Metformin Attenuates the High-Glucose Effect on MORG1 Expression in HEK293 Cells

Reduced expression of MAPK organiser 1 (MORG1) exerts renoprotective effects in MORG1^+/− mice in models of type 1 and type 2 diabetes. To investigate the regulation of MORG1 expression, we generated endogenous hMORG1-luciferase-tagged HEK293 cells carrying a firefly luciferase reporter inserted downstream of the human MORG1 gene using the CRISPR/Cas9 method. This study analysed the time-dependent effects of 20 mM D-glucose on MORG1-luciferase activity and examined whether 20 µM metformin influences MORG1 expression. HEK293 cells were genomically modified using CRISPR/Cas9 to insert the firefly luciferase gene downstream of MORG1. Stable clones were selected with puromycin. The influence of D-glucose concentration on MORG1 expression was analysed in a dose- and time-dependent manner. Luciferase assays assessed MORG1 transcriptional activity, while Western blotting determined protein expression. qRT-PCR was used to assess MORG1 mRNA levels. The pharmacological effect of metformin was evaluated in parental and tagged HEK293 cells and TKPTS cells, simultaneously exposed to 5.5 mM or 20 mM D-glucose in the presence or absence of 20 µM metformin. High glucose significantly increased luciferase activity and MORG1 protein expression compared with 5.5 mM glucose controls. Time course experiments demonstrated significant induction of MORG1 transcription, confirmed by corresponding increases in protein levels. Metformin treatment significantly reduced glucose-induced luciferase activity, MORG1 mRNA levels, and MORG1 protein expression at 24 h. Analyses of TKPTS cells show that 20 mM D-glucose elevated Morg1 mRNA levels, while this induction was attenuated in the presence of 20 µM metformin. High glucose induces time-dependent upregulation of MORG1 transcription and protein expression in MORG1-luciferase-tagged HEK293 cells. Metformin application attenuates, but does not fully prevent, glucose-induced MORG1 mRNA and proteinexpression.