Calpain II colocalizes with detergent-insoluble rafts on human and Jurkat T-cells

• Published in: Biochemical and biophysical research communications Vol. 295; no. 2; pp. 540 - 546
• Main Authors: Morford, Lorri A, Forrest, Kathy, Logan, Barbara, Overstreet, L.Kevin, Goebel, Jens, Brooks, William H, Roszman, Thomas L
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.07.2002
• Subjects: Calpain - metabolism; Calpain II; Cellular activation; Detergents; Human; Humans; Jurkat; Jurkat Cells; Lipid rafts; Membrane Lipids - metabolism; microdomains; Signal transduction; T lymphocyte; T-Lymphocytes - enzymology; T-Lymphocytes - metabolism; talin; Human; Signal transduction; Calpain II; Lipid rafts; T lymphocyte; Jurkat; Cellular activation
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(02)00676-9

Calpain, a calcium-dependent cysteine protease, is known to associate with the T-cell plasma membrane and subsequently cleave a number of cytoskeletal-associated proteins. In this study, we report the novel observation that calpain II, but not calpain I, associates with membrane lipid rafts on human peripheral blood T-cells and Jurkat cells. Raft-associated calpain activity is enhanced with exogenous calcium and inhibited with calpeptin, a specific inhibitor of calpain activity. In addition, we demonstrate that calpain cleaves the cytoskeletal-associated protein, talin, during the first 30-min after cell stimulation. We propose that lipid raft associated-calpain II could function in early TCR signaling to facilitate immune synapse formation through cytoskeletal remodeling mechanisms. Hence, we demonstrate that the positioning of calpain II within T-cell lipid rafts strategically places it in close proximity to known calpain substrates that are cleaved during Ag-specific T-cell signaling and immune synapse formation.