TY - JOUR

T1 - Endothelial and lipoprotein lipases in human and mouse placenta

AU - Lindegaard, Marie L S

AU - Olivecrona, Gunilla

AU - Christoffersen, Christina

AU - Kratky, Dagmar

AU - Hannibal, Jens

AU - Petersen, Bodil L

AU - Zechner, Rudolf

AU - Damm, Peter

AU - Nielsen, Lars B

PY - 2005/11

Y1 - 2005/11

N2 - Placenta expresses various lipase activities. However, a detailed characterization of the involved genes and proteins is lacking. In this study, we compared the expression of endothelial lipase (EL) and LPL in human term placenta. When placental protein extracts were separated by heparin-Sepharose affinity chromatography, the EL protein eluted as a single peak without detectable phospholipid or triglyceride (TG) lipase activity. The major portion of LPL protein eluted slightly after EL. This peak also had no lipase activity and most likely contained monomeric LPL. Fractions eluting at a higher NaCl concentration contained small amounts of LPL protein (most likely dimeric LPL) and had substantial TG lipase activity. In situ hybridization studies showed EL mRNA expression in syncytiotrophoblasts and endothelial cells and LPL mRNA in syncytiotrophoblasts. In contrast, immunohistochemistry showed EL and LPL protein associated with both cell types. In mouse placentas, lack of LPL expression resulted in increased EL mRNA expression. These results suggest that the cellular expression of EL and LPL in human placenta is different. Nevertheless, the two lipases might have overlapping functions in the mouse placenta. Our data also suggest that the major portions of both proteins are stored in an inactive form in human term placenta.

AB - Placenta expresses various lipase activities. However, a detailed characterization of the involved genes and proteins is lacking. In this study, we compared the expression of endothelial lipase (EL) and LPL in human term placenta. When placental protein extracts were separated by heparin-Sepharose affinity chromatography, the EL protein eluted as a single peak without detectable phospholipid or triglyceride (TG) lipase activity. The major portion of LPL protein eluted slightly after EL. This peak also had no lipase activity and most likely contained monomeric LPL. Fractions eluting at a higher NaCl concentration contained small amounts of LPL protein (most likely dimeric LPL) and had substantial TG lipase activity. In situ hybridization studies showed EL mRNA expression in syncytiotrophoblasts and endothelial cells and LPL mRNA in syncytiotrophoblasts. In contrast, immunohistochemistry showed EL and LPL protein associated with both cell types. In mouse placentas, lack of LPL expression resulted in increased EL mRNA expression. These results suggest that the cellular expression of EL and LPL in human placenta is different. Nevertheless, the two lipases might have overlapping functions in the mouse placenta. Our data also suggest that the major portions of both proteins are stored in an inactive form in human term placenta.

KW - Animals

KW - Biopsy

KW - Blotting, Western

KW - Chromatography, Affinity

KW - Dimerization

KW - Endothelium

KW - Heparin

KW - Humans

KW - Immunohistochemistry

KW - In Situ Hybridization

KW - Lipoprotein Lipase

KW - Mice

KW - Mice, Transgenic

KW - Phospholipids

KW - Placenta

KW - RNA, Messenger

KW - Sepharose

KW - Sodium Chloride

KW - Species Specificity

KW - Triglycerides

KW - Trophoblasts

U2 - 10.1194/jlr.M500277-JLR200

DO - 10.1194/jlr.M500277-JLR200

M3 - Journal article

C2 - 16150822

VL - 46

SP - 2339

EP - 2346

JO - Journal of Lipid Research

JF - Journal of Lipid Research

SN - 0022-2275

IS - 11

ER -