Biology subjects

Bressan, F. F.

Publications and source records attributed to Bressan, F. F..

3 recordsLinked to original sources

bioRxiv2026

Epigenetic Remodeling Increases Plasticity of Bovine Fibroblasts Without Improving Embryo and Stem Cell Development

Epigenetic memory, reinforced by redundant heterochromatic networks, is a major barrier to somatic cell reprogramming. In cattle, single-agent chromatin-modifying treatments show inconsistent efficacy, likely due to compensatory crosstalk among repressive marks. Here, we evaluated a multi-target small-molecule cocktail, GUSTC, combining GSK343 (EZH2 inhibitor), UNC0638 (G9a/GLP inhibitor), Sodium Butyrate (HDAC inhibitor), Trichostatin A (HDAC inhibitor), and Chaetocin (SUV39H1 inhibitor) to simultaneously target facultative and constitutive heterochromatin in bovine fibroblasts. At optimized, non-cytotoxic concentrations, GUSTC treatment reduced H3K9me2, H3K9me3, H3K27me3, and HP1-alpha levels while increasing H3K9 acetylation by immunofluorescence. Using GUSTC-treated fibroblasts as donor cells for somatic cell nuclear transfer did not significantly change cleavage (83.6% vs. 92.2%; p = 0.15), blastocyst rate (28.4% vs. 39.0%; p = 0.20), bovine embryonic stem cell line derivation efficiency (26.3% vs. 33.3% of seeded blastocysts; p = 0.57), or the core pluripotency marker profile (OCT4, NANOG, SOX2) of the resulting lines. In a separate, serum-free, pluripotency-permissive culture system, GUSTC-treated cells adopted a colony-like morphology and showed increased POU5F1 and NANOG expression, along with increased DNMT1, EHMT2, HDAC1, HDAC2, and SUV39H1 transcripts. GUSTC thus reduces repressive heterochromatin marks in donor fibroblasts and is associated with a potentially more reprogramming-permissive state, without detectable improvement in preimplantation developmental competence. It provides a starting point for chemical reprogramming strategies in cattle.

developmental biology↗

bioRxiv2022

Evaluation of targeted oxidative stress induced by oxygen-ozone gas mixtures in vitro after ischemic induction

Encephalic vascular accident, or stroke, is the most common pathology of the central nervous system in humans. It is the second leading cause of death, as well as physical and cognitive disabilities, in developing countries. It is a vascular disorder that may present in an ischemic (more common) or hemorrhagic form. Ozone is a gas capable of oxidizing double bonds of organic molecules, thereby producing lipoperoxides and aldehydes. Stimulation of the immune and antioxidant system, and improvement in tissue vascularization and oxygenation, are few among several effects exerted by ozone. Ozone therapy has previously been shown to be effective in neuromodulation, neuroprotection, and nerve regeneration. The present study aimed to evaluate the effect of targeted mild ozone after inducing cerebral ischemia in vitro. The experiment was divided into two steps; in the first step, neuroblastoma lineage cells (SH-SY5Y) were subjected to 24 hours of hypoxia in an incubator culture chamber. Treatment with different concentrations of ozone (2-10 {micro}g/mL), followed by an 2,5-diphenyl-2H-tetrazolium bromide assay, indicated a possible neuroregenerative effect at low concentrations. The same protocol was applied to canine amniotic membrane stem cells that were evaluated via colorimetric assay spectrophotometry, fluorescence microscopy, and flow cytometry. The metabolic conditions and cellular regeneration in cells at low ozone concentrations (3-8 {micro}g/mL) correlated with lower levels of apoptosis and oxidative stress compared to cells not subjected to hypoxia. High concentrations of ozone (18-30 {micro}g/mL) promoted an increase in rate of apoptosis and cell death. Therefore, we developed a novel protocol that mimics ozone therapy for ischemic stroke, using ozonized culture medium after hypoxia induction. Although more studies are needed to open new avenues for translational medicine, we conclude that ozone has a dose-dependent hormetic effect and can reverse the effect of ischemia in vitro at low concentrations.

molecular biology↗

bioRxiv2019

Catalytic inhibition of H3K9me2 writers disturbs epigenetic marks during bovine nuclear reprogramming.

Orchestrated events, including extensive changes in epigenetic marks, allow a somatic nucleus to become totipotent after transfer into an oocyte, a process termed nuclear reprogramming. Recently, several strategies have been applied in order to improve reprogramming efficiency, mainly focused on removing repressive epigenetic marks such as histone methylation from the somatic nucleus. Herein we used the specific and non-toxic chemical probe UNC0638 to inhibit the catalytic activity of the histone metyltransferases EHMT1 and EHMT2. Either the donor cell (before reconstruction) or the early embryo was exposed to the probe to assess its effect on developmental rates and epigenetic marks. First, we showed that the treatment of bovine fibroblasts with UNC0638 did mitigate the levels of H3K9me2. Moreover, H3K9me2 levels were decreased in cloned embryos regardless of treating either donor cells or early embryos with UNC0638. Additional epigenetic marks such as H3K9me3, 5mC, and 5hmC were also affected by the UNC0638 treatment. Therefore, the use of UNC0638 did diminish the levels of H3K9me2 and H3K9me3 in SCNT-derived blastocysts, but this was unable to improve their preimplantation development. These results indicate that the specific reduction of H3K9me2 by inhibiting EHMT1/2 causes diverse modifications to the chromatin during early development, suggesting an intense epigenetic crosstalk during nuclear reprogramming.

developmental biology↗