title: Intracellular Ca(2+) release triggers translocation of membrane marker FM1-43 from the extracellular leaflet of plasma membrane into endoplasmic reticulum in T lymphocytes.
abstract: Stimulation of T cell receptor in lymphocytes enhances Ca(2+) signaling and accelerates membrane trafficking. The relationships between these processes are not well understood. We employed membrane-impermeable lipid marker FM1-43 to explore membrane trafficking upon mobilization of intracellular Ca(2+) in Jurkat T cells. We established that liberation of intracellular Ca(2+) with T cell receptor agonist phytohemagglutinin P or with Ca(2+)-mobilizing agents ionomycin or thapsigargin induced accumulation of FM1-43 within the lumen of the endoplasmic reticulum (ER), nuclear envelope (NE), and Golgi. FM1-43 loading into ER-NE and Golgi was not mediated via the cytosol because other organelles such as mitochondria and multivesicular bodies located in close proximity to the FM1-43-containing ER were free of dye. Intralumenal FM1-43 accumulation was observed even when Ca(2+) signaling in the cytosol was abolished by the removal of extracellular Ca(2+). Our findings strongly suggest that release of intracellular Ca(2+) may create continuity between the extracellular leaflet of the plasma membrane and the lumenal membrane leaflet of the ER by a mechanism that does not require global cytosolic Ca(2+) elevation.
authors.affiliation: Department of Physiology and Membrane Biology, University of California, Davis, California 95616, USA.
authors.forename: Sepehr
authors.initials: S
authors.lastname: Dadsetan
authors.forename: Vyacheslav
authors.initials: V
authors.lastname: Shishkin
authors.forename: Alla F
authors.initials: AF
authors.lastname: Fomina
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D011726:Pyridinium Compounds / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: C073804:FM1 43; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D011948:Receptors, Antigen, T-Cell; D002118:Calcium