Search

Background Prenatal alcohol exposure is recognized for altering DNA methylation profiles of brain cells during development, and to be part of the molecular basis underpinning Fetal Alcohol Spectrum Disorder (FASD) etiology. However, we have negligible information on the effects of alcohol exposure during pre-implantation, the early embryonic window marked with dynamic DNA methylation reprogramming, and on how this may rewire the brain developmental program. Results Using a pre-clinical in vivo mouse model, we show that a binge-like alcohol exposure during pre-implantation at the 8-cell stage leads to surge in morphological brain defects and adverse developmental outcomes during fetal life. Genome-wide DNA methylation analyses of fetal forebrains uncovered sex-specific alterations, including partial loss of DNA methylation maintenance at imprinting control regions, and abnormal de novo DNA methylation profiles in various biological pathways (e.g., neural/brain development). Conclusion These findings support that alcohol-induced DNA methylation programming deviations during pre-implantation could contribute to the manifestation of neurodevelopmental phenotypes associated with FASD.

Exposure to alcohol during in-utero development can permanently change the developmental programming of physiological responses, thereby increasing the risk of neurological illnesses during childhood and later adverse health outcomes associated with fetal alcohol spectrum disorder (FASD). There is an increasing body of evidence indicating that exposure to alcohol during gestation triggers lasting epigenetic alterations in offspring, long after the initial insult; together, these studies support the role of epigenetics in FASD etiology. However, we still have little information about how ethanol interferes with the fundamental epigenetic reprogramming wave (e.g., erasure and re-establishment of DNA methylation marks) that characterizes pre-implantation embryo development. This review examines key epigenetic processes that occur during pre-implantation development and especially focus on the current knowledge regarding how prenatal exposure to alcohol during this period could affect the developmental programming of the early stage pre-implantation embryo. We will also outline the current limitations of studies examining the in-vivo and in-vitro effects of alcohol exposure on embryos and underline the next critical steps to be taken if we want to better understand the implicated mechanisms to strengthen the translational potential for epigenetic markers for non-invasive early detection, and the treatment of newborns that have higher risk of developing FASD.

Made available in DSpace on 2020-12-12T01:15:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-02 In early embryos, DNA methylation is remodelled to initiate the developmental program but for mostly unknown reasons, methylation marks are acquired unequally between embryonic and placental cells. To better understand this, we generated high-resolution DNA methylation maps of mouse mid-gestation (E10.5) embryo and placenta. We uncovered specific subtypes of differentially methylated regions (DMRs) that contribute directly to the developmental asymmetry existing between mid-gestation embryonic and placental DNA methylation patterns. We show that the asymmetry occurs rapidly during the acquisition of marks in the post-implanted conceptus (E3.5-E6.5), and that these patterns are long-lasting across subtypes of DMRs throughout prenatal development and in somatic tissues. We reveal that at the peri–implantation stages, the de novo methyltransferase activity of DNMT3B is the main driver of methylation marks on asymmetric DMRs, and that DNMT3B can largely compensate for lack of DNMT3A in the epiblast and extraembryonic ectoderm, whereas DNMT3A can only partially compensate in the absence of DNMT3B. However, as development progresses and as DNMT3A becomes the principal de novo methyltransferase, the compensatory DNA methylation mechanism of DNMT3B on DMRs becomes less effective. Research Center of the CHU Sainte-Justine Department of Biochemistry and Molecular Medicine Université De Montréal Research Institute of the McGill University Health Centre School of Veterinary Medicine São Paulo State University (Unesp) Department of Human Genetics McGill University McGill University and Genome Quebec Innovation Centre Canadian Center for Computational Genomics Department of Pediatrics Université De Montréal Department of Obstetrics and Gynecology Université De Montréal School of Veterinary Medicine São Paulo State University (Unesp)

Preterm infants are vulnerable to inflammation‐induced white matter injury (WMI), which is associated with neurocognitive impairment and increased risk of neuropsychiatric diseases in adulthood. Epigenetic mechanisms, particularly DNA methylation, play a role in normal development and modulate the response to pathological challenges. Our aims were to determine how WMI triggered DNA methylation alterations in brains of neonatal rats and if such changes persisted over time. We used a robust model of WMI by injecting lipopolysaccharide (LPS) or sterile saline in the corpus callosum of 3‐day‐old (P3) rat pups. Brains were collected 24 hours (P4) and 21 days post‐injection (P24). We extracted genomic DNA from the brain to establish genome‐wide quantitative DNA methylation profiles using reduced representation bisulfite sequencing. Neonatal LPS exposure induced a persistent increased methylation of genes related to nervous system development and a reduced methylation of genes associated with inflammatory pathways. These findings suggest that early‐life neuroinflammatory exposure impacts the cerebral methylation landscape with determining widespread epigenetic modifications especially in genes related to neurodevelopment.

DNA methylation is a common mechanism of epigenetic regulation involved in transcriptional modulation and genome stability. With the evolution of next-generation sequencing technologies, establishing quantitative genome-wide DNA methylation profiles is becoming routine in many laboratories. However, many of these approaches take several days to accomplish and use subjective PCR methods to amplify sequencing libraries, which can induce amplification bias. Here we propose a rapid Reduced Representation Bisulfite Sequencing (rRRBS) protocol to minimize PCR amplification bias and reduce total time of multiplexed library construction. In this modified approach, the precise quantification of the final library amplification step is accomplished and monitored by qPCR, instead of using standard PCR and gel electrophoresis, to determine the appropriate number of cycles to perform. The main advantages of this rRRBS method are: i) Reduced amount of amplification enzyme used for library prep, ii) Reduced number of PCR cycles resulting in less PCR amplification bias, and iii) Preparation of quality multiplexed rRRBS libraries in only ~2 days.

Epigenetics has tremendously progressed since its beginnings and now has the potential to explain unsolved mechanisms of disease. In this introductory article, we provide an overview of terms and concepts associated with the most common epigenetic modifications (i.e., DNA methylation, posttranslational histone modifications and noncoding RNAs) investigated in endocrine disorders and some of the next-generation sequencing tools used in genome-wide epigenomic profiling for biomarker discovery.

α-Tubulin acetyltransferase 1 (ATAT1) catalyzes acetylation of α-tubulin at lysine 40 in various organisms ranging from Tetrahymena to humans. Despite the importance in mammals suggested by studies of cultured cells, the mouse Atat1 gene is non-essential for survival, raising an intriguing question about its real functions in vivo. To address this question, we systematically analyzed a mouse strain lacking the gene. The analyses revealed that starting at postnatal day 5, the mutant mice display enlarged lateral ventricles in the forebrain, resembling ventricular dilation in human patients with ventriculomegaly. In the mice, ventricular dilation is due to hypoplasia in the septum and striatum. Behavioral tests of the mice uncovered deficits in motor coordination. Birth-dating experiments revealed that neuronal migration to the mutant septum and striatum is impaired during brain development. In the mutant embryonic fibroblasts, we found mild defects in cell proliferation and primary cilium formation. Notably, in these cells, ATAT1 is indispensable for tubulin hyperacetylation in response to high salt, high glucose, and hydrogen peroxide-induced oxidative stress. We investigated the role of ATAT1 in the hematopoietic system using multicolor flow cytometry and found that this system remains normal in the mutant mice. Although tubulin acetylation was undetectable in a majority of mutant tissues, residual levels were detected in the heart, skeletal muscle, trachea, oviduct, thymus and spleen. This study thus not only establishes the importance of ATAT1 in regulating mouse forebrain development and governing tubulin hyperacetylation during stress responses, but also suggests the existence of an additional α-tubulin acetyltransferase.