α-Tocopherol enhances degranulation in RBL-2H3 mast cells

✍ Scribed by Jana Hemmerling; Sandra Nell; Anna Kipp; Sara Schumann; Stefanie Deubel; Michael Haack; Regina Brigelius-Flohé

• Book ID: 102512930
• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 291 KB
• Volume: 54
• Category: Article
• ISSN: 1613-4125
• DOI: 10.1002/mnfr.200900462

✦ Synopsis

Abstract

Based on the observation that 3 months α‐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 μM α‐tocopherol enhanced the basal and phorbol‐12‐myristyl‐13‐acetate/ionomycin‐stimulated release of β‐hexosaminidase and cathepsin D as measured by enzymatic analysis as well as Western blotting and immunocytochemistry, respectively. β‐Tocopherol exerted the same effect, whereas α‐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. α‐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 α‐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.