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Journal of Obstetrics and Gynaecology... Jun 2024To study the association between the blastulation rate, the presence of 1 pro nucleus (1PN) zygotes, and the ploidy of the cohort of blastocysts.
PURPOSE
To study the association between the blastulation rate, the presence of 1 pro nucleus (1PN) zygotes, and the ploidy of the cohort of blastocysts.
METHODS
A cross-sectional study using the existing databases of two university fertility centers in Canada. We included 345 cycles from 235 couples who underwent next generation sequencing PGT-A in the study.
RESULTS
A total of 1456 blastocysts were biopsied. In multivariate analysis, only female age and the number of 1PN/2PN embryos showed a negative association with euploid ratio. Surprisingly, when the analysis was limited to cycles with no delayed blastulation, the blastulation rate was also negatively associated with the euploid ratio.
CONCLUSION
This study sheds some light on the stages of early embryo development. Further study on the mechanisms governing embryo development and the different cell cycle checkpoints in embryo development is warranted.
PubMed: 38878821
DOI: 10.1016/j.jogc.2024.102586 -
Proceedings of the National Academy of... Jun 2024Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule,...
Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule, microtubule-based pulling forces in early embryos align the spindle with the short axis of the cell. We combine theory with experiments to reveal that in order to correct this misalignment, inward forces generated by the constricting cytokinetic ring rotate the entire cell until the spindle is aligned with the cell's long axis. Experiments with slightly compressed mouse zygotes indicate that this cytokinetic ring-driven mechanism of ensuring Hertwig's rule is general for cells capable of rotating inside a confining shell, a scenario that applies to early cell divisions of many systems.
Topics: Animals; Caenorhabditis elegans; Mice; Spindle Apparatus; Microtubules; Cytokinesis; Rotation; Zygote; Embryo, Nonmammalian; Embryonic Development; Models, Biological
PubMed: 38870057
DOI: 10.1073/pnas.2318838121 -
The International Journal of... Jun 2024Enhancers play an essential role in gene regulation by receiving cues from transcription factors and relaying these signals to modulate transcription from target...
Enhancers play an essential role in gene regulation by receiving cues from transcription factors and relaying these signals to modulate transcription from target promoters. Enhancer-promoter communications occur across large linear distances of the genome and with high specificity. The molecular mechanisms that underlie enhancer-mediated control of transcription remain unresolved. In this review, we focus on research in uncovering the molecular mechanisms governing enhancer-promoter communication and discuss the current understanding of developmental gene regulation. The functions of protein acetylation, pausing of RNA polymerase II, transcriptional bursting, and the formation of nuclear hubs in the induction of tissue-specific programs of transcription during zygotic genome activation are considered.
PubMed: 38869221
DOI: 10.1387/ijdb.230218gh -
Journal of Biosciences 2024We have extensively described that the neoplastic process (NP) has deep evolutionary roots and we have made specific predictions about the connection between cancer and... (Review)
Review
We have extensively described that the neoplastic process (NP) has deep evolutionary roots and we have made specific predictions about the connection between cancer and the formation of the first embryo, which allowed for the evolutionary radiation of metazoans. My main hypothesis is that the NP is at the heart of cellular mechanisms responsible for animal morphogenesis, and given its embryological basis, also at the center of cell differentiation-one of the most interesting and relevant aspects of embryogenesis. In this article, I take forward the idea of the role of physics in the modeling of the neoplastic functional module (NFM) and its contribution to morphogenesis to reveal the totipotency of the zygote. In my consideration of these arguments, I examine mechanical and biophysical clues and their intimate connection with cellular differentiation. I expound on how cancer biology is perfectly intertwined with embryonic differentiation and why it is considered a disease of cell differentiation. The neoplasia is controlled by textural gradients that lead to cell differentiation within the embryo. Thus, the embryo would be a benign tumor. Finally, inspired by evolutionary history and by what the nervous system represents for current biology and based on the impressive nervous system of ctenophores as seen in fossil records, I propose a hypothesis with physical foundations (mechanical morphogenesis) for the formation of a preneural pattern of the nervous system of the first animal embryo.
Topics: Animals; Cell Differentiation; Morphogenesis; Neoplasms; Embryonic Development; Phylogeny; Humans; Biological Evolution; Zygote
PubMed: 38864237
DOI: No ID Found -
Journal of Animal Science and... Jun 2024Previous studies have shown that the vitrification of metaphase II (MII) oocytes significantly represses their developmental potential. Abnormally increased oxidative...
BACKGROUND
Previous studies have shown that the vitrification of metaphase II (MII) oocytes significantly represses their developmental potential. Abnormally increased oxidative stress is the probable factor; however, the underlying mechanism remains unclear. The walnut-derived peptide TW-7 was initially isolated and purified from walnut protein hydrolysate. Accumulating evidences implied that TW-7 was a powerful antioxidant, while its prospective application in oocyte cryopreservation has not been reported.
RESULT
Here, we found that parthenogenetic activation (PA) zygotes derived from vitrified MII oocytes showed elevated ROS level and delayed progression of pronucleus formation. Addition of 25 μmol/L TW-7 in warming, recovery, PA, and embryo culture medium could alleviate oxidative stress in PA zygotes from vitrified mouse MII oocytes, furtherly increase proteins related to histone lactylation such as LDHA, LDHB, and EP300 and finally improve histone lactylation in PA zygotes. The elevated histone lactylation facilitated the expression of minor zygotic genome activation (ZGA) genes and preimplantation embryo development.
CONCLUSIONS
Our findings revealed the mechanism of oxidative stress inducing repressed development of PA embryos from vitrified mouse MII oocytes and found a potent and easy-obtained short peptide that could significantly rescue the decreased developmental potential of vitrified oocytes, which would potentially contribute to reproductive medicine, animal protection, and breeding.
PubMed: 38858724
DOI: 10.1186/s40104-024-01045-0 -
ELife Jun 2024Once fertilized, mouse zygotes rapidly proceed to zygotic genome activation (ZGA), during which long terminal repeats (LTRs) of murine endogenous retroviruses with...
Once fertilized, mouse zygotes rapidly proceed to zygotic genome activation (ZGA), during which long terminal repeats (LTRs) of murine endogenous retroviruses with leucine tRNA primer (MERVL) are activated by a conserved homeodomain-containing transcription factor, DUX. However, -knockout embryos produce fertile mice, suggesting that ZGA is redundantly driven by an unknown factor(s). Here, we present multiple lines of evidence that the multicopy homeobox gene, , encodes a transcription factor that is highly expressed in mouse two-cell embryos and redundantly drives ZGA. Genome-wide profiling revealed that OBOX4 specifically binds and activates MERVL LTRs as well as a subset of murine endogenous retroviruses with lysine tRNA primer (MERVK) LTRs. Depletion of is tolerated by embryogenesis, whereas concomitant / depletion markedly compromises embryonic development. Our study identified OBOX4 as a transcription factor that provides genetic redundancy to preimplantation development.
Topics: Animals; Homeodomain Proteins; Zygote; Mice; Embryonic Development; Gene Expression Regulation, Developmental; Genome; Mice, Knockout
PubMed: 38856708
DOI: 10.7554/eLife.95856 -
BioRxiv : the Preprint Server For... May 2024For a damaged tissue to regenerate, the injured site must repair the wound, proliferate, and restore the correct patterning and cell types. We found that Zelda, a...
For a damaged tissue to regenerate, the injured site must repair the wound, proliferate, and restore the correct patterning and cell types. We found that Zelda, a pioneer transcription factor largely known for its role in embryonic zygotic genome activation, is dispensable for normal wing development but crucial for wing disc patterning during regeneration. Impairing Zelda function during disc regeneration resulted in adult wings with a plethora of cell fate errors, affecting the veins, margins, and posterior compartment identity. Using CUT&RUN, we identified and validated targets of Zelda including the cell fate genes and , which failed to return to their normal expression patterns upon loss of Zelda. In addition, Zelda controls expression of factors previously established to preserve cell fate during regeneration like and which stabilizes expression during regeneration, thereby preserving posterior identity. Finally, Zelda ensures proper expression of the integrins encoded by and during regeneration to prevent blisters in the resuting adult wing. Thus, Zelda is crucial for maintaining cell fate and structural architecture of the regenerating tissue.
PubMed: 38854062
DOI: 10.1101/2024.05.30.596672 -
Research Square May 2024Understanding the mechanisms of polyploidization in cardiomyocytes is crucial for advancing strategies to stimulate myocardial regeneration. Although endoreplication has...
Understanding the mechanisms of polyploidization in cardiomyocytes is crucial for advancing strategies to stimulate myocardial regeneration. Although endoreplication has long been considered the primary source of polyploid human cardiomyocytes, recent animal work suggests the potential for cardiomyocyte fusion. Moreover, the effects of polyploidization on the genomic-transcriptomic repertoire of human cardiomyocytes have not been studied previously. We applied single-nuclei whole genome sequencing, single nuclei RNA sequencing, and multiome ATAC + gene expression (from the same nuclei) techniques to nuclei isolated from 11 healthy hearts. Utilizing post-zygotic non-inherited somatic mutations occurring during development as "endogenous barcodes," to reconstruct lineage relationships of polyploid cardiomyocytes. Of 482 cardiomyocytes from multiple healthy donor hearts 75.7% can be sorted into several developmental clades marked by one or more somatic single-nucleotide variants (SNVs). At least ~10% of tetraploid cardiomyocytes contain cells from distinct clades, indicating fusion of lineally distinct cells, whereas 60% of higher-ploidy cardiomyocytes contain fused cells from distinct clades. Combined snRNA-seq and snATAC-seq revealed transcriptome and chromatin landscapes of polyploid cardiomyocytes distinct from diploid cardiomyocytes, and show some higher-ploidy cardiomyocytes with transcriptional signatures suggesting fusion between cardiomyocytes and endothelial and fibroblast cells. These observations provide the first evidence for cell and nuclear fusion of human cardiomyocytes, raising the possibility that cell fusion may contribute to developing or maintaining polyploid cardiomyocytes in the human heart.
PubMed: 38853931
DOI: 10.21203/rs.3.rs-4414468/v1 -
BMC Genomics Jun 2024Transgenic (Tg) mice are widely used in biomedical research, and they are typically generated by injecting transgenic DNA cassettes into pronuclei of one-cell stage...
BACKGROUND
Transgenic (Tg) mice are widely used in biomedical research, and they are typically generated by injecting transgenic DNA cassettes into pronuclei of one-cell stage zygotes. Such animals often show unreliable expression of the transgenic DNA, one of the major reasons for which is random insertion of the transgenes. We previously developed a method called "pronuclear injection-based targeted transgenesis" (PITT), in which DNA constructs are directed to insert at pre-designated genomic loci. PITT was achieved by pre-installing so called landing pad sequences (such as heterotypic LoxP sites or attP sites) to create seed mice and then injecting Cre recombinase or PhiC31 integrase mRNAs along with a compatible donor plasmid into zygotes derived from the seed mice. PITT and its subsequent version, improved PITT (i-PITT), overcome disadvantages of conventional Tg mice such as lack of consistent and reliable expression of the cassettes among different Tg mouse lines, and the PITT approach is superior in terms of cost and labor. One of the limitations of PITT, particularly using Cre-mRNA, is that the approach cannot be used for insertion of conditional expression cassettes using Cre-LoxP site-specific recombination. This is because the LoxP sites in the donor plasmids intended for achieving conditional expression of the transgene will interfere with the PITT recombination reaction with LoxP sites in the landing pad.
RESULTS
To enable the i-PITT method to insert a conditional expression cassette, we modified the approach by simultaneously using PhiC31o and FLPo mRNAs. We demonstrate the strategy by creating a model containing a conditional expression cassette at the Rosa26 locus with an efficiency of 13.7%. We also demonstrate that inclusion of FLPo mRNA excludes the insertion of vector backbones in the founder mice.
CONCLUSIONS
Simultaneous use of PhiC31 and FLP in i-PITT approach allows insertion of donor plasmids containing Cre-loxP-based conditional expression cassettes.
Topics: Animals; Mice; Mice, Transgenic; Integrases; Genome; Transgenes; Gene Targeting; Gene Transfer Techniques; Plasmids; RNA, Messenger; Mutagenesis, Insertional
PubMed: 38840068
DOI: 10.1186/s12864-024-10250-0 -
Pharmacogenomics and Personalized... 2024The IQ motif and Sec7 domain ArfGEF 2 (), an X-linked gene that encodes the BRAG1 protein, is a guanine nucleotide exchange factor for the ADP ribosylation factor (ARF)...
BACKGROUND
The IQ motif and Sec7 domain ArfGEF 2 (), an X-linked gene that encodes the BRAG1 protein, is a guanine nucleotide exchange factor for the ADP ribosylation factor (ARF) protein family in the small guanosine triphosphate (GTP) binding protein. Mutations in this gene result in disorders such as intellectual disability (ID) and epilepsy. In this study, we analyze the clinical features of two patients with -mutation-related disease and discuss their possible pathogenesis.
METHODS
The two patients were diagnosed with ID and epilepsy. Genetic testing was performed using whole-exome sequencing, and the three-dimensional protein structure was analyzed. UCSC Genome Browser was used to analyze the conservation of in different species. We compared expression in the proband families with that in a control group, as well as the expression of the postsynaptic identity protein 95 (PSD-95), synapse-associated protein 97 (SAP97), ADP ribosylation factor 6 (ARF-6), and insulin receptor substrate 53kDa () genes interacting with .
RESULTS
We identified two semi-zygote mutations located in conserved positions in different species: an unreported mutation, C.3576C>A (p. Tyr1192*), and a known mutation, c.2983C>T (p. Arg995Trp). mutations resulted in significant changes in the predicted three-dimensional protein structure, while its expression in the two probands was significantly lower than that in the age-matched control group, and expression in proband 1 was lower than that in his family members. The expression levels of , and , which interact with , were also significantly different from those in the family members and age-matched healthy children.
CONCLUSION
The clinical phenotype resulting from mutations can be explained by the significant decrease in its expression, loss of function of the mutant protein, and change in the expression of related genes. Our results provide novel insights into the molecular phenotype conferred by the variants.
PubMed: 38827181
DOI: 10.2147/PGPM.S455840