Palmitic acid declines glucose uptake in HepG2 cells via modulating phosphoglucomutase 1 to repress phosphatidylinositol 3 kinase/protein kinase B and JNK pathways via inducing microRNA-124-3p

Authors: LINGHUI ZHANG, SHENGLI ZHANG

Abstract: Diabetes resulting from insufficient insulin secretion or insulin resistance (IR) is a highly prevalent metabolic disease. Since microRNAs have been linked with elevated IR, the current research hypothesized that miR-124-3p has a role in IR and the establishment of IR and type 2 diabetes (T2DM). The study aimed to explore the molecular mechanisms of miR-124-3p which influence IR leading to T2DM establishment. HepG2 cells were cultured in vitro, and palmitic acid (PA) was used to construct the IR cell model. In the IR model, transfection of miR-124-3p or phosphoglucomutase 1 (PGM1) linked plasmids were transfected into HepG2 cells. RT-qPCR was used to determine the miR-124-3p and PGM1 expressions in the cells. Cell viability was assessed through CCK-8 assays, while glucose consumption was studied using a glucose uptake test. Interaction between miR-124-3p and PGM1 was examined using a dual-luciferase reporter assay. Autophagy, phosphatidylinositol 3 kinases (PI3K)/protein kinase B (AKT) and JNK pathways-linked factors, glucose transporter 4 (GLUT4), and c-Jun were determined through western blotting assays. MiR-124-3p expression was elevated, but PGM1 was reduced in the IR model. Glucose uptake was reduced posttreatment with 0.8 mM PA. There was a significantly increased PI3K, p-PI3K, AKT, p-AKT, GLUT4, LC3I/II, Beclin-1, p-JNK1/2, and c-Jun, but reduced p62 expressions were presented in the PA + miR-124-3p inhibitor compared to the PA and PA + inhibitor NC groups. PGM1 binds directly to miR-124-3p through the 3? UTR region target. Overall, miR-124-3p downregulates glucose consumption via targeting PGM1 to repress PI3K/AKT and JNK pathways. Silencing PGM1 inhibited the suppressor role of miR-124-3p on glucose uptake, cell proliferation, and inflammation. In conclusion, miR-124-3p reduces glucose uptake in HepG2 cells via PGM1/PI3K/AKT modulation. MiR-124-3p targets PGM1 in IR and may provide an effective therapeutic alternative for T2DM.

Keywords: Palmitic acid, microRNA-124-3p, phosphoglucomutase 1, PI3K/AKT, JNK, insulin resistance, autophagy, cell proliferation, inflammatory response

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