Nuclear receptor interacting protein 140 (RIP 140) may be involved with the onset of human labour

Abstract

Nuclear receptor interacting protein 1 (NRIP1) [also known as receptor interacting protein 140 (RIP140)] interacts with nuclear receptors in a ligand-dependent manner. Transfection studies suggest that it can act as a co-repressor. Knockout mice for RIP140 are completely infertile because of failure of mature follicles to release oocytes at ovulation. Embryo transfer in RIP140^−/− mice resulted in normal implantation rates, but the gestation period was longer which implies that RIP140 may have a role in labour. Our object was to explore the possibility that RIP140 is involved as a co-factor in the signalling cascade that precedes the onset of human labour. RIP140 expression was quantified in primary amnion cells before and after the onset of labour (labour− vs. labour+) using real-time RT-PCR. The effect of IL-1β on RIP140 was assessed. To determine the effect of RIP140 upon PR function, 293 T cells and amnion cells were transfected with an MMTV-luc reporter vector (a reporter activated by progesterone/PR binding). Co-transfection experiments with RIP140 expression vectors were performed. Expression of RIP140 is increased threefold in labour+ amnion cells in comparison with labour−amnion cells (P < 0.05). IL-1β treatment had no effect on the expression of RIP140. Transfection studies showed an increase in MMTV promoter activity when cells were co-transfected with PRB expression vector. Co-transfection with RIP140 significantly reduced MMTV luciferase activity.