Cowan E, Sun J, Hamilton A, Ruhrmann S, Karagiannopoulos A, Westholm E, Ofori J K, Luan C, Zhang E, Mulder H, Eliasson L
Unit of Islet Cell Exocytosis, Department of Clinical Sciences Malmö, Lund University Diabetes Centre, Lund University, Lund, Sweden.
Unit of Molecular Metabolism, Department of Clinical Sciences Malmö, Lund University Diabetes Centre, Lund University, Lund, Sweden.
Acta Physiol (Oxf). 2024 Aug;240(8):e14180. doi: 10.1111/apha.14180. Epub 2024 May 27.
MicroRNAs (miRNAs) regulate β-cell function, and β-cell mitochondria and insulin secretion are perturbed in diabetes. We aimed to identify key miRNAs regulating β-cell mitochondrial metabolism and novel β-cell miRNA-mitochondrial pathways.
TargetScan (http://www.targetscan.org/) was used to predict if 16 miRNAs implicated in β-cell function target 27 cis-eGenes implicated in mitochondrial activity. The expression of candidate miRNAs and insulin secretion after 24 and 1 h pre-incubation in 2.8, 11.1- and 16.7-mM glucose was measured in clonal INS-1 832/13 β-cells. MiR-29 silenced INS-1 832/13 cells were assessed for insulin secretion (glucose, pyruvate, and K), target cis-eGene expression (Ndufv3 and Ndufa10 components of mitochondrial complex I (CI)), OXPHOS (CI-V) protein expression, and mitochondrial OXPHOS respiration/activity. The expression of differentially expressed miR-29 miRNAs was evaluated in Goto-Kakizaki (GK) rat, db/db mouse and type 2 diabetic (T2D) human islets, as well as NMRI mouse islets cultured under glucolipotoxic conditions.
MiR-29, miR-15 and miR-124 were predicted to regulate ~20 cis-eGenes, while miR-29 alone was predicted to regulate ≥12 of these in rat and human species. MiR-29 expression and insulin secretion were reduced in INS-1 832/13 cells after 24 h in elevated glucose. MiR-29 knockdown increased all tested insulin secretory responses, Nudfv3, Ndufa10, complex I and II expression, and cellular mitochondrial OXPHOS. MiR-29 expression was reduced in db/db islets but increased in GK rat and T2D human islets.
We conclude miR-29 is a key miRNA in regulating β-cell mitochondrial metabolism and insulin secretion via underlying miR-29-OXPHOS complex pathways. Furthermore, we infer reduced miR-29 expression compensatorily enhances insulin secretion under glucotoxicity.
微小RNA（miRNA）调节β细胞功能，且糖尿病中β细胞线粒体和胰岛素分泌受到干扰。我们旨在鉴定调节β细胞线粒体代谢的关键miRNA以及新的β细胞miRNA-线粒体途径。
使用TargetScan（http://www.targetscan.org/）预测16种与β细胞功能相关的miRNA是否靶向27种与线粒体活性相关的顺式e基因。在克隆的INS-1 832/13β细胞中，测量在2.8、11.1和16.7 mM葡萄糖中预孵育24小时和1小时后候选miRNA的表达及胰岛素分泌。对miR-29沉默的INS-1 832/13细胞进行胰岛素分泌（葡萄糖、丙酮酸和钾）、靶顺式e基因表达（线粒体复合物I（CI）的Ndufv3和Ndufa10成分）、氧化磷酸化（CI-V）蛋白表达以及线粒体氧化磷酸化呼吸/活性的评估。在Goto-Kakizaki（GK）大鼠、db/db小鼠和2型糖尿病（T2D）人类胰岛以及在糖脂毒性条件下培养的NMRI小鼠胰岛中评估差异表达的miR-29 miRNA的表达。
预测miR-29、miR-15和miR-124调节约20种顺式e基因，而仅miR-29在大鼠和人类物种中预测调节其中≥12种。在高糖环境中24小时后，INS-1 832/13细胞中miR-29表达和胰岛素分泌降低。miR-29敲低增加了所有测试的胰岛素分泌反应、Nudfv3、Ndufa10、复合物I和II的表达以及细胞线粒体氧化磷酸化。db/db胰岛中miR-29表达降低，但在GK大鼠和T2D人类胰岛中升高。
我们得出结论，miR-29是通过潜在的miR-29-氧化磷酸化复合物途径调节β细胞线粒体代谢和胰岛素分泌的关键miRNA。此外，我们推断在糖毒性下miR-29表达降低会代偿性增强胰岛素分泌。
