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Genes Jan 2021Advances in embryo and reproductive genetics have influenced clinical approaches to overcome infertility. Since the 1990s, many attempts have been made to decipher the...
Advances in embryo and reproductive genetics have influenced clinical approaches to overcome infertility. Since the 1990s, many attempts have been made to decipher the genetic causes of infertility and to understand the role of chromosome aneuploidies in embryo potential. At the embryo stage, preimplantation genetic testing for chromosomal abnormalities and genetic disorders has offered many couples the opportunity to have healthy offspring. Recently, the application of new technologies has resulted in more comprehensive and accurate diagnoses of chromosomal abnormalities and genetic conditions to improve clinical outcome. In this Special Issue, we include a collection of reviews and original articles covering many aspects of embryo diagnosis, genome editing, and maternal-embryo cross-communication during the implantation process.
Topics: Aneuploidy; Animals; Disease Models, Animal; Embryo Implantation; Embryo, Mammalian; Embryonic Development; Genetic Testing; Humans; Infertility; Mice; Preimplantation Diagnosis
PubMed: 33477974
DOI: 10.3390/genes12010118 -
Cell Apr 2023Aneuploidy, the presence of chromosome gains or losses, is a hallmark of cancer. Here, we describe KaryoCreate (karyotype CRISPR-engineered aneuploidy technology), a...
Aneuploidy, the presence of chromosome gains or losses, is a hallmark of cancer. Here, we describe KaryoCreate (karyotype CRISPR-engineered aneuploidy technology), a system that enables the generation of chromosome-specific aneuploidies by co-expression of an sgRNA targeting chromosome-specific CENPA-binding ɑ-satellite repeats together with dCas9 fused to mutant KNL1. We design unique and highly specific sgRNAs for 19 of the 24 chromosomes. Expression of these constructs leads to missegregation and induction of gains or losses of the targeted chromosome in cellular progeny, with an average efficiency of 8% for gains and 12% for losses (up to 20%) validated across 10 chromosomes. Using KaryoCreate in colon epithelial cells, we show that chromosome 18q loss, frequent in gastrointestinal cancers, promotes resistance to TGF-β, likely due to synergistic hemizygous deletion of multiple genes. Altogether, we describe an innovative technology to create and study chromosome missegregation and aneuploidy in the context of cancer and beyond.
Topics: Humans; Aneuploidy; Centromere; Chromosome Deletion; Neoplasms; Clustered Regularly Interspaced Short Palindromic Repeats; Genetic Techniques
PubMed: 37075754
DOI: 10.1016/j.cell.2023.03.029 -
Science (New York, N.Y.) Aug 2023Most cancers exhibit aneuploidy, but its functional significance in tumor development is controversial. Here, we describe ReDACT (Restoring Disomy in Aneuploid cells...
Most cancers exhibit aneuploidy, but its functional significance in tumor development is controversial. Here, we describe ReDACT (Restoring Disomy in Aneuploid cells using CRISPR Targeting), a set of chromosome engineering tools that allow us to eliminate specific aneuploidies from cancer genomes. Using ReDACT, we created a panel of isogenic cells that have or lack common aneuploidies, and we demonstrate that trisomy of chromosome 1q is required for malignant growth in cancers harboring this alteration. Mechanistically, gaining chromosome 1q increases the expression of and suppresses p53 signaling, and we show that mutations are mutually exclusive with 1q aneuploidy in human cancers. Thus, tumor cells can be dependent on specific aneuploidies, raising the possibility that these "aneuploidy addictions" could be targeted as a therapeutic strategy.
Topics: Humans; Cell Cycle Proteins; Mutation; Neoplasms; Oncogenes; Proto-Oncogene Proteins; Trisomy; Gene Editing; Tumor Suppressor Protein p53; Carcinogenesis
PubMed: 37410869
DOI: 10.1126/science.adg4521 -
International Journal of Molecular... Mar 2022This review focuses on recent findings in the preimplantation genetic testing (PGT) of embryos. Different preimplantation genetic tests are presented along with... (Review)
Review
This review focuses on recent findings in the preimplantation genetic testing (PGT) of embryos. Different preimplantation genetic tests are presented along with different genetic materials and their analysis. Original material concerning preimplantation genetic testing for aneuploidy (PGT-A) was sourced by searching the PubMed and ScienceDirect databases in October and November 2021. The searches comprised keywords such as 'preimplantation', 'cfDNA'; 'miRNA', 'PGT-A', 'niPGT-A', 'aneuploidy', 'mosaicism', 'blastocyst biopsy', 'blastocentesis', 'blastocoel fluid', 'NGS', 'FISH', and 'aCGH'. Non-invasive PGT-A (niPGT-A) is a novel approach to the genetic analysis of embryos. The premise is that the genetic material in the spent embryo culture media (SECM) corresponds to the genetic material in the embryo cells. The limitations of niPGT-A are a lower quantity and lesser quality of the cell-free genetic material, and its unknown origin. The concordance rate varies when compared to invasive PGT-A. Some authors have also hypothesized that mosaicism and aneuploid cells are preferentially excluded from the embryo during early development. Cell-free genetic material is readily available in the spent embryo culture media, which provides an easier, more economic, and safer extraction of genetic material for analysis. The sampling of the SECM and DNA extraction and amplification must be optimized. The origin of the cell-free media, the percentage of apoptotic events, and the levels of DNA contamination are currently unknown; these topics need to be further investigated.
Topics: Aneuploidy; Blastocyst; Culture Media; Female; Genetic Testing; Humans; Mosaicism; Pregnancy; Preimplantation Diagnosis
PubMed: 35408927
DOI: 10.3390/ijms23073568 -
International Journal of Molecular... Mar 2022Human female fertility and reproductive lifespan decrease significantly with age, resulting in an extended post-reproductive period. The central dogma in human female... (Review)
Review
Human female fertility and reproductive lifespan decrease significantly with age, resulting in an extended post-reproductive period. The central dogma in human female reproduction contains two important aspects. One is the pool of oocytes in the human ovary (the ovarian reserve; approximately 10 at birth), which diminishes throughout life until menopause around the age of 50 (approximately 10 oocytes) in women. The second is the quality of oocytes, including the correctness of meiotic divisions, among other factors. Notably, the increased rate of sub- and infertility, aneuploidy, miscarriages, and birth defects are associated with advanced maternal age, especially in women above 35 years of age. This postponement is also relevant for human evolution; decades ago, the female aging-related fertility drop was not as important as it is today because women were having their children at a younger age. Spindle assembly is crucial for chromosome segregation during each cell division and oocyte maturation, making it an important event for euploidy. Consequently, aberrations in this segregation process, especially during the first meiotic division in human eggs, can lead to implantation failure or spontaneous abortion. Today, human reproductive medicine is also facing a high prevalence of aneuploidy, even in young females. However, the shift in the reproductive phase of humans and the strong increase in errors make the problem much more dramatic at later stages of the female reproductive phase. Aneuploidy in human eggs could be the result of the non-disjunction of entire chromosomes or sister chromatids during oocyte meiosis, but partial or segmental aneuploidies are also relevant. In this review, we intend to describe the relevance of the spindle apparatus during oocyte maturation for proper chromosome segregation in the context of maternal aging and the female reproductive lifespan.
Topics: Aging; Aneuploidy; Chromosome Segregation; Female; Humans; Meiosis; Oocytes; Pregnancy; Spindle Apparatus
PubMed: 35270022
DOI: 10.3390/ijms23052880 -
The Journal of Cell Biology May 2023Enduring chromosome segregation errors represent potential threats to genomic stability due to eventual chromosome copy number alterations (aneuploidy) and formation of... (Review)
Review
Enduring chromosome segregation errors represent potential threats to genomic stability due to eventual chromosome copy number alterations (aneuploidy) and formation of micronuclei-key intermediates of a rapid mutational process known as chromothripsis that is found in cancer and congenital disorders. The spindle assembly checkpoint (SAC) has been viewed as the sole surveillance mechanism that prevents chromosome segregation errors during mitosis and meiosis. However, different types of chromosome segregation errors stemming from incorrect kinetochore-microtubule attachments satisfy the SAC and are more frequent than previously anticipated. Remarkably, recent works have unveiled that most of these errors are corrected during anaphase and only rarely result in aneuploidy or formation of micronuclei. Here, we discuss recent progress in our understanding of the origin and fate of chromosome segregation errors that satisfy the SAC and shed light on the surveillance, correction, and clearance mechanisms that prevent their transmission, to preserve genomic stability.
Topics: Humans; Anaphase; Aneuploidy; Chromosome Segregation; Kinetochores; Microtubules; Mitosis; Spindle Apparatus; Genomic Instability
PubMed: 37017932
DOI: 10.1083/jcb.202301106 -
American Journal of Human Genetics Dec 2021Chromosome imbalance (aneuploidy) is the major cause of pregnancy loss and congenital disorders in humans. Analyses of small biopsies from human embryos suggest that...
Chromosome imbalance (aneuploidy) is the major cause of pregnancy loss and congenital disorders in humans. Analyses of small biopsies from human embryos suggest that aneuploidy commonly originates during early divisions, resulting in mosaicism. However, the developmental potential of mosaic embryos remains unclear. We followed the distribution of aneuploid chromosomes across 73 unselected preimplantation embryos and 365 biopsies, sampled from four multifocal trophectoderm (TE) samples and the inner cell mass (ICM). When mosaicism impacted fewer than 50% of cells in one TE biopsy (low-medium mosaicism), only 1% of aneuploidies affected other portions of the embryo. A double-blinded prospective non-selection trial (NCT03673592) showed equivalent live-birth rates and miscarriage rates across 484 euploid, 282 low-grade mosaic, and 131 medium-grade mosaic embryos. No instances of mosaicism or uniparental disomy were detected in the ensuing pregnancies or newborns, and obstetrical and neonatal outcomes were similar between the study groups. Thus, low-medium mosaicism in the trophectoderm mostly arises after TE and ICM differentiation, and such embryos have equivalent developmental potential as fully euploid ones.
Topics: Aneuploidy; Blastocyst; Double-Blind Method; Embryo Transfer; Embryonic Development; Female; Fertilization in Vitro; Genetic Testing; Humans; Incidence; Infant, Newborn; Male; Mosaicism; Pregnancy; Pregnancy Outcome; Prospective Studies
PubMed: 34798051
DOI: 10.1016/j.ajhg.2021.11.002 -
Fertility and Sterility Nov 2021Preimplantation genetic testing for aneuploidy (PGT-A) remains one of the most controversial topics in reproductive medicine. With more than 40% of in vitro... (Review)
Review
Preimplantation genetic testing for aneuploidy (PGT-A) remains one of the most controversial topics in reproductive medicine. With more than 40% of in vitro fertilization cycles in the United States reportedly involving PGT, both those in favor of and those opposed to PGT-A have significant interest in the efficacy of PGT-A. Ongoing issues include what patient population, if any, benefits from PGT-A, the true frequency of chromosomal mosaicism, whether embryonic aneuploidies self-correct, and how practitioners manage embryos designated as "mosaic." This review addresses several misconceptions and misinterpretations of data surrounding the genetic analysis and prediction of mosaicism in the preimplantation embryo.
Topics: Aneuploidy; Blastocyst; Embryo Transfer; Female; Genetic Counseling; Genetic Testing; Humans; Infertility; Male; Mosaicism; Predictive Value of Tests; Pregnancy; Prenatal Diagnosis; Reproducibility of Results; Reproductive Techniques, Assisted; Risk Assessment; Risk Factors; Treatment Outcome
PubMed: 34304887
DOI: 10.1016/j.fertnstert.2021.06.027 -
Cell Aug 2022Human cleavage-stage embryos frequently acquire chromosomal aneuploidies during mitosis due to unknown mechanisms. Here, we show that S phase at the 1-cell stage shows...
Human cleavage-stage embryos frequently acquire chromosomal aneuploidies during mitosis due to unknown mechanisms. Here, we show that S phase at the 1-cell stage shows replication fork stalling, low fork speed, and DNA synthesis extending into G2 phase. DNA damage foci consistent with collapsed replication forks, DSBs, and incomplete replication form in G2 in an ATR- and MRE11-dependent manner, followed by spontaneous chromosome breakage and segmental aneuploidies. Entry into mitosis with incomplete replication results in chromosome breakage, whole and segmental chromosome errors, micronucleation, chromosome fragmentation, and poor embryo quality. Sites of spontaneous chromosome breakage are concordant with sites of DNA synthesis in G2 phase, locating to gene-poor regions with long neural genes, which are transcriptionally silent at this stage of development. Thus, DNA replication stress in mammalian preimplantation embryos predisposes gene-poor regions to fragility, and in particular in the human embryo, to the formation of aneuploidies, impairing developmental potential.
Topics: Aneuploidy; Animals; Chromosome Breakage; Chromosome Segregation; DNA; DNA Replication; Embryonic Development; Humans; Mammals
PubMed: 35858625
DOI: 10.1016/j.cell.2022.06.028 -
Developmental Cell Sep 2021Aneuploidy is a ubiquitous feature of human tumors, but the acquisition of aneuploidy typically antagonizes cellular fitness. To investigate how aneuploidy could...
Aneuploidy is a ubiquitous feature of human tumors, but the acquisition of aneuploidy typically antagonizes cellular fitness. To investigate how aneuploidy could contribute to tumor growth, we triggered periods of chromosomal instability (CIN) in human cells and then exposed them to different culture environments. We discovered that transient CIN reproducibly accelerates the acquisition of resistance to anti-cancer therapies. Single-cell sequencing revealed that these resistant populations develop recurrent aneuploidies, and independently deriving one chromosome-loss event that was frequently observed in paclitaxel-resistant cells was sufficient to decrease paclitaxel sensitivity. Finally, we demonstrated that intrinsic levels of CIN correlate with poor responses to numerous therapies in human tumors. Our results show that, although CIN generally decreases cancer cell fitness, it also provides phenotypic plasticity to cancer cells that can allow them to adapt to diverse stressful environments. Moreover, our findings suggest that aneuploidy may function as an under-explored cause of therapy failure.
Topics: Aneuploidy; Cell Line, Tumor; Chromosomal Instability; Drug Resistance; Environment; Humans; Neoplasms; Treatment Outcome
PubMed: 34352222
DOI: 10.1016/j.devcel.2021.07.009