title: Certain carotenoids enhance the intracellular glutathione level in a murine cultured macrophage cell line by inducing glutamate-cysteine-ligase.
abstract: METHODS
  Glutathione (GSH) increases in RAW264 murine macrophage cells exposed to β-carotene or β-cryptoxanthin, however, the underlying mechanism has not been clarified. In the present study, we investigated the expression of glutamate-cysteine-ligase (GCL), the rate-limiting enzyme in GSH synthesis, in these cells.
  
  
  RESULTS
  Both the protein and mRNA expression of GCL increased in a β-carotene concentration-dependent manner. Buthionine sulfoximine, a GCL inhibitor, abolished the β-carotene-induced GSH increase without affecting the β-carotene-induced GCL protein expression. Both cycloheximide, a translation inhibitor, and actinomycin D, a transcription inhibitor, completely suppressed the β-carotene-induced GCL protein expression and the concomitant GSH increase. Actinomycin D inhibited the β-carotene-induced Gcl mRNA expression as well. Similarly to β-carotene, β-cryptoxanthin upregulated the GCL protein expression, but lutein did not. The c-Jun N-terminal kinase (JNK) inhibitor, SP600125, suppressed the β-carotene-induced GSH increase, whereas a p38 mitogen-activated protein kinase inhibitor or an extracellular signal-regulated kinase 1/2 inhibitor did not. The JNK inhibitor also suppressed the β-carotene-induced GCL protein expression, and consistently β-carotene induced JNK phosphorylation.
  
  
  CONCLUSIONS
  These findings revealed that certain carotenoids induce the Gcl mRNA expression in RAW264 cells and subsequently the GCL protein expression, which concomitantly enhances the intracellular GSH level, in a JNK pathway-related manner.
authors.affiliation: Department of Food Science, Graduate School of Nutrition and Biosciences, The University of Tokushima, Tokushima, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Akaboshi
authors.forename: Rintaro
authors.initials: R
authors.lastname: Yamanishi
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002460:Cell Line; D065366:Cryptoxanthins / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D014975:Lutein / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D019207:beta Carotene / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000873:Anthracenes; D065366:Cryptoxanthins; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D019207:beta Carotene; D003609:Dactinomycin; C432165:pyrazolanthrone; D019328:Buthionine Sulfoximine; D003513:Cycloheximide; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D014975:Lutein
keywords: Glutamate-cysteine-ligase; Glutathione; Macrophage; β-Carotene; β-Cryptoxanthin