ABSTRACT
T lymphocytes from many patients with systemic lupus erythematosus (SLE) express decreased levels of the T cell receptor (TCR)-associated CD3 zeta (ζ) signaling chain, a feature directly linked to their abnormal phenotype and function. Reduced mRNA expression partly due to defective alternative splicing, contributes to the reduced expression of CD3ζ chain. We previously identified by oligonucleotide pulldown and mass spectrometry approaches, the serine arginine-rich splicing factor 1 (SRSF1) binding to the 3' untranslated region (UTR) of CD3ζ mRNA. We showed that SRSF1 regulates alternative splicing of the 3'UTR of CD3ζ to promote expression of the normal full length 3`UTR over an unstable splice variant in human T cells. In this study we show that SRSF1 regulates transcriptional activation of CD3ζ. Specifically, overexpression and silencing of SRSF1 respectively increases and decreases CD3ζ total mRNA and protein expression in Jurkat and primary T cells. Using promoter-luciferase assays, we show that SRSF1 enhances transcriptional activity of the CD3ζ promoter in a dose dependent manner. Chromatin immunoprecipitation assays show that SRSF1 is recruited to the CD3ζ promoter. These results indicate that SRSF1 contributes to transcriptional activation of CD3ζ. Thus our study identifies a novel mechanism whereby SRSF1 regulates CD3ζ expression in human T cells and may contribute to the T cell defect in SLE.
Subject(s)
CD3 Complex/genetics , Lupus Erythematosus, Systemic/genetics , Receptors, Antigen, T-Cell/genetics , Serine-Arginine Splicing Factors/genetics , Transcriptional Activation , 3' Untranslated Regions , Alternative Splicing , CD3 Complex/metabolism , Case-Control Studies , Chromatin Immunoprecipitation , Dose-Response Relationship, Drug , Genes, Reporter , Humans , Jurkat Cells , Luciferases/genetics , Luciferases/metabolism , Lupus Erythematosus, Systemic/metabolism , Lupus Erythematosus, Systemic/pathology , Primary Cell Culture , Promoter Regions, Genetic , Protein Binding , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Receptors, Antigen, T-Cell/metabolism , Serine-Arginine Splicing Factors/antagonists & inhibitors , Serine-Arginine Splicing Factors/metabolism , Signal Transduction , T-Lymphocytes/drug effects , T-Lymphocytes/metabolism , T-Lymphocytes/pathologyABSTRACT
Advances in the understanding of the cellular biological events that underlie systemic lupus erythematosus (SLE) have led to the identification of key molecules and signaling pathways that are aberrantly expressed. The parallel development of small molecule drugs that inhibit or interfere with the specific perturbations identified, offers perspective for more rational, effective and less toxic therapy. In this review, we present data from preclinical and clinical studies of such emerging novel therapies with a particular focus on kinase inhibitors and other compounds that modulate signal transduction. Moreover, we highlight the use of chromatin-modifying medications, bringing attention to the central role of epigenetics in SLE pathogenesis.
