Functional roles of the chromatin remodeler SMARCA5 in mouse and bovine preimplantation embryos

Author(s):  
Yan Shi ◽  
Panpan Zhao ◽  
Yanna Dang ◽  
Shuang Li ◽  
Lei Luo ◽  
...  

Abstract Upon fertilization, extensive chromatin reprogramming occurs during preimplantation development. Growing evidence reveals species-dependent regulations of this process in mammals. ATP-dependent chromatin remodeling factor SMARCA5 (also known as SNF2H) is required for peri-implantation development in mice. However, the specific functional role of SMARCA5 in preimplantation development and if it is conserved among species remain unclear. Herein, comparative analysis of public RNA-seq datasets reveals that SMARCA5 is universally expressed during oocyte maturation and preimplantation development in mice, cattle, humans and pigs with species-specific patterns. Immunostaining analysis further describes the temporal and spatial changes of SMARCA5 in both mouse and bovine models. siRNA-mediated SMARCA5 depletion reduces the developmental capability and compromises the specification and differentiation of inner cell mass in mouse preimplantation embryos. Indeed, OCT4 is not restricted into the inner cell mass and the formation of epiblast and primitive endoderm disturbed with reduced NANOG and SOX17 in SMARCA5-deficient blastocysts. RNA-seq analysis shows SMARCA5 depletion causes limited effects on the transcriptomics at the morula stage, however, dysregulates 402 genes, including genes involved in transcription regulation and cell proliferation at the blastocyst stage in mice. By comparison, SMARCA5 depletion does not affect the development through the blastocyst stage but significantly compromises the blastocyst quality in cattle. Primitive endoderm formation is greatly disrupted with reduced GATA6 in bovine blastocysts. Overall, our studies demonstrate the importance of SMARCA5 in fostering the preimplantation development in mice and cattle while there are species-specific effects.

2020 ◽  
Vol 21 (18) ◽  
pp. 6488
Author(s):  
Arkadiusz Kajdasz ◽  
Ewelina Warzych ◽  
Natalia Derebecka ◽  
Zofia E. Madeja ◽  
Dorota Lechniak ◽  
...  

Compared to other mammalian species, porcine oocytes and embryos are characterized by large amounts of lipids stored mainly in the form of droplets in the cytoplasm. The amount and the morphology of lipid droplets (LD) change throughout the preimplantation development, however, relatively little is known about expression of genes involved in lipid metabolism of early embryos. We compared porcine and bovine blastocyst stage embryos as well as dissected inner cell mass (ICM) and trophoblast (TE) cell populations with regard to lipid droplet storage and expression of genes functionally annotated to selected lipid gene ontology terms using RNA-seq. Comparing the number and the volume occupied by LD between bovine and porcine blastocysts, we have found significant differences both at the level of single embryo and a single blastomere. Aside from different lipid content, we found that embryos regulate the lipid metabolism differentially at the gene expression level. Out of 125 genes, we found 73 to be differentially expressed between entire porcine and bovine blastocyst, and 36 and 51 to be divergent between ICM and TE cell lines. We noticed significant involvement of cholesterol and ganglioside metabolism in preimplantation embryos, as well as a possible shift towards glucose, rather than pyruvate dependence in bovine embryos. A number of genes like DGAT1, CD36 or NR1H3 may serve as lipid associated markers indicating distinct regulatory mechanisms, while upregulated PLIN2, APOA1, SOAT1 indicate significant function during blastocyst formation and cell differentiation in both models.


2021 ◽  
Author(s):  
Lei Luo ◽  
Yan Shi ◽  
Huanan Wang ◽  
Zizengchen Wang ◽  
Yanna Dang ◽  
...  

The emergence of the first three lineages during development are orchestrated by a network of transcription factors, which are best characterized in mice. However, the role and regulation of these factors are not completely conserved in other mammals, including human and cattle. Here, we establish a gene inactivation system by introducing premature codon with cytosine base editor in bovine embryos with a robust efficiency. Of interest, SOX2 is universally localized in early blastocysts but gradually restricted into the inner cell mass in cattle. SOX2 knockout results in a failure of the establishment of pluripotency. Indeed, OCT4 level is significantly reduced and NANOG was barely detectable. Furthermore, the formation of primitive endoderm is compromised with few SOX17 positive cells. Single embryo RNA-seq reveals a dysregulation of 2074 genes, among which 90% are up-regulated in SOX2-null blastocysts. Intriguingly, more than a dozen lineage-specific genes, including OCT4 and NANOG, are down-regulated. Moreover, SOX2 expression is sustained in the trophectoderm in absence of CDX2 in bovine late blastocysts. Overall, we propose that SOX2 is dispensable for OCT4 and NANOG expression and disappearance of SOX2 in the trophectoderm depends on CDX2 in cattle, which are all in sharp contrast with results in mice.


Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 305-312
Author(s):  
M. Aghayan ◽  
L.V. Rao ◽  
R.M. Smith ◽  
L. Jarett ◽  
M.J. Charron ◽  
...  

Two general mechanisms mediate glucose transport, one is a sodium-coupled glucose transporter found in the apical border of intestinal and kidney epithelia, while the other is a sodium-independent transport system. Of the latter, several facilitated transporters have been identified, including GLUT1 (erythrocyte/brain), GLUT2 (liver) and GLUT4 (adipose/muscle) isoforms. In this study, we used Western-blot analysis and high resolution immunoelectron microscopy (IEM) to investigate the stage-related expression and cellular localization of GLUT1, 2 and 4. The Western blot results demonstrate that GLUT1 is detectable in the oocyte and throughout preimplantation development. GLUT2 isoforms were not detectable until the blastocyst stage, while the GLUT4 isoform was undetectable in the oocyte through blastocyst stages. The present findings confirm previous studies at the molecular level which demonstrated that mRNAs encoding the same GLUT isoforms are detectable at corresponding developmental stages. GLUT1 and GLUT2 display different cellular distributions at the blastocyst stage as shown by IEM studies. GLUT1 has a widespread distribution in both trophectoderm and inner cell mass cells, while GLUT2 is located on trophectoderm membranes facing the blastocyst cavity. This observation suggests a different functional significance for these isoforms during mouse preimplantation development.


2013 ◽  
Vol 25 (1) ◽  
pp. 255
Author(s):  
C. Sauvegarde ◽  
D. Paul ◽  
R. Rezsohazy ◽  
I. Donnay

Hox genes encode for homeodomain transcription factors well known to be involved in developmental control after gastrulation. However, the expression of some of these genes has been detected during oocyte maturation and early embryo development. An interesting expression profile has been obtained for HOXB9 in the bovine (Paul et al. 2011 Mol. Reprod. Dev. 78, 436): its relative expression increases between the immature oocyte and the zygote, further increases at the 5- to 8-cell stage to peak at the morula stage before decreasing at the blastocyst stage. The main objective of this work is to establish the HOXB9 protein profile from the immature oocyte to the blastocyst in the bovine. Bovine embryos were produced in vitro from immature oocytes obtained from slaughterhouse ovaries. Embryos were collected at the following stages: immature oocyte, mature oocyte, zygote (18 h post-insemination, hpi), 2-cell (26 hpi), 5 to 8 cell (48 hpi), 9 to 16 cell (96 hpi), morula (120 hpi), and blastocyst (180 hpi). The presence and distribution of HOXB9 proteins were detected by whole-mount immunofluorescence followed by confocal microscopy using an anti-human HOXB9 polyclonal antibody directed against a sequence showing 100% homology with the bovine protein. Its specificity to the bovine protein was controlled by Western blot on total protein extract from the bovine uterus and revealed, among a few bands of weak intensities, 2 bands of high intensity corresponding to the expected size. Oocytes or embryos were fixed and incubated overnight with rabbit anti-HOXB9 (Sigma, St. Louis, MO, USA) and mouse anti-E-cadherin (BD Biosciences, Franklin Lakes, NJ, USA) primary antibodies and then for 1 h with goat anti-rabbit Alexafluor 555 conjugated (Cell Signaling Technology, Beverly, MA, USA) and goat anti-mouse FITC-conjugated (Santa Cruz Biotechnology Inc., Santa Cruz, CA, USA) secondary antibodies. Embryos were then mounted in Vectashield containing DAPI. HOXB9 is detected from the immature oocyte to the blastocyst stage. At the immature oocyte stage, it is mainly localised in the germinal vesicle with a weak signal in the cytoplasm. At the mature oocyte stage, HOXB9 labelling is present in the cytoplasm. At the zygote stage, a stronger immunoreactivity is observed in the pronuclei than in the cytoplasm. From the 2-cell stage to the morula stage, the presence of HOXB9 is also more important in the nuclei than in the cytoplasm. HOXB9 is also observed at the blastocyst stage where it is localised in the nuclei of the trophectoderm cells, whereas an inconstant or weaker labelling is observed in the inner cell mass cells. In conclusion, we have shown for the first time the presence of the HOXB9 protein throughout early bovine embryo development. The results obtained suggest the presence of the maternal HOXB9 protein because it is already detected before the maternal to embryonic transition that occurs during the fourth cell cycle in the bovine. Finally, the pattern obtained at the blastocyst stage suggests a differential role of HOXB9 in the inner cell mass and trophectoderm cells. C. Sauvegarde holds a FRIA PhD grant from the Fonds National de la Recherche Scientifique (Belgium).


Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2232 ◽  
Author(s):  
Claudia Springer ◽  
Valeri Zakhartchenko ◽  
Eckhard Wolf ◽  
Kilian Simmet

The role of the pluripotency factor NANOG during the second embryonic lineage differentiation has been studied extensively in mouse, although species-specific differences exist. To elucidate the role of NANOG in an alternative model organism, we knocked out NANOG in fibroblast cells and produced bovine NANOG-knockout (KO) embryos via somatic cell nuclear transfer (SCNT). At day 8, NANOG-KO blastocysts showed a decreased total cell number when compared to controls from SCNT (NT Ctrl). The pluripotency factors OCT4 and SOX2 as well as the hypoblast (HB) marker GATA6 were co-expressed in all cells of the inner cell mass (ICM) and, in contrast to mouse Nanog-KO, expression of the late HB marker SOX17 was still present. We blocked the MEK-pathway with a MEK 1/2 inhibitor, and control embryos showed an increase in NANOG positive cells, but SOX17 expressing HB precursor cells were still present. NANOG-KO together with MEK-inhibition was lethal before blastocyst stage, similarly to findings in mouse. Supplementation of exogenous FGF4 to NANOG-KO embryos did not change SOX17 expression in the ICM, unlike mouse Nanog-KO embryos, where missing SOX17 expression was completely rescued by FGF4. We conclude that NANOG mediated FGF/MEK signaling is not required for HB formation in the bovine embryo and that another—so far unknown—pathway regulates HB differentiation.


2019 ◽  
Vol 31 (4) ◽  
pp. 724 ◽  
Author(s):  
M. Lim ◽  
H. M. Brown ◽  
K. L. Kind ◽  
J. Breen ◽  
M. R. Anastasi ◽  
...  

Haemoglobin expression is not restricted to erythroid cells. We investigated the gene expression of the haemoglobin subunits haemoglobin, alpha adult chain 1 (Hba-a1) and haemoglobin, beta (Hbb), 2,3-bisphosphoglycerate mutase (Bpgm) and the oxygen-regulated genes BCL2/adenovirus E1B interacting protein 3 (Bnip3), solute carrier family 2 (facilitated glucose transporter), member 1 (Slc2a1) and N-myc downstream regulated gene 1 (Ndrg1) in the murine preimplantation embryo, comparing invivo to invitro gene expression. Relatively high levels of Hba-a1 and Hbb were expressed invivo from the 2-cell to blastocyst stage; in contrast, little or no expression occurred invitro. We hypothesised that the presence of haemoglobin invivo creates a low oxygen environment to induce oxygen-regulated gene expression, supported by high expression of Slc2a1 and Ndrg1 in invivo relative to invitro embryos. In addition, analysis of an invitro-derived human embryo gene expression public dataset revealed low expression of haemoglobin subunit alpha (HBA) and HBB, and high expression of BPGM. To explore whether there was a developmental stage-specific effect of haemoglobin, we added exogenous haemoglobin either up to the 4-cell stage or throughout development to the blastocyst stage, but observed no difference in blastocyst rate or the inner cell mass to trophectoderm cell ratio. We conclude that haemoglobin in the invivo preimplantation embryo raises an interesting premise of potential mechanisms for oxygen regulation, which may influence oxygen-regulated gene expression.


Reproduction ◽  
2003 ◽  
pp. 161-169 ◽  
Author(s):  
GA Thouas ◽  
GM Jones ◽  
AO Trounson

A novel system of in vitro culture termed the 'glass oviduct' or 'GO' culture system is described. Mouse zygotes were cultured in pairs to the blastocyst stage in open-ended 1 microl glass capillaries. 'GO' culture supported the development of significantly more hatching or hatched blastocysts than did a standard microdroplet (10 zygotes per 20 microl) control culture (48.3 versus 3.3%, respectively). 'GO' bslastocysts contained significantly larger populations of cells (92+/-3 versus 75+/-3), and inner cell mass (25+/-1 versus 21+/-1) and trophectoderm (68+/-2 versus 53+/-3) subpopulations, compared with microdroplet-derived blastocysts. Before blastulation, 'GO'-derived morulae were found to contain significantly more cells than microdroplet-derived morulae (27+/-0.7 versus 14+/-0.5). After implantation, 'GO' blastocysts formed fetuses at a similar rate to microdroplet-derived blastocysts (55 versus 62%), but at a lower rate than blastocysts derived in vivo (80%). 'GO'- and microdroplet-derived fetuses were similar in wet weight to each other (0.412 and 0.415 g, respectively) but were heavier than fetuses derived from flushed blastocysts (0.390 g). An additional experiment investigated whether the beneficial effect of 'GO' culture was due to the significantly increased embryo density. Proportions of hatching or hatched blastocysts after 'GO' culture (50%) were higher than after standard microdroplet culture (7.6%), but were not different from culture in high embryo density microdroplets (20 zygotes per 10 microl; 42%). 'GO' blastocysts contained more cells (79.6+/-2.1) than did standard microdroplet-derived blastocysts (68.7+/-2.0), but were similar to high density microdroplet-derived blastocysts (85.8+/-2.7). Similarly, 'GO' blastocysts contained more trophectoderm cells (62.2+/-2.0) than did standard microdroplet-derived blastocysts (52.7+/-1.7), but were similar to the high density microdroplet blastocysts (68.8+/-2.5). Numbers of inner cell mass cells ('GO', standard microdroplet and high density microdroplet culture) were not different from each other (17.4+/-0.5, 16+/-0.5 and 17+/-0.4, respectively). In conclusion, the 'GO' culture system represents an alternative method to the microdroplet system for small numbers of preimplantation embryos, without detriment to implantation potential.


2021 ◽  
Author(s):  
Joke Mertens ◽  
Marius Regin ◽  
Neelke De Munck ◽  
Edouard Couvreu de Deckersberg ◽  
Florence Belva ◽  
...  

Humans present remarkable mitochondrial DNA (mtDNA) variant mosaicism, not only across tissues but even across individual cells within one person. The timing of the first appearance of this mosaicism has not yet been established. In this study, we hypothesized it occurs during preimplantation development. To investigate this, we deep-sequenced the mtDNA of 254 oocytes from 85 donors, 158 single blastomeres of 25 day-3 embryos, 17 inner cell mass and trophectoderm samples of 7 day-5 blastocysts, 142 bulk DNA and 68 single cells of different adult tissues. We found that day-3 preimplantation embryos already present blastomeres that carry variants unique to that cell, showing that the first events of mtDNA mosaicism happen very early in human development. We classified the mtDNA variants based on their recurrence or uniqueness across sibling oocytes and embryos, and between single cells and samples from the same embryos or adult individuals. Variants that recurred across samples had higher heteroplasmic loads and more frequently resulted in synonymous changes or were located in non-coding regions than variants that were unique to one oocyte or single embryonic cell. These differences were maintained through developmental stages, suggesting that the mtDNA mosaicism arising in preimplantation development is maintained into adulthood. Further, the results support a model in which close clustering of mitochondria carrying specific mtDNA variants in the ooplasm leads to asymmetric distribution of these mitochondria throughout the cell divisions of the preimplantation embryo, resulting in the appearance of the first form of mtDNA mosaicism in human development.


2019 ◽  
Vol 25 (4) ◽  
pp. 422-438 ◽  
Author(s):  
Giovanni Coticchio ◽  
Cristina Lagalla ◽  
Roger Sturmey ◽  
Francesca Pennetta ◽  
Andrea Borini

Abstract BACKGROUND Assisted reproduction technology offers the opportunity to observe the very early stages of human development. However, due to practical constraints, for decades morphological examination of embryo development has been undertaken at a few isolated time points at the stages of fertilisation (Day 1), cleavage (Day 2–3) and blastocyst (Day 5–6). Rather surprisingly, the morula stage (Day 3–4) has been so far neglected, despite its involvement in crucial cellular processes and developmental decisions. OBJECTIVE AND RATIONALE The objective of this review is to collate novel and unsuspected insights into developmental processes occurring during formation of the morula, highlighting the key importance of this stage for a better understanding of preimplantation development and an improvement of ART. SEARCH METHODS PubMed was used to search the MEDLINE database for peer-reviewed English-language original articles and reviews concerning the morula stage in mammals. Searches were performed by adopting ‘embryo’, ‘morula’, ‘compaction’, ‘cell fate’ and ‘IVF/assisted reproduction’ as main terms, in association with other keywords expressing concepts relevant to the subject (e.g. cell polarity). The most relevant publications, i.e. those concerning major phenomena occurring during formation of the morula in established experimental models and the human species, were assessed and discussed critically. OUTCOMES Novel live cell imaging technologies and cell biology studies have extended our understanding of morula formation as a key stage for the development of the blastocyst and determination of the inner cell mass (ICM) and the trophectoderm (TE). Cellular processes, such as dynamic formation of filopodia and cytoskeleton-mediated zippering cell-to-cell interactions, intervene to allow cell compaction (a geometrical requisite essential for development) and formation of the blastocoel, respectively. At the same time, differential orientation of cleavage planes, cell polarity and cortical tensile forces interact and cooperate to position blastomeres either internally or externally, thereby influencing their cellular fate. Recent time lapse microscopy (TLM) observations also suggest that in the human the process of compaction may represent an important checkpoint for embryo viability, through which chromosomally abnormal blastomeres are sensed and eliminated by the embryo. WIDER IMPLICATIONS In clinical embryology, the morula stage has been always perceived as a ‘black box’ in the continuum of preimplantation development. This has dictated its virtual exclusion from mainstream ART procedures. Recent findings described in this review indicate that the morula, and the associated process of compaction, as a crucial stage not only for the formation of the blastocyst, but also for the health of the conceptus. This understanding may open new avenues for innovative approaches to embryo manipulation, assessment and treatment.


Endocrinology ◽  
2005 ◽  
Vol 146 (9) ◽  
pp. 4105-4116 ◽  
Author(s):  
Kazuhiro Kawamura ◽  
Jun Fukuda ◽  
Jin Kumagai ◽  
Yasushi Shimizu ◽  
Hideya Kodama ◽  
...  

Abstract Both GnRH-I and its receptor (GnRHR)-I have been shown to be expressed in the mammalian preimplantation embryo. In this study, we investigated the molecular mechanisms of GnRH-I in the regulation of early embryonic development in mouse. We found that GnRH-I and GnRHR-I mRNAs were detectable throughout early embryonic stages and that expression levels of both increased significantly after the early blastocyst stage. In blastocysts, GnRH-I and GnRHR-I expression was detected in both inner cell mass and trophectoderm cells. The pregnant uterus also expressed both genes, suggesting that preimplantation embryos could be affected by GnRH through both paracrine and autocrine signaling. Treatment with GnRH-I agonist, buserelin, promoted development of two-cell-stage embryos to the expanded and hatched blastocyst stages and inhibited apoptosis in a dose-dependent manner. In contrast, treatment with GnRH-I antagonist, ganirelix acetate, inhibited development of preimplantation embryos beyond the expanded blastocyst stage and induced apoptosis; both effects could be reversed by cotreatment with GnRH-I agonist. GnRH-I antagonist-induced cell death was mediated by disruption of mitochondrial function, release of cytochrome c, and activation of caspase-3. Furthermore, treatment with GnRH-I antagonist decreased expression of two antiapoptotic growth factors, epidermal growth factor and IGF-II, in blastocysts. These results indicate that GnRH-I, acting as an antiapoptotic factor, is an important growth factor in development of mouse blastocysts.


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