TTF, a gene encoding a novel small G protein, fuses to the lymphoma-associated LAZ3 gene by t(3;4) chromosomal translocation.
We have previously shown that the LAZ3/BCL6 gene encoding a potential transcription factor, is disrupted in B-diffuse large cell non-Hodgkin's lymphomas (NHL) with 3q27 chromosomal abnormalities involving the immunoglobulin (IG) genes. However, LAZ3 rearrangement also occurs in NHL bearing 3q27 translocations without involvement of the IG genes: for example the VAl cell line exhibits t(3;4)(q27;p11). In the present work we have used a RT-PCR method to detect and to sequence the LAZ3 mRNA products from the VAL cell line. We report that the consequence of the t(3;4) is the expression of a chimeric transcript of LAZ3 with a new gene encoding a small G-like protein, termed TTF (Translocation Three Four). Nucleotide sequence analysis of a 1.4 kb cDNA predicts that the TTF gene encodes a protein of 191 amino-acids similar to members of the RAS superfamily including HRAS (27% identical), RAB1A (30% identical) and RHO proteins: the human RAC1, RHOB and CDC42Hs proteins (respectively 43, 44 and 45% identical) and the yeast RHO2 protein (44% identical). Unlike most other small G proteins which are expressed ubiquitously, TTF was transcribed only in hemopoietic cells as a 2.2 kb transcript. TTF may define a new subgroup of RHO-like proteins.
Dallery
E
E
U. 124 INSERM, Institut de Recherches sur le Cancer de Lille, France.
Galiègue-Zouitina
S
S
Collyn-d'Hooghe
M
M
Quief
S
S
Denis
C
C
Hildebrand
M P
MP
Lantoine
D
D
Deweindt
C
C
Tilly
H
H
Bastard
C
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D002893:Chromosomes, Human, Pair 3; D002894:Chromosomes, Human, Pair 4; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D051560:Proto-Oncogene Proteins c-bcl-6; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured
C084103:BCL6 protein, human; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051560:Proto-Oncogene Proteins c-bcl-6; D012333:RNA, Messenger; D014157:Transcription Factors; D019204:GTP-Binding Proteins