Lefranc M P, Alexandre D
Laboratoire d'ImmunoGénétique Moléculaire, CNRS, Université Montpellier I.
Eur J Immunol. 1995 Feb;25(2):617-22. doi: 10.1002/eji.1830250246.
The expression of the T cell receptor (TcR) gamma genes is restricted to TcR gamma delta + T lymphocytes. Transgenic and somatic cell hybrid experiments had suggested that the expression of a functionally rearranged TcR gamma gene was extinguished in TcR alpha beta + T cells, possibly by putative cis-acting transcriptional silencers. We have identified such negative cis-acting sequences in the 3' non-coding region of the human TcR gamma (TRG) locus, upstream of an enhancer located at 6.5 kb of the TcR C gamma 2 gene (TRGC2). These silencers were capable of repressing the transcription from a minimal heterologous promoter in a position- and orientation-independent fashion. When analyzed individually, the silencers and the enhancer were equally active in the TcR alpha beta + and TcR gamma delta + T cell lines studied. In contrast, the association of the enhancer with either silencer was shown to restrict transcription to the TcR gamma delta + T cell lines.
T细胞受体（TcR）γ基因的表达仅限于TcRγδ+T淋巴细胞。转基因和体细胞杂交实验表明，功能性重排的TcRγ基因在TcRαβ+T细胞中表达被抑制，可能是由假定的顺式作用转录沉默子所致。我们已在人TcRγ（TRG）基因座的3'非编码区中，位于TcR Cγ2基因（TRGC2）6.5 kb处的增强子上游，鉴定出此类负性顺式作用序列。这些沉默子能够以位置和方向独立的方式抑制来自最小异源启动子的转录。单独分析时，沉默子和增强子在所研究的TcRαβ+和TcRγδ+T细胞系中活性相当。相比之下，增强子与任一沉默子的结合显示将转录限制于TcRγδ+T细胞系。
