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Updated: Jun 12, 2025

Evaluation of Substrate Ubiquitylation by E3 Ubiquitin-ligase in Mammalian Cell Lysates
Published on: May 10, 2022
MARCH8 Mediates K27-Linked Polyubiquitination of IL-7 Receptor α to Negatively Regulate IL-7-Triggered T Cell
Deng Gao1, Xue-Mei Yi1, Lu Feng1
1Department of Infectious Diseases, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China; Frontier Science Center for Immunology and Metabolism, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan, China; and Research Unit of Innate Immune and Inflammatory Diseases (2019RU063), Chinese Academy of Medical Sciences, Wuhan, China.
Abstract:
IL-7 is a cytokine produced by stromal cells, which binds to IL-7Rα and plays an important role for homeostasis of T lymphocytes. Excessive activities of IL-7-triggered signaling pathways causes autoimmune diseases. How IL-7-triggered signaling and immune effects are regulated is not fully understood. In this study, we show that the membrane-associated RING-CH (MARCH) E3 ligase family member MARCH8 mediates K27-linked polyubiquitination of IL-7Rα, leading to its lysosomal degradation. Site-directed mutagenesis suggests that MARCH8 meditates polyubiquitination of IL-7Rα at K265/K266, and mutation of these residues renders IL-7Rα resistance to MARCH8-mediated polyubiquitination and degradation. MARCH8 deficiency increases IL-7-triggered activation of the downstream transcription factor STAT5 and transcriptional induction of the effector genes in human T lymphoma cells. MARCH8 deficiency also promotes IL-7-triggered T cell proliferation and splenic memory CD8+ T cell differentiation in mice. Our findings suggest that MARCH8 negatively regulates IL-7-triggered signaling by mediating K27-linked polyubiquitination and lysosomal degradation of IL-7Rα, which reveals a negative regulatory mechanism of IL-7-triggered T cell homeostasis.
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