miR-196a-5p suppresses the MAPK/ERK pathway by targeting HOXA7 to regulate the proliferation and apoptosis of placental trophoblasts in gestational diabetes.

INTRODUCTION

Gestational diabetes mellitus (GDM) disrupts placental trophoblast function through hyperglycemia-induced apoptosis and impaired proliferation. Non-coding RNAs, particularly miR-196a-5p, are implicated in GDM pathogenesis, but their mechanistic roles remain unclear. HOXA7, a homeobox transcription factor, and the MAPK/ERK pathway are critical in cellular regulation, however, their interplay in GDM is unexplored.

METHODS

Clinical samples (blood and placental tissues) from GDM patients and controls were analyzed via miRNA-seq, qRT-PCR, and Western blot. Bioinformatics (TargetScan, miRDB, miRWalk) identified miR-196a-5p targets. Functional validation used HTR8-Svneo trophoblasts under high-glucose (25 mM) conditions, with miR-196a-5p mimics/inhibitors and HOXA7 overexpression and two key functional rescue assays: co-treatment with a miR-196a-5p mimic and HOXA7 overexpression, and co-treatment with a mimic and a MEK activator, including CCK-8, Transwell, flow cytometry, and dual-luciferase reporter analysis. miR-196a-5p was upregulated in GDM patients and directly targeted HOXA7 via three conserved 3'UTR binding sites.

RESULTS

Hyperglycemia suppressed MAPK/ERK phosphorylation, reducing trophoblast proliferation, migration, and invasion while increasing apoptosis. miR-196a-5p-mimic exacerbated these effects, whereas inhibitors or HOXA7 overexpression restored MAPK/ERK activity and cellular functions. Crucially, rescue experiments confirmed that HOXA7 is a necessary mediator for miR-196a-5p's effects and that activating the MAPK/ERK pathway downstream is sufficient to reverse the induced dysfunction. miR-196a-5p suppresses the MAPK/ERK pathway by specifically regulating HOXA7, thereby reducing proliferation and increasing apoptosis of placental trophoblasts.

DISCUSSION: This study demonstrated that miR-196a-5p with higher expression in GDM suppresses the HOXA7/MAPK/ERK axis to inhibit placental trophoblasts proliferation and promote its apoptosis.