OP0193 CAMP RESPONSE ELEMENT MODULATOR (CREM)A INDUCES DUAL SPECIFICITY PROTEIN PHOSPHATASE (DUSP)4 THROUGH EPIGENETIC REMODELING, PROMOTING IL-17A AND REDUCING IL-2 EXPRESSION IN T CELLS

Abstract

Background Tissue inflammation and organ damage in systemic lupus erythematosus (SLE) have been linked to effector T cells that are characterized by increased IL-17A and reduced IL-2 production(1). T cells from patients with SLE express increased levels of the transcription factor cAMP response element modulator (CREM)α that contributes to altered cytokine expression(1-3). However, the exact molecular events contributing to dysregulated IL-17A and IL-2 expression are incompletely understood. Objectives To investigate molecular events that promote effector T cells in health and disease. The definition of molecular regulators of effector T cell generation and activity may deliver new biomarkers and potential therapeutic targets in disorders characterized by altered effector T cell function, including (but not limited to) SLE. Methods Using CRISPR/Cas9 genome editing and lentiviral transduction, we generated CREMα deficient or overexpressing Jurkat T cells. Gene expression profiles in Jurkat and primary human CD4+ T cells were assessed by qRT-PCR and mRNA probe-based hybridization techniques. Gene regulation events were investigated using luciferase reporter assays (trans-activation) and ChIP. Interactions between CREMα and the transcriptional co-activator p300 were assessed using proximity ligation assays and p300 knock-down with siRNAs. Results We link CREMα production in effector CD4+ T cells with increased expression of dual specificity protein phosphatase (DUSP)4. Using genetically modified Jurkat T cells, we demonstrate that CREMα induces DUSP4 through recruitment of the transcriptional co-activator p300 and histone H3K18 acetylation. Using DUSP4 transfection models and genetically modified Jurkat T cells, we support previous reports suggesting that DUSP4 induces IL-17A while limiting IL-2 expression. Furthermore, we demonstrate that CD4+ T cells from patients with juvenile-onset SLE share the phenotype with CREMα over-expressing CD4+ T cells with increased DUSP4 expression that contributes to imbalanced IL-17A and IL-2 production. Conclusion Collectively, our results deliver previously unknown CREMα-mediated molecular mechanisms promoting effector T cells and support the central involvement of CREMα in the pathophysiology of SLE. CREMα and DUSP4 may prove valuable as disease biomarkers and/or targets in the search for individualized and target-directed treatments.