Lactylation of BCAT2-K377 Contributes to the Progression of Severe Preeclampsia

Preeclampsia is a pregnancy-specific disorder characterized by placental hypoxia and superficial invasion of trophoblast cells. However, the precise mechanisms by which hypoxia induces lactate and lactylation remain unclear.

Pan lysine lactylation levels were analyzed in the placentae of 36 patients with severe preeclampsia (sPE) and 36 normotensive pregnancies. A global lactylome analysis was performed, and branched-chain amino acid transaminase 2-lysine 377 (BCAT2-K377) was selected for further investigation. The BCAT2 mutant with lysine 377 mutated to arginine (BCAT2-377R) was constructed to evaluate the effect on trophoblast migration, invasion, tube formation, and oxidative stress. The impact of the BCAT2-377R mutant on BCAT2 ubiquitination and degradation was further examined using MG132 and cycloheximide supplementation. Co-immunoprecipitation and double-immunofluorescence staining were conducted to identify the lactyltransferase of BCAT2. The specialized antibody was developed to validate branched-chain amino acid transaminase 2-lysine 377 lactylation (BCAT2-K377la) abundance in tissues and treated cells. A preeclampsia-like rat model was constructed to further verify whether the results were consistent with the clinical findings.

Lactylation levels were elevated in the placentae of sPE. High lactate concentration enhanced Pan lysine lactylation and reduced BCAT2 protein levels while inhibiting cell migration, invasion, and tube formation. BCAT2-K377la impaired cell biological behaviors, increased oxidative stress, and promoted BCAT2 ubiquitination. The EP300 lysine acetyltransferase (p300) acted as a lysine lactylation writer of BCAT2. BCAT2-K377la abundance was upregulated in sPE placentae and cells treated with hypoxia and lactate. In the rat model, elevated placental Pan lysine lactylation and BCAT2-K377la levels mirrored findings in clinical samples.

Our findings emphasized the role of nonhistone lactylation in sPE pathogenesis. Targeting BCAT2-K377la may serve as a potential intervention strategy for sPE.