Milk-fat globule epidermal growth factor 8 (MFGE8) is expressed at the embryo- and fetal-maternal interface in equine pregnancy.

This study examines the expression of Milk-fat globule epidermal growth factor 8 (MFGE8), a protein that promotes cell adhesion, in equine pregnancies. Researchers found that MFGE8 is expressed at significant junctures in mares’ pregnancies and that its expression might be influenced by estrogen.

Protein of Interest: MFGE8

• In the field of biological research, the subject protein is Milk-fat globule epidermal growth factor 8 (MFGE8) which is also known as lactadherin.
• MFGE8 is known for its ability to promote cell adhesion. This happens through a mode that is Arg-Gly-Asp (RGD)-dependent via integrins, which means it relies on a particular sequence of amino acids and particles called integrins to bind cells together effectively.

Expression of MFGE8 during Equine Pregnancy

• The researchers investigate MFGE8’s presence and behavior in equine endometrium—the lining of mares’ uteruses—at different stages of pregnancy.
• Comparison between pregnant and non-pregnant horses was done on Day 12 and Day 16 post-ovulation, as well as five months into gestation.
• They discovered that MFGE8 is expressed at the embryo and fetal-maternal interface throughout equine pregnancy. This interface is where the embryo or fetus contacts and interacts with the mare’s body, suggesting a crucial function of MFGE8 in this context.

Role of Estrogen in Regulating MFGE8

• The study emphasizes the role of estrogen upregulating MFGE8’s expression in non-pregnant endometrium, based on verification using endometrial explant culture.
• It implies that estrogen might be an important regulator of MFGE8 and possibly of cell adhesion in the uterine context.

Further Observations on MFGE8

• MFGE8 expression levels remained fairly consistent in conceptuses collected 13 and 14 days post-ovulation, and in allantochorion sampled during the fifth month of gestation. The allantochorion is part of the placenta, furthering support for MFGE8’s important role in pregnancy.
• Moreover, the MFGE8 expression has been observed in pericytes of endometrial blood vessels upon in situ hybridization. Pericytes are cells that wrap around the endothelial cells that line the capillaries and venules throughout the body.
• This expression was even more pronounced in the fetal side of the allantochorionic villi (tiny hair-like structures on the placenta) during the fifth month of gestation, again confirming MFGE8’s continuous role in equine pregnancy.

Potential Role of MFGE8 in Equine Pregnancy

• Researchers suggest that the observed expression and behavior of MFGE8 in equine pregnancy may have important implications.
• Possible roles include mediating cell-cell adhesion (crucial for embryo implantation and growth), promoting angiogenesis (blood vessel formation—important for the development of the fetus and placenta), and aiding in the placental transfer of fatty acids (a key nutrient supply for the growing fetus).