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1.
BMC Bioinformatics ; 21(Suppl 14): 369, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32998686

RESUMO

BACKGROUND: Chromosome conformation capture-based methods, especially Hi-C, enable scientists to detect genome-wide chromatin interactions and study the spatial organization of chromatin, which plays important roles in gene expression regulation, DNA replication and repair etc. Thus, developing computational methods to unravel patterns behind the data becomes critical. Existing computational methods focus on intrachromosomal interactions and ignore interchromosomal interactions partly because there is no prior knowledge for interchromosomal interactions and the frequency of interchromosomal interactions is much lower while the search space is much larger. With the development of single-cell technologies, the advent of single-cell Hi-C makes interrogating the spatial structure of chromatin at single-cell resolution possible. It also brings a new type of frequency information, the number of single cells with chromatin interactions between two disjoint chromosome regions. RESULTS: Considering the lack of computational methods on interchromosomal interactions and the unsurprisingly frequent intrachromosomal interactions along the diagonal of a chromatin contact map, we propose a computational method dedicated to analyzing interchromosomal interactions of single-cell Hi-C with this new frequency information. To the best of our knowledge, our proposed tool is the first to identify regions with statistically frequent interchromosomal interactions at single-cell resolution. We demonstrate that the tool utilizing networks and binomial statistical tests can identify interesting structural regions through visualization, comparison and enrichment analysis and it also supports different configurations to provide users with flexibility. CONCLUSIONS: It will be a useful tool for analyzing single-cell Hi-C interchromosomal interactions.


Assuntos
Cromossomos/metabolismo , Análise de Célula Única/métodos , Animais , Cromatina/metabolismo , Fase G1 , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Camundongos , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Oócitos/citologia , Oócitos/metabolismo , Fase S , Zigoto/citologia , Zigoto/metabolismo
2.
Nat Commun ; 11(1): 4486, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32900989

RESUMO

Centromeres are epigenetically determined nuclear domains strictly required for chromosome segregation and genome stability. However, the mechanisms regulating centromere and kinetochore chromatin modifications are not known. Here, we demonstrate that LSH is enriched at meiotic kinetochores and its targeted deletion induces centromere instability and abnormal chromosome segregation. Superresolution chromatin analysis resolves LSH at the inner centromere and kinetochores during oocyte meiosis. LSH knockout pachytene oocytes exhibit reduced HDAC2 and DNMT-1. Notably, mutant oocytes show a striking increase in histone H3 phosphorylation at threonine 3 (H3T3ph) and accumulation of major satellite transcripts in both prophase-I and metaphase-I chromosomes. Moreover, knockout oocytes exhibit centromere fusions, ectopic kinetochore formation and abnormal exchange of chromatin fibers between paired bivalents and asynapsed chromosomes. Our results indicate that loss of LSH affects the levels and chromosomal localization of H3T3ph and provide evidence that, by maintaining transcriptionally repressive heterochromatin, LSH may be essential to prevent deleterious meiotic recombination events at repetitive centromeric sequences.


Assuntos
DNA Helicases/metabolismo , Meiose/fisiologia , Oócitos/citologia , Oócitos/metabolismo , Animais , Centrômero/genética , Centrômero/metabolismo , DNA Helicases/deficiência , DNA Helicases/genética , Feminino , Histonas/metabolismo , Cinetocoros/metabolismo , Masculino , Meiose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Transcrição Genética
3.
Nature ; 585(7824): 239-244, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32879485

RESUMO

Obligate endosymbiosis, in which distantly related species integrate to form a single replicating individual, represents a major evolutionary transition in individuality1-3. Although such transitions are thought to increase biological complexity1,2,4-6, the evolutionary and developmental steps that lead to integration remain poorly understood. Here we show that obligate endosymbiosis between the bacteria Blochmannia and the hyperdiverse ant tribe Camponotini7-11 originated and also elaborated through radical alterations in embryonic development, as compared to other insects. The Hox genes Abdominal A (abdA) and Ultrabithorax (Ubx)-which, in arthropods, normally function to differentiate abdominal and thoracic segments after they form-were rewired to also regulate germline genes early in development. Consequently, the mRNAs and proteins of these Hox genes are expressed maternally and colocalize at a subcellular level with those of germline genes in the germplasm and three novel locations in the freshly laid egg. Blochmannia bacteria then selectively regulate these mRNAs and proteins to make each of these four locations functionally distinct, creating a system of coordinates in the embryo in which each location performs a different function to integrate Blochmannia into the Camponotini. Finally, we show that the capacity to localize mRNAs and proteins to new locations in the embryo evolved before obligate endosymbiosis and was subsequently co-opted by Blochmannia and Camponotini. This pre-existing molecular capacity converged with a pre-existing ecological mutualism12,13 to facilitate both the horizontal transfer10 and developmental integration of Blochmannia into Camponotini. Therefore, the convergence of pre-existing molecular capacities and ecological interactions-as well as the rewiring of highly conserved gene networks-may be a general feature that facilitates the origin and elaboration of major transitions in individuality.


Assuntos
Formigas/embriologia , Formigas/microbiologia , Bactérias , Evolução Biológica , Regulação da Expressão Gênica no Desenvolvimento/genética , Individualidade , Simbiose/genética , Animais , Formigas/citologia , Formigas/genética , Desenvolvimento Embrionário/genética , Feminino , Genes Homeobox/genética , Herança Materna/genética , Oócitos/citologia , Oócitos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
4.
Nat Commun ; 11(1): 3922, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764664

RESUMO

The Plasmodium falciparum chloroquine resistance transporter (PfCRT) is a key contributor to multidrug resistance and is also essential for the survival of the malaria parasite, yet its natural function remains unresolved. We identify host-derived peptides of 4-11 residues, varying in both charge and composition, as the substrates of PfCRT in vitro and in situ, and show that PfCRT does not mediate the non-specific transport of other metabolites and/or ions. We find that drug-resistance-conferring mutations reduce both the peptide transport capacity and substrate range of PfCRT, explaining the impaired fitness of drug-resistant parasites. Our results indicate that PfCRT transports peptides from the lumen of the parasite's digestive vacuole to the cytosol, thereby providing a source of amino acids for parasite metabolism and preventing osmotic stress of this organelle. The resolution of PfCRT's native substrates will aid the development of drugs that target PfCRT and/or restore the efficacy of existing antimalarials.


Assuntos
Antimaláricos/farmacologia , Cloroquina/farmacologia , Proteínas de Membrana Transportadoras/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Animais , Transporte Biológico Ativo , Resistência a Medicamentos/genética , Feminino , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Proteínas de Membrana Transportadoras/genética , Modelos Biológicos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Oligopeptídeos/metabolismo , Oócitos/metabolismo , Plasmodium falciparum/genética , Transporte Proteico , Proteínas de Protozoários/genética , Xenopus laevis
5.
PLoS Biol ; 18(7): e3000811, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32735558

RESUMO

One of the earliest and most prevalent barriers to successful reproduction is polyspermy, or fertilization of an egg by multiple sperm. To prevent these supernumerary fertilizations, eggs have evolved multiple mechanisms. It has recently been proposed that zinc released by mammalian eggs at fertilization may block additional sperm from entering. Here, we demonstrate that eggs from amphibia and teleost fish also release zinc. Using Xenopus laevis as a model, we document that zinc reversibly blocks fertilization. Finally, we demonstrate that extracellular zinc similarly disrupts early embryonic development in eggs from diverse phyla, including Cnidaria, Echinodermata, and Chordata. Our study reveals that a fundamental strategy protecting human eggs from fertilization by multiple sperm may have evolved more than 650 million years ago.


Assuntos
Fertilização , Oócitos/metabolismo , Zinco/metabolismo , Ambystoma mexicanum , Animais , Feminino , Hidrozoários , Masculino , Strongylocentrotus purpuratus , Xenopus laevis , Peixe-Zebra
6.
Proc Natl Acad Sci U S A ; 117(28): 16283-16291, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32611810

RESUMO

The difficulty of achieving robust functional expression of insect nicotinic acetylcholine receptors (nAChRs) has hampered our understanding of these important molecular targets of globally deployed neonicotinoid insecticides at a time when concerns have grown regarding the toxicity of this chemotype to insect pollinators. We show that thioredoxin-related transmembrane protein 3 (TMX3) is essential to enable robust expression in Xenopus laevis oocytes of honeybee (Apis mellifera) and bumblebee (Bombus terrestris) as well as fruit fly (Drosophila melanogaster) nAChR heteromers targeted by neonicotinoids and not hitherto robustly expressed. This has enabled the characterization of picomolar target site actions of neonicotinoids, findings important in understanding their toxicity.


Assuntos
Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Neonicotinoides/farmacologia , Agonistas Nicotínicos/farmacologia , Receptores Nicotínicos/metabolismo , Acetilcolina/farmacologia , Animais , Abelhas/metabolismo , Relação Dose-Resposta a Droga , Drosophila melanogaster/metabolismo , Proteínas de Insetos/agonistas , Proteínas de Insetos/genética , Oócitos/metabolismo , Subunidades Proteicas/antagonistas & inibidores , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Receptores Nicotínicos/genética , Tiorredoxinas/genética , Tiorredoxinas/metabolismo , Xenopus laevis
7.
PLoS Biol ; 18(7): e3000745, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32667908

RESUMO

Mutations create genetic variation for other evolutionary forces to operate on and cause numerous genetic diseases. Nevertheless, how de novo mutations arise remains poorly understood. Progress in the area is hindered by the fact that error rates of conventional sequencing technologies (1 in 100 or 1,000 base pairs) are several orders of magnitude higher than de novo mutation rates (1 in 10,000,000 or 100,000,000 base pairs per generation). Moreover, previous analyses of germline de novo mutations examined pedigrees (and not germ cells) and thus were likely affected by selection. Here, we applied highly accurate duplex sequencing to detect low-frequency, de novo mutations in mitochondrial DNA (mtDNA) directly from oocytes and from somatic tissues (brain and muscle) of 36 mice from two independent pedigrees. We found mtDNA mutation frequencies 2- to 3-fold higher in 10-month-old than in 1-month-old mice, demonstrating mutation accumulation during the period of only 9 mo. Mutation frequencies and patterns differed between germline and somatic tissues and among mtDNA regions, suggestive of distinct mutagenesis mechanisms. Additionally, we discovered a more pronounced genetic drift of mitochondrial genetic variants in the germline of older versus younger mice, arguing for mtDNA turnover during oocyte meiotic arrest. Our study deciphered for the first time the intricacies of germline de novo mutagenesis using duplex sequencing directly in oocytes, which provided unprecedented resolution and minimized selection effects present in pedigree studies. Moreover, our work provides important information about the origins and accumulation of mutations with aging/maturation and has implications for delayed reproduction in modern human societies. Furthermore, the duplex sequencing method we optimized for single cells opens avenues for investigating low-frequency mutations in other studies.


Assuntos
Envelhecimento/genética , Mamíferos/genética , Mitocôndrias/genética , Mutação/genética , Oócitos/metabolismo , Especificidade de Órgãos/genética , Animais , Análise Mutacional de DNA , DNA Mitocondrial/genética , Feminino , Frequência do Gene/genética , Deriva Genética , Células Germinativas/metabolismo , Padrões de Herança/genética , Modelos Logísticos , Masculino , Camundongos , Modelos Genéticos , Taxa de Mutação , Nucleotídeos/genética , Linhagem
8.
PLoS One ; 15(6): e0234357, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32516339

RESUMO

Congenital heart defects (CHDs) affect approximately 1% of newborns. Epidemiological studies have identified several genetically-mediated maternal phenotypes (e.g., pregestational diabetes, chronic hypertension) that are associated with the risk of CHDs in offspring. However, the role of the maternal genome in determining CHD risk has not been defined. We present findings from gene-level, genome-wide studies that link CHDs to maternal effect genes as well as to maternal genes related to hypertension and proteostasis. Maternal effect genes, which provide the mRNAs and proteins in the oocyte that guide early embryonic development before zygotic gene activation, have not previously been implicated in CHD risk. Our findings support a role for and suggest new pathways by which the maternal genome may contribute to the development of CHDs in offspring.


Assuntos
Cardiopatias Congênitas/genética , Herança Materna/genética , Adulto , Estudos de Casos e Controles , Pré-Escolar , Família , Feminino , Testes Genéticos/métodos , Cardiopatias Congênitas/etiologia , Humanos , Hipertensão/genética , Lactente , Recém-Nascido , Masculino , Exposição Materna/efeitos adversos , Pessoa de Meia-Idade , Oócitos/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal/genética , Proteostase/genética , Fatores de Risco
9.
Proc Natl Acad Sci U S A ; 117(26): 15075-15084, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32532919

RESUMO

Some lineage-determining transcription factors are overwhelmingly important in directing embryonic cells to a particular differentiation pathway, such as Ascl1 for nerve. They also have an exceptionally strong ability to force cells to change from an unrelated pathway to one preferred by their action. Transcription factors are believed to have a very short residence time of only a few seconds on their specific DNA or chromatin-binding sites. We have developed a procedure in which DNA containing one copy of the binding site for the neural-inducing factor Ascl1 is injected directly into a Xenopus oocyte nucleus which has been preloaded with a limiting amount of the Ascl1 transcription factor protein. This is followed by a further injection of DNA as a competitor, either in a plasmid or in chromosomal DNA, containing the same binding site but with a different reporter. Importantly, expression of the reporter provides a measure of the function of the transcription factor in addition to its residence time. The same long residence time and resistance to competition are seen with the estrogen receptor and its DNA response elements. We find that in this nondividing oocyte, the nerve-inducing factor Ascl1 can remain bound to a specific chromatin site for hours or days and thereby help to stabilize gene expression. This stability of transcription factor binding to chromatin is a necessary part of its action because removal of this factor causes discontinuation of its effect on gene expression. Stable transcription factor binding may be a characteristic of nondividing cells.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Cromatina/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Sítios de Ligação , Cromatina/genética , DNA/genética , DNA/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Oócitos/crescimento & desenvolvimento , Oócitos/metabolismo , Ligação Proteica , Xenopus laevis/embriologia , Xenopus laevis/genética , Xenopus laevis/metabolismo
10.
Life Sci ; 256: 117895, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32502545

RESUMO

AIMS: We aimed to investigate the effect of sperm miR-34c on early human embryonic development kinetics and clinical outcomes of in vitro fertilization (IVF) patients. MATERIALS AND METHODS: After oocyte insemination, residual sperm specimens were collected from 58 patients undergoing IVF. miR-34c expression levels in sperm, oocytes, zygotes, and embryos/blastocysts were detected with qRT-PCR, and embryonic development kinetics were observed using time-lapse technology. To confirm the role of miR-34c in regulation of early embryonic development, miR-34c siRNA was injected into zygotes obtained from in vitro-matured oocytes. A ROC curve was used to determine the cutoff value. Comparisons of embryonic development kinetics and clinical outcomes were performed according to the cutoff value. KEY FINDINGS: The miR-34c expression level was highest in 3PN zygotes, but was not expressed in human oocytes. In the miR-34c siRNA group, embryonic development kinetic parameters t2, t3, t4, and t5 were significantly prolonged, but the cleavage rate and high-quality embryo rate were lower than in the control group. The levels of sperm miR-34c were negatively correlated with t5 and positively correlated with rates of blastocyst formation, high-quality blastocysts, and pregnancy. The miR-34c levels and the blastocyst formation rate were higher in the pregnancy group (p < 0.05). Logistic regression analysis showed that sperm miR-34c level was significantly correlated with pregnancy (OR: 5.056, 95% CI: 1.560-16.384; p = 0.007). SIGNIFICANCE: The sperm miR-34c expression level is associated with embryonic development kinetics and clinical outcomes. Thus, miR-34c expression is beneficial to embryonic development and may be used as an indicator of IVF outcomes.


Assuntos
Desenvolvimento Embrionário , MicroRNAs/metabolismo , Espermatozoides/metabolismo , Adulto , Blastocisto/metabolismo , Desenvolvimento Embrionário/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Cinética , Masculino , MicroRNAs/genética , Oócitos/metabolismo , Gravidez , Curva ROC
11.
Nature ; 582(7812): 443-447, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32499642

RESUMO

TWIK-related acid-sensitive potassium (TASK) channels-members of the two pore domain potassium (K2P) channel family-are found in neurons1, cardiomyocytes2-4 and vascular smooth muscle cells5, where they are involved in the regulation of heart rate6, pulmonary artery tone5,7, sleep/wake cycles8 and responses to volatile anaesthetics8-11. K2P channels regulate the resting membrane potential, providing background K+ currents controlled by numerous physiological stimuli12-15. Unlike other K2P channels, TASK channels are able to bind inhibitors with high affinity, exceptional selectivity and very slow compound washout rates. As such, these channels are attractive drug targets, and TASK-1 inhibitors are currently in clinical trials for obstructive sleep apnoea and atrial fibrillation16. In general, potassium channels have an intramembrane vestibule with a selectivity filter situated above and a gate with four parallel helices located below; however, the K2P channels studied so far all lack a lower gate. Here we present the X-ray crystal structure of TASK-1, and show that it contains a lower gate-which we designate as an 'X-gate'-created by interaction of the two crossed C-terminal M4 transmembrane helices at the vestibule entrance. This structure is formed by six residues (243VLRFMT248) that are essential for responses to volatile anaesthetics10, neurotransmitters13 and G-protein-coupled receptors13. Mutations within the X-gate and the surrounding regions markedly affect both the channel-open probability and the activation of the channel by anaesthetics. Structures of TASK-1 bound to two high-affinity inhibitors show that both compounds bind below the selectivity filter and are trapped in the vestibule by the X-gate, which explains their exceptionally low washout rates. The presence of the X-gate in TASK channels explains many aspects of their physiological and pharmacological behaviour, which will be beneficial for the future development and optimization of TASK modulators for the treatment of heart, lung and sleep disorders.


Assuntos
Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas do Tecido Nervoso/química , Canais de Potássio de Domínios Poros em Tandem/antagonistas & inibidores , Canais de Potássio de Domínios Poros em Tandem/química , Anestésicos/farmacologia , Animais , Cristalografia por Raios X , Condutividade Elétrica , Feminino , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Modelos Moleculares , Mutação , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Técnicas de Patch-Clamp , Canais de Potássio de Domínios Poros em Tandem/genética , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Xenopus laevis
12.
Arch Biochem Biophys ; 689: 108436, 2020 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-32492375

RESUMO

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels belong to the superfamily of voltage-gated potassium (Kv) and cyclic nucleotide-gated (CNG) channels. HCN channels contain the glycine-tyrosine-glycine (GYG) sequence that forms part of the selectivity filter, a similar structure than some potassium channels; however, they permeate both sodium and potassium, giving rise to an inward current. Yet a second amino acid sequence, leucine-cysteine-isoleucine (LCI), next to GYG, is well-preserved in all HCNs but not in the selective potassium channels. In this study we used site-directed mutagenesis and electrophysiology in frog oocytes to determine whether the LCI sequence affects the kinetics of HCN2 currents. Permeability and voltage dependence were evaluated, and we found a role of LCI in the gating mechanism combined with changes in ion permeability. The I residue resulted critical to this function.


Assuntos
Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus/metabolismo , Sequência de Aminoácidos , Animais , Células Cultivadas , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/química , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/genética , Ativação do Canal Iônico , Potenciais da Membrana , Mutagênese Sítio-Dirigida , Oócitos/metabolismo , Permeabilidade , Potássio/metabolismo , Sódio/metabolismo , Xenopus/genética , Proteínas de Xenopus/química , Proteínas de Xenopus/genética
13.
Proc Natl Acad Sci U S A ; 117(24): 13437-13446, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32482881

RESUMO

Pentameric ligand-gated ion channels (pLGICs) are allosteric receptors that mediate rapid electrochemical signal transduction in the animal nervous system through the opening of an ion pore upon binding of neurotransmitters. Orthologs have been found and characterized in prokaryotes and they display highly similar structure-function relationships to eukaryotic pLGICs; however, they often encode greater architectural diversity involving additional amino-terminal domains (NTDs). Here we report structural, functional, and normal-mode analysis of two conformational states of a multidomain pLGIC, called DeCLIC, from a Desulfofustis deltaproteobacterium, including a periplasmic NTD fused to the conventional ligand-binding domain (LBD). X-ray structure determination revealed an NTD consisting of two jelly-roll domains interacting across each subunit interface. Binding of Ca2+ at the LBD subunit interface was associated with a closed transmembrane pore, with resolved monovalent cations intracellular to the hydrophobic gate. Accordingly, DeCLIC-injected oocytes conducted currents only upon depletion of extracellular Ca2+; these were insensitive to quaternary ammonium block. Furthermore, DeCLIC crystallized in the absence of Ca2+ with a wide-open pore and remodeled periplasmic domains, including increased contacts between the NTD and classic LBD agonist-binding sites. Functional, structural, and dynamical properties of DeCLIC paralleled those of sTeLIC, a pLGIC from another symbiotic prokaryote. Based on these DeCLIC structures, we would reclassify the previous structure of bacterial ELIC (the first high-resolution structure of a pLGIC) as a "locally closed" conformation. Taken together, structures of DeCLIC in multiple conformations illustrate dramatic conformational state transitions and diverse regulatory mechanisms available to ion channels in pLGICs, particularly involving Ca2+ modulation and periplasmic NTDs.


Assuntos
Proteínas de Bactérias/química , Canais Iônicos de Abertura Ativada por Ligante/química , Regulação Alostérica , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Cálcio/metabolismo , Cristalografia por Raios X , Deltaproteobacteria/química , Deltaproteobacteria/metabolismo , Canais Iônicos de Abertura Ativada por Ligante/genética , Canais Iônicos de Abertura Ativada por Ligante/metabolismo , Ligantes , Modelos Moleculares , Oócitos/metabolismo , Periplasma/metabolismo , Ligação Proteica , Domínios Proteicos , Estrutura Quaternária de Proteína , Relação Estrutura-Atividade , Xenopus laevis
14.
Ecotoxicol Environ Saf ; 201: 110826, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32521368

RESUMO

As an effective feed additive in the livestock industry, olaquindox (OLA) has been widely used in domestic animal production. However, it is unclear whether OLA has negative effects on mammalian oocyte quality and fetal development. In this study, toxic effects of OLA were tested by intragastric gavage ICR mice with water, low-dose OLA (5 mg/kg/day), or high-dose OLA (60 mg/kg/day) for continuous 45 days. Results showed that high-dose OLA gavage severely affected the offspring birth and growth. Significantly, high-dose OLA impaired oocyte maturation and early embryo development, indicated by the decreased percentage of germinal vesicle breakdown, first polar body extrusion and blastocyst formation. Meanwhile, oxidative stress levels were increased in oocytes or ovaries, indexed by the increased levels of ROS, MDA, H2O2, NO, and decreased levels of GSH, SOD, CAT, GSH-Px and GSH-Rd. Furthermore, aberrant mitochondria distribution, defective spindle assembly, abnormal H3K4me2/H3K9me3 levels, increased DNA double-strand breaks and early apoptosis rate, were observed after high-dose OLA gavage. Taken together, our results for the first time illustrated that high-dose OLA gavage led to sub-fertility of females, which means that restricted utilization of OLA as feed additive should be considered.


Assuntos
Desenvolvimento Embrionário/efeitos dos fármacos , Aditivos Alimentares/toxicidade , Oócitos/efeitos dos fármacos , Oogênese/efeitos dos fármacos , Quinoxalinas/toxicidade , Administração Oral , Animais , Apoptose/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Peróxido de Hidrogênio/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Mitocôndrias/efeitos dos fármacos , Oócitos/metabolismo , Oócitos/patologia , Ovário/efeitos dos fármacos , Ovário/metabolismo , Oxirredução , Estresse Oxidativo/efeitos dos fármacos
15.
PLoS One ; 15(5): e0232759, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32453737

RESUMO

SUMMARY: Reprogramming autologous adult cells to pluripotent cells allows for relatively safe cell replacement therapy. This can be achieved by nuclear transfer, cell fusion, or induced pluripotent stem cell technology However, the epigenetic memory of the cell is considered as a great challenge facing the complete reprograming of cells by these methods. Introducing oocyte-specific factors into differentiated cells may present a promising approach by mimicking cellular reprogramming during fertilization. METHODS: Human bone marrow mesenchymal stromal cells (hBM-MSCs) were cultured with different concentrations of human metaphase II (M II) oocyte extract (0.1, 1, 5, 10, 30 ng/µl). Reprogramming was assessed at various exposure times (1, 4, 7 days). Cells were tested for their proliferation rate, morphological changes, expression of pluripotency markers, expression of mesenchymal to epithelial transition markers, and mitochondrial rejuvenation. (mitochondrial localization, morphological changes, bioenergetics, transmembrane potential, and levels of reactive oxygen species, ROS). RESULTS: Treatment of human BM-MSCs with 10 ng/µl oocyte extract resulted in increased cell proliferation, which was associated with the upregulation of the pluripotency genes OCT-4, NANOG, and SOX-2 and a concomitant downregulation of mesenchymal-specific genes. MSCs exhibited small, immature round mitochondria with few swollen cristae localized proximal to the cell nucleus. This was accompanied by morphological cell changes, a metabolic shift towards oxidative phosphorylation, a high mitochondrial membrane potential, and increased ROS production. CONCLUSION: These data show that treatment with 10 ng/µl human MII-phase oocyte extract induced genetic and mitochondrial reprogramming of human BM-MSCs to a more embryonic phenotype.


Assuntos
Extratos Celulares/farmacologia , Reprogramação Celular/genética , Células-Tronco Mesenquimais/metabolismo , Mitocôndrias/metabolismo , Oócitos/metabolismo , Biomarcadores/metabolismo , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Células Cultivadas , Reprogramação Celular/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Potenciais da Membrana/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Oócitos/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Fatores de Tempo
16.
Nature ; 582(7812): 426-431, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32461690

RESUMO

Sex chromosomes in males of most eutherian mammals share only a small homologous segment, the pseudoautosomal region (PAR), in which the formation of double-strand breaks (DSBs), pairing and crossing over must occur for correct meiotic segregation1,2. How cells ensure that recombination occurs in the PAR is unknown. Here we present a dynamic ultrastructure of the PAR and identify controlling cis- and trans-acting factors that make the PAR the hottest segment for DSB formation in the male mouse genome. Before break formation, multiple DSB-promoting factors hyperaccumulate in the PAR, its chromosome axes elongate and the sister chromatids separate. These processes are linked to heterochromatic mo-2 minisatellite arrays, and require MEI4 and ANKRD31 proteins but not the axis components REC8 or HORMAD1. We propose that the repetitive DNA sequence of the PAR confers unique chromatin and higher-order structures that are crucial for recombination. Chromosome synapsis triggers collapse of the elongated PAR structure and, notably, oocytes can be reprogrammed to exhibit spermatocyte-like levels of DSBs in the PAR simply by delaying or preventing synapsis. Thus, the sexually dimorphic behaviour of the PAR is in part a result of kinetic differences between the sexes in a race between the maturation of the PAR structure, formation of DSBs and completion of pairing and synapsis. Our findings establish a mechanistic paradigm for the recombination of sex chromosomes during meiosis.


Assuntos
Quebras de DNA de Cadeia Dupla , Meiose , Regiões Pseudoautossômicas/genética , Regiões Pseudoautossômicas/metabolismo , Animais , Proteínas de Ciclo Celular/metabolismo , Montagem e Desmontagem da Cromatina , Pareamento Cromossômico/genética , Proteínas de Ligação a DNA , Feminino , Heterocromatina/genética , Heterocromatina/metabolismo , Heterocromatina/ultraestrutura , Cinética , Masculino , Meiose/genética , Camundongos , Repetições Minissatélites/genética , Oócitos/metabolismo , Recombinação Genética/genética , Caracteres Sexuais , Troca de Cromátide Irmã , Espermatócitos/metabolismo , Ubiquitina-Proteína Ligases/metabolismo
17.
Cell Prolif ; 53(6): e12825, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32391621

RESUMO

OBJECTIVES: Little is known about the roles of integral membrane proteins beyond channels, carriers or receptors in meiotic oocytes. The transmembrane protein Fam70A was previously identified as a likely "female fertility factor" in Fox3a-knockout mouse ovaries where almost all follicles underwent synchronous activation and the mice became infertile very early. However, whether Fam70A functions in oocyte meiosis remains unknown. Therefore, the present study aimed to address this question. MATERIALS AND METHODS: Co-immunoprecipitation, immunogold labelling-electron microscopy, co-localization and yeast two-hybrid assays were used to verify the interaction. Antibody or small interfering RNA transfection was used to deplete the proteins. Immunofluorescence, immunohistochemistry and live tracker staining were used to examine the localization or characterize phenotypes. Western blot was used to examine the protein level. RESULTS: Fam70A was enriched in oocyte membranes important for normal meiosis. Fam70A depletion remarkably disrupted spindle assembly, chromosome congression and first polar body extrusion, which subsequently increased aneuploidy and abnormal fertilization. Moreover, Fam70A directly bound Wnt5a, the most abundant Wnt member within oocytes. Depletion of either Fam70A or Wnt5a remarkably increased adenomatous polyposis coli (APC), which stabilizes active ß-catenin and microtubules. Consequently, depletion of either Fam70A or Wnt5a remarkably increased p-ß-catenin (inactive form) and acetylated tubulin, while APC knockdown remarkably decreased these two. Furthermore, Fam70A depletion remarkably reduced Akt phosphorylation. CONCLUSIONS: Fam70A regulates meiosis and quality of mouse oocytes through both canonical and non-canonical Wnt5a signalling pathways.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Meiose , Proteínas de Membrana/metabolismo , Oócitos/metabolismo , Proteína Wnt-5a/metabolismo , Proteína da Polipose Adenomatosa do Colo/metabolismo , Animais , Camundongos , Microtúbulos/metabolismo , Células NIH 3T3 , Proteínas Proto-Oncogênicas c-akt/metabolismo , beta Catenina/metabolismo
18.
Proc Natl Acad Sci U S A ; 117(19): 10455-10464, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32350135

RESUMO

Aneuploidy is the leading contributor to pregnancy loss, congenital anomalies, and in vitro fertilization (IVF) failure in humans. Although most aneuploid conceptions are thought to originate from meiotic division errors in the female germline, quantitative studies that link the observed phenotypes to underlying error mechanisms are lacking. In this study, we developed a mathematical modeling framework to quantify the contribution of different mechanisms of erroneous chromosome segregation to the production of aneuploid eggs. Our model considers the probabilities of all possible chromosome gain/loss outcomes that arise from meiotic errors, such as nondisjunction (NDJ) in meiosis I and meiosis II, and premature separation of sister chromatids (PSSC) and reverse segregation (RS) in meiosis I. To understand the contributions of different meiotic errors, we fit our model to aneuploidy data from 11,157 blastocyst-stage embryos. Our best-fitting model captures several known features of female meiosis, for instance, the maternal age effect on PSSC. More importantly, our model reveals previously undescribed patterns, including an increased frequency of meiosis II errors among eggs affected by errors in meiosis I. This observation suggests that the occurrence of NDJ in meiosis II is associated with the ploidy status of an egg. We further demonstrate that the model can be used to identify IVF patients who produce an extreme number of aneuploid embryos. The dynamic nature of our mathematical model makes it a powerful tool both for understanding the relative contributions of mechanisms of chromosome missegregation in human female meiosis and for predicting the outcomes of assisted reproduction.


Assuntos
Aneuploidia , Oócitos/metabolismo , Blastocisto , Deleção Cromossômica , Segregação de Cromossomos , Feminino , Fertilização In Vitro , Humanos , Cariótipo , Idade Materna , Meiose/fisiologia , Modelos Teóricos , Não Disjunção Genética/genética , Não Disjunção Genética/fisiologia , Oócitos/fisiologia , Diagnóstico Pré-Implantação
19.
Nat Commun ; 11(1): 2652, 2020 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-32461611

RESUMO

Acentrosomal meiosis in oocytes represents a gametogenic challenge, requiring spindle bipolarization without predefined bipolar cues. While much is known about the structures that promote acentrosomal microtubule nucleation, less is known about the structures that mediate spindle bipolarization in mammalian oocytes. Here, we show that in mouse oocytes, kinetochores are required for spindle bipolarization in meiosis I. This process is promoted by oocyte-specific, microtubule-independent enrichment of the antiparallel microtubule crosslinker Prc1 at kinetochores via the Ndc80 complex. In contrast, in meiosis II, cytoplasm that contains upregulated factors including Prc1 supports kinetochore-independent pathways for spindle bipolarization. The kinetochore-dependent mode of spindle bipolarization is required for meiosis I to prevent chromosome segregation errors. Human oocytes, where spindle bipolarization is reportedly error prone, exhibit no detectable kinetochore enrichment of Prc1. This study reveals an oocyte-specific function of kinetochores in acentrosomal spindle bipolarization in mice, and provides insights into the error-prone nature of human oocytes.


Assuntos
Cinetocoros/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Oócitos/metabolismo , Fuso Acromático/metabolismo , Animais , Proteínas de Ciclo Celular/metabolismo , Segregação de Cromossomos , Proteínas do Citoesqueleto/metabolismo , Feminino , Gametogênese/fisiologia , Meiose/fisiologia , Camundongos , Microtúbulos/metabolismo , Proteínas Nucleares/metabolismo
20.
Nat Commun ; 11(1): 2598, 2020 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-32451402

RESUMO

DNA double-strand breaks (DSBs) are toxic to mammalian cells. However, during meiosis, more than 200 DSBs are generated deliberately, to ensure reciprocal recombination and orderly segregation of homologous chromosomes. If left unrepaired, meiotic DSBs can cause aneuploidy in gametes and compromise viability in offspring. Oocytes in which DSBs persist are therefore eliminated by the DNA-damage checkpoint. Here we show that the DNA-damage checkpoint eliminates oocytes via the pro-apoptotic BCL-2 pathway members Puma, Noxa and Bax. Deletion of these factors prevents oocyte elimination in recombination-repair mutants, even when the abundance of unresolved DSBs is high. Remarkably, surviving oocytes can extrude a polar body and be fertilised, despite chaotic chromosome segregation at the first meiotic division. Our findings raise the possibility that allelic variants of the BCL-2 pathway could influence the risk of embryonic aneuploidy.


Assuntos
Mutação , Oócitos/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Reparo de DNA por Recombinação/genética , Aneuploidia , Animais , Apoptose , Proteínas Reguladoras de Apoptose/deficiência , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ciclo Celular/deficiência , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Segregação de Cromossomos , Quebras de DNA de Cadeia Dupla , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endodesoxirribonucleases/deficiência , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/metabolismo , Feminino , Fertilização , Genes bcl-2 , Meiose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oócitos/citologia , Proteínas de Ligação a Fosfato/deficiência , Proteínas de Ligação a Fosfato/genética , Proteínas de Ligação a Fosfato/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/deficiência , Proteínas Proto-Oncogênicas c-bcl-2/genética , Transdução de Sinais , Proteínas Supressoras de Tumor/deficiência , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Proteína X Associada a bcl-2/deficiência , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo
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