Molecular Basis of Vitamin E Action TOCOTRIENOL POTENTLY INHIBITS GLUTAMATE-INDUCED pp60c-Src KINASE ACTIVATION AND DEATH OF HT4 NEURONAL CELLS

From 2000 and I bet there was not a single followup human clinical trial.
Is this the solution to the glutamate poisoning problem in the neuronal cascade of death?
We'll never know because we have NO strategy or stroke leadership at all.
Molecular Basis of Vitamin E Action TOCOTRIENOL POTENTLY INHIBITS GLUTAMATE-INDUCED pp60c-Src KINASE ACTIVATION AND DEATH OF HT4 NEURONAL CELLS

1. Chandan K. Sen‡§,
2. Savita Khanna¶,
3. Sashwati Roy‡ and
4. Lester Packer¶

+ Author Affiliations

1. From the ^‡Lawrence Berkeley National Laboratory and ^¶Department of Molecular & Cell Biology, University of California, Berkeley, California 94720

Abstract

HT4 hippocampal neuronal cells were studied to compare the efficacy of tocopherols and tocotrienol to protect against glutamate-induced death. Tocotrienols were more effective than α-tocopherol in preventing glutamate-induced death. Uptake of tocotrienols from the culture medium was more efficient compared with that of α-tocopherol. Vitamin E molecules have potent antioxidant properties. Results show that at low concentrations, tocotrienols may have protected cells by an antioxidant-independent mechanism. Examination of signal transduction pathways revealed that protein tyrosine phosphorylation processes played a central role in the execution of death. Activation of pp60^c-Src kinase and phosphorylation of ERK were observed in response to glutamate treatment. Nanomolar amounts of α-tocotrienol, but not α-tocopherol, blocked glutamate-induced death by suppressing glutamate-induced early activation of c-Src kinase. Overexpression of kinase-active c-Src sensitized cells to glutamate-induced death. Tocotrienol treatment prevented death of Src-overexpressing cells treated with glutamate. α-Tocotrienol did not influence activity of recombinant c-Src kinase suggesting that its mechanism of action may include regulation of SH domains. This study provides first evidence describing the molecular basis of tocotrienol action. At a concentration 4–10-fold lower than levels detected in plasma of supplemented humans, tocotrienol regulated unique signal transduction processes that were not sensitive to comparable concentrations of tocopherol.

Abbreviations:

ROS

reactive oxygen species

DCF

dichlorofluorescein

DCFH-DA

dichlorodihydrofluorescein diacetate

PBS

phosphate-buffered saline

HPLC

high performance liquid chromatography

AAPH

2,2′-azobis[2-amidinopropane]hydrochloride

ERK

extracellular signal-regulated kinase

• Received August 19, 1999.
• Revision received January 12, 2000.

• The American Society for Biochemistry and Molecular Biology, Inc.