HIGH-LEVEL EXPRESSION OF HUMAN LEUKEMIA INHIBITORY FACTOR (LIF) FROM A SYNTHETIC GENE IN ESCHERICHIA-COLI AND THE PHYSICAL AND BIOLOGICAL CHARACTERIZATION OF THE PROTEIN

LIF is a multi-functional cytokine that elicits effects on a broad ran ge of cell types. In this report, we present the high level expression of human LIF (hLIF) from a chemically synthesized gene template in Es cherichia coli where it comprises up to 25% of the cellular protein. T he recombinant hLIF, after purification and folding, was examined usin g CD, FTIR spectroscopy and light scattering. CD and FTIR spectra show ed that the hLIF is an a-helical protein and has a distinct tertiary s tructure. The IFTR spectrum resembles that of other four helical bundl e proteins including G-CSF and IL-6. Light scattering analysis indicat ed that it is a monomeric protein, distinguishing it from M-CSF and in terferon gamma, which also belong to the class of four helical bundle proteins but are dimeric. Recombinant hLIF was assayed for its activit y on the murine leukemic cell line, M-l as well as on human leukemic c ell line, ML-1. It inhibited the growth of M-l cells and differentiate d them towards macrophages. However, it did not have any differentiati on inducing effect on human leukemic cell lines alone or in combinatio n with other cytokines.