PDF(Pubmed)
Abstract：
Growing evidence proves that amino acid restriction can reverse obesity by reducing adipose tissue mass. Amino acids are not only the building blocks of proteins but also serve as signaling molecules in multiple biological pathways. The study of adipocytes\' response to amino acid level changes is crucial. It has been reported that a low concentration of lysine suppresses lipid accumulation and transcription of several adipogenic genes in 3T3-L1 preadipocytes. However, the detailed lysine-deprivation-induced cellular transcriptomic changes and the altered pathways have yet to be fully studied. Here, using 3T3-L1 cells, we performed RNA sequencing on undifferentiated and differentiated cells, and differentiated cells under a lysine-free environment, and the data were subjected to KEGG enrichment. We found that the differentiation process of 3T3-L1 cells to adipocytes required the large-scale upregulation of metabolic pathways, mainly on the mitochondrial TCA cycle, oxidative phosphorylation, and downregulation of the lysosomal pathway. Single amino acid lysine depletion suppressed differentiation dose dependently. It disrupted the metabolism of cellular amino acids, which could be partially reflected in the changes in amino acid levels in the culture medium. It inhibited the mitochondria respiratory chain and upregulated the lysosomal pathway, which are essential for adipocyte differentiation. We also noticed that cellular interleukin 6 (IL6) expression and medium IL6 level were dramatically increased, which was one of the targets for suppressing adipogenesis induced by lysine depletion. Moreover, we showed that the depletion of some essential amino acids such as methionine and cystine could induce similar phenomena. This suggests that individual amino acid deprivation may share some common pathways. This descriptive study dissects the pathways for adipogenesis and how the cellular transcriptome was altered under lysine depletion.
摘要：
越来越多的证据证明，氨基酸限制可以通过减少脂肪组织质量来逆转肥胖。氨基酸不仅是蛋白质的构建块，而且在多种生物途径中充当信号分子。研究脂肪细胞对氨基酸水平变化的反应至关重要。据报道,低浓度的赖氨酸抑制3T3-L1前脂肪细胞中的脂质积累和几种脂肪生成基因的转录。然而,详细的赖氨酸剥夺诱导的细胞转录组变化和改变的途径尚未得到充分研究。这里,使用3T3-L1细胞，我们对未分化和分化的细胞进行了RNA测序，在无赖氨酸环境下分化的细胞，并对数据进行KEGG富集。我们发现3T3-L1细胞向脂肪细胞的分化过程需要代谢途径的大规模上调,主要是线粒体TCA循环，氧化磷酸化，和溶酶体途径的下调。单氨基酸赖氨酸消耗剂量依赖性地抑制分化。它破坏了细胞氨基酸的代谢，这可以部分反映在培养基中氨基酸水平的变化上。它抑制线粒体呼吸链并上调溶酶体途径，这对脂肪细胞分化至关重要。我们还注意到细胞白细胞介素6（IL6）表达和中等IL6水平急剧增加，这是抑制赖氨酸耗竭诱导的脂肪形成的靶标之一。此外，我们表明，一些必需氨基酸如蛋氨酸和胱氨酸的消耗可以引起类似的现象。这表明个体氨基酸剥夺可能共享一些共同的途径。这项描述性研究剖析了脂肪形成的途径以及在赖氨酸消耗下细胞转录组如何改变。
