RESUMO
Oncostatin M (OSM) is a cytokine which shares a common gene structure and amino acid sequence similarity with leukemia inhibitory factor (LIF), granulocyte colony-stimulating factor (G-CSF) and interleukin 6 (IL-6), suggesting evolution from a common ancestral gene. These four cytokines share several biological activities including the ability to induce the differentiation of the murine M1 myeloid leukemic cell line. To further define the functional similarities within this family, we have investigated whether OSM can substitute for LIF in the maintenance in vitro of the undifferentiated state of pluripotent embryonic stem (ES) cells. In this study, we demonstrate that human recombinant OSM is similar to LIF in its ability to inhibit the differentiation of MBL-5 murine ES cells cultured in vitro. The level of differentiation was determined by morphological criteria and by the continued expression of the embryonic stem cell-specific surface antigen defined by the ECMA-7 monoclonal antibody. Competition binding studies demonstrate that OSM binds to the LIF receptor on MBL-5 ES cells. Our results implicate OSM as a developmental regulatory factor for embryonic stem cells in vivo.
