背景:皮下脂肪组织(SAT)的功能变化发生在衰老过程的早期,在与年龄相关的代谢性疾病的发生和发展中起重要作用。这种现象的机理尚不清楚,脂肪组织随年龄的变化知之甚少。
方法:我们使用转录组测序(RNAseq)在mRNA水平上筛选差异表达基因,并通过GO和KEGG分析分析了各年龄段人类SAT的差异基因的功能特征。为了明确功能变化的具体机制,我们通过高通量测序的转座酶可接近染色质测定法(ATAC-seq)分析了RNAseq中使用的相同SAT中启动子区域的染色质可接近性,并获得了SAT中随年龄变化的功能基因。要验证这些更改,我们扩大了人类SAT的样本内容。提取原代小鼠脂肪细胞,用不同浓度的甲状腺激素刺激,构建动物模型,并通过实时聚合酶链反应(RT-PCR)确定基因的表达。用氧耗试验和免疫荧光染色测定SAT的线粒体功能。
结果:RNA-seq显示了年轻人和老年人SAT的特征性基因表达,其中331个基因上调,349个基因下调。ATAC-seq,RNA-seq,结合小鼠预测模型,确定了七个基因的功能变化特征。所有这些基因在不同年龄的SAT中表达不同,其中,NCF1、NLRP3、DUOX1与年龄呈正相关;IFI30、P2RX1、P2RX6、PRODH、然而,随着年龄的增长而减少。在小鼠SAT中,所有这些基因在三碘甲状腺素的治疗下都显示出剂量依赖性的变化。耗氧率揭示了不同年龄人SAT线粒体功能和ROS积累的显着变化。
结论:在老年人中,功能,除了分配,SAT经历了重大变化,主要在线粒体中,这可能是由于对甲状腺激素信号不敏感。这些结果确定了七个由甲状腺激素调节的新基因,不同年龄的SAT表现出显著变化,并且可能与由于线粒体损伤和ROS积累而导致的老年SAT功能障碍有关。
Functional changes in subcutaneous adipose tissue (SAT) occur earlier in the aging process and play an important role in the occurrence and development of age-related metabolic diseases. The mechanism of this phenomenon is still unclear, and the change in adipose tissue with age is poorly understood.
We used transcriptome sequencing (RNA seq) to screen differentially expressed genes at the mRNA level, and analyzed the functional characteristics of the differential genes through GO and KEGG analysis in human SAT of all ages. In order to clarify the specific mechanism of the functional change, we analyzed the chromatin accessibility in the promoter region in the same SAT used in the RNA seq by the assay for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) and obtained the functional genes in SAT changed with age. To verify these changes, we enlarged our sample content of human SAT. The primary mice adipocytes were extracted and stimulated by thyroid hormone of different concentration to construct an animal model, and the expression of the genes were determined through real-time Polymerase Chain Reaction(RT-PCR). The oxygen consumption test and immunofluorescence staining were used to determine the mitochondrial function of SAT.
RNA-seq showed characteristic gene expression of young and old human SAT, in which 331 genes were up-regulated and 349 genes were down-regulated. ATAC-seq, RNA-seq, combined with the mouse prediction model, determined the functional changed characteristics of seven genes. All these genes expressed differently in SAT of different ages, in which, NCF1, NLRP3, DUOX1 showed positive correlation with age; The expression of IFI30, P2RX1, P2RX6, PRODH, however, decreased with age. And all these genes showed dose dependent alternations under treatment of triiodothyroxine in mice SAT. The oxygen consumption rate revealed significant changes of the mitochondrial function and ROS accumulation in human SAT of different ages.
In elderly individuals, the function, in addition to distribution, of SAT undergoes significant changes, primarily in mitochondria, which may be due to insensitivity to thyroid hormone signaling. These results identified seven novel genes regulated by thyroid hormone, exhibiting significant changes in SAT of different age, and are probably related to the dysfunction of the aged SAT due to the mitochondrial damage and ROS accumulation.