State Key Laboratory of Chemical Oncogenomics, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, P. R. China.
Key Lab in Healthy Science and Technology, Division of Life Science, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, P. R. China.
Clin Transl Med. 2022 Feb;12(2):e699. doi: 10.1002/ctm2.699.
Persistent hyperglycemia decreases the sensitivity of insulin-sensitive organs to insulin, owing to which cells fail to take up and utilize glucose, which exacerbates the progression of type 2 diabetes mellitus (T2DM). lncRNAs' abnormal expression is reported to be associated with the progression of diabetes and plays a significant role in glucose metabolism. Herein, we study the detailed mechanism underlying the functions of lncRNA EPB41L4A-AS1in T2DM.
Data from GEO datasets were used to analyze the expression of EPB41L4A-AS1 between insulin resistance or type 2 diabetes patients and the healthy people. Gene expression was evaluated by qRT-PCR and western blotting. Glucose uptake was measured by Glucose Uptake Fluorometric Assay Kit. Glucose tolerance of mice was detected by Intraperitoneal glucose tolerance tests. Cell viability was assessed by CCK-8 assay. The interaction between EPB41L4A-AS1 and GCN5 was explored by RNA immunoprecipitation, RNA pull-down and RNA-FISH combined immunofluorescence. Oxygen consumption rate was tested by Seahorse XF Mito Stress Test.
EPB41L4A-AS1 was abnormally increased in the liver of patients with T2DM and upregulated in the muscle cells of patients with insulin resistance and in T2DM cell models. The upregulation was associated with increased TP53 expression and reduced glucose uptake. Mechanistically, through interaction with GCN5, EPB41L4A-AS1 regulated histone H3K27 crotonylation in the GLUT4 promoter region and nonhistone PGC1β acetylation, which inhibited GLUT4 transcription and suppressed glucose uptake by muscle cells. In contrast, EPB41L4A-AS1 binding to GCN5 enhanced H3K27 and H3K14 acetylation in the TXNIP promoter region, which activated transcription by promoting the recruitment of the transcriptional activator MLXIP. This enhanced GLUT4/2 endocytosis and further suppressed glucose uptake.
Our study first showed that the EPB41L4A-AS1/GCN5 complex repressed glucose uptake via targeting GLUT4/2 and TXNIP by regulating histone and nonhistone acetylation or crotonylation. Since a weaker glucose uptake ability is one of the major clinical features of T2DM, the inhibition of EPB41L4A-AS1 expression seems to be a potentially effective strategy for drug development in T2DM treatment.
持续性高血糖会降低胰岛素敏感器官对胰岛素的敏感性，导致细胞无法摄取和利用葡萄糖，从而加剧 2 型糖尿病（T2DM）的进展。lncRNAs 的异常表达与糖尿病的进展有关，并在葡萄糖代谢中发挥重要作用。在此，我们研究了长链非编码 RNA EPB41L4A-AS1 在 T2DM 中作用的详细机制。
使用 GEO 数据集的数据来分析胰岛素抵抗或 2 型糖尿病患者与健康人群之间 EPB41L4A-AS1 的表达。通过 qRT-PCR 和 Western blot 评估基因表达。通过葡萄糖摄取荧光测定试剂盒测量葡萄糖摄取。通过腹腔内葡萄糖耐量试验检测小鼠的葡萄糖耐量。通过 CCK-8 测定评估细胞活力。通过 RNA 免疫沉淀、RNA 下拉和 RNA-FISH 联合免疫荧光探索 EPB41L4A-AS1 与 GCN5 之间的相互作用。通过 Seahorse XF Mito Stress Test 测试耗氧量。
在 T2DM 患者的肝脏中，EPB41L4A-AS1 异常升高，在胰岛素抵抗和 T2DM 细胞模型中的肌肉细胞中上调。这种上调与 TP53 表达增加和葡萄糖摄取减少有关。机制上，通过与 GCN5 的相互作用，EPB41L4A-AS1 调节 GLUT4 启动子区域的组蛋白 H3K27 丙二酰化和非组蛋白 PGC1β 乙酰化，抑制肌肉细胞中 GLUT4 的转录和葡萄糖摄取。相反，EPB41L4A-AS1 与 GCN5 结合增强了 TXNIP 启动子区域的 H3K27 和 H3K14 乙酰化，通过促进转录激活子 MLXIP 的募集来激活转录。这增强了 GLUT4/2 的内吞作用，进一步抑制了葡萄糖摄取。
我们的研究首次表明，EPB41L4A-AS1/GCN5 复合物通过调节组蛋白和非组蛋白乙酰化或丙二酰化来靶向 GLUT4/2 和 TXNIP，从而抑制葡萄糖摄取。由于较弱的葡萄糖摄取能力是 2 型糖尿病的主要临床特征之一，因此抑制 EPB41L4A-AS1 的表达似乎是治疗 2 型糖尿病药物开发的一种潜在有效策略。
