Unusual forms of T cell gamma mRNA in a human T cell leukemia cell line: implications for gamma gene expression.
The expression and rearrangement of T cell rearranging (TRG) gamma genes in human leukemic cell lines has been examined. The cell line MOLT-17 produces abundant gamma mRNA which is translated into a protein found on the cell surface which is associated with the CD3 molecule. The analysis of the gamma mRNA sequences in MOLT-17, by cDNA cloning, shows transcripts of aberrantly rearranged genes as well as the productively rearranged allele. The productive allele consists of a rearranged V gamma 8 gene joined to J gamma 2. Two forms of aberrant transcript originate from the other rearranged gamma allele. One of these initiates just upstream of the unrearranged J gamma 2 segment, and the other initiates from a V gamma 8 gene segment joined to another J gamma segment, upstream of J gamma 2. An unusual feature of the latter transcript is that polyadenlyation has occurred at the end of the first exon of C gamma 2, where two conserved poly(A) addition signals occur. The MOLT-4 cell line, on the other hand, has productively and nonproductively rearranged gamma alleles, from which relatively little transcription occurs. These results define new J gamma segments in the human TRG gamma locus and suggest that positive activation of the gamma locus is necessary for high level transcription after rearrangement.
D000595:Amino Acid Sequence; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004220:Disulfides; D005786:Gene Expression Regulation; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013601:T-Lymphocytes / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000502:physiology*
D000945:Antigens, Differentiation, T-Lymphocyte; D004220:Disulfides; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D016692:Receptors, Antigen, T-Cell, gamma-delta; D014157:Transcription Factors; D004247:DNA