BMP5 promotes trophoblast functions upon N-glycosylation via the BMP5-SMAD1/5 signaling pathway in preeclampsia

Introduction: Preeclampsia (PE) is one of the most common pregnancy-related complications worldwide and currently lacks an effective treatment. While trophoblast cell dysfunction has been identified as the fundamental cause of PE, the underlying mechanisms remain unclear. Bone morphogenetic protein 5 (BMP5) is a secreted glycoprotein highly expressed in the placenta that is involved in cell proliferation, migration, and invasion. However, the role and mechanism of BMP5 glycosylation of trophoblast cell function remain unclear.

Methods: The expression of BMP5 and N-glycosylation in preeclamptic placental tissues was investigated. We predicted and validated the N-glycosylation sites of BMP5. Additionally, we evaluated the effect of BMP5 N-glycosylation on the proliferation, migration, invasion, and angiogenesis of human immortalized trophoblastic HTR-8/SVneo cells. Furthermore, the role of N-glycosylated BMP5 in activating the BMP5-SMAD1/5 signaling pathway and regulating trophoblastic cell functions was explored.

Results: Our study reveals that PHA-E + L (recognizing branching N-glycans) reactive N-glycans and BMP5 expression levels are lower in preeclamptic villous tissues compared to normal placental tissues. Additionally, we demonstrated that BMP5 is an N-glycosylation-modified protein. Furthermore, N-glycosylated BMP5 promoted the functional trophoblastic cells (HTR-8/SVneo). We also revealed that N-glycosylation of BMP5 regulates multiple cell functions through the BMP5-SMAD1/5 signaling pathway.

Conclusion: N-glycosylated BMP5 promotes trophoblast cell proliferation, migration, invasion, and angiogenesis. This study provides mechanistic insight as to how N-glycosylation of BMP5 in trophoblast cells can contribute to the pathogenesis of preeclampsia and provides a new basis for its diagnosis and treatment.