Characterization of deciduoma marker proteins in hamster uterus: detection in decidual cell cultures

The objective of this study was first, to identify the proteins associated with decidualization of the hamster uterus by comparing the protein maps of decidualized and nondecidualized endometrium in vivo, and second, to determine whether decidual cell cultures produced these characteristic proteins. Decidualization was induced in one uterine horn, and the contralateral horn was not stimulated (control tissue). Animals were ovariectomized and a subcutaneous progesterone implant was used to maintain decidualization. Uterine proteins from nuclear and cytosol fractions were analyzed by two-dimensional electrophoresis using a highly sensitive protein staining technique. Analysis of nuclear extract and cytosol from decidualized and nondecidualized endometrium from Days 6, 7, and 8 of pseudopregnancy demonstrated the presence of 11 nuclear and five cytosolic deciduoma-associated proteins. Serum and erythrocyte proteins were identified by two-dimensional electrophoresis, and none of the 16 deciduoma-associated proteins was a serum or erythrocyte contaminant. Forty-eight-hour cultures of decidual cells harvested from Day 5 of pseudopregnancy produced all 16 of the deciduoma-associated proteins found in whole tissue in situ. Culture conditions minimized serum and erthrocyte contamination, enhancing the detection of deciduomal cell proteins. Four nuclear and two cytosolic proteins were considered deciduoma specific, i.e., they were not associated with cellular proliferation, as evidenced by their absence from cultures of rapidly dividing fetal hamster fibroblasts. Thus, these studies show that the detection of deciduomal proteins may be a useful criterion for the assessment of decidualization in vitro and in vivo.