alpha-Tocopherol enhances degranulation in RBL-2H3 mast cells.
Based on the observation that 3 months alpha-tocopherol supplementation caused an up-regulation of the mRNA of vesicular transport proteins in livers of mice, the functional relevance was investigated in RBL-2H3 cells, a model for mast cell degranulation. In total, 24 h incubation with 100 muM alpha-tocopherol enhanced the basal and phorbol-12-myristyl-13-acetate/ionomycin-stimulated release of beta-hexosaminidase and cathepsin D as measured by enzymatic analysis as well as Western blotting and immunocytochemistry, respectively. beta-Tocopherol exerted the same effect, whereas alpha-tocopheryl phosphate and trolox were inactive, indicating that both the side chain and the 6-OH group at the chroman ring are essential for activation of degranulation. alpha-Tocopherol did not induce mRNA expression of soluble NSF-attachment protein receptor (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins, such as N-ethylmaleimide sensitive fusion protein, complexin-2, SNAP23 or syntaxin-3, in the RBL-2H3 cell model. In view of the well known alpha-tocopherol-mediated activation of protein phosphatases, which regulate soluble NSF-attachment protein receptor activities by dephosphorylation, underlying mechanisms are discussed in terms of preventing oxidative inactivation of protein phosphatases and so far unknown functions in certain membrane domains.
Hemmerling
Jana
J
German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany.
Nell
Sandra
S
Kipp
Anna
A
Schumann
Sara
S
Deubel
Stefanie
S
Haack
Michael
M
Brigelius-Flohé
Regina
R
D000818:Animals; D002402:Cathepsin D / Q000187:drug effects / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects; D045744:Cell Line, Tumor; D017931:DNA Primers; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007700:Kinetics; D015471:Leukemia, Basophilic, Acute / Q000201:enzymology; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D051379:Mice; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D024502:alpha-Tocopherol / Q000494:pharmacology* / Q000627:therapeutic use; D001619:beta-N-Acetylhexosaminidases / Q000187:drug effects / Q000378:metabolism
D017931:DNA Primers; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D007041:Hypoxanthine Phosphoribosyltransferase; D001619:beta-N-Acetylhexosaminidases; D002402:Cathepsin D; D024502:alpha-Tocopherol