ChREBPα: a central metabolic sensor driving lipid droplet renewal in preimplantation mouse embryos

Lipid droplets (LDs) are abundant during early embryogenesis; however, yet, the mechanisms that govern their synthesis, maintenance, and functional relevance remain poorly defined. This study aimed to investigate how early mouse embryos sense lipid depletion and activate adaptive metabolic responses to sustain developmental progression.

Mouse zygotes were mechanically delipidated and cultured under fatty acid-free conditions, and LD recovery was quantified by BODIPY staining across development. RNA sequencing was performed at the 2-cell stage embryos to identify transcriptional responses to delipidation. Furthermore, immunofluorescence microscopy, quantitative assays, and functional studies were conducted by the use of inhibitors to investigate molecular actors of LDs de novo synthesis and their role in embryonic survival.

Delipidated embryos rapidly regenerated LDs and progressed to the blastocyst stage at rates comparable to controls. Transcriptomic profiling identified ChREBP (Mlxipl) as the principal gene upregulated in response to lipid depletion, with both mRNA and protein levels markedly increased in delipidated embryos. ChREBP displayed dynamic subcellular localization, including nuclear accumulation associated with LD biogenesis and the formation of cytoplasmic foci preferentially localized at the cell cortex and in proximity to endoplasmic reticulum-enriched regions. Partial co-localization of ChREBP with LDs was observed across stages of de novo LD synthesis following delipidation. Furthermore, an association with lipid LDs was observed during active LD regeneration following delipidation. Notably, the inhibition of ChREBP impaired lipid droplet regeneration and resulted in developmental arrest, identifying the morula-to-blastocyst transition as a critical window of sensitivity and the trophectoderm formation as a vulnerable bottleneck.

These findings identify ChREBP as a key metabolic sensor that coordinates LD synthesis and supports normal developmental progression during early embryogenesis, highlighting LDs as critical regulators of early embryonic competence.