title: Calcineurin-dependent lytic granule exocytosis in NK-92 natural killer cells.
abstract: Cytotoxic T cells (CTLs) and natural killer cells (NKs) both kill virus-infected cells and tumor cells by releasing the cytoxic contents of their lytic granules. We recently demonstrated a role for calcineurin in lytic granule exocytosis in TALL-104 human leukemic CTLs [M.J. Grybko, J.P. Bartnik, G.A. Wurth, A.T. Pores-Fernando, A. Zweifach, Calcineurin activation is only one calcium-dependent step in cytotoxic T lymphocyte granule exocytosis, J. Biol. Chem. 282 (2007) 18009-18017]. However, whether calcineurin plays a similar role in NK lytic granule release is not known. We tested whether calcineurin is involved in lytic granule exocytosis in human leukemic NK-92 cells using immunosuppressive drugs that block calcineurin function and by overexpressing a constitutively active calcineurin fusion protein. Our results indicate that calcineurin does play a role in lytic granule exocytosis in NK-92 cells, and suggest that, as was the case in TALL-104 cells, there are likely to be multiple calcium-dependent steps.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut at Storrs, 91 North Eagleville Road, CT 06268-3125, USA.
authors.forename: Arun T
authors.initials: AT
authors.lastname: Pores-Fernando
authors.forename: Surabhi
authors.initials: S
authors.lastname: Gaur
authors.forename: Michelle Y
authors.initials: MY
authors.lastname: Doyon
authors.forename: Adam
authors.initials: A
authors.lastname: Zweifach