Pediatric Rheumatology Online Journal → August 2003 →  Basic Immunology  → Abstract #166

THE ROLE OF NUCLEAR FACTOR REGULATED BY IL-3 (NFIL3) IN IL-4 MEDIATED TRANSCRIPTION

D. L. Miller,¹ P. B. Rothman.²

¹Pediatric Rheumatology, Columbia University, NY, NY, United States; ²Medicine, Columbia University, New York, NY, United States

Background: Interleukin-4 (IL-4) has a critical role in B cell biology and the immune response, however, the molecular mechanisms regulating IL-4 signaling remain incompletely characterized. IL-4 plays a role in the differentiation of CD4+ T helper (Th) cells into either Th1 cells, which are important for cell-mediated immunity and autoimmunity, or Th2 cells, which are important for humoral immune responses. IL-4 polarizes this differentiation towards the development of Th2 cells. Both Th1 and Th2 cells are important in the rheumatic diseases, thus understanding IL-4 signaling may increase our understanding of autoimmunity. Recent microarray experiments have illustrated the importance of several genes in IL-4 signaling. One of these genes, nuclear factor regulated by IL-3 (NFIL3) was identified as being strongly induced by IL-4 in a STAT6 (signal transducer and activator of transcription)-dependent manner. NFIL3, a bZIP DNA binding protein, plays an important role in IL-3 biology, however, its role in IL-4 biology remains undefined. Objective: To determine the role of NFIL3 in IL-4 dependent transcription. Methods: Molecular biology and immunology laboratory methods were utilized, including Immunoblotting, Chromatin Immunoprecipitation, Polymerase Chain Reaction (PCR), and Dual Luciferase Reporter Assays. The IL-4 responsive B cell lines M12 and Ba/F3 were used in these studies. Results: We demonstrated that NFIL3 is dramatically induced by IL-4 and thus may play a role in IL-4 signaling. Functional studies using an overexpression model further demonstrated that NFIL3 represses transcription driven by I Epsilon, an IL-4 responsive promoter element. Interestingly, repression was observed in an NFIL3 dose-dependent manner, in both the presence and absence of IL-4 stimulation. Conclusions: NFIL3 may function as an important negative repressor of IL-4 mediated transcription, and further biochemical studies will provide greater insight into the possible role of NFIL3 in the negative feedback effect on transcription.