Effects of a chromatin low molecular weight peptidic fraction on differentiation markers and virus production in Friend leukemia cells.

Low molecular weight chromatin peptides exert a dose-dependent inhibition of Dimethylsulfoxide (DMSO)-induced erythroid differentiation of murine Friend Leukemia Cells (FLC). This effect correlates with the degree of purification of the peptide fractions. Crot analysis of globin mRNA amounts in DMSO-treated FLC given the peptides showed a 4-5-fold decrease of messenger RNA in the cytoplasma with no nuclear storage of globin transcripts. Spectrin accumulation in "induced" FLC is inhibited as well. The effects of the peptides on erythroid markers are reversible upon removal of the compounds. They also appear to be specific for induced gene expression as (1) no effects are observed on cell growth and RNA synthesis in normal non-differentiating cell lines; and (2) no changes have been detected with regard to the expression of integrated viral genes coding for continuous shedding of viral particles.