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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Cloning and Endometrial Expression of Porcine High Density Lipoprotein Receptor Sr-Bi During the Estrous Cycle and Early Pregnancy

Authors
item Kim, Jong
item VALLET, JEFFREY
item NONNEMAN, DANNY
item Christenson, Ronald

Submitted to: Molecular and Cellular Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 21, 2004
Publication Date: July 20, 2004
Citation: Kim, J.G., Vallet, J.L., Nonneman, D., Christenson, R.K. 2004. Molecular cloning and endometrial expression of porcine high density lipoprotein receptor SR-BI during the estrous cycle and early pregnancy. Molecular and Cellular Endocrinology. 222(1-2):105-112.

Interpretive Summary: The uterus of pregnant pigs accommodates a large number of rapidly growing embryos; therefore, the uterus has to grow rapidly during this period. Genes that are expressed by the uterus during early pregnancy may influence or be associated with differences in uterine capacity and therefore litter size. The receptor for high density lipoprotein (HDL), scavenger receptor class B type I (SR-BI), is suggested to deliver critical lipid nutrients to the ovary for membrane synthesis, and steroid hormone production. SR-BI may be expressed in the uterus to provide cholesterol for uterine membrane synthesis and maintenance. SR-BI expression has not been studied in the pig. During rapid development of the fetus, levels of HDL are elevated in pregnant women. SR-BI mediates selective cholesteryl ester uptake and SR-BI message is produced in the human placenta. Because of the rapid growth of uterus during early pregnancy and differences in placentation between swine and humans, we hypothesized that SR-BI message may be produced in the porcine uterus to take up HDL cholesterol. The objectives of this study were to obtain the full coding region for porcine SR-BI, determine uterine SR-BI message production during the estrous cycle and early pregnancy, and map the gene. By screening of a porcine DNA library, we obtained the full coding region of SR-BI. Uterine SR-BI message production in crossbred gilts was determined on days 10, 13, and 15 of the estrous cycle, and on days 10, 13, 15, 20, 30, and 40 of pregnancy. In cyclic gilts, uterine SR-BI message production did not change between days 10 and 13, but increased between days 13 and 15. In pregnant gilts, uterine SR-BI message production increased between days 10 and 13, remained elevated until day 30, and decreased on day 40. The SR-BI gene was mapped to 46.3 cM on chromosome 14. These results show that uterine SR-BI message production changes during the estrous cycle and early pregnancy, and suggest that SR-BI takes up HDL for uterine development during early pregnancy.

Technical Abstract: During rapid development of the fetus, levels of high density lipoprotein (HDL) are elevated in pregnant women. The receptor for HDL, scavenger receptor class B type I (SR-BI), mediates selective cholesteryl ester uptake and is highly expressed in the human placenta. Because of the rapid growth of uterus during early pregnancy and differences in placentation between swine and humans, we hypothesized that SR-BI may be expressed in porcine endometrium to take up HDL cholesterol. The objectives of this study were to obtain the full coding region for porcine SR-BI, determine endometrial expression of SR-BI mRNA during the estrous cycle and early pregnancy, and map the gene. By iterative screening of a porcine expressed-sequence tag library, we obtained the full coding region of SR-BI. Endometrial expression of SR-BI in White composite gilts (n = 3 to 4 each) was determined by Northern blotting on days 10, 13, and 15 cyclic gilts, and days 10, 13, 15, 20, 30, and 40 pregnant gilts. In cyclic gilts, endometrial expression of SR-BI did not change between days 10 and 13, but increased (P < 0.01) between days 13 and 15. In pregnant gilts, endometrial expression of SR-BI increased (P < 0.01) between days 10 and 13, remained elevated until day 30, and decreased (P = 0.015) on day 40. The SR-BI gene was mapped to 46.3 cM on chromosome 14. These results show that endometrial expression of SR-BI changes during the estrous cycle and early pregnancy, and suggest that SR-BI takes up HDL for endometrial development during early pregnancy.

Last Modified: 9/29/2014