Krüppel-like factor 4 regulates extravillous trophoblast invasion and angiogenic function and is reduced in gestational diabetes mellitus.

INTRODUCTION

Placental extravillous trophoblasts (EVTs) are essential for decidual invasion and spiral artery remodeling, yet the transcriptional mechanisms that sustain EVT function under metabolic stress, such as gestational diabetes mellitus (GDM), remain incompletely understood, raising the possibility that metabolically responsive transcription factors such as Krüppel-like factor 4 (KLF4) may be involved.

METHODS

KLF4 expression and localization were examined in human placental tissues, including early second-trimester basal plates and term placentas from normoglycemic and GDM pregnancies. Functional and molecular analyses were performed in EVT-like HTR-8/SVneo cells cultured under normal or high-glucose conditions with gain- and loss-of-function modulation of KLF4. EVT migration, invasion, and angiogenic activity were assessed using wound healing, transwell, Matrigel invasion, and tube formation assays. Transcriptional regulation was evaluated by qPCR and luciferase reporter assays.

RESULTS

KLF4 was localized to the nuclei of EVTs in second-trimester placentas, and its expression was reduced in GDM placentas. In HTR-8/SVneo cells, high-glucose exposure (15-45 mM) suppressed KLF4 expression and reduced expression of invasion- and angiogenesis-related genes, including MMP2, MMP9, VEGFA, and PGF. Exposure to 30 mM glucose impaired EVT migration, invasion, and tube formation. Restoration of KLF4 improved migratory and angiogenic capacity. Under normal glucose conditions, KLF4 overexpression selectively increased MMP9, VEGFA, and PGF expression, whereas CRISPR-Cas9-mediated KLF4 knockdown reduced expression of all four genes. Luciferase assays demonstrated selective activation of MMP9, VEGFA, and PGF promoters by KLF4.

CONCLUSION

KLF4 supports EVT invasion and angiogenic function, and its downregulation under hyperglycemic conditions may contribute to impaired placental vascular remodeling in GDM.