|Kothapalli, Nagarama - UNI OF NE-LINCOLN|
|Zempleni, Janos - UNI OF NE-LINCOLN|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 11, 2005
Publication Date: October 1, 2005
Citation: Kothapalli, N., Sarath, G., Zempleni, J. 2005. Biotinylation of k12 in histone h4 decreases in response to dna double stranded reaks in human jar choriocarcinoma cells. Journal of Nutrition, 135(1):2337-2442. Interpretive Summary: Covalent modification of histones by small molecules plays an essential role in chromatin remodeling and thus in most cellular processes involving DNA. In this study we have used antibodies to a site-specific modification to understand the role of biotinylation of lysine 12 on Histone H4. Our studies demonstrate that a transient decrease in biotinylation of Histone H4 might be an important signal for double stranded break in DNA. Breaks in DNA are hallmarks for chromosomal abnormalities, potentially leading malignant states.
Technical Abstract: Posttranslational modifications of histones play essential roles in remodeling of chromatin structure and DNA repair. Recently, biotinylation of distinct lysine residues of histones H2A, H3, and H4 has been identified as novel modifications. Evidence has been provided that these modifications participate in cell proliferation, gene silencing, and the cellular response to UV-induced DNA damage. Here, we tested the hypothesis that biotinylation of K12 in histone H4 plays a role in the cellular response to double-strand breaks (DSB) of DNA. DSB were caused experimentally by treating human choriocarcinoma (JAr) cells with etoposide. Addition of etoposide to the culture medium elicited approximately 50% loss in the biotinylation of K12 in histone H4 after 20 min of treatment. Biotinylation returned to initial levels 120 min after addition of etoposide to the medium. Interestingly, phosphorylation of S14 of histone H2B and poly(ADP-ribosylation) of glutamate residues on histone H2A that are known markers of DSB in DNA occurred substantially later than the observed decrease in K12-biotinylation. Moreover, decreased biotinylation of K12 of histone H4 was specific for DSB but was not detectable in response to single-strand breaks or formation of thymine dimers. Decreased biotinylation of histone H4 in response to DSB was not specific for choriocarcinoma cells but was also observed in lymphoid (Jurkat) cells. Biotin-deficient choriocarcinoma cells showed decreased rates of survival in response to etoposide treatment compared with biotin-sufficient controls. Collectively, these studies suggest that biotinylation of K12 in histone H4 is an early signaling event in response to DSB.