Comparative analysis of circRNA expression profile and circRNA-miRNA-mRNA regulatory network between palmitic and stearic acid-induced lipotoxicity to pancreatic β cells

Chronic exposure to high concentrations of circulating palmitic acid and stearic acid leads to impaired β cell function, which accelerates the development of type 2 diabetes. However, differences in the mechanisms underlying this process between these two saturated fatty acids remain largely unknown. In this study, we screened for potential circular RNAs (circRNAs) and their associated regulatory pathways in palmitic acid- and stearic acid-induced mouse β-TC6 cell dysfunction. CircRNA high-throughput sequencing, gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes analysis were performed and co-expression and competing endogenous RNAs (ceRNA) networks were constructed. We identified that four circRNAs that were differentially expressed specifically in β cells exposed to palmitic acid, whereas four circRNAs were differentially expressed specifically in β cells exposed to stearic acid. Seven circRNAs were differentially co-expressed in palmitic acid- and stearic acid-treated β cells. In pathway exploration, we identified the core protein Solute carrier family 2 member 2 (SLc2a2), which is mainly involved in insulin resistance, maturity onset diabetes of the young and type 2 diabetes. The expressions of key circRNAs in β-TC6 cells were validated by Real time quantitative PCR, with a consistent result in high-throughput sequencing. The findings aid our understanding of the mechanisms governing the difference between palmitic acid- and stearic acid-induced β cell dysfunction and provide potential therapeutic targets for developing treatments against long-term high fat diet-induced β cell injury. <b>Abbreviations:</b> Acvr1c: Activin A receptor, type 1C; CeRNA, Competing endogenous RNAs; circRNA, circular RNA; DEcircRNA: Differentially Expressed circular RNA; DEmiRNA: Differentially Expressed microRNA; DEmRNA: Differentially Expressed mRNA; GO: Gene Ontology; HPDHigh Palmitic acid Diet; HSD: High Stearic acid Diet; KEGG: Kyoto Encyclopedia of Genes and Genomes; miRNA: microRNA; ncRNAs: non-coding RNAs; qPCR: Real time quantitative PCRS; FAs: Saturated Fatty Acids; SLc2a2: Solute carrier family 2 member 2; T2D: Type 2 Diabetes

长期暴露于高浓度循环棕榈酸与硬脂酸环境，可引发β细胞功能受损，进而加速2型糖尿病（type 2 diabetes，T2D）的发生进展。然而，目前对于这两种饱和脂肪酸（Saturated Fatty Acids，FAs）介导该病理过程的分子机制差异，仍知之甚少。本研究以棕榈酸与硬脂酸诱导的小鼠β-TC6细胞功能障碍为模型，筛选潜在的环状RNA（circular RNA，circRNA）及其关联调控通路。本研究开展了环状RNA高通量测序、基因本体（Gene Ontology，GO）富集分析与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）通路分析，并构建了共表达网络与内源竞争RNA（competing endogenous RNAs，ceRNA）调控网络。研究结果显示，暴露于棕榈酸的β细胞中存在4种特异性差异表达的环状RNA，而暴露于硬脂酸的β细胞中则另有4种特异性差异表达的环状RNA；另有7种环状RNA在经棕榈酸与硬脂酸处理的β细胞中均呈差异共表达状态。在通路探索环节，我们鉴定出核心蛋白溶质载体家族2成员2（Solute carrier family 2 member 2，SLC2A2），该蛋白主要参与胰岛素抵抗、青少年发病的成年型糖尿病以及2型糖尿病的病理过程。我们通过实时定量PCR（Real-time quantitative PCR，qPCR）验证了β-TC6细胞中关键环状RNA的表达水平，结果与高通量测序结果高度一致。本研究结果有助于阐明棕榈酸与硬脂酸诱导β细胞功能障碍的差异机制，并为开发针对长期高脂饮食诱导β细胞损伤的治疗策略提供潜在靶点。<b>缩略词对照表：</b>Acvr1c：激活素A型受体1C（Activin A receptor, type 1C）；ceRNA：内源竞争RNA（Competing endogenous RNAs）；circRNA：环状RNA（circular RNA）；DEcircRNA：差异表达环状RNA（Differentially Expressed circular RNA）；DEmiRNA：差异表达微小RNA（Differentially Expressed microRNA）；DEmRNA：差异表达信使RNA（Differentially Expressed mRNA）；GO：基因本体（Gene Ontology）；HPD：高脂棕榈酸饮食（High Palmitic acid Diet）；HSD：高脂硬脂酸饮食（High Stearic acid Diet）；KEGG：京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes）；miRNA：微小RNA（microRNA）；ncRNAs：非编码RNA（non-coding RNAs）；qPCR：实时定量PCR（Real-time quantitative PCR）；FAs：饱和脂肪酸（Saturated Fatty Acids）；SLC2A2：溶质载体家族2成员2（Solute carrier family 2 member 2）；T2D：2型糖尿病（Type 2 Diabetes）