TCRzeta mRNA splice variant forms observed in the peripheral blood T cells from systemic lupus erythematosus patients.
ABSTRACT Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown etiology. Tyrosine phosphorylation and protein expression of the T-cell receptor zeta chain (zeta) have been reported to be significantly decreased in SLE T cells. In addition, zeta mRNA with alternatively spliced 3' untranslated region (zetamRNA/as-3'UTR) is detected predominantly in SLE T cells, and aberrant zeta mRNA accompanied by the mutations in the open reading frame including zeta mRNA lacking exon7 (zetamRNA/exon7-) is observed in SLE T cells. These zeta mRNA splice variant forms exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface due to the instability of zeta mRNA splice variant forms as well as the reduction in interleukin (IL)-2 production after stimulating with anti-CD3 antibody. Data from cDNA microarray showed that 36 genes encoding cytokines and chemokines, including IL-2, IL-15, IL-18, and TGF-beta2, were down-regulated in the MA5.8 cells transfected with the zeta mRNA splice variant forms. Another 16 genes were up-regulated and included genes associated with membranous proteins and cell damage granules, including the genes encoding poliovirus-receptor-related 2, syndecan-1, and granzyme A.
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ABSTRACT: A conserved sequence motif has been identified in a number of signaling subunits associated with hematopoietic cell antigen receptors. Here, we characterize signaling by a 17 amino acid motif that is triplicated in the T cell antigen receptor zeta chain. Analysis of zeta truncations and constructs containing the isolated motif demonstrates that this motif is sufficient for the induction of both proximal and distal events associated with T cell activation. Stimulation of truncations that contain either one, two, or three copies of the motif results in induction of an identical pattern of tyrosine phosphoproteins. Moreover, triplication of the NH2-terminal zeta motif results in enhanced signaling, suggesting a redundant role in signal amplification for the three motifs in zeta. Finally, we demonstrate the association of a recently identified protein tyrosine kinase ZAP-70 with this motif, and provide evidence for its involvement in zeta function.Journal of Experimental Medicine 05/1993; 177(4):1093-103. · 13.21 Impact Factor
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ABSTRACT: Epidermal growth factor (EGF) produced rapid and striking effects on parathyroid hormone-related protein (PTHrP) gene expression in the immortalized human keratinocyte cell line, HaCaT. Steady-state levels of PTHrP mRNA and secreted PTHrP were increased 10-fold by maximally effective concentrations of EGF. EGF increased both PTHrP gene transcription and PTHrP mRNA stability. Nuclear run-on assays demonstrated a 4-fold increase in transcriptional rate in EGF-stimulated cells while transient transfection analysis indicated that the action of EGF on transcription involved both the GC-rich promoter, P2, and the downstream TATA promoter, P3, but apparently not the upstream TATA promoter, P1. In experiments where EGF treatment produced more stable PTHrP transcripts, the half-life of c-fos mRNA was unaltered, suggesting a relatively specific effect of EGF. Moreover, only those species of PTHrP mRNA containing two of the alternative 3' exons (exons VII and VIII) were stable, those containing exon IX were not. Reverse-transcription PCR demonstrated that EGF produced differential increases in the abundance of PTHrP mRNA species initiated by the three PTHrP promoters. The major effect was seen on the abundance of transcripts initiated by P1 and P2, with less marked regulation of P3-initiated transcripts. Thus EGF regulation of PTHrP gene expression in HaCaT cells is multifactorial and the combination of its actions at the 5' and 3' ends of the gene favours the accumulation of subpopulations of PTHrP mRNA containing exons I, VII and VIII.Biochemical Journal 05/1995; 307 ( Pt 1):159-67. · 4.65 Impact Factor
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ABSTRACT: We have recently described Poliovirus Receptor Related 2 (PRR2), a new cell surface molecule homologous to the poliovirus receptor (PVR/CD155). Both molecules are transmembrane glycoproteins belonging to the Ig superfamily (IgSF). They contain 3 Ig domains of V, C2, and C2 types in their extracellular regions that share 51% aa identity. The PRR2 gene encodes two mRNA isoforms of 3.0 kb (hPRR2 [short form]) and 4.4 kb (hPRR2delta [long form]), both widely expressed in human tissues, including hematopoietic cells. To further characterize PRR2 expression during hematopoiesis and to analyze its function, we have developed a monoclonal antibody (MoAb) directed against its extracellular region (R2.477). PRR2 was expressed in 96% of the CD34(+), 88% of the CD33(+), and 95% of the CD14(+) hematopoietic lineages and faintly in the CD41 compartment. Ectopic expression of both PRR2 cDNAs induced marked cell aggregation. A soluble chimeric receptor construct with the Fc fragment of human IgG1 (PRR2-Fc) as well as a fab fragment of the anti-PRR2 MoAb (R2.477) inhibit aggregation. PRR2-Fc binds specifically to PRR2-expressing cells. These results suggest that PRR2 is a homophilic adhesion receptor. PRR2 was also expressed at the surface of endothelial cells at the intercellular junctions of adjacent cells but not at the free cellular edges. Homophilic interactions are associated with dimerization of isoforms of PRR2 and lead to the tyrosine phosphorylation of PRR2delta. Altogether, these results suggest that homophilic properties of PRR2 could participate to the regulation of hematopoietic/endothelial cell functions.Blood 01/1999; 92(12):4602-11. · 9.06 Impact Factor