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EXPRESSION OF PROTEIN TYROSINE PHOSPHATASE RECEPTOR TYPE Z (Ptprz) IN THE UTERUS DURING DECIDUALIZATION.
Bany, Brent 1, Schultz, Gilbert1, 1
ABSTRACT- Previously we have found that pleiotrophin is expressed in mouse endometrial stromal cells during decidualization. Pleiotrophin is a secreted heparin-binding cytokine that has been shown to play a role in normal and deregulated cellular growth and differentiation. It has recently been shown to be a high affinity ligand of Ptprz, a membrane receptor with an intracellular tyrosine phosphatase domain. Since nothing is known about Ptprz expression in the uterus, the present study was undertaken to determine if and where Ptprz is expressed in the uterus during early pregnancy and during artificially-induced decidualization. Ptprz transcripts were detected in the endometrial stroma during early pregnancy and during artificially-induced decidualization by reverse-transcription polymerase chain reaction. Using immunohistochemisty, immunodetectable Ptprz protein was detected in the endometrium of day 4, 6 and 8 pregnant uteri. Ptprz protein was detected throughout the endometrial stroma in sections from implantation and inter-implantation segments on days 4 and 6. By day 8 staining did not occur in zones that had undergone decidualization. Immunodetectable Ptprz protein was also detected in the endometrial stroma of non-stimulated and stimulated uterine horns during artificially-induced decidualization. At 24 h, Ptprz protein staining was found throughout the stroma in sections from non-stimulated and stimulated horns. Ptprz protein was absent in a portion of the antimesometrial deciduoma by 48 h and by 72 h staining was absent in areas that had undergone decidualization. Ptprz protein was not detected in the luminal or glandular epithelia of the endometrium in any of the sections. Because both pleiotrophin and its receptor (Ptprz) are expressed, it is possible that pleiotrophin is acting as a paracrine/autocrine factor in the endometrium during decidualization. (The Canadian Institute of Health Research and Alberta Heritage Foundation for Medical Research supported this work).
KEY WORDS: uterus, endometrium, decidualization, pleiotrophin