A disease-associated PTPN22 variant promotes systemic autoimmunity in murine models

• Published in: The Journal of clinical investigation Vol. 123; no. 5; pp. 2024 - 2036
• Main Authors: Dai, Xuezhi, James, Richard G, Habib, Tania, Singh, Swati, Jackson, Shaun, Khim, Socheath, Moon, Randall T, Liggitt, Denny, Wolf-Yadlin, Alejandro, Buckner, Jane H, Rawlings, David J
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.05.2013
• Subjects: Animals; Autoimmune Diseases - genetics; Autoimmunity; Autoimmunity - genetics; B-Lymphocytes - cytology; Biomedical research; Calcium - metabolism; Cell Lineage; Cell Survival; Cellular proteins; Cellular signal transduction; Crosses, Genetic; Cycloheximide - pharmacology; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay - methods; Gene expression; Genetic aspects; Genetic Variation; Homeostasis; Kinases; Lymphocytes; Lymphocytes - cytology; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mutation; Properties; Protein Tyrosine Phosphatase, Non-Receptor Type 12 - metabolism; Protein Tyrosine Phosphatase, Non-Receptor Type 22 - genetics; Protein Tyrosine Phosphatase, Non-Receptor Type 22 - physiology; Proteins; Rodents; T-Lymphocytes - cytology
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/jci66963

Multiple autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, Graves disease, and systemic lupus erythematosus, are associated with an allelic variant of protein tyrosine phosphatase nonreceptor 22 (PTPN22), which encodes the protein LYP. To model the human disease-linked variant LYP-R620W, we generated knockin mice expressing the analogous mutation, R619W, in the murine ortholog PEST domain phosphatase (PEP). In contrast with a previous report, we found that this variant exhibits normal protein stability, but significantly alters lymphocyte function. Aged knockin mice exhibited effector T cell expansion and transitional, germinal center, and age-related B cell expansion as well as the development of autoantibodies and systemic autoimmunity. Further, PEP-R619W affected B cell selection and B lineage-restricted variant expression and was sufficient to promote autoimmunity. Consistent with these features, PEP-R619W lymphocytes were hyperresponsive to antigen-receptor engagement with a distinct profile of tyrosine-phosphorylated substrates. Thus, PEP-R619W uniquely modulates T and B cell homeostasis, leading to a loss in tolerance and autoimmunity.