DUSP9-mediated inhibition of IRS1/PI3K/AKT pathway contributes to insulin resistance and metabolic dysfunction in gestational diabetes mellitus.

BACKGROUND: Gestational diabetes mellitus (GDM) is a common pregnancy complication associated with adverse maternal and fetal outcomes. Recent studies suggest a role for dual-specificity phosphatase 9 (DUSP9) in insulin resistance and metabolic dysregulation, though its specific contribution to GDM remains unclear. This study aims to investigate the function of DUSP9 in GDM pathophysiology and its underlying molecular mechanisms.

METHODS: We analyzed DUSP9 expression in umbilical cord blood and placental tissues from GDM patients (n = 16) and healthy controls (n = 14) using RT-qPCR and western blot assays. In vitro, functional assays were conducted on high glucose-induced HTR-8/SVneo trophoblast cells to evaluate the effects of DUSP9 knockdown on cell viability, apoptosis, and insulin signaling. In vivo, a GDM mouse model was constructed, and lentivirus-mediated shRNA was used to downregulate DUSP9 expression. Furthermore, metabolic parameters, including insulin resistance indices, lipid metabolism, and placental apoptosis were assessed, along with the phosphorylation status of key proteins in the IRS1/PI3K/AKT pathway.

RESULTS: We first observed that DUSP9 expression was significantly upregulated in the umbilical cord blood and placental tissues of GDM patients compared to healthy controls (p < 0.01). Using high glucose-induced HTR-8/SVneo trophoblast cells to mimic GDM conditions, we found that downregulation of DUSP9 increased cell viability and inhibited apoptosis (p < 0.01). Mechanistically, co-immunoprecipitation and pull-down assays demonstrated that DUSP9 directly interacts with insulin receptor substrate 1 (IRS1) and inhibits HG-mediated IRS1 phosphorylation at Tyr632, impairing downstream insulin signaling (p < 0.01). In vivo, a GDM mouse model revealed elevated DUSP9 expression, along with significant metabolic dysfunction, including insulin resistance and increased placental apoptosis (p < 0.01). Lentivirus-mediated knockdown of DUSP9 in these mice ameliorated insulin resistance, improved lipid metabolism, and reduced placental apoptosis by improving fasting glucose and insulin levels, lipid profiles, and decreased apoptotic markers (p < 0.01). Moreover, DUSP9 knockdown in these mice promoted activation of the IRS1/PI3K/AKT signaling pathway (p < 0.01).

CONCLUSIONS: DUSP9 contributes to GDM progression by inhibiting the IRS1/PI3K/AKT pathway, leading to insulin resistance and metabolic dysfunction. The knockdown of DUSP9 ameliorates key pathological features of GDM, including insulin resistance, impaired lipid metabolism, and placental apoptosis, suggesting that targeting DUSP9 may represent a potential therapeutic strategy for GDM.