Abstract:In many cell types, epigenetic changes are partially regulated by the availability of metabolites involved in the activity of chromatin-modifying enzymes. Even so, the association between metabolism and the typical epigenetic reprogramming that occurs during preimplantation embryo development remains poorly understood. In this work, we explore the link between energy metabolism, more specifically the tricarboxylic acid cycle (TCA), and epigenetic regulation in bovine preimplantation embryos. Using a morphokine… Show more
“…Accumulating evidences showed that crosstalk between metabolism and epigenetics plays important roles in gene expression, cell proliferation and cell differentiation [ 56 ], and has been attracting increasing interests in the context of development [ 57 ]. Recently, it was reported that high level of α-Ketoglutarate, an intermediary metabolite in the TCA cycle, regulates DNA methylation/demethylation dynamics through TET activity to promote pluripotency and improve embryonic development [ 58 , 59 ]. Here, we propose that lactate, as an important cellular metabolite, not only provides energy for post-compaction embryonic development [ 25 ], but also regulates dynamics of histone lactylation [ 11 ].…”
Background
Dynamic changes of histone posttranslational modifications are important contexts of epigenetic reprograming after fertilization in pre-implantation embryos. Recently, lactylation has been reported as a novel epigenetic modification that regulates various cellular processes, but its role during early embryogenesis has not been elucidated.
Results
We examined nuclear accumulation of H3K23la, H3K18la and pan histone lactylation in mouse oocytes and pre-implantation embryos by immunofluorescence with specific antibodies. All of the three modifications were abundant in GV stage oocytes, and both H3K23la and pan histone lactylation could be detected on the condensed chromosomes of the MII oocytes, while H3K18la were not detected. After fertilization, the nuclear staining of H3K23la, H3K18la and pan histone lactylation was faint in zygotes but homogeneously stained both of the parental pronuclei. The signal remained weak in the early cleavage stage embryos and increased remarkably in the blastocyst stage embryos. Comparison of the embryos cultured in four different conditions with varying concentrations of oxygen found that H3K23la, H3K18la and pan histone lactylation showed similar and comparable staining pattern in embryos cultured in atmospheric oxygen concentration (20% O2), gradient oxygen concentration (5% O2 to 2% O2) and embryos obtained from in vivo, but the modifications were greatly reduced in embryos cultured in hypoxic condition (2% O2). In contrast, nuclear accumulation of H3K18ac or H3K23ac was not significantly affected under hypoxic condition. Moreover, the developmental rate of in vitro cultured embryo was significantly reduced by low oxygen concentration and small molecule inhibition of LDHA activity led to decreased lactate production, as well as reduced histone lactylation and compromised developmental rate.
Conclusions
We provided for the first time the dynamic landscape of H3K23la, H3K18la and pan histone lactylation in oocytes and pre-implantation embryos in mice. Our data suggested that histone lactylation is subjected to oxygen concentration in the culture environment and hypoxic in vitro culture reduces histone lactylation, which in turn compromises developmental potential of pre-implantation embryos in mice.
“…Accumulating evidences showed that crosstalk between metabolism and epigenetics plays important roles in gene expression, cell proliferation and cell differentiation [ 56 ], and has been attracting increasing interests in the context of development [ 57 ]. Recently, it was reported that high level of α-Ketoglutarate, an intermediary metabolite in the TCA cycle, regulates DNA methylation/demethylation dynamics through TET activity to promote pluripotency and improve embryonic development [ 58 , 59 ]. Here, we propose that lactate, as an important cellular metabolite, not only provides energy for post-compaction embryonic development [ 25 ], but also regulates dynamics of histone lactylation [ 11 ].…”
Background
Dynamic changes of histone posttranslational modifications are important contexts of epigenetic reprograming after fertilization in pre-implantation embryos. Recently, lactylation has been reported as a novel epigenetic modification that regulates various cellular processes, but its role during early embryogenesis has not been elucidated.
Results
We examined nuclear accumulation of H3K23la, H3K18la and pan histone lactylation in mouse oocytes and pre-implantation embryos by immunofluorescence with specific antibodies. All of the three modifications were abundant in GV stage oocytes, and both H3K23la and pan histone lactylation could be detected on the condensed chromosomes of the MII oocytes, while H3K18la were not detected. After fertilization, the nuclear staining of H3K23la, H3K18la and pan histone lactylation was faint in zygotes but homogeneously stained both of the parental pronuclei. The signal remained weak in the early cleavage stage embryos and increased remarkably in the blastocyst stage embryos. Comparison of the embryos cultured in four different conditions with varying concentrations of oxygen found that H3K23la, H3K18la and pan histone lactylation showed similar and comparable staining pattern in embryos cultured in atmospheric oxygen concentration (20% O2), gradient oxygen concentration (5% O2 to 2% O2) and embryos obtained from in vivo, but the modifications were greatly reduced in embryos cultured in hypoxic condition (2% O2). In contrast, nuclear accumulation of H3K18ac or H3K23ac was not significantly affected under hypoxic condition. Moreover, the developmental rate of in vitro cultured embryo was significantly reduced by low oxygen concentration and small molecule inhibition of LDHA activity led to decreased lactate production, as well as reduced histone lactylation and compromised developmental rate.
Conclusions
We provided for the first time the dynamic landscape of H3K23la, H3K18la and pan histone lactylation in oocytes and pre-implantation embryos in mice. Our data suggested that histone lactylation is subjected to oxygen concentration in the culture environment and hypoxic in vitro culture reduces histone lactylation, which in turn compromises developmental potential of pre-implantation embryos in mice.
“…Similar to DNA demethylation, histone demethylase enzymes also use α-KG as a co-factor to remove methyl groups from histones residues. Although α-KG is crucial for histone demethylation, it has been shown that the accumulation of succinate within the cell may antagonize the activity of histone demethylases and promote cell differentiation from embryonic stem cells ( Carey et al., 2015 ; Ispada et al., 2020 ; TeSlaa et al., 2016 ). Figure 4 DNA and histone demethylation are controlled by metabolism Connection between metabolism and DNA and histone demethylation of human (purple), mouse (green) and bovine (yellow) in vivo (full lines) and in vitro (dashed lines) pre-implantation stages (MII, 2, 4, 8, 16C/MO and BL).…”
Section: Resultsmentioning
confidence: 99%
“…The importance of metabolites in regulating the cellular epigenome, inducing long-term changes to the cells, the so-called ‘metaboloepigenetic regulation’, has been reported in different cell types, such as stem cells and tumor cells ( Donohoe and Bultman, 2012 , reviewed by Etchegaray and Mostoslavsky, 2016 ; Reid et al., 2017 ; Van Winkle and Ryznar, 2019 ). More recently, studies have shown that epigenetic reprogramming might also be dependent on the metabolic pattern during the early stages of embryonic development ( Ispada et al., 2020 ; Zhang et al., 2019 ). In this sense, understanding the metaboloepigenetic profile of in vivo embryos and how it differs from in vitro derived embryos in different species is essential to guiding future studies on modifying in vitro culture systems to improve embryo viability and progeny health.…”
“…Also, H3K27me3 is generally localized in gene‐rich regions with low DNA methylation and is mostly associated with facultative heterochromatin (Wiles, 2017). In bovine blastocysts, slow embryos show lower levels of H3K9me3 (Ispada, 2021) and DNA methylation than fast embryos (Ispada, 2020). In this manner, methylation of H3K27 might be overrepresent in response to this highly permissive chromatin structure.…”
Section: Discussionmentioning
confidence: 99%
“…Embryo early cleavages have been used as a model to classify and even select mammalian embryos for transfer in the last decades (Basile, 2015; Carrasco, 2017; Dal Canto, 2012; Herrero, 2013; Pribenszky, 2010; Wong, 2010). Studies report that fast and slow developing embryos diverge in terms of metabolism, response to environment and stress, energy production pathways and storage, and epigenetic reprogramming profiles that result in transcription alteration (Annes, 2019; de Lima, 2020; dos‐Santos, 2016; Ispada, 2020; Milazzotto, 2016; Silva, 2016). So far, fast embryos perform better than slow embryos regarding quality parameters (de Lima, 2020).…”
The kinetics of the first cleavages is a predictor of blastocyst development and implantation. For bovine embryos, this attribute was previously related to distinct metabolic, molecular and epigenetic profiles, including DNA and histone modifications. In the present work, we described the dynamics of trimethylation of lysine 27 on histone H3 (H3K27me3) in fast and slow developing embryos and verified if this epigenetic mark was also influenced by the speed of the first cleavages. In vitro‐produced bovine embryos were classified as fast (4 or more cells) or slow (2 cells) at 40 hr post fertilization (hpf) and either collected or cultured until 96 hpf or 186 hpf. Immunofluorescence analysis was performed in these three time points and showed that although both groups presented the same levels of H3K27me3 at 40 hpf, slow embryos presented a pronounced increase in this mark at 186 hpf when compared to fast embryos, resulting in blastocysts with remarkable differences in H3K27me3 levels. In conclusion, the increased levels of this repressive histone post‐translation modification (PTM) might be an attempt of slow embryos to promote gene expression control and chromatin integrity, since it was already reported that these embryos present reduced levels of other epigenetic repressive marks as DNA methylation and trimethylation of lysine 9 on histone H3 (H3K9me3).
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