The nuclease activity of the endogenous differentiation factor of the HL-60 cell line

A structural homology between the endogenous differentiation factor of the HL-60 cell line of promyelocyte leukemia (HLDF) End several DNA/RNA-binding and DNA/RNA-hydrolyzing proteins was revealed, and expression of the hldf gene in prokaryotic systems was studied. On the basis of these experiments, the amino acid sequence of an 8-membered fragment of HLDF with potential n uclease activity was identified. The synthetic octapeptide RRWHRLKE was sho wn to be capable of the cleavage of RNA, linear DNA from phage lambda, and all forms of plasmid DNA. We established that treatment of the HL-60 cell c ulture with this peptide (10(-6) M) results in an increase in the number of apoptotic cells and suggested that HLDF is involved in processes of apopto sis.