IMPLANTATION AND PREGNANCY - B
Tuesday, August 3, 2004
10:30 AM–12:30 PM
(493) DECIDUAL CELLS PRODUCE A HEPARIN-BINDING CYTOKINE, PROLACTIN-LIKE PROTEIN-J: EXPRESSION AND BIOLOGICAL TARGETS.
Alam, Sheikh1, Konno, Toshihiro1, Sahgal, Namita1, 2, Li, Chunbin1, Lu, Lu1, Canham, Lindsey1, Soares, Michael1, 1 University of Kansas Medical Center, Kansas City, Kansas2 University of Kansas Medical Center, Kansas City, Kansas
ABSTRACT- Pregnancy in the mouse and rat are associated with the production of a large family of hormones/cytokines related to prolactin (PRL). The hormones/cytokines are hypothesized to coordinate maternal and fetal adaptations to pregnancy. Target tissues and physiological roles for many members of the PRL family are yet to be determined. PRL-like protein-J (PLP-J) is a product of the uterine decidua and a prominent postimplantation cytokine. The rat PLP-J protein contains 211 amino acids with a 29 amino acid signal peptide and two putative N-linked glycosylation sites. In this study, a series of recombinant PLP-J proteins have been generated using both prokaryotic and mammalian cellular expression systems. The recombinant proteins have been purified and used as antigens for antibody generation and as ligands for investigating biological targets. Antibodies to rat PLP-J were used for Western blotting and immunocytochemistry. PLP-J migrates as a 36 kDa protein and localizes to a band of decidual cells surrounding trophoblast cells on day 8 of pregnancy. PLP-J protein localization mirrored the distribution of PLP-J mRNA and was most intense in the antimesometrial uterine compartment. Putative PLP-J target tissues were identified using an alkaline phosphatase-PLP-J (AP-PLP-J) fusion protein in situ binding assay. AP-PLP-J was found to bind to virtually all tissues. The widespread-binding was due to PLP-J interactions with heparin-containing molecules. Furthermore, we determined that PLP-J does not interact with PRL receptors. The proximity of PLP-J synthesis to trophoblast cells prompted an analysis of their interaction. PLP-J binds to trophoblast cells and affects trophoblast cell behavior. The expression of PLP-J and its restricted distribution through interactions with heparin-containing molecules suggests that it acts locally as a cytokine within the vicinity of the implantation site. (Supported by HD20676, HD39878 and the Hall Family Foundation)
KEY WORDS: prolactin, pregnancy, decidua, heparin