Localization and modulation of NEDD8 protein in the human placenta.

Neural precursor cell-expressed, developmentally down-regulated-8 (NEDD8) is a 76-amino-acid ubiquitin-like polypeptide. NEDD8 affects the signaling of various molecules but the major cellular target proteins are cullins. The neddylation process is correlated closely with apoptosis, cell-cycle regulation, embryogenesis and development. The purpose of the present work was to investigate NEDD8 distribution and expression in the human placenta during gestation. A total of 30 samples, 15 chorionic villous samples from first trimester and 15 from full-term placentae, were used for the immunohistochemical analysis of NEDD8 expression. The gestation period ranged from 5 to 40 weeks. NEDD8 was highly expressed in the cytotrophoblast of the first trimester of gestation, whereas in the third trimester, it was localized in the endothelial cells and stroma of placental villi. Our results suggest that NEDD8 may play an important role in the control of proliferation and differentiation of human placenta throughout pregnancy.