Regulation of T-cell antigen receptor (TCR) α-chain expression by TCR β-chain transcripts

Abstract

The TCR is an αβ heterodimer, a part of the multimeric structure through which physiological T-cell activation occurs. The expression of TCR α chain is greatly diminished in a β-chain-deficient mutant Jurkat cell line (J.RT3-T3.5). The relationship between the expression of the TCR α and β chains has been examined by stable transfection of a series of TCR β-chain mutant constructs into this mutant cell line. The level of α-chain transcript was dramatically upregulated by the expression of the β chain and specifically by a transcript of the β-chain variable region alone, including a transcript in which the ATG start codon was mutated. The downregulation of the endogenous α-chain transcripts in mutants cells lacking complete β;-chain transcripts occurred primarily at the posttranscriptional level. This evidence for a regulatory function of the TCR β-chain gene represents an unusual regulatory pathway in which the transcript of one gene is required for the optimal expression of another gene.