IDENTIFICATION AND CHARACTERIZATION OF A MOUSE HOMOLOG FOR DECIDUAL TROPHOBLAST PROLACTIN-RELATED PROTEIN/

Decidual/trophoblast PRL-related protein (d/tPRP) is one member of a l arge placental PRL gene family composed of at least nine members in th e rat and four in the mouse. Only placental lactogen I and II have bee n characterized in both rat and mouse. The identification of mouse hom ologs for rat placental PRL family members will facilitate gene manipu lation studies aimed at identifying functions for these hormones. In t his report, we establish the presence of d/tPRP in the mouse and chara cterize its complementary DNA, protein, and pattern of expression duri ng mouse gestation. Evaluation of the National Center for Biotechnolog y Information database of expressed sequence tags resulted in the iden tification of several mouse complementary DNA clones exhibiting signif icant homology to rat d/tPRP. One of these clones was obtained from IM AGE Consortium and Research Genetics for further investigation. The fu ll-length mouse clone was found to have an 81% nucleotide homology wit h rat d/tPRP and to encode a 239-amino acid protein. Like rat d/tPRP, the mouse protein contains two putative N-linked glycosylation sites a nd six homologously located cysteine residues. Mouse d/tPRP maps to ch romosome 13 along with other members of the mouse PRL family. Like the rat, mouse d/tPRP messenger RNA and protein are expressed by antimeso metrial decidual cells and spongiotrophoblast and trophoblast giant ce lls in the junctional zone of the placenta. In summary, we have establ ished the presence of d/tPRP in the mouse and demonstrated its similar ity in structure and pattern of expression to rat d/tPRP. This level o f conservation between species expands the biological significance of d/tPRP during pregnancy and provides additional opportunities for eval uating its function.