Granzyme A released upon stimulation of cytotoxic T lymphocytes activates the thrombin receptor on neuronal cells and astrocytes.

作者：Hana S. Suidan, Jacques Bouvier, Esther Schaerer, Stuart R. Stone, Denis Monard, Jürg Tschopp · 发表于：Proceedings of the National Academy of Sciences · 年份：1994 · DOI：10.1073/pnas.91.17.8112 · 被引用次数：128 · 研究领域：Blood Coagulation and Thrombosis Mechanisms、Cancer-related gene regulation、Signaling Pathways in Disease

Granzymes are a family of serine proteases that are harbored in cytoplasmic granules of activated T lymphocytes and are released upon target cell interaction. Immediate and complete neurite retraction was induced in a mouse neuronal cell line when total extracts of granule proteins were added. This activity was isolated and identified as granzyme A. This protease not only induced neurite retraction at nanomolar concentrations but also reversed the stellation of astrocytes. Both effects were critically dependent on the esterolytic activity of granzyme A. As neurite retraction is known to be induced by thrombin, possible cleavage and activation of the thrombin receptor were investigated. A synthetic peptide spanning the N-terminal thrombin receptor activation sequence was cleaved by granzyme A at the authentic thrombin cleavage site Leu-Asp-Pro-Arg-Ser. Antibodies to the thrombin receptor inhibited both thrombin and granzyme A-mediated neurite retraction. Thus, T-cell-released granzyme A induces cellular responses by activation of the thrombin receptor. As brain-infiltrating CD4+ lymphocytes are the effector cells in experimental allergic encephalomyelitis, granzyme A released in the brain may contribute to the etiology of autoimmune disorders in the nervous system.