Gestational diabetes mellitus-derived miR-7-19488 targets PIK3R2 mRNA to stimulate the abnormal development and maturation of offspring-islets.

AIMS

Gestational diabetes mellitus (GDM) provides offspring with a hyper-metabolic intrauterine microenvironment. In this study, we aimed to identify key differential microRNAs in GDM-derived exosomes and explore the potential mechanisms of abnormal embryonic development of islets in offspring.

MAIN METHODS

Exosomes were extracted from umbilical vein blood of GDM and non-GDM (NGDM) parturients for microRNA sequencing. Offspring islets were collected on E18.5 and P0 to detect the expression and location of key proteins by immunofluorescence. Target binding of miR-7-19488 and PIK3R2 mRNA was verified using a dual-luciferase reporter assay. The miR-7-19488-mimic, PI3K/mTOR inhibitors were used to treat primarily islet cells to explore the relationship among miR-7-19488, PI3K, and Akt-FoxO1/mTORC1 signaling. The miR-7-19488 agomir was synthesized for further in vivo validation.

KEY FINDINGS

GDM-derived exosomes caused the overdevelopment of offspring-islets at E18.5 with an increased production of insulin and glucagon co-staining cells, increased number of α cells synthesizing GLP-1, and stimulation of mTORC1 singling, which were more serious at birth. The up-regulated miR-7-19488 in GDM-exosomes targeted PIK3R2 mRNA, leading to translation stagnation of p85β and activation of PI3K-Akt singling in fetal islets. Importantly, the activated PI3K-Akt-FoxO1 singling promoted development and differentiation of α and β cells and enhanced the GLP-1/GLP-1R axis, which cooperates with miR-7-19488 to activate PI3K-Akt-FoxO1/mTORC1 signaling, leading to the early initiation of the functional maturation of overdeveloped β cells.

SIGNIFICANCE

miR-7-19488 loaded in GDM-derived exosomes induce the abnormal overdevelopment and functional maturation of fetal islets, which is one of the contributors of high incidence of diabetes in adulthood.