ZK1, a novel Krüppel-type zinc finger gene, is induced following exposure to ionizing radiation and enhances apoptotic cell death on hematopoietic cells.

To identify and early response factor by exposure to ionizing radiation, we cloned the cDNA of a novel Krüppel-type zinc finger (ZNF) gene, ZK1, from a cDNA library constructed from the human leukemia cell line, CMK86, using degenerate primers. This cDNA encoded a protein of 671 amino acids with an A box of Krüppel-associated box (KRAB) domain at the N-terminus, followed by 15 ZNF motifs. The expression level of the ZK1 mRNA in human leukemia cells lines, CMK86 and U937, was increased after exposure to ionizing radiation. Furthermore, murine myeloid precursor 32D cells that were stably transfected with ZK1 cDNA had higher sensitivity to ionizing radiation than the 32D parent cells. These data suggest that the ZK1 gene is one of early response genes by exposure to ionizing radiation, and may have some functions on radiation-induced apoptotic cell death on hematopoietic cells.