Lipid droplets (LDs) are highly abundant in early mammalian embryos, yet their functional relevance to preimplantation development and cell fate decisions remains largely unexplored. Given their prevalence, we hypothesized that LDs contribute to developmental competence and cell fate. This thesis investigates the role of LDs in sheep embryos, combining physical manipulation, molecular interference, and phenotypic analysis. Using hyperosmotic centrifugation and micromanipulation, we removed LDs from zygotes, which led to significantly reduced blastocyst formation (20% vs. 38.7%, P < 0.05), despite normal cleavage and restored LD content at the blastocyst stage. These blastocysts lacked the typical LD enrichment in the inner cell mass (ICM), exhibited altered SOX2-positive cell distribution, a higher ICM-to-trophectoderm ratio, and increased histone H3K9 acetylation and lysine crotonylation—pointing to a link between lipid availability, cell identity, and epigenetic regulation. To further dissect the contribution of lipid biosynthesis, we targeted ATP citrate lyase (ACLY) and/or acetyl-CoA synthetase short family member 2 (ACSS2), key enzymes in cytosolic/nuclear acetyl-CoA production. ACLY knockdown impaired blastocyst development and arrested embryos at early stages, whereas chemical inhibition of ACLY did not affect blastocyst formation or lipid biosynthesis but altered the pattern of histone acylation. Importantly, inhibition of ACLY and ACSS2 following LD removal further compromised lipid recovery and exacerbated disruptions in histone acylation, underscoring a synergistic effect between lipid availability and acetyl-CoA metabolism in supporting chromatin regulation and embryonic development. Together, these findings demonstrate that LDs and lipid metabolism influence not only early embryo viability but also cell lineage allocation and chromatin remodelling. This work positions lipid dynamics as a critical, previously underappreciated layer of developmental regulation.
The Crucial Dynamics of Lipid Droplets in Early Ovine Embryonic Development / Moncada, Margherita. - (2025 Jan 01).
The Crucial Dynamics of Lipid Droplets in Early Ovine Embryonic Development
Margherita Moncada
2025-01-01
Abstract
Lipid droplets (LDs) are highly abundant in early mammalian embryos, yet their functional relevance to preimplantation development and cell fate decisions remains largely unexplored. Given their prevalence, we hypothesized that LDs contribute to developmental competence and cell fate. This thesis investigates the role of LDs in sheep embryos, combining physical manipulation, molecular interference, and phenotypic analysis. Using hyperosmotic centrifugation and micromanipulation, we removed LDs from zygotes, which led to significantly reduced blastocyst formation (20% vs. 38.7%, P < 0.05), despite normal cleavage and restored LD content at the blastocyst stage. These blastocysts lacked the typical LD enrichment in the inner cell mass (ICM), exhibited altered SOX2-positive cell distribution, a higher ICM-to-trophectoderm ratio, and increased histone H3K9 acetylation and lysine crotonylation—pointing to a link between lipid availability, cell identity, and epigenetic regulation. To further dissect the contribution of lipid biosynthesis, we targeted ATP citrate lyase (ACLY) and/or acetyl-CoA synthetase short family member 2 (ACSS2), key enzymes in cytosolic/nuclear acetyl-CoA production. ACLY knockdown impaired blastocyst development and arrested embryos at early stages, whereas chemical inhibition of ACLY did not affect blastocyst formation or lipid biosynthesis but altered the pattern of histone acylation. Importantly, inhibition of ACLY and ACSS2 following LD removal further compromised lipid recovery and exacerbated disruptions in histone acylation, underscoring a synergistic effect between lipid availability and acetyl-CoA metabolism in supporting chromatin regulation and embryonic development. Together, these findings demonstrate that LDs and lipid metabolism influence not only early embryo viability but also cell lineage allocation and chromatin remodelling. This work positions lipid dynamics as a critical, previously underappreciated layer of developmental regulation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
