title: Mitochondria distinguish granule-stored from de novo synthesized tumor necrosis factor secretion in human mast cells.
abstract: BACKGROUND
  Mast cells are immune cells derived from hematopoietic precursors that mature in the tissue microenvironment. Mast cells are critical for allergic, immune and inflammatory processes, many of which involve tumor necrosis factor (TNF). These cells uniquely store TNF in their secretory granules. Upon stimulation, mast cells rapidly (30 min) secrete β-hexosaminidase and granule-stored TNF through degranulation, but also increase TNF mRNA and release de novo synthesized TNF 24 h later. The regulation of these two distinct pathways is poorly understood.
  
  
  METHODS
  Human LAD2 leukemic mast cells are stimulated by substance P. TNF secretion and gene expression were measured by ELISA and real-time PCR, and mitochondrial dynamics was observed in live cells under confocal microscopy. Cell energy consumption was measured in terms of oxygen consumption rate.
  
  
  RESULTS
  Here, we show that granule-stored TNF is preformed, and its secretion from LAD2 mast cells stimulated by substance P (1) exhibits higher energy consumption and is inhibited by the mitochondrial ATP pump blocker oligomycin, (2) shows rapid increase in intracellular calcium levels, and (3) exhibits reversible mitochondrial translocation, from a perinuclear distribution to the cell surface, as compared to de novo synthesized TNF release induced by lipopolysaccharide. This mitochondrial translocation is confirmed using primary human umbilical cord blood-derived mast cells stimulated by an allergic trigger (IgE/streptavidin).
  
  
  CONCLUSIONS
  Our findings indicate that unique mitochondrial functions distinguish granule-stored from newly synthesized TNF release from human mast cells, thus permitting the versatile involvement of mast cells in different biological processes.
authors.affiliation: Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Molecular Physiology and Pharmacology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Bodi
authors.initials: B
authors.lastname: Zhang
authors.forename: Zuyi
authors.initials: Z
authors.lastname: Weng
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Sismanopoulos
authors.forename: Sharhzad
authors.initials: S
authors.lastname: Asadi
authors.forename: Anastasia
authors.initials: A
authors.lastname: Therianou
authors.forename: Konstantinos-Dionysios
authors.initials: KD
authors.lastname: Alysandratos
authors.forename: Asimenia
authors.initials: A
authors.lastname: Angelidou
authors.forename: Orian
authors.initials: O
authors.lastname: Shirihai
authors.forename: Theoharis C
authors.initials: TC
authors.lastname: Theoharides
mesh_terms: D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology*; D008928:Mitochondria / Q000187:drug effects / Q000276:immunology*; D009840:Oligomycins / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D022142:Secretory Vesicles / Q000276:immunology*; D013373:Substance P / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology*; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D008070:Lipopolysaccharides; D009840:Oligomycins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D014475:Uncoupling Agents; D013373:Substance P; D002118:Calcium