its ubiquitin ligase IDOL, respectively. We also found a significant correlation for other genes with established roles in LDLR regulation. No other gene products, including those previously proposed as Lp(a) receptors, exhibited a significant effect on Lp(a) uptake in our screen. We validated the functional influence of LDLR expression on HuH7 Lp(a) uptake, confirmed in vitro binding between the LDLR extracellular domain and purified Lp(a), and detected an association between loss-of-function LDLR variants and increased circulating Lp(a) levels in the UK Biobank cohort.
Our findings support a central role for the LDL receptor in mediating Lp(a) uptake by hepatocytes.
血液中脂蛋白(a) [Lp(a)]水平升高与动脉粥样硬化性心血管疾病及钙化性主动脉瓣狭窄的发生存在因果关系。循环脂蛋白的稳态水平受其清除率调节，但其Lp(a)摄取受体的身份一直存在争议。
我们进行了全基因组CRISPR筛选，以功能研究HuH7细胞中所有潜在的Lp(a)摄取调节因子。通过单基因破坏和过表达进行筛选验证。使用生物膜干涉术检测纯化脂蛋白与重组蛋白之间的直接结合。在英国生物银行队列中分析人类基因变异与循环Lp(a)水平之间的关联。
我们筛选中Lp(a)摄取的主要正向和负向调节因子分别是LDLR和MYLIP，它们分别编码低密度脂蛋白受体及其泛素连接酶IDOL。我们还发现其他在LDLR调节中具有既定作用的基因存在显著相关性。在我们的筛选中，没有其他基因产物，包括那些先前被提议作为Lp(a)受体的基因产物，对Lp(a)摄取表现出显著影响。我们验证了LDLR表达对HuH7细胞Lp(a)摄取的功能影响，证实了LDLR细胞外结构域与纯化Lp(a)之间的体外结合，并在英国生物银行队列中检测到功能缺失的LDLR变异与循环Lp(a)水平升高之间的关联。
我们的研究结果支持低密度脂蛋白受体在介导肝细胞摄取Lp(a)中起核心作用。
