Biochemistry & Molecular Biology
Activation of Apoptotic Proteins by Epigallocatechin-3-gallate in Human Non-Small Cell Lung Cancer Cells
Document Type
Poster Presentation
Location
Indianapolis, IN
Subject Area
Biochemistry & Molecular Biology
Start Date
11-4-2014 8:30 AM
End Date
11-4-2014 9:30 AM
Sponsor
Jeff Thompson (Denison University)
Description
Histone proteins are integral components of chromatin in eukaryotic cells that act as molecular "spools" for the compaction and organization of DNA. Chemical modifications to these proteins serve a fundamental role in controlling the expression of genes and initiating DNA repair mechanisms. Specifically, the methylation of lysine residue 79 on histone H3 (H3K79) is required for cells to delay their normal rates of propagation in response to damage caused by UV radiation. This study sought to determine the sufficiency of each distinct methylation state (mono-, di-, or trimethylation) in initiating the UV-induced G1/S checkpoint response in Saccharomyces cerevisiae. Budding assays were conducted to characterize the checkpoint phenotypes of various yeast mutant strains. The H3K79 methylation patterns of each strain were then measured by western blotting with state-specific antibodies. From these experiments it was determined that the monomethylated state is alone insufficient in initiating the G1/S checkpoint delay. In contrast, the dimethylated state in the absence (or significant depletion) of trimethylation appears to be sufficient for activating the checkpoint response. However, this conclusion is complicated by our studies of the bre1 D mutant checkpoint phenotype, which suggests that H2B ubiquitination also plays a role in the checkpoint response. Additionally, western blot experiments were conducted in order to investigate a potential "histone crosstalk" relationship between histone H4 acetylation on the N-terminal tail and H3K79 methylation in response to UV damage. Results are pending but suggest a model in which H4 acetylation stimulates changes in the methylation states of H3K79, which play specific roles in coordinating and facilitating DNA repair.
Activation of Apoptotic Proteins by Epigallocatechin-3-gallate in Human Non-Small Cell Lung Cancer Cells
Indianapolis, IN
Histone proteins are integral components of chromatin in eukaryotic cells that act as molecular "spools" for the compaction and organization of DNA. Chemical modifications to these proteins serve a fundamental role in controlling the expression of genes and initiating DNA repair mechanisms. Specifically, the methylation of lysine residue 79 on histone H3 (H3K79) is required for cells to delay their normal rates of propagation in response to damage caused by UV radiation. This study sought to determine the sufficiency of each distinct methylation state (mono-, di-, or trimethylation) in initiating the UV-induced G1/S checkpoint response in Saccharomyces cerevisiae. Budding assays were conducted to characterize the checkpoint phenotypes of various yeast mutant strains. The H3K79 methylation patterns of each strain were then measured by western blotting with state-specific antibodies. From these experiments it was determined that the monomethylated state is alone insufficient in initiating the G1/S checkpoint delay. In contrast, the dimethylated state in the absence (or significant depletion) of trimethylation appears to be sufficient for activating the checkpoint response. However, this conclusion is complicated by our studies of the bre1 D mutant checkpoint phenotype, which suggests that H2B ubiquitination also plays a role in the checkpoint response. Additionally, western blot experiments were conducted in order to investigate a potential "histone crosstalk" relationship between histone H4 acetylation on the N-terminal tail and H3K79 methylation in response to UV damage. Results are pending but suggest a model in which H4 acetylation stimulates changes in the methylation states of H3K79, which play specific roles in coordinating and facilitating DNA repair.