A splice variant of the TCR zeta mRNA lacking exon 7 leads to the down-regulation of TCR zeta, the TCR/CD3 complex, and IL-2 production in systemic lupus erythematosus T cells.
The reduction or absence of TCR zeta-chain (zeta) expression in patients with systemic lupus erythematosus (SLE) is thought to be a factor in the pathogenesis of SLE. We previously reported a splice variant of zeta mRNA that lacks the 36-bp exon 7 (zeta mRNA/exon 7(-)) and is accompanied by the down-regulation of zeta protein in T cells from SLE patients. In this study, we show that EX7- mutants (MA5.8 cells deficient in zeta protein that have been transfected with zeta mRNA/exon 7(-)) exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface as well as a reduction in the production of IL-2 after stimulation with anti-CD3 Ab, compared with that in wild-type (WT) mutants (MA5.8 cells transfected with the WT zeta mRNA). Furthermore, real-time PCR analyses demonstrated that zeta mRNA/exon 7(-) in EX7- mutants was easily degraded compared with zeta mRNA by the WT mutants. Pulse-chase experiment showed zeta protein produced by this EX7- mutants was more rapidly decreased compared with the WT mutants. 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.
Tsuzaka
Kensei
K
Second Department of Internal Medicine, Saitama Medical Center, Saitama Medical School, Kawagoe, Saitama, Japan. kentsu@saitama-med.ac.jp
Setoyama
Yumiko
Y
Yoshimoto
Keiko
K
Shiraishi
Kiyono
K
Suzuki
Katsuya
K
Abe
Tohru
T
Takeuchi
Tsutomu
T
D017398:Alternative Splicing; D000818:Animals; D002460:Cell Line; D015536:Down-Regulation; D005091:Exons; D006801:Humans; D006825:Hybridomas; D007376:Interleukin-2 / Q000096:biosynthesis*; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000235:genetics*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*
D007376:Interleukin-2; D008565:Membrane Proteins; D012333:RNA, Messenger; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain