Identification of the TCL1/MTCP1-like 1 (TML1) gene from the region next to the TCL1 locus

The region on chromosome 14q32.1 is frequently involved in chromosomal tran slocations and inversions with one of the T-cell receptor loci in human T-c ell leukemias and lymphomas, The breakpoints of the different rearrangement s segregate into two clusters: inversion on the centromeric side and simple balanced translocations on the telomeric side. If the target gene activate d by these different types of chromosomal rearrangements is the same, the g ene must reside between the two clusters of breakpoints in a region of simi lar to 160 kb, By screening of a placenta cDNA library using genomic probes derived from the vicinity of TCL1 locus, we have identified a gene coding for a 1.7-kb transcript that is expressed in leukemic cells carrying a t(14 ;14)(q11;q32) chromosome translocation, The cognate cDNA sequence reveals a n open reading frame of 384 nucleotides encoding a M-r 15,000 protein with similar to 30% of homology with both p14(TCL1) and p13(MTCP1) oncoproteins, The genomic organization of the TML1 locus was characterized, with three e xons located 15 kb from and tail-to-tail in relation to TCL1 locus. Because of its location and sequence similarity with TCL1 and MTCP1 oncoproteins, this gene, named TML1 (TCL1/MTCP1-like 1) is a candidate gene that is poten tially involved in leukemogenesis.