Recently, we reported that in SLE T cells, the residual TCR zeta protein is predominantly derived from an alternatively spliced form that undergoes splice deletion of 562 nt (from 672 to 1233 bases) within the 3' untranslated region (UTR) of TCR zeta mRNA.
Thus, the lower stability of zeta mRNA/exon 7(-) might also be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.
It is also shown that in the majority of patients with systemic lupus erythematosus (SLE), who are known to express decreased levels of T cell receptor (TCR) zeta chain and mRNA, the 80-kDa Elf-1 protein does not undergo proper post-transcriptional modification, which results in low levels of the 98-kDa protein, lack of Elf-binding to the TCR zeta promoter, and decreased gene transcription.
Thus, the lower stability of zetamRNA/as-3'UTR, which is predominant in SLE T cells, may be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.
Mutations found in six of these patients corresponded to those of the third immunoreceptor tyrosine-based activation motif (ITAM) domain or the GTP/GDP binding site in TCR zetaThus, these mutations in TCR zeta mRNA could be responsible for the decreased expression of the TCR zeta protein in SLE T cells.