Two types of genomic rearrangements create alternative E2A-HLF fusion proteins in t(17;19)-ALL.
The t(17;19)(q21-q22;p13.3) in acute lymphoblastic leukemia results in creation of an E2A-HLF fusion protein with structural and functional properties of a chimeric transcription factor. Two types of genomic rearrangements underlie fusion of E2A with HLF. In type I rearrangements, an insertion that codes for a portion of the chimera not found in either wild type protein occurs between E2A exon 13- and HLF exon 4-encoded sequences. This insertion is derived from a cryptic exon created at the junction between chromosomes 17 and 19, and includes intronic portions of both E2A and HLF with intervening nontemplated N nucleotides. Type II rearrangements arise from more 5' breakpoints in E2A and result in fusion cDNAs with E2A exon 12 spliced directly to HLF exon 4. Analysis of the genomic structure of HLF shows that these different modes of protein fusion result from selective constraints to maintain the proper HLF reading frame, because a direct E2A exon 13 to HLF exon 4 splice would lead to translation of a truncated E2A protein lacking any contribution from HLF. These features underscore the requirement for DNA binding and/or dimerization conferred by the bZIP portion of the E2A-HLF chimera in t(17;19)-ALL.
Hunger
S P
SP
Department of Pathology, Stanford University School of Medicine, CA 94305.
Devaraj
P E
PE
Foroni
L
L
Secker-Walker
L M
LM
Cleary
M L
ML
D000595:Amino Acid Sequence; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D002886:Chromosomes, Human, Pair 17; D002888:Chromosomes, Human, Pair 19; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D051790:G-Box Binding Factors; D015321:Gene Rearrangement; D006801:Humans; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis*; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; D014178:Translocation, Genetic
D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D011994:Recombinant Proteins; D051820:TCF Transcription Factors; C544912:TCF7L1 protein, human; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors