Expression of the imprinted genes MEST/Mest in human and murine placenta suggests a role in angiogenesis

In the mouse fetus, Mest is widely expressed in mesoderm derived tissues. I n separate studies in mice and in humans, it has been shown to be maternall y imprinted, that is, only the paternally inherited allele is active, Here, we show that starting with implantation, Mest is also expressed in materna l decidua of the mouse and in placenta of both humans and mice. Expression in murine decidua was restricted to endothelial cells. After Day 7, express ion in the decidua gradually decreased, Mest-specific RT-PCR and restrictio n fragment length variant (RFLV) analysis of decidualized endometrium isola ted from (M. musculus x M. spretus) F1 females showed that only the paterna lly derived Mest allele was activated in the decidual endothelium, In the m ouse extraembryonic tissues, Mest transcripts were detected in derivatives of extraembryonic mesoderm only, Here, hemangioblast precursor cells and en dothelial cells were positive, At all developmental stages of the mouse, tr ophoblast-derived cells were clearly devoid of Mest transcripts. In the hum an placenta MEST transcripts were also detected in hemangioblast precursor cells, however, MEST was also expressed in villous and invasive cytotrophob last, In a human choriocarcinoma/trophoblastic tumour grown in a nude mouse , human MEST was expressed in the tumour cells, whereas murine Mest was exp ressed in endothelia of the murine capillaries, The expression pattern exhi bited by both Mest and MEST in extraembryonic tissues during development an d during formation of choriocarcinoma/trophoblast tumour suggests a functio nal role of the MEST proteins related to oncofetal angiogenesis. (C) 2000 W iley-Liss, Inc.