Isolation of PEBP2αB cDNA representing the mouse homolog of human acute myeloid leukemia gene, AML1

Breakpoints of the t(8;21) chromosome translocation in acute myeloid leukemia are clustered within the human gene, AML1, located on chromosome 21. The product of AML1 has a region about 130 amino acids long that is highly homologous to the Drosophila segmentation gene runt (runt homology region). The cDNA isolated from mouse fibroblasts encoding the α-subunit of polyomavirus enhancer binding protein 2 (PEBP2/PEA2) revealed that it also has a runt homology region. In this study, a different cDNA clone presumed to represent the mouse homolog of human AML1 (PEBP2αB) was isolated from a cDNA library derived from B cells. The deduced amino acid sequence of PEBP2αB is 99% identical to that of AML1 for the first 241 residues, including the runt homology region, though their sequences diverge thereafter. On the other hand, PEBP2αB and PEBP2α share only 92% and 82% homologies at the amino acid and nucleotide levels respectively, even for the runt homology region, indicating that these proteins are encoded by distinct genes. While PEBP2α is highly expressed in T-cell lines but not in most of the B-cell lines and functions as an activator of T-cell-specific genes, PEBP2αB is expressed in both types of cells. A possible functional relationship between PEBP2α and PEBP2αB is discussed in relation to leukemogenic potential of AML1.