title: Lipopolysaccharide-Stimulated Transglutaminase 2 Expression Enhances Endocytosis Activity in the Mouse Microglial Cell Line BV-2.
abstract: OBJECTIVE
  In peripheral macrophages, tissue-type transglutaminase (TG2) is reported to be involved in phagocytosis of apoptotic cells. However, the contribution of TG2 to microglial phagocytosis has not been investigated. In this study, using a microglial cell line, BV-2, we examined the changes in TG2 expression, phagocytosis and pinocytosis in cells stimulated by lipopolysaccharide (LPS).
  
  
  METHODS
  Cells of the mouse microglial cell line BV-2 were stimulated by LPS with or without cystamine, an inhibitor of TG enzyme activity, for 24 h. TG2 expression was measured by real-time RT-PCR and Western blotting. TG activity was evaluated using biotinylated pentylamine as a substrate. Pinocytosis was determined by uptake of 1-µm fluorescent microbeads. Phagocytosis was assessed by uptake of dead cells, human neuroblastoma SH-SY5Y cells, which were pretreated with H2O2 for 24 h.
  
  
  RESULTS
  Phagocytosis of dead cells and pinocytosis of fluorescent microbeads were up-regulated by LPS stimulation together with TG2 expression. Blockade of TG enzyme activity by cystamine suppressed TG2 expression, phagocytosis and pinocytosis.
  
  
  CONCLUSIONS
  These results suggested that LPS-induced TG2 was involved in the mechanism of pinocytosis and phagocytosis in microglia.
authors.affiliation: Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Prefecture University, Izumisano, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawabe
authors.forename: Katsura
authors.initials: K
authors.lastname: Takano
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Moriyama
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D004705:Endocytosis / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D017628:Microglia / Q000378:metabolism*; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins