Polymorphisms/Mutations of TCR-ζ-Chain Promoter and 3′ Untranslated Region and Selective Expression of TCR ζ-Chain with an Alternatively Spliced 3′ Untranslated Region in Patients with Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE), the prototypic autoimmune disease, is characterized by defective expression of TCR ζ-chain. Elf-1 (E-74-like factor) is a member of the Ets (E-26-specific) family and is crucial for the basal transcription of TCR ζ-chain in Jurkat cells. We previously demonstrated that Elf-1 exists in the cytoplasm mainly as 80-kDa form and after phosphorylation and O-glycosylation it moves to the nucleus as a 98-kDa which binds DNA. We now demonstrate that Elf-1 is crucial for the transactivation of TCR ζ-chain promoter in normal and SLE T cells. Defective expression of TCR ζ-chain in SLE T cells is associated with two distinct molecular defects in the generation of the 98-kDa DNA binding Elf-1 form. In the first, the levels of the 98-kDa form were either decreased or absent. In the second, the apparent levels of the nuclear Elf-1 form were normal but included only two of the three bands into which the nuclear Elf-1 form separated in isoelectric focusing gels. Because both the transcription and the translation processes of Elf-1 gene are normal in SLE T cells, our data demonstrate that abnormal posttranslational mechanisms of the Elf-1 protein result in defective expression of functional Elf-1, and consequently, the transcriptional defect of TCR ζ-chain in patients of SLE.

Section: Discussionmentioning

confidence: 99%

Defective Production of Functional 98-kDa Form of Elf-1 Is Responsible for the Decreased Expression of TCR ζ-Chain in Patients with Systemic Lupus Erythematosus

Juang

Tenbrock

Nambiar

et al. 2002

“…We previously reported the aberrant form of mRNA lacking exon 7 ( mRNA/exon 7Ϫ) observed in SLE patients (5). Moreover, we and other groups have demonstrated that an aberrant form of the mRNA 3Ј-untranslated region (3Ј UTR), which is alternatively spliced and 562 bp shorter than the WT 3Ј UTR, is predominantly expressed in SLE T cells ( mRNA/as-3Ј UTR) (9,10). Predominant expression of these two mRNA splice variant forms ( mRNA/as-3Ј UTR and mRNA/exon 7Ϫ) leads to down-regulation not only of but of the other TCR/CD3 components because of the instability of these mRNA splice variant forms (11)(12)(13).…”

Section: S Ystemic Lupus Erythematosus (Sle)mentioning

confidence: 98%

DNA Microarray Gene Expression Profile of T Cells with the Splice Variants of TCRζ mRNA Observed in Systemic Lupus Erythematosus

Tsuzaka

Nozaki

Kumazawa

et al. 2006

We have reported that the TCRζ mRNA with alternatively spliced 3′ UTR (ζ mRNA/as-3′-untranslated region (UTR)) and ζ mRNA lacking exon 7 (ζ mRNA/exon 7−) observed in systemic lupus erythematosus patient T cells can lead to down-regulation of both ζ and TCR/CD3 complexes. To determine whether these T cells expressing decreased ζ exhibit differential transcription patterns, we transfected retrovirus vectors containing wild-type ζ cDNA, ζ cDNA/as-3′ UTR, and ζ cDNA/exon 7− into murine T cell hybridoma MA5.8 cells which lack ζ expression to construct the MA5.8 mutants WT, AS3′ UTR, and EX7−, respectively. FACS analyses demonstrated reduced cell surface expression of ζ and TCR/CD3 complexes on the AS3′ UTR mutant and the EX7− mutant in comparison to that on the WT mutant. Total RNA was collected after stimulating the MA5.8 mutants with anti-CD3 Ab. Reverse-transcribed cDNA was applied to the mouse cDNA microarray containing 8691 genes, and the results were confirmed by real-time PCR. The results showed that 36 genes encoding cytokines and chemokines, including IL-2, IL-15, IL-18, and TGF-β2, were down-regulated in both the AS3′ UTR mutant and the EX7− mutant. Another 16 genes were up-regulated in both, and included genes associated with membranous proteins and cell damage granules, including the genes encoding poliovirus receptor-related 2, syndecan-1, and granzyme A. Increased protein expression of these genes was confirmed by Western blot and FACS analyses. Identification of these responsive genes in T cells in which the ζ and TCR/CD3 complexes were down-regulated may help to better understand the pathogenesis of systemic lupus erythematosus.

“…The resultant TCR mRNA displays decreased stability and translation efficiency and thus contributes to diminished expression of TCR -chain in SLE T cells (20,24) implying a stabilizing role for the deleted region (Fig. 1).…”

Section: Expression Of Tcr Protein By Splice-deleted 3ј Utr Tcrmentioning

confidence: 99%

“…The defective TCR protein expression in SLE T cells inversely correlates with the level of TCR mRNA with alternatively spliced 3Ј UTR and directly with mRNA bearing the wild-type (WT) 3Ј UTR (20). This correlation indicates the existence of regulatory elements in the alternatively spliced region of TCR mRNA that are critical for its cellular expression.…”

mentioning

confidence: 99%

Stability and Translation of TCR ζ mRNA Are Regulated by the Adenosine-Uridine-Rich Elements in Splice-Deleted 3′ Untranslated Region of ζ-Chain

Chowdhury

Krishnan

Tsokos

et al. 2006

Self Cite

Systemic lupus erythematosus (SLE) T cells display reduced expression of TCR ζ protein. Recently, we reported that in SLE T cells, the residual TCR ζ 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 ζ mRNA. The stability and translation of the alternatively spliced form of TCR ζ mRNA are low compared with that of the wild-type TCR ζ mRNA. We report that two adenosine-uridine-rich sequence elements (AREs), defined by the splice-deleted 3′ UTR region, but not an ARE located upstream are responsible for securing TCR ζ mRNA stability and translation. The stabilizing effect of the splice-deleted region-defined AREs extended to the luciferase mRNA and was not cell type-specific. The findings demonstrate distinct sequences within the splice-deleted region 672 to 1233 of the 3′ UTR, which regulate the transcription, mRNA stability, and translation of TCR ζ mRNA. The absence of these sequences represents a molecular mechanism that contributes to altered TCR ζ-chain expression in lupus.