SLC25A21 regulates insulin sensitivity in subjects with obesity through ROS/AKT/KLF15-mediated alteration of GLUT4 expression

In the state of obesity, miR-548ab targets and downregulates SLC25A21, leading to reduced GLUT4 expression. However, the precise mechanism by which SLC25A21 regulates GLUT4 expression remains unclear. This study aims to investigate whether downregulation of SLC25A21 reduces GLUT4 expression by increasing reactive oxygen species (ROS) levels and inhibiting the PI3K/AKT/KLF15 signaling pathway, thereby contributing to impaired glucose metabolism. In vitro, SLC25A21 was either overexpressed or knocked down in 3T3-L1 adipocytes and C2C12 myotubes, and N-acetylcysteine (NAC) was administered during knockdown experiments. In vivo, adeno-associated viruses (AAVs) carrying SLC25A21 overexpression or knockdown constructs were injected into the adipose and skeletal muscle tissues of high-fat diet (HFD)-induced obesity mice. The levels of ROS, mitochondrial function, and the expression of key components within the PI3K/AKT/KLF15/GLUT4 signaling pathway were evaluated to elucidate the molecular mechanism through which SLC25A21 regulates GLUT4 expression. In both 3T3-L1 adipocytes and C2C12 myotubes, knockdown of SLC25A21 led to significantly increased ROS levels, impaired mitochondrial function, and suppression of the PI3K/AKT/KLF15 signaling pathway. These changes were associated with reduced GLUT4 expression, as well as decreased glucose consumption and uptake capacity. Treatment with NAC effectively restored GLUT4 expression and glucose uptake. The role of SLC25A21 in regulating GLUT4 expression through this pathway was further confirmed in a mouse model of HFD-induced obesity. SLC25A21 reduces ROS levels, activating the PI3K/AKT/KLF15 pathway and increasing GLUT4 expression, thereby improving glucose metabolism in vitro and in vivo.