Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2003
Publication Date: June 1, 2003
Citation: KIM, J.G., VALLET, J.L., CHRISTENSON, R.K. MOLECULAR CLONING AND ENDOMETRIAL EXPRESSION OF PORCINE HIGH DENSITY LIPOPROTEIN RECEPTOR SR-BI DURING THE ESTROUS CYCLE AND EARLY PREGNANCY. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. 2003. v. 81(Suppl. 1). p. 142. Abstract No. 563. Technical Abstract: Rapid development of the placenta and fetus is associated with elevated levels of circulating high density lipoprotein (HDL) in humans. HDL receptor SR-BI (CD36L1) mediates selective cholesterol uptake and it is expressed in the human placenta. Endometrial expression of HDL receptor SR-BI mRNA has not been studied. We hypothesized that HDL receptor SR-BI may be expressed in porcine endometrium to take up maternal HDL cholesterol during early pregnancy to support endometrial development. The objectives of this study were to 1) clone and sequence the full coding region for HDL receptor SR-BI and 2) characterize SR-BI gene expression in the endometrium during the estrous cycle and early pregnancy in swine. By iterative screening of a porcine expressed sequence tag library, we obtained a clone (2601 bp, GenBank AF467889) containing the full coding region of HDL receptor SR-BI. Percent identities of porcine SR-BI amino acid sequence with bovine, human, mouse and rat SR-BI were 88, 87, 80 and 79%, respectively. Endometrial expression of SR-BI mRNA in White composite gilts (n = 3 to 4) was determined by Northern blotting using total RNA from d 10, 13 and 15 cyclic and from d 10, 13, 15, 20, 30 and 40 pregnant gilts, followed by densitometry. There was an interaction (status x day) in SR-BI mRNA expression (P<0.01). In cyclic gilts, endometrial expression of SR-BI mRNA did not change between days 10 and 13, and increased (P<0.01) between d 13 (84.4 +/- 10.8 arbitrary units) and 15 (151.7 +/- 9.3). In pregnant gilts, endometrial expression of SR-BI mRNA increased (P<0.01) between d 10 (100.0 +/- 9.3) and 13 (140.5 +/- 9.3), remained elevated until d 30 (157.5 +/- 10.9), and decreased (P = 0.015) on d 40 (113.4 +/- 10.8). These results show that endometrial SR-BI mRNA expression is temporally regulated during early pregnancy and the estrous cycle. This pattern of gene expression suggests that HDL receptor SR-BI plays a role in endometrial function during the estrous cycle and early pregnancy in swine.