Within this sequence we identified a DNA motif that shares high similarity to the consensus binding site of a transcription factor denoted SP-1 (Fig. promoter. We conclude that protein phosphatase 2A accounts for enhanced SP-1 dephosphorylation at Ser59in SLE T cells. More importantly, CREM promoter activity mirrors reliably disease activity in SLE patients, underscoring its potential role as a biomarker for the prediction of flares in SLE patients. Keywords:Immunology, Interleukin, PP2A, Promoters, Transcription Factors, CREM, SLE, SP-1, GSK5182 Lupus == Introduction == Systemic lupus erythematosus (SLE)3is a chronic inflammatory disease characterized by an autoimmune process affecting every organ, including joints, kidneys, skin, and the central nervous system (1). T cells have been demonstrated to be important in the pathogenesis of SLE (2). Functional abnormalities in SLE T cells are largely underwritten by altered gene transcription, and recent studies have revealed a vast number of transcription factors in SLE T cells displaying changes in their expression levels and function. Among them, the -isoform of the transcriptional regulator cAMP-responsive element modulator (CREM) has emerged as a potent regulator of target genes that are crucially involved in T cell physiology,e.g.interleukin (IL)-2, T cell receptor chain, and transcription factor c-fos(35). The CREM protein family constitutes a group of transcription factors that belong to the superfamily of basic domain/leucine zipper domain proteins such as cAMP-responsive element-binding protein (CREB) and activating transcription factors. All of them share high structural similarities and possess the ability to bind specificallycis-regulatory DNA sequences as homo- or heterodimers. The target motifs are palindromic DNA GSK5182 sequences denoted cAMP response elements (CRE,TGACGTCA) as well as the 5-TGAChalf-sites of this palindrome, both of which are highly conserved within numerous promoters of eukaryotic genes (6). Increased intracellular cAMP levels stimulate a multitude of kinases,e.g.calmodulin kinaseIV, that subsequently phosphorylate and thereby activate CREM (7). Previous studies from our group have provided evidence that CREM expression is increased in T cells from SLE patients (8). We have GSK5182 shown that GSK5182 CREM binds to the 180 site of the IL-2 promoter in SLE T cells and thereby suppresses IL-2 production in these cells. Decreased IL-2 levels render SLE patients more susceptible to infections (9). In turn, suppression of CREM expression in SLE T cells by introducing a plasmid encoding antisense CREM into these cells sufficiently restores their IL-2 content and normalizes effector cell function (10). Transcriptional down-regulation of T cell receptor chain by CREM binding to the corresponding promoter contributes to the structural abnormalities of the CD3 complex in SLE T cells. Because CREM also represses transcription of the AP-1 family member c-fos, it limits the activity of this transcription enhancer family and thereby indirectly contributes to the defective IL-2 production in SLE T cells (2). The CREM gene was initially isolated almost 20 years ago and comprises multiple exons (11). Since that time, a large number of different CREM isoforms has been identified, and the composition of the individual exons in these isoforms determines the functional propensities,e.g.whether they act as transcriptional activators or repressors (12). In contrast to CREB, expression and activity of the various CREM isoforms are finely regulated, not only post-transcriptionally, but also at the level of gene transcription. The CREM gene contains at least two distinct functional promoters. The inducible cAMP early repressor (ICER) isoforms of the CREM family are transcriptionally controlled through the intronic ICER promoter (11). ICER inducibility is highly cell type-specific, and its kinetics is characteristic of the early response genes. So, for example, ICER manifestation peaks rapidly upon activation with corticotrophin-releasing hormone in pituitary gland cells (13). In contrast, the CREM promoter located in the 5-end of the CREM gene regulates transcription of the additional CREM isoforms and was initially thought to be constitutively activated as manifestation of most CREM isoforms is definitely ubiquitous and not inducible. However, because we found an increased amount of the transcriptional repressor CREM mRNA in T cells from individuals with SLE compared with healthy individuals (8) we asked whether elevated CREM mRNA levels may represent the result of enhanced transcriptional activation through the CREM promoter in these cells and what important factors Rabbit Polyclonal to MED8 may be involved in CREM gene transcription. == EXPERIMENTAL Methods == == == == == == Study Subjects == All SLE individuals included in our studies were diagnosed according to the American College of Rheumatology classification criteria (14) and were recruited from your Division of Rheumatology at Beth Israel Deaconess Medical Center, Boston, MA, and the Division of Medicine in the Uniformed Solutions University or college of the Health Sciences, Bethesda, MD. All 12 SLE individuals included in the CREM promoter assessment (as depicted inFig. 2) were females at.