What is LIF?
Introduction to Leukemia Inhibitory Factor (LIF)
Leukemia inhibitory factor (LIF) is a cytokine encoded by the LIF gene. LIF is an IL-6 class protein that inhibits cell differentiation, affecting cell growth. A decrease in LIF levels signals the cells to differentiate. In developing embryos, trophectoderm expresses LIF. LIF binds to LIF-receptor (LIFR), present throughout the embryonic inner cell mass. During the blastocyst stage, the inner cell mass produces embryonic stem cells, and if we remove these cells from the inner cell mass, the embryo loses its LIF source.
LIF is produced as a 202 amino acid precursor protein. Upon removing 22 amino acids post-translationally, it processes the precursor protein into a 20 kilodalton active form. LIF is a stable and compact helix bundle composed of four helices, helix A, helix B, helix C, and helix D. LIF binds to its receptor LIFR and forms a heterodimer with the signal-transducing subunit GP130. GP130 is common to all LIFR receptor families. The heterodimer-complex formed activates the JAK/STAT and MAPK cascades, which in turn activates several pluripotency factors including Nanog, Sox-2, and Oct-4.
Some of the LIF aliases are LIF IL-6 6 Family Cytokine 2 3 5, Leukemia Inhibitory Factor 2 3 4, Hilda 2 3 4, Differentiation Inhibitory Activity 2 3, Cholinergic Differentiation Factor 2 3, Differentiation-Stimulating Factor 3 4.