Expression of Cytokine Receptors in Pre-implantation Mouse Embryos

The proliferation and differentiation of most cells are regulated by cytokine signaling, but the mechanism that regulates pre-implantation development remains unclear. Recently, it has been shown that Jak2, which mediates various cytokine signaling pathways, is expressed in pre-implantation mouse embryos. In this study, we investigated the expression of the cytokine receptors that activate Jak2, i.e., the receptors for prolactin (PrlR), growth hormone (GHR), tumor necrosis factor (TNFR), interleukin-3 (IL-3R), interleukin-5 (IL-5R), and granulocyte-macrophage colony stimulating factor (GM-CSFR). RT-PCR analysis revealed that PrlR was expressed in MII stage oocytes at a relatively high level, and that the level of expression decreased between the 2-cell and 4-cell stages. The expression levels of GHR, TNFR, IL-3R, IL-5R and GM-CSFR were relatively low before the morula stage, but they increased thereafter until the hatched blastocyst stage. These results suggest that various cytokine signaling pathways mediated by Jak2 activation are involved in the regulation of pre-implantation development.