The t(3;5)(q25.1;q34) of myelodysplastic syndrome and acute myeloid leukemia produces a novel fusion gene, NPM-MLF1

Oncogene. 1996 Jan 18;12(2):265-75.


A t(3;5)(q25.1;q34) chromosomal translocation associated with myelodysplastic syndrome and acute myeloid leukemia (AML) was found to rearrange part of the nucleophosmin (NPM) gene on chromosome 5 with sequences from a novel gene on chromosome 3. Chimeric transcripts expressed by these cells contain 5' NPM coding sequences fused in-frame to those of the new gene, which we named myelodysplasia/myeloid leukemia factor 1 (MLF1). RNA-based polymerase chain reaction analysis revealed identical NPM-MLF1 mRNA fusions in each of the three t(3;5)-positive cases of AML examined. The predicted MLF1 amino acid sequence lacked homology to previously characterized proteins and did not contain known functional motifs. Normal MLF1 transcripts were expressed in a variety of tissues, most abundantly in testis, ovary, skeletal muscle, heart, kidney and colon. Anti-MLF1 antibodies detected the wild-type 31 kDa protein in K562 and HEL erythroleukemia cell lines, but not in HL-60, U937 or KG-1 myeloid leukemia lines. By contrast, t(3;5)-positive leukemia cells expressed a 54 kDa NPM-MLF1 protein, but not normal MLF1. Immunostaining experiments indicated that MLF1 is normally located in the cytoplasm, whereas NPM-MLF1 is targeted to the nucleus, with highest levels in the nucleolus. The nuclear/nucleolar localization of NPM-MLF1 mirrors that of NPM, indicating that NPM trafficking signals direct MLF1 to an inappropriate cellular compartment in myeloid leukemia cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Chromosomes, Human, Pair 3*
  • Chromosomes, Human, Pair 5*
  • Cloning, Molecular
  • Gene Rearrangement
  • Humans
  • Leukemia, Myeloid, Acute / genetics*
  • Molecular Sequence Data
  • Myelodysplastic Syndromes / genetics*
  • Nuclear Proteins / genetics*
  • RNA, Messenger / analysis
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / genetics*
  • Translocation, Genetic*


  • Nuclear Proteins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • nucleophosmin

Associated data

  • GENBANK/L49054