Analysis of CD2 and TCR-β gene expression in Jurkat cell mutants suggests a cis regulation of gene transcription

Thirty CD2^- J32 stable clones, derived by mutagenesis and subsequent immunoselection with anti-CD2 Ab, were used to study the regulation of CD2 and TCR gene expression. Analysis of RNA expression revealed that the loss of surface expression of CD2 was due to a lack of expression of CD2 mRNA and was associated with a lack of expression of VDJ TCR-β transcripts in 12 of these mutants, sparing the expression of DJ TCR-β, TCR-α, CD3γ δ, ε, and ζ RNA. The expression of other differentiation molecules was unaffected, except for CD1, CD4, and CD5, which were either decreased or absent in most of these mutants. A gain in the expression of TCR-γ transcripts was observed in each of these mutants, while, as expected, no TCR-γ transcripts were detected in wild-type J32 cells. Several mutants were able to use the human CD2 enhancer and the murine TCR-β enhancer and promoter to activate transcription from reporter genes in the context of heterologous promoters, indicating that the mutation(s) does not affect transcription pathways. Consistent with this finding is the adequate expression in these mutants of several lineage- specific transcription factors. The expression of CD2 in several of these mutants was rescued by gene transfer using a genomic 28.5-kb CD2 fragment, suggesting that the enhancer function of this gene may be dependent on the enhancer site. These observations suggest that the coordinate expressions of CD2 and TCR-β genes share common regulatory mechanisms involving factors regulating chromatin structure and accessibility.