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Epigenetic Modifications of Histones
Published in Cristina Camprubí, Joan Blanco, Epigenetics and Assisted Reproduction, 2018
George Rasti, Alejandro Vaquero
Oocytes remain arrested during prophase of the first meiotic division (prophase-I) for decades in humans. This prophase-I arrest is highly conserved in metazoans and is critical for oocyte differentiation because allows the oocyte to accumulate maternal components to ensure completion of oogenesis and activation of the embryonic genome upon fertilization. The oocyte contains histone-bound maternal DNA acquired during oogenesis comprising PTMs related to stalled metaphase-II. The most important difference between the chromatin of oocytes and of somatic nuclei is the absence of somatic linker histone H1 in oocytes, which is replaced with a specific histone H1 variant whose function remains elusive. Moreover, the histone H4 acetylation pattern changes during oogenesis, whereby the levels of H4K8ac and H4K12ac decrease as the oocytes mature, while that of H4K16ac increases (Figure 2.1). Interestingly, HDAC1 and 2 are important regulators of oogenesis through gene repression. While HDAC2 is essential in oocyte development, HDAC1 is more responsible for cell-cycle regulation and zygotic development (29,30). In contrast, SIRT1 deficiency does not seem to alter oocyte production in female mice (31).
Effect of titanium dioxide nanoparticles on histone modifications and histone modifying enzymes expression in human cell lines
Published in Nanotoxicology, 2022
Marta Pogribna, Beverly Word, Beverly Lyn-Cook, George Hammons
Cells extracts containing equal quantities of proteins were separated by BoltTM4–12% Bis-Tris mini protein gels (ThermoFisher Scientific; Rockford, IL) and transferred to polyvinylidene difluoride membranes. The level of trimethylation of histone 3 lysine 4 (H3K4me3), histone 3 lysine 9 (H3K9me3), histone 3 lysine 27 (H3K27me3), histone 3 lysine 36 (H3K36me3); acetylation of histone 3 lysine 9 (H3K9ac), histone H3 lysine 18 (H3K18ac), histone H4 lysine 8 (H4K8ac); and histone 3 citrulline (H3cit) was determined by Western blot analysis with respective primary antibodies. Primary antibodies (anti-H3K4me3 (1:2000), anti-H3K9me3 (1:500), anti-H3K27me (1:2000), anti-H3K36me3 (1:2000); anti-H3K9ac (1:2000), H3K18ac (1:5000) and H4K8ac (1:2000)) were purchased from EMD Millipore (Burlington, MA); anti-H3cit (1:500) from Abcam (Cambridge, MA). Secondary horseradish peroxidase (HRP)-coupled goat antirabbit antibody (Abcam) and the SuperSignalTMWest Dura Extended Duration Substrate (ThermoFisher Scientific) were used for the chemiluminescence detection measured directly by a ChemiDocTMTouch Gel Imaging System (BioRad; Hercules, CA). Signal intensities were analyzed using ImageLab software (BioRad). Equal protein loading was confirmed by immunostaining with GAPDH antibodies (Millipore/Sigma; Billerica, MA).
Transcriptional regulation of B cell class-switch recombination: the role in development of noninfectious complications
Published in Expert Review of Clinical Immunology, 2022
Stelios Vlachiotis, Hassan Abolhassani
H3K4me3, H3K36me3, H2BK5ac, H3K9ac/K14ac, H3K27ac, and H4K8ac open-state chromatin signatures are constitutively present in the Sμ donor region of naive B cells [86]. 14-3-3 adaptor proteins interact with AID and H3K9acS10ph modifications in the 5′-AGCT-3′-rich motifs of the S regions to mediate CSR in activated B cells [87]. It has been suggested that 14-3-3 adaptor proteins act as readers of the histone code and recruit other effector molecules involved in the process. Other proteins recruited to the S-regions have been proposed; Rev1 [88], RPA [77], and 53BP1, potentially functioning as a scaffold for CSR mediation. Moreover, H4K20me2 has been proposed to recruit 53BP1 for CSR mediation [89]. As we now begin to understand the specialized ‘histone code’ written in the S-regions that are to undergo CSR, it becomes more and more apparent that chromatin structure is important. However, caution is needed to recap the phenotypes in primary B cells, and future studies are needed to evaluate the impact of specific interleukins/cytokines or T helper polarization within GC on an accessible frame of S-regions for specific isotype switching to IgG, IgA, and IgE. Moreover, very little knowledge is available regarding the epigenetic regulation of other CSR-related receptors, TFs and modifiers; however, some recently discovered genetic defects in DNMT3B, ZBTB24, CDCA7, HELLS, and even TET2 with prominent B cell impairment highlighted the importance of DNA methylation and histone modification on the expression profiles of these CSR elements (Figure 1). In more detail, TET-2 deficiency has been associated with reduced AID expression and IgG1 B cell formation in vitro [90], while in vivo, it is involved in lymphangiogenesis through DNA hypermethylation in genes associated with GC B cell exit [91]. Interestingly, it has been suggested that BATF facilitates the recruitment of TET to the Aicda enhancer [90].
Prolactin activates IRF1 and leads to altered balance of histone acetylation: Implications for systemic lupus erythematosus
Published in Modern Rheumatology, 2020
Yiu Tak Leung, Kelly Maurer, Li Song, Jake Convissar, Kathleen E. Sullivan
CD14 PE (BD Biosciences, San Jose, CA) defined monocytes. Antibodies to total acetylated H4 (H4ac), H4K5ac, H4K8ac, H4K12ac and H4K16ac (EMD Millipore, Billerica, MA) were utilized for detection, as previously described [47]. Rabbit anti-GST was used as the negative control secondary antibody. PRL-treated cell MFI is reported as fold change over unstimulated and raw MFI.