MiR-99 Family of Exosomes Targets Myotubularin-related Protein 3 to Regulate Autophagy in Trophoblast Cells and Influence Insulin Resistance.

Abstract: The global incidence of gestational diabetes mellitus (GDM) continues to rise and is associated with negative outcomes in pregnancy. This study aims to investigate how the miR-99 family of exosomes derived from the placenta targets myotubularin-related protein 3 (MTMR3) to trigger autophagy and alter insulin resistance (IR) in trophoblast cells. In this study, placenta-derived exosomes from plasma samples of patients with GDM and normal pregnant women were isolated to evaluate the expression levels of miR-99 family members (miR-99a, miR-99b, and miR-100) by quantitative real-time polymerase chain reaction. Furthermore, we used Targeted Scan prediction and dual luciferase reporter assays to identify a potential target of the miR-99 family. Finally, Western blotting, CCK8 assay, and glucose level measurement were used to confirm that the miR-99 family regulates autophagy in trophoblast cells through targeting potential targets, thereby affecting IR. Through comprehensive molecular biology techniques, our analysis revealed that, in contrast to normal pregnant women, the placenta-derived exosomes of women with GDM exhibited a significant downregulation of the miR-99 family. Moreover, MTMR3 emerged as a potential target of the miR-99 family, revealing a negative correlation with the levels of miR-99. An increase in MTMR3 expression impaired cellular autophagy and contributed to IR. Conversely, augmenting the miR-99 family can lead to a downregulation of MTMR3, promotion of cellular autophagy, and mitigation of IR. This research demonstrated that the expression of the miR-99 family was reduced in plasma exosomes of GDM. The miR-99 family can directly target MTMR3, leading to its downregulation. This process activated autophagy in trophoblast cells and enhances insulin sensitivity. Consequently, the miR-99 family holds potential as a therapeutic strategy for patients with GDM.