Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 12, 2002
Publication Date: December 20, 2002
Citation: Kim, J.G., Vallet, J.L., Christenson, R.K. 2002. Characterization of uterine epidermal growth factor receptor expression during the estrous cycle and early pregnancy in pigs [abstract]. Journal of Animal Science. 80 (Supplement 1):300. (Abstract No. 1200) Technical Abstract: Uterine capacity is a component contributing to litter size in swine. The epidermal growth factor (EGF) gene is located near a uterine capacity quantitative trait locus on chromosome 8. EGF has been reported to stimulate epithelial cell growth, and therefore may influence endometrial function. We have reported the cloning and sequencing of the cDNA for EGF along with changes in EGF mRNA levels in porcine endometrium. For porcine EGF receptor (EGFR), only partial cDNA sequences have been reported previously. Furthermore, the changes in mRNA levels in the endometrium have not been well characterized. The objectives of this study were to 1) clone the full coding region for EGFR, and 2) determine EGFR gene expression in endometrium during the estrous cycle and early pregnancy. Using iterative screening of a porcine reproductive tissue cDNA library, we obtained a 5037 bp cDNA clone containing the entire coding region for EGFR. The predicted protein sequence of the EGFR contains 1209 amino acids, similar to that of human EGFR (1210 amino acids, 88.3% identity). All the major domains of the EGFR, including three tyrosine residues in the cytoplasmic domain that are autophosphorylation sites in human EGFR, are conserved in porcine EGFR. Twenty ug of total RNA from endometrium of day 10, 13, and 15 cyclic gilts and day 10, 13, 15, 20, 30 and 40 pregnant gilts were used for Northern blotting. The probe used consisted of the entire EGFR clone. Bands corresponding to EGFR mRNA were determined by densitometry and results were analyzed by ANOVA. EGFR mRNA expression did not change during the estrous cycle and pregnancy between day 10 and 15, and decreased significantly (P = 0.03) from day 15 (102 +/ 14) to 20 (72 +/ 10 arbitrary units) of pregnancy. Endometrial EGFR gene expression, along with the decrease of EGF mRNA expression from day 13 to 15 of pregnancy, suggests that EGF and EGFR may play a role in the endometrial response to conceptus estrogen.