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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 -
Nature Genetics Jun 2024Long interspersed nuclear element-1 (LINE-1 or L1) is a retrotransposon group that constitutes 17% of the human genome and shows variable expression across cell types....
Long interspersed nuclear element-1 (LINE-1 or L1) is a retrotransposon group that constitutes 17% of the human genome and shows variable expression across cell types. However, the control of L1 expression and its function in gene regulation are incompletely understood. Here we show that L1 transcription activates long-range gene expression. Genome-wide CRISPR-Cas9 screening using a reporter driven by the L1 5' UTR in human cells identifies functionally diverse genes affecting L1 expression. Unexpectedly, altering L1 expression by knockout of regulatory genes impacts distant gene expression. L1s can physically contact their distal target genes, with these interactions becoming stronger upon L1 activation and weaker when L1 is silenced. Remarkably, L1s contact and activate genes essential for zygotic genome activation (ZGA), and L1 knockdown impairs ZGA, leading to developmental arrest in mouse embryos. These results characterize the regulation and function of L1 in long-range gene activation and reveal its importance in mammalian ZGA.
PubMed: 38849613
DOI: 10.1038/s41588-024-01789-5 -
Molecular Ecology Jul 2024Human-facilitated introductions of nonnative populations can lead to secondary contact between allopatric lineages, resulting in lineage homogenisation or the formation...
Human-facilitated introductions of nonnative populations can lead to secondary contact between allopatric lineages, resulting in lineage homogenisation or the formation of stable hybrid zones maintained by reproductive barriers. We investigated patterns of gene flow between the native Sacramento Valley red fox (Vulpes vulpes patwin) and introduced conspecifics of captive-bred origin in California's Central Valley. Considering their recent divergence (20-70 kya), we hypothesised that any observed barriers to gene flow were primarily driven by pre-zygotic (e.g. behavioural differences) rather than post-zygotic (e.g. reduced hybrid fitness) barriers. We also explored whether nonnative genes could confer higher fitness in the human-dominated landscape resulting in selective introgression into the native population. Genetic analysis of red foxes (n = 682) at both mitochondrial (cytochrome b + D-loop) and nuclear (19,051 SNPs) loci revealed narrower cline widths than expected under a simulated model of unrestricted gene flow, consistent with the existence of reproductive barriers. We identified several loci with reduced introgression that were previously linked to behavioural divergence in captive-bred and domestic canids, supporting pre-zygotic, yet possibly hereditary, barriers as a mechanism driving the narrowness and stability of the hybrid zone. Several loci with elevated gene flow from the nonnative into the native population were linked to genes associated with domestication and adaptation to human-dominated landscapes. This study contributes to our understanding of hybridisation dynamics in vertebrates, particularly in the context of species introductions and landscape changes, underscoring the importance of considering how multiple mechanisms may be maintaining lineages at the species and subspecies level.
Topics: Animals; Foxes; Gene Flow; Hybridization, Genetic; Introduced Species; Genetics, Population; DNA, Mitochondrial; California; Polymorphism, Single Nucleotide; Genetic Introgression; Animal Distribution
PubMed: 38847182
DOI: 10.1111/mec.17418 -
Cell Jun 2024The cleavage of zygotes generates totipotent blastomeres. In human 8-cell blastomeres, zygotic genome activation (ZGA) occurs to initiate the ontogenesis program....
The cleavage of zygotes generates totipotent blastomeres. In human 8-cell blastomeres, zygotic genome activation (ZGA) occurs to initiate the ontogenesis program. However, capturing and maintaining totipotency in human cells pose significant challenges. Here, we realize culturing human totipotent blastomere-like cells (hTBLCs). We find that splicing inhibition can transiently reprogram human pluripotent stem cells into ZGA-like cells (ZLCs), which subsequently transition into stable hTBLCs after long-term passaging. Distinct from reported 8-cell-like cells (8CLCs), both ZLCs and hTBLCs widely silence pluripotent genes. Interestingly, ZLCs activate a particular group of ZGA-specific genes, and hTBLCs are enriched with pre-ZGA-specific genes. During spontaneous differentiation, hTBLCs re-enter the intermediate ZLC stage and further generate epiblast (EPI)-, primitive endoderm (PrE)-, and trophectoderm (TE)-like lineages, effectively recapitulating human pre-implantation development. Possessing both embryonic and extraembryonic developmental potency, hTBLCs can autonomously generate blastocyst-like structures in vitro without external cell signaling. In summary, our study provides key criteria and insights into human cell totipotency.
Topics: Humans; Spliceosomes; Cell Differentiation; Totipotent Stem Cells; Blastomeres; Pluripotent Stem Cells; Zygote; Animals; Cellular Reprogramming; Germ Layers; Mice; Blastocyst; RNA Splicing; Embryonic Development
PubMed: 38843832
DOI: 10.1016/j.cell.2024.05.010 -
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 -
Nature Cell Biology Jun 2024Dynamic epigenomic reprogramming occurs during mammalian oocyte maturation and early development. However, the underlying transcription circuitry remains poorly...
Dynamic epigenomic reprogramming occurs during mammalian oocyte maturation and early development. However, the underlying transcription circuitry remains poorly characterized. By mapping cis-regulatory elements using H3K27ac, we identified putative enhancers in mouse oocytes and early embryos distinct from those in adult tissues, enabling global transitions of regulatory landscapes around fertilization and implantation. Gene deserts harbour prevalent putative enhancers in fully grown oocytes linked to oocyte-specific genes and repeat activation. Embryo-specific enhancers are primed before zygotic genome activation and are restricted by oocyte-inherited H3K27me3. Putative enhancers in oocytes often manifest H3K4me3, bidirectional transcription, Pol II binding and can drive transcription in STARR-seq and a reporter assay. Finally, motif analysis of these elements identified crucial regulators of oogenesis, TCF3 and TCF12, the deficiency of which impairs activation of key oocyte genes and folliculogenesis. These data reveal distinctive regulatory landscapes and their interacting transcription factors that underpin the development of mammalian oocytes and early embryos.
Topics: Animals; Oocytes; Female; Enhancer Elements, Genetic; Gene Expression Regulation, Developmental; Basic Helix-Loop-Helix Transcription Factors; Oogenesis; Mice; Histones; Embryo, Mammalian; Mice, Inbred C57BL; Embryonic Development; Ovarian Follicle; Mice, Knockout
PubMed: 38839978
DOI: 10.1038/s41556-024-01422-x