Molecular analysis of T-cell receptor transcripts in a human T-cell leukemia bearing a t(1;14) and an inv(7); cell surface expression of a TCR-beta chain in the absence of alpha chain.
The polymerase chain reaction (PCR) was used to amplify cDNA in order to characterize normal and hybrid T-cell receptor (TCR) gene rearrangements derived from a T-cell acute lymphoblastic leukemia (T-ALL) bearing a chromosome 7 inversion. The nucleotide sequence analysis of the amplified product showed the presence of an out-of-frame V beta/J gamma/C gamma transcript and an in-frame V gamma/J gamma/C beta transcript which result from an interlocus recombination between the TCR-beta and gamma loci and the transcription of the reciprocal hybrid TCR gene. The sequence analysis of the reciprocal DNA segment directly involved in the breakpoint of the inversion showed a recombination between a J gamma-sequence heptamer signal and a coding J beta gene segment. The exonuclease nibbling of each DNA extremity and the non-templated nucleotide insertion observed at both coding and reciprocal joints demonstrate that the inversion is mediated by the lymphocyte recombinase complex. During T-cell differentiation, TCR-beta genes are rearranged prior to TCR-alpha genes. In the present case of T-ALL, we have shown that TCR-delta genes are rearranged at both loci, excluding productive rearrangements of TCR-alpha genes. The molecular analysis of the normal TCR genes derived from the leukemic cells revealed the presence of productively rearranged TCR-beta, gamma, and delta genes. Cell surface staining of these cells showed the presence of CD3 molecules and of a TCR-beta chain corresponding to the normal beta allele expressed in a disulfide-linked complex with a protein which is not TCR-alpha, gamma, or delta. This could represent the cell surface expression of the hybrid TCR-V gamma/C beta protein or the expression of a TCR-beta homodimer.
Bernard
O
O
Institut National de la Santé et de la Recherche Médicale (INSERM)-U.301, Paris, France.
Groettrup
M
M
Mugneret
F
F
Berger
R
R
Azogui
O
O
D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D007446:Chromosome Inversion; D002878:Chromosomes, Human, Pair 1 / Q000502:physiology*; D002883:Chromosomes, Human, Pair 14 / Q000502:physiology*; D002897:Chromosomes, Human, Pair 7 / Q000502:physiology*; D004273:DNA, Neoplasm / Q000032:analysis / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D015329:Gene Rearrangement, T-Lymphocyte / Q000235:genetics; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D010641:Phenotype; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics*
D004273:DNA, Neoplasm; D012334:RNA, Neoplasm; D016693:Receptors, Antigen, T-Cell, alpha-beta