A SELECTIVE SWITCH-ON SYSTEM FOR SELF-RENEWAL OF EMBRYONIC STEM-CELLSUSING CHIMERIC CYTOKINE RECEPTORS

Propagation of embryonic stem (ES) cells with an undifferentiated plur ipotential phenotype depends on leukemia inhibitory factor (LIF). The LIF receptor complex is composed of a heterodimer of LIF receptor ct ( LIFR alpha) and gp130. To activate LIFR signaling pathways independent ly from endogenous ones, we constructed chimeric receptors by Linking the extracellular domain of human granulocyte-macrophage colony-stimul ating factor (GM-CSF) receptor alpha or beta (hGMR alpha or beta) to t he transmembrane and cytoplasmic regions of either mouse LIFR alpha or gp130. hGMR alpha-mLIFR/hGMR beta-mgp130 or hGMR alpha-mgp130/hGMR be ta-mgp130, but not hGMR alpha-mLIFR/hGMR beta-mLIFR, preserved the sel f-renewal activity in A3 ES cells. All of these chimeric receptors wer e phosphorylated after hGM-CSF stimulation without phosphorylation of endogenous gp130. Phosphorylation of the signal transducer and activat or of transcription 3 through chimeric receptors correlated with the u ndifferentiated phenotype. Therefore, these chimeric receptors prove u seful to analyze mechanisms of the self-renewal of ES cells. (C) 1998 Academic Press.