Effect of Leptin on Mouse Trophoblast Giant Cells

Leptin, a hormone produced primarily by adipose tissue, plays a role in both energy homeostasis and reproduction, and is required in early pregnancy. Leptin stimulates metalloproteinase activity in cultured human trophoblast and stimulates invasiveness of cultured mouse trophoblast. The goal of the present study was to examine molecular mechanisms of this function in primary cultures of mouse trophoblast. Leptin was found to stimulate the phosphorylation of MEK, but not STAT3.. It also increased levels of the protein SOCS3. The ability of leptin to stimulate metalloproteinase activity was blocked by the MEK inhibitor PD98059, but also by the vehicle inhibitor DMSO. Microarray analysis revealed that leptin stimulated some genes associated with cell motility, such as Stmn1. In addition, leptin appeared to inhibit changes in gene expression associated with terminal differentiation of trophoblast giant cells, including inhibition of members of the TGFß signaling pathway and of genes associated with endoreduplication. However, feulgen staining revealed a loss of cells with low ploidy. We conclude that leptin may be promoting trophoblast invasion by maintaining cells in an intermediate stage of differentiation. Keywords: time course, response to hormone treatment, primary cell culture The experiments were performed on primary cultures of mouse trophoblast cells which were isolated from placentas on day 10 of pregnancy. There were two treatments: control (serum-free medium) and recombinant mouse leptin (50 ng/mL). RNA was collected at two time points, 1 hour and 24 hours, for the controls. RNA was collected at three time points after leptin treatment: 1 hour, 6 hours, and 24 hours. Thus, there were 5 samples for each experiment. The experiment was repeated four times, for a total of 20 arrays.