In our earlier study, we have shown that PG transporters such as ATP-binding cassette, subfamily C, member 4 (ABCC4; also known as multidrug resistance protein 4 [MRP4]) and solute carrier organic anion transporter family, member 2A1 (SLCO2A1, also known as PG transporter [PGT] or organic anion-transporting polypeptide 2A1 [OATP2A1 ]), are expressed in the uterine endometrium during early pregnancy in pigs .
Our previous study has shown that the patterns of ABCC4 and SLCO2A1 expression during pregnancy were biphasic with the highest levels on D12 and D90 of pregnancy .
Expression of ABCC4 and SLCO2A1 mRNA and protein has also been shown in conceptus tissues and chorioallaltoic tissues .
However, expression of ABCC1 and ABCC9 mRNAs was not detected in endothelial cells of endometrial blood vessels, which express SLCO2A1 .
Results of this study showed that levels of ABCC1 and SLCO2A1 mRNA were significantly higher on D12 of pregnancy than the estrous cycle and levels of ABCC9 and SLCO4C1 mRNA were higher during pregnancy than during the estrous cycle.
Our previous study has also shown that IL1B, but not estrogen, increases the expression of ABCC4 and SLCO2A1 mRNAs, which show higher levels of endometrial expression on D12 of pregnancy than during the estrous cycle in pigs .
Mutations at hydroxy-prostaglandin dehydrogenase enzyme which is responsible for PGE2 degradation or at SLCO2A1 which is PGE2 transporter result in increase of serum levels of PGE2 that stimulate various intracellular signaling pathways including vascular endothelial growth factor expression (VEGF).
Homozygous and combined heterozygous mutation of this enzyme increases the level of PGE2 through impairment of its degradation process; on the other hand, mutation at SLCO2A1 results in impairment of PGE2 cellular uptake.
Rhee, "Identification of the mutations in the prostaglandin transporter gene, SLCO2A1 and clinical characterization in Korean patients with pachydermoperiostosis," Journal of Korean Medical Science, vol.