title: Proteomic analysis reveals that treatment with tocotrienols reverses the effect of H₂O₂ exposure on peroxiredoxin expression in human lymphocytes from young and old individuals.
abstract: Vitamin E has been suggested to modulate age-associated changes by altering the redox balance resulting in altered gene and/or protein expression. Here we have utilized proteomics to determine whether such regulation in protein expression occurs in human lymphocytes from two different age groups stressed with H₂O₂ and then treated with vitamin E in the form of tocotrienol-rich fraction (TRF). In this study, lymphocytes obtained from young (30-49 years old) and old (>50 years old) volunteers were first challenged with 1 mM H₂O₂. They were then treated by exposure to 50, 100 and 200 μg/ml TRF. Two-dimensional gel electrophoresis followed by MALDI-TOF/TOF (matrix-assisted laser desorption/ionization time-of-flight/time-of-flight) tandem mass spectrometry was then performed on whole-cell protein extracts to identify proteins that have changed in expression. A total of 24 proteins were found to be affected by H₂O₂ and/or TRF treatment. These included proteins that were related to metabolism, antioxidants, structural proteins, protein degradation and signal transduction. Of particular interest was the regulation of a number of proteins involved in stress response--peroxiredoxin-2, peroxiredoxin-3 and peroxiredoxin-6-all of which were shown to be down-regulated with H₂O₂ exposure. The effect was reversed following TRF treatment. The expression of peroxiredoxin-2 and peroxiredoxin-6 was confirmed by quantitative reverse transcriptase polymerase chain reaction. These results suggested that TRF directly influenced the expression dynamics of the peroxiredoxin-2, thus improving the cells ability to resist damage caused by oxidative stress.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur City Campus, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
authors.forename: Hasnizawati Mohamed
authors.initials: HM
authors.lastname: Dahlan
authors.forename: Saiful Anuar
authors.initials: SA
authors.lastname: Karsani
authors.forename: Mariati Abdul
authors.initials: MA
authors.lastname: Rahman
authors.forename: Noor Aini Abdul
authors.initials: NA
authors.lastname: Hamid
authors.forename: A Gapor Mat
authors.initials: AG
authors.lastname: Top
authors.forename: Wan Zurinah Wan
authors.initials: WZ
authors.lastname: Ngah
mesh_terms: D000328:Adult; D000367:Age Factors; D000975:Antioxidants / Q000494:pharmacology*; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis / Q000187:drug effects; D040901:Proteomics / Q000379:methods*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D024508:Tocotrienols / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D000975:Antioxidants; D024508:Tocotrienols; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins