Browsing by Author "Spath, Sabine"

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    FOXP3 exon 2 controls Treg stability and autoimmunity
    (American Association for the Advancement of Science, 2022) Du, Jianguang; Wang, Qun; Yang, Shuangshuang; Chen, Si; Fu, Yongyao; Spath, Sabine; Domeier, Phillip; Hagin, David; Anover-Sombke, Stephanie; Haouili, Maya; Liu, Sheng; Wan, Jun; Han, Lei; Liu, Juli; Yang, Lei; Sangani, Neel; Li, Yujing; Lu, Xiongbin; Janga, Sarath Chandra; Kaplan, Mark H.; Torgerson, Troy R.; Ziegler, Steven F.; Zhou, Baohua; Pediatrics, School of Medicine
    Differing from the mouse Foxp3 gene that encodes only one protein product, human FOXP3 encodes two major isoforms through alternative splicing-a longer isoform (FOXP3 FL) containing all the coding exons and a shorter isoform lacking the amino acids encoded by exon 2 (FOXP3 ΔE2). The two isoforms are naturally expressed in humans, yet their differences in controlling regulatory T cell phenotype and functionality remain unclear. In this study, we show that patients expressing only the shorter isoform fail to maintain self-tolerance and develop immunodeficiency, polyendocrinopathy, and enteropathy X-linked (IPEX) syndrome. Mice with Foxp3 exon 2 deletion have excessive follicular helper T (TFH) and germinal center B (GC B) cell responses, and develop systemic autoimmune disease with anti-dsDNA and antinuclear autoantibody production, as well as immune complex glomerulonephritis. Despite having normal suppressive function in in vitro assays, regulatory T cells expressing FOXP3 ΔE2 are unstable and sufficient to induce autoimmunity when transferred into Tcrb-deficient mice. Mechanistically, the FOXP3 ΔE2 isoform allows increased expression of selected cytokines, but decreased expression of a set of positive regulators of Foxp3 without altered binding to these gene loci. These findings uncover indispensable functions of the FOXP3 exon 2 region, highlighting a role in regulating a transcriptional program that maintains Treg stability and immune homeostasis.