Dataset Information

Global Level Quantification of Histone Post-Translational Modifications in a 3D Cell Culture Model of Hepatic Tissue.

ABSTRACT: Flat cultures of mammalian cells are a widely used in vitro approach for understanding cell physiology, but this system is limited in modeling solid tissues due to unnaturally rapid cell replication. This is particularly challenging when modeling mature chromatin, as fast replicating cells are frequently involved in DNA replication and have a heterogeneous polyploid population. Presented below is a workflow for modeling, treating, and analyzing quiescent chromatin modifications using a three-dimensional (3D) cell culture system. Using this protocol, hepatocellular carcinoma cell lines are grown as reproducible 3D spheroids in an incubator providing active nutrient diffusion and low shearing forces. Treatment with sodium butyrate and sodium succinate induced an increase in histone acetylation and succinylation, respectively. Increases in levels of histone acetylation and succinylation are associated with a more open chromatin state. Spheroids are then collected for isolation of cell nuclei, from which histone proteins are extracted for the analysis of their post-translational modifications. Histone analysis is performed via liquid chromatography coupled online with tandem mass spectrometry, followed by an in-house computational pipeline. Finally, examples of data representation to investigate the frequency and occurrence of combinatorial histone marks are shown.

SUBMITTER: Joseph-Chowdhury JN

PROVIDER: S-EPMC10042382 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Global Level Quantification of Histone Post-Translational Modifications in a 3D Cell Culture Model of Hepatic Tissue.

Joseph-Chowdhury Jazmine-Saskya N JN Stransky Stephanie S Graff Sarah S Cutler Ronald R Young Dejauwne D Kim Julie S JS Madrid-Aliste Carlos C Aguilan Jennifer T JT Nieves Edward E Sun Yan Y Yoo Edwin J EJ Sidoli Simone S

Journal of visualized experiments : JoVE 20220505 183

Flat cultures of mammalian cells are a widely used in vitro approach for understanding cell physiology, but this system is limited in modeling solid tissues due to unnaturally rapid cell replication. This is particularly challenging when modeling mature chromatin, as fast replicating cells are frequently involved in DNA replication and have a heterogeneous polyploid population. Presented below is a workflow for modeling, treating, and analyzing quiescent chromatin modifications using a three-dim ...[more]

PMID: 35604167

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Project description:BackgroundPost-translational modifications (PTMs) on the N-terminal tails of histones and histone variants regulate distinct transcriptional states and nuclear events. Whereas the functional effects of specific PTMs are the current subject of intense investigation, most studies characterize histone PTMs/variants in a non-temporal fashion and very few studies have reported kinetic information about these histone forms. Previous studies have used radiolabeling, fluorescence microscopy and chromatin immunoprecipitation to determine rates of histone turnover, and have found interesting correlations between increased turnover and increased gene expression. Therefore, histone turnover is an understudied yet potentially important parameter that may contribute to epigenetic regulation. Understanding turnover in the context of histone modifications and sequence variants could provide valuable additional insight into the function of histone replacement.ResultsIn this study, we measured the metabolic rate of labeled isotope incorporation into the histone proteins of HeLa cells by combining stable isotope labeling of amino acids in cell culture (SILAC) pulse experiments with quantitative mass spectrometry-based proteomics. In general, we found that most core histones have similar turnover rates, with the exception of the H2A variants, which exhibit a wider range of rates, potentially consistent with their epigenetic function. In addition, acetylated histones have a significantly faster turnover compared with general histone protein and methylated histones, although these rates vary considerably, depending on the site and overall degree of methylation. Histones containing transcriptionally active marks have been consistently found to have faster turnover rates than histones containing silent marks. Interestingly, the presence of both active and silent marks on the same peptide resulted in a slower turnover rate than either mark alone on that same peptide. Lastly, we observed little difference in the turnover between nearly all modified forms of the H3.1, H3.2 and H3.3 variants, with the notable exception that H3.2K36me2 has a faster turnover than this mark on the other H3 variants.ConclusionsQuantitative proteomics provides complementary insight to previous work aimed at quantitatively measuring histone turnover, and our results suggest that turnover rates are dependent upon site-specific post-translational modifications and sequence variants.

Dataset Information

Global Level Quantification of Histone Post-Translational Modifications in a 3D Cell Culture Model of Hepatic Tissue.

Publications

Global Level Quantification of Histone Post-Translational Modifications in a 3D Cell Culture Model of Hepatic Tissue.

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