Browsing by Subject "Chromatin"

Now showing 1 - 4 of 4
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    Chromatin condensation but not DNA integrity of pig sperm is greater in the sperm-rich fraction
    (BMC, 2023-11-06) Viñolas Vergés, Estel; Ribas Maynou, Jordi; Barranco, Isabel; Peres Rubio, Camila; Bonet, Sergi; Roca, Jordi; Yeste, Marc; Medicina y Cirugía Animal
    Background protamination and condensation of sperm chromatin as well as DNA integrity play an essential role during fertilization and embryo development. In some mammals, like pigs, ejaculates are emitted in three separate fractions: pre-sperm, sperm-rich (SRF) and post sperm-rich (PSRF). These fractions are known to vary in volume, sperm concentration and quality, as well as in the origin and composition of seminal plasma (SP), with differences being also observed within the SRF one. Yet, whether disparities in the DNA integrity and chromatin condensation and protamination of their sperm exist has not been interrogated. Results This study determined chromatin protamination (Chromomycin A3 test, CMA3), condensation (Dibromobi‑mane test, DBB), and DNA integrity (Comet assay) in the pig sperm contained in the frst 10 mL of the SRF (SRF-P1), the remaining portion of the sperm-rich fraction (SRF-P2), and the post sperm-rich fraction (PSRF). While chromatin protamination was found to be similar between the diferent ejaculate fractions (P>0.05), chromatin condensation was seen to be greater in SRF-P1 and SRF-P2 than in the PSRF (P=0.018 and P=0.004, respectively). Regarding DNA integrity, no diferences between fractions were observed (P>0.05). As the SRF-P1 has the highest sperm concentra‑tion and ejaculate fractions are known to difer in antioxidant composition, the oxidative stress index (OSi) in SP, calcu‑ lated as total oxidant activity divided by total antioxidant capacity, was tested and confrmed to be higher in the SRFP1 than in SRF-P2 and PSRF (0.42±0.06 vs. 0.23±0.09 and 0.08±0.00, respectively; P<0.01); this index, in addition, was observed to be correlated to the sperm concentration of each fraction (Rs=0.973; P<0.001). Conclusion While sperm DNA integrity was not found to difer between ejaculate fractions, SRF-P1 and SRF-P2 were observed to exhibit greater chromatin condensation than the PSRF. This could be related to the OSi of each fraction.
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    Chromatin in embryonic stem cell neuronal differentiation
    (Murcia : F. Hernández, 2007) Meshorer, E.
    Chromatin, the basic regulatory unit of the eukaryotic genetic material, is controlled by epigenetic mechanisms including histone modifications, histone variants, DNA methylation and chromatin remodeling. Cellular differentiation involves large changes in gene expression concomitant with alterations in genome organization and chromatin structure. Such changes are particularly evident in self-renewing pluripotent embryonic stem cells, which begin, in terms of cell fate, as a tabula rasa, and through the process of differentiation, acquire distinct identities. Here I describe the changes in chromatin that accompany neuronal differentiation, particularly of embryonic stem cells, and discuss how chromatin serves as the master regulator of cellular destiny.
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    Role of chromatin disruption and histone acetylation in thyroid hormone receptor action: implications in the regulation of HIV-1 LTR
    (Murcia : F. Hernández, 2003) Hsia, S.C.V.; Tomita, A.; Obata, Kazuya; Paul, B.; Buchholz, D.; Shi, Y.B.
    Thyroid hormone (TH) affects a wide variety of biological processes, from development to physiological function of different cells and organs. Alterations in plasma TH concentrations lead to developmental abnormalities and pathological consequences. Earlier studies have observed that plasma TH levels vary in AIDS patients such that low levels of TH correlate with survival rate. Furthermore, studies on the regulation of the human immunodeficiency virus type 1 (HIV-1) have shown that TH receptor (TR) is capable of binding to two regions within the long terminal repeat (LTR), which controls the transcription of HIV-1 genome. The frog oocyte is an in vivo system that allows microinjected DNA to be chromatinized in a process mimicking the process that occurs in somatic cells. Studies in the frog oocyte have provided in vivo evidence on the role of chromatin remodeling in transcriptional regulation by TR and have shown that TR utilizes similar mechanisms in the regulation of the HIV- 1 LTR. That is, TR binds to LTR in chromatin in vivo and represses the LTR in the absence of TH by recruiting corepressor complexes containing histone deacetylases, and upon TH binding, TR causes chromatin remodeling and LTR activation.
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    Tripartite Motif-containing 33 (TRIM33) protein functions in the poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response through interaction with Amplified in Liver Cancer 1 (ALC1) protein
    (American Society for Biochemistry and Molecular Biology [Society Publisher], 2013-11-08) Kulkarni, Atul; Oza, Jay; Yao, Ming; Sohail, Honeah; Ginjala, Vasudeva; Tomas-Loba, Antonia; Horejsi, Zuzana; Tan, Antoinette R; Boulton, Simon J; Ganesan, Shridar; Fisiología
    Activation of poly(ADP-ribose) polymerase (PARP) near sites of DNA breaks facilitates recruitment of DNA repair proteins and promotes chromatin relaxation in part through the action of chromatin-remodeling enzyme Amplified in Liver Cancer 1 (ALC1). Through proteomic analysis we find that ALC1 interacts after DNA damage with Tripartite Motif-containing 33 (TRIM33), a multifunctional protein implicated in transcriptional regulation, TGF-β signaling, and tumorigenesis. We demonstrate that TRIM33 is dynamically recruited to DNA damage sites in a PARP1- and ALC1-dependent manner. TRIM33-deficient cells show enhanced sensitivity to DNA damage and prolonged retention of ALC1 at sites of DNA breaks. Conversely, overexpression of TRIM33 alleviates the DNA repair defects conferred by ALC1 overexpression. Thus, TRIM33 plays a role in PARP-dependent DNA damage response and regulates ALC1 activity by promoting its timely removal from sites of DNA damage.