title: Resistance to tumor necrosis factor-induced cell death mediated by PMCA4 deficiency.
abstract: We used retrovirus insertion-mediated random mutagenesis to generate tumor necrosis factor (TNF)-resistant lines from L929 cells. Using this approach, we discovered that the plasma membrane calcium ATPase 4 (PMCA4) is required for TNF-induced cell death in L929 cells. Under basal conditions, PMCA4-deficient (PMCA(mut)) cells have a normal phenotype. However, stimulation with TNF induces an abnormal increase in the intracellular calcium concentration ([Ca(2+)](i)). The substantially elevated [Ca(2+)](i) caused resistance to TNF-induced cell death. We found that an increase in the total volume of acidic compartments (VAC), mainly constituted by lysosomes, is a common event in cell death caused by a variety of agonists. The increased [Ca(2+)](i) in PMCA(mut) cells promoted lysosome exocytosis, which, at least in part, accounted for the inhibition of TNF-induced increase in VAC and cell death. Promoting lysosome exocytosis by calcium inhibited TNF-induced cell death in wild-type L929 cells, while inhibition of lysosome exocytosis or increase of VAC by sucrose restored the sensitivity of PMCA(mut) cells to TNF-induced cell death. Thus, increase of the volume of acidic compartment is a part of the cell death process, and the antideath effect of calcium is mediated, at least in part, by inhibition of the TNF-induced increase in VAC.
authors.affiliation: Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: K
authors.initials: K
authors.lastname: Ono
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Han
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism* / Q000502:physiology*; D027682:Cation Transport Proteins; D016923:Cell Death; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis; D005089:Exocytosis; D005822:Genetic Vectors; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018021:Lithium Chloride / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016296:Mutagenesis; D053499:Plasma Membrane Calcium-Transporting ATPases; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; D014409:Tumor Necrosis Factor-alpha; D000001:Calcimycin; D001619:beta-N-Acetylhexosaminidases; D053499:Plasma Membrane Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D018021:Lithium Chloride; D002118:Calcium