Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Republic of Korea.
Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Republic of Korea; Gwangju Center, Korea Basic Science Institute (KBSI), Gwangju, Republic of Korea.
J Lipid Res. 2022 Jun;63(6):100221. doi: 10.1016/j.jlr.2022.100221. Epub 2022 May 6.
Neuronal growth regulator 1 (NEGR1) is a glycosylphosphatidylinositol-anchored membrane protein associated with several human pathologies, including obesity, depression, and autism. Recently, significantly enlarged white adipose tissue, hepatic lipid accumulation, and decreased muscle capacity were reported in Negr1-deficient mice. However, the mechanism behind these phenotypes was not clear. In the present study, we found NEGR1 to interact with cluster of differentiation 36 (CD36), the major fatty acid translocase in the plasma membrane. Binding assays with a soluble form of NEGR1 and in situ proximal ligation assays indicated that NEGR1-CD36 interaction occurs at the outer leaflet of the cell membrane. Furthermore, we show that NEGR1 overexpression induced CD36 protein destabilization in vitro. Both mRNA and protein levels of CD36 were significantly elevated in the white adipose tissue and liver tissues of Negr1 mice. Accordingly, fatty acid uptake rate increased in NEGR1-deficient primary adipocytes. Finally, we demonstrated that Negr1 mouse embryonic fibroblasts showed elevated reactive oxygen species levels and decreased adenosine monophosphate-activated protein kinase activation compared with control mouse embryonic fibroblasts. Based on these results, we propose that NEGR1 regulates cellular fat content by controlling the expression of CD36.
神经元生长调节因子 1（NEGR1）是一种糖基磷脂酰肌醇锚定的膜蛋白，与多种人类疾病有关，包括肥胖、抑郁和自闭症。最近，研究报道 NEGR1 缺陷型小鼠的白色脂肪组织显著增大、肝脏脂质积累减少和肌肉能力下降。然而，这些表型背后的机制尚不清楚。在本研究中，我们发现 NEGR1 与分化簇 36（CD36）相互作用，CD36 是质膜中主要的脂肪酸转运蛋白。可溶性 NEGR1 的结合实验和原位近末端连接实验表明，NEGR1-CD36 相互作用发生在细胞膜的外叶。此外，我们证明 NEGR1 过表达可诱导 CD36 蛋白在体外不稳定。NEGR1 敲除小鼠的白色脂肪组织和肝脏组织中 CD36 的 mRNA 和蛋白水平均显著升高。因此，NEGR1 缺陷型原代脂肪细胞中的脂肪酸摄取率增加。最后，我们证明与对照小鼠胚胎成纤维细胞相比，Negr1 小鼠胚胎成纤维细胞的活性氧水平升高，腺苷一磷酸激活蛋白激酶的激活减少。基于这些结果，我们提出 NEGR1 通过控制 CD36 的表达来调节细胞内脂肪含量。
