T-cell receptor ζ mRNA with an alternatively spliced 3′ untranslated region is generated predominantly in the peripheral blood T cells of systemic lupus erythematosus patients

Abstract

To investigate the mechanism of the downregulation of T-cell receptor chain (TCR ) expression in the peripheral blood T cells (PBTs) of systemic lupus erythematosus (SLE) patients, we analyzed the 3Ј untranslated region (3ЈUTR) of TCR mRNA, because the 3ЈUTR in mRNA is responsible for posttranscriptional regulation. Use of the reverse transcriptase polymerase chain reaction (RT-PCR) to amplify the 917 bp TCR 3ЈUTR cDNA demonstrated that the short variant cDNA (355 bp), expressed as an alternatively spliced 3ЈUTR with 562-bp deletion, was predominated in the PBTs of 11 of 14 SLE patients, whereas mainly the wild-form cDNA (917 bp) was detected in the PBTs of seven negative controls (two systemic sclerosis patients, five normal controls) and in two T-cell line hybridomas. Semiquantitative PCR also revealed the predominant expression of the TCR mRNA with alternatively spliced 3ЈUTR (TCR mRNA/as-3ЈUTR), and a decreased expression of TCR mRNA with the wild form 3ЈUTR (TCR mRNA/w-3ЈUTR) in SLE T cells. However, there was no difference in the expression of the open reading frame (ORF) TCR mRNA between the negative controls and SLE patients. The TCR protein expression level according to Western blot analysis correlated well with that of TCR mRNA/w-3ЈUTR (r ϭ 0.931) and reversibly with TCR mRNA/as-3ЈUTR (r ϭ Ϫ0.614), but not with ORF TCR mRNA (r ϭ Ϫ0.296). It can be concluded that the reduced expression of TCR mRNA/w-3ЈUTR and the predominant expression of TCR mRNA/as-3ЈUTR lead to downregulation of the TCR protein in SLE T cells.

Comprehensive analysis of surface proteins of peripheral mononuclear blood cells in patients with systemic lupus erythematosus

“…It was reported that cyclin L1 was involved in the splicing of mRNA [22,23]. In T cells of patients with SLE, abnormal splicing of TCR zeta chain was reported [24,25]. Our data and their reports indicate possible involvement of translocation of cyclin L1 in the abnormal splicing in T cells of patients with SLE.…”

The CD3Z 844 T>A polymorphism within the 3′‐UTR of CD3Z confers increased risk of incidence of systemic lupus erythematosus

“…The spliced mRNA product is 1.492-kb long, composed of a 492-bp coding region, and a 3#-UTR of 906 bp (43). Expression of the CD3Z gene is regulated at transcriptional, posttranscriptional, and posttranslational levels (37)(38)(39)(40)44). However, the expression of CD3-z is mainly regulated at the posttranscriptional level through the 3#-UTR.…”

“…However, the expression of CD3-z is mainly regulated at the posttranscriptional level through the 3#-UTR. This CD3-z transcript region plays an essential role in that it changes mRNA stability, transport, and localization (37)(38)(39)(40). Downregulation of CD3-z expression has also been linked to increased degradation of this protein through ubiquitination, granzyme B, and caspase actions (33-36, 41, 45).…”

“…Tsuzaka et al reported that variants of CD3-z mRNA lacking the 36-bp exon 7 were associated with the downregulation of CD3-z protein expression in T cells and reduced Interleukin 2 (IL-2) production after stimulation with anti-CD3 antibody (46). Reduced mRNA stability was also observed for the 3# UTR 344-bp product (compared with the wildtype 906-bp fragment) form with a deletion of nucleotides from 672 to 1233 of exon 8 of the mRNA (37)(38)(39)(40). However, none of these splicing variant abnormalities have been clearly associated with SLE susceptibility.…”

“…It has been believed that T cells are central in the pathogenesis of SLE, and dysfunctions in their regulatory action may result in changes in immune response (32). Numerous investigations have demonstrated that T cells from patients with SLE display both quantitative and qualitative differences in their levels and function of CD3-z compared with T cells from healthy controls (12,(33)(34)(35)(36)(37)(38)(39)(40)(41). However, the molecular mechanisms of a reduced expression of CD3-z mRNA and protein in SLE T cells are still unclear.…”