Department of Nutrition and Integrative Physiology, and the Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT 84112, USA.
Department of Biochemistry, Metabolomics and Proteomics Core Research Facility, University of Utah, Salt Lake City, UT 84112, USA.
J Clin Endocrinol Metab. 2021 Jul 13;106(8):e3098-e3109. doi: 10.1210/clinem/dgab155.
Genome-wide association studies have identified associations between a common single nucleotide polymorphism (SNP; rs267738) in CERS2, a gene that encodes a (dihydro)ceramide synthase that is involved in the biosynthesis of very-long-chain sphingolipids (eg, C20-C26) and indices of metabolic dysfunction (eg, impaired glucose homeostasis). However, the biological consequences of this mutation on enzyme activity and its causal roles in metabolic disease are unresolved.
The studies described herein aimed to characterize the effects of rs267738 on CERS2 enzyme activity, sphingolipid profiles, and metabolic outcomes.
We performed in-depth lipidomic and metabolic characterization of a novel CRISPR knock-in mouse modeling the rs267738 variant. In parallel, we conducted mass spectrometry-based, targeted lipidomics on 567 serum samples collected through the Utah Coronary Artery Disease study, which included 185 patients harboring 1 (n = 163) or both (n = 22) rs267738 alleles.
In-silico analysis of the amino acid substitution within CERS2 caused by the rs267738 mutation suggested that rs267738 is deleterious for enzyme function. Homozygous knock-in mice had reduced liver CERS2 activity and enhanced diet-induced glucose intolerance and hepatic steatosis. However, human serum sphingolipids and a ceramide-based cardiac event risk test 1 score of cardiovascular disease were not significantly affected by rs267738 allele count.
The rs267738 SNP leads to a partial loss-of-function of CERS2, which worsened metabolic parameters in knock-in mice. However, rs267738 was insufficient to effect changes in serum sphingolipid profiles in subjects from the Utah Coronary Artery Disease Study.
全基因组关联研究已经确定了 CERS2 中常见的单核苷酸多态性 (SNP; rs267738) 与代谢功能障碍指标（如葡萄糖稳态受损）之间的关联，该基因编码一种参与非常长链鞘脂生物合成的二氢神经酰胺合酶（dihydroceramide synthase）。然而，该突变对酶活性的生物学后果及其在代谢疾病中的因果作用仍未得到解决。
本文旨在描述 rs267738 对 CERS2 酶活性、鞘脂谱和代谢结果的影响。
我们对模拟 rs267738 变异的新型 CRISPR 敲入小鼠进行了深入的脂质组学和代谢特征分析。同时，我们对通过犹他州冠状动脉疾病研究收集的 567 份血清样本进行了基于质谱的靶向脂质组学分析，其中包括 185 名携带 1 个（n=163）或 2 个（n=22）rs267738 等位基因的患者。
rs267738 突变引起的 CERS2 氨基酸取代的计算机分析表明，rs267738 对酶功能是有害的。纯合敲入小鼠的肝脏 CERS2 活性降低，并且增强了饮食诱导的葡萄糖不耐受和肝脂肪变性。然而，人类血清鞘脂和基于神经酰胺的心血管疾病风险测试 1 评分并未因 rs267738 等位基因计数而显著受到影响。
rs267738 SNP 导致 CERS2 的部分功能丧失，从而使敲入小鼠的代谢参数恶化。然而，在犹他州冠状动脉疾病研究的受试者中，rs267738 不足以引起血清鞘脂谱的变化。
