PROTEOMICS IDENTIFICATION OF PROTEIN TARGETS OF POLYPHENOLS IN RODENT BRAIN





1,4Helen Kim (P), 1,4Jessy Deshane, 1,3Landon Wilson, 1,5Marion Kirk, 1,5Scott Isbell, 2Clinton Grubbs, 1,4,5Stephen Barnes, and 3Sreelatha Meleth

Departments of 1Pharmacology & Toxicology, 2Surgery and 3Biostatistics, 4UAB Mass Spectrometry and Proteomics Shared Facility, and 5Purdue/UAB Botanicals Center for Age-Related Diseases, University of Alabama at Birmingham, AL 35294



Many botanically-derived dietary supplements are thought to have health benefits due to the anti-oxidant activities of constituent polyphenolic compounds; examples of such polyphenols are the catechin in teas, the procyanidins in grape seeds, and the isoflavones in soy. Previous findings by others indicated that oxidative stress is a risk factor for age-related cognitive decline, as well as for Alzheimer's disease.

We hypothesized that dietary supplementation with polyphenols would have neuroprotective actions in rodent brain that would be manifested as either enhancement of expression or modifications of proteins important for neuronal viability, and/or reduction of expression or modifications of, proteins linked with neuropathology. Normal female adult rats were maintained on 5% grape seed extract-supplemented diets for six weeks, after which they were sacrificed, and homogenates of their whole brains analyzed by proteomics technology (2-dimensional electrphoresis followed by mass spectrometry) to assess protein differences between the two sets of brain homogenates. Software-assisted image analysis of the 2D gel images identified several gel "spots" that quantitatively differed in intensity or in horizontal position between the two sets of gels representing the dietary groups. Matrix-assisted laser-desorption ionization time of flight mass spectrometry (MALDI-TOF MS) followed by quadrupole time of flight mass spectrometry (Qtof MS) identified the proteins contained in the gel spots of interest.

With the exception of one novel protein, and a cytoskeletal protein, all the proteins identified in this study were previously implicated in either Alzheimer's disease, or mouse models of neurodegeneration. Moreover, the direction of the differences determined in this study were in the opposite direction to those detected for these proteins in the disease tissues. These results strongly suggest that ingestion of components in grape seed extract was neuroprotective.




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