Department of Nutrition, Diabetes and Metabolism, School of Medicine, Pontificia Universidad Católica de Chile, 8331150, Chile.
Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, United States.
Biochim Biophys Acta Mol Basis Dis. 2021 Sep 1;1867(9):166167. doi: 10.1016/j.bbadis.2021.166167. Epub 2021 May 12.
Adipocytes from lipodystrophic Agpat2 mice have impaired adipogenesis and fewer caveolae. Herein, we examined whether these defects are associated with changes in lipid composition or abnormal levels of caveolae-associated proteins. Lipidome changes were quantified in differentiated Agpat2 adipocytes to identify lipids with potential adipogenic roles.
Agpat2 and wild type brown preadipocytes were differentiated in vitro. Plasma membrane was purified by ultracentrifugation. Number of caveolae and caveolae-associated proteins, as well as sterol, sphingolipid, and phospholipid lipidome were determined across differentiation.
Differentiated Agpat2 adipocytes had decreased caveolae number but conserved insulin signaling. Caveolin-1 and cavin-1 levels were equivalent between Agpat2 and wild type adipocytes. No differences in PM cholesterol and sphingolipids abundance were detected between genotypes. Levels of phosphatidylserine at day 10 of differentiation were increased in Agpat2 adipocytes. Wild type adipocytes had increased whole cell triglyceride, diacylglycerol, phosphatidylglycerol, phosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, and trihexosyl ceramide, and decreased 24,25-dihydrolanosterol and sitosterol, as a result of adipogenic differentiation. By contrast, adipogenesis did not modify whole cell neutral lipids but increased lysophosphatidylcholine, sphingomyelin, and trihexosyl ceramide levels in Agpat2 adipocytes. Unexpectedly, adipogenesis decreased PM levels of main phospholipids in both genotypes.
In Agpat2 adipocytes, decreased caveolae is not associated with changes in PM cholesterol nor sphingolipid levels; however, increased PM phosphatidylserine content may be implicated. Abnormal lipid composition is associated with the adipogenic abnormalities of Agpat2 -/- adipocytes but does not prevent insulin signaling.
脂肪营养不良 Agpat2 小鼠的脂肪细胞在脂肪生成和更少的 caveolae 方面存在缺陷。在此，我们研究了这些缺陷是否与脂质组成的变化或 caveolae 相关蛋白的异常水平有关。在分化的 Agpat2 脂肪细胞中定量测定脂质组变化，以确定具有潜在脂肪生成作用的脂质。
体外分化 Agpat2 和野生型棕色前体脂肪细胞。通过超速离心纯化质膜。在分化过程中测定 caveolae 的数量和 caveolae 相关蛋白，以及固醇、鞘脂和磷脂脂质组。
分化的 Agpat2 脂肪细胞 caveolae 数量减少，但胰岛素信号不变。Caveolin-1 和 cavin-1 水平在 Agpat2 和野生型脂肪细胞之间相等。两种基因型之间质膜胆固醇和鞘脂丰度无差异。分化第 10 天，Agpat2 脂肪细胞中磷脂酰丝氨酸水平升高。野生型脂肪细胞中，甘油三酯、二酰基甘油、磷脂酰甘油、磷酸酰基、溶血磷脂酰胆碱、溶血磷脂酰乙醇胺和三己糖神经酰胺的全细胞水平增加，而 24,25-二氢羊毛甾醇和谷甾醇减少，这是由于脂肪生成分化的结果。相比之下，脂肪生成不会改变全细胞中性脂质，但增加了 Agpat2 脂肪细胞中溶血磷脂酰胆碱、鞘磷脂和三己糖神经酰胺的水平。出乎意料的是，脂肪生成降低了两种基因型质膜主要磷脂的水平。
在 Agpat2 脂肪细胞中，caveolae 的减少与质膜胆固醇或鞘脂水平的变化无关；然而，增加的质膜磷脂酰丝氨酸含量可能与此有关。异常的脂质组成与 Agpat2-/-脂肪细胞的脂肪生成异常有关，但不阻止胰岛素信号。
