4 THE HISTONE METHYLTRANSFERASE Suv39h2 ADOPTS A NUCLEAR LOCALIZATION DURING CLEAVAGE DEVELOPMENT IN PARTHENOGENETIC PORCINE EMBRYOS

2009 ◽  
Vol 21 (1) ◽  
pp. 102
Author(s):  
C. M. Johnson ◽  
R. A. Cabot
Keyword(s):  
Nuclear Localization ◽  
Uv Light ◽  
Transcript Abundance ◽  
Histone Methyltransferase ◽  
Epifluorescence Microscopy ◽  
Cell Stage ◽  
Heterochromatin Formation ◽  
Treatment Groups ◽  
Stage Of Development ◽  
Chi Square Analysis

Successful cleavage development of mammalian embryos requires precise activation and repression of transcription. Covalent modifications to histone proteins, such as methylation and acetylation, play a key role in transcriptional regulation. In particular, dimethylation of the lysine 9 residue of histone protein H3 (H3K9) results in gene silencing and heterochromatin formation. Our lab has previously shown that transcripts encoding the five histone methyltransferases known to methylate H3K9 (Suv39h1, Suv39h2, ESET, G9a, and EHMT1) are present in different amounts during oocyte maturation and cleavage development. Specifically, Suv39h2 is in the greatest abundance in GV and metaphase II stage oocytes and is also present throughout cleavage development. The aim of this study was to determine the localization of Suv39h2 protein in the GV-stage oocyte and pronuclear, 2 cell, and 4 cell stage parthenogenetic porcine embryos. We hypothesized that Suv39h2 protein would localize to the nucleus based on its high transcript abundance throughout cleavage development. To test this hypothesis, we performed a microinjection experiment in which mRNA encoding a porcine Suv39h2-GFP fusion protein was injected into metaphase II porcine oocytes. Porcine oocytes were matured in a defined medium (TCM-199 supplemented with 0.1% PVA, 0.069 mg mL–1 cysteine, 10 ng mL–1 EGF, 0.5 IU mL–1 LH and FSH) for 42 to 44 h at 39°C in 5% CO2, then denuded of cumulus cells just before microinjection. Two separate treatment groups were microinjected intracytoplasmically with 1 μg μL–1 GFP or Suv39h2-GFP mRNA, respectively. Microinjection was performed using a FemtoJet microinjector (Eppendorf, Hamburg, Germany). The treatment groups and non-injected controls were electroactivated independently and cultured in PZM medium supplemented with 3 mg mL–1 BSA for 12 (pronuclear), 24 (2 cell), or 48 (4 cell) hours at 39°C in 5% CO2, depending on desired stage of development. Before visualization under UV light, embryos were stained with Hoechst 33342 for 15 minutes. Oocytes and embryos were analyzed for GFP expression at the GV, pronuclear, 2 and 4 cell stages of development using epifluorescence microscopy. Two to four biological replicates were performed for each stage of embryo development. We found that Suv39h2-GFP protein showed nuclear localization in most GV-stage oocytes (n = 11/14) and pronuclear (n = 17/17), 2-cell (n = 34/36), and 4-cell (n = 9/9) stage embryos. Chi square analysis revealed this pattern to be different from that observed in embryos injected with GFP mRNA, where GFP did not display nuclear localization at any stage of development (n = 12; P < 0.05). These results indicate that Suv39h2 is localized in the nucleus of oocytes and cleaved embryos, which suggests that this histone methyltransferase plays an important role in methylating H3K9.

334 EFFECT OF INSULIN ON IN VITRO MATURATION OF CANINE OOCYTES

2006 ◽  
Vol 18 (2) ◽  
pp. 275
Author(s):  
H. S. Lee ◽  
Y. I. Seo ◽  
X. J. Yin ◽  
S. G. Cho ◽  
I. H. Bae ◽  
...  
Keyword(s):  
In Vitro Maturation ◽  
Uv Light ◽  
Cumulus Cells ◽  
Oocyte Activation ◽  
Cell Stage ◽  
Oocyte Competence ◽  
Treatment Groups ◽  
Maturation Medium ◽  
Oviduct Fluid

In spite of our increased knowledge of in vitro oocyte maturation techniques, the success rate of obtaining mature canine oocytes in vitro remains very low compared with that for other domestic animals. The inefficient rate of meiotic resumption of canine oocytes is probably due to both the unique reproductive cycle and inappropriate in vitro maturation (IVM) medium. In an unpublished experiment, we found that the concentration of insulin was higher in estrus bitch serum (EBS; 8833 pg/mL) than in dog follicular fluid (DFF; preovulatory follicle, 122 pg/mL), which implies its possible role in the acquisition of oocyte competence. Therefore, in the present study we investigated the effects of supplementing the IVM medium with insulin on the incidence of maturation to metaphase II. Ovaries were collected from various stages of the estrous cycle by ovariohysterectomy, and oocytes with two or more intact cumulus layers and with a diameter >110 �m were selected and used for IVM. Oocytes were cultured in modified synthetic oviduct fluid (2004 Reprod. Nutr. Dev. 44, 105-109) supplemented with 10% EBS, 20 �g/mL estradiol, and different concentrations of insulin (0, 10, 100, or 1000 ng/mL) at 38.5�C, 5% CO2 in air. After 72 h, cumulus cells were removed from around oocytes using a small glass pipette. Denuded oocytes were fixed in 3.7% paraformaldehyde supplemented with 10 �g/mL Hoechst 33342 at room temperature for 40 min. Nuclear status was observed under UV light using a fluorescence microscope. The percentage of oocytes at the metaphase II stage was not different among the four groups 6.8, 1.8, 5.4, and 2.1% in the control, 10, 100, and 1000 ng/mL insulin groups, respectively. The incidence of oocytes with pronuclear-like structures or cleaving beyond the two-cell stage was not significant higher in the 10 and 100 ng/mL insulin treatment groups than in the control and 1000 ng/mL insulin groups 20.0 and 19.6% vs. 6.8 and 6.4%, respectively. These results indicate that the addition of insulin to the in vitro maturation medium of dog oocytes had no effect on the incidence of meiotic maturation to metaphase II, nor did it affect the frequency of occurrence of spontaneous oocyte activation.

scholarly journals 119 THE LOCALIZATION OF A METHYL BINDING DOMAIN PROTEIN (MBD4) IN MURINE AND BOVINE OOCYTES AND PRE-IMPLANTATION EMBRYOS

2005 ◽  
Vol 17 (2) ◽  
pp. 210
Author(s):  
N. Ruddock ◽  
J. Xue ◽  
L. Sanchez-Partida ◽  
M. Cooney ◽  
N. Korfiatis ◽  
...  
Keyword(s):  
Binding Domain ◽  
Primary Antibody ◽  
Epifluorescence Microscopy ◽  
Cell Stage ◽  
Embryonic Genome Activation ◽  
Stage Of Development ◽  
Embryonic Genome ◽  
Genome Activation ◽  
Bovine Oocytes

The presence of MBD4, a member of the methyl binding domain family, was investigated in both murine and bovine oocytes and pre-implantation embryos. MBD4 is the only MBD family member that is involved in DNA repair but not active in transcriptional repression or in the formation of complexes with histone deacetylase complexes (HDACs). It contains a mismatch-specific glycosylase domain that acts to repair G:T mismatches within a CpG context. Bovine cumulus oocyte complexes were collected from abattoir-derived ovaries, matured in vitro and used for IVF as described previously (Ruddock et al. 2004 Biol. Reprod. 70, 1131–1135). Samples were analyzed at all steps in this process. Murine oocytes were collected from superovulated mice (C57BL6 × CBA) and subjected to conventional IVF. A polyclonal antibody derived in the rabbit against human peptides from specific regions of MBD4 (Imgenex, San Diego, CA, USA) was used to localize MBD4 protein. This antibody was tested at a variety of concentrations against both human HL60 leukemia cells and bovine embryos. Staining of HL60 cells was optimum at 32–64 μg/mL and embryos at 64 μg/mL. Briefly, the staining protocol consisted of fixing cells and zona-free oocytes or embryos in 4% paraformaldehyde for 15 min, followed by 15 min in 0.1% Triton X-100. Primary antibody incubation was performed overnight at 4°C. Embryos were then washed in blocking buffer for 1 hr prior to incubation at 4°C in mouse anti-rabbit IgG conjugated to FITC in blocking buffer for 30 min in the dark. Lastly, embryos were incubated in 10 μg/L Hoescht 33342 for 15 min, and then washed and mounted with Vectashield (Vector Labs, Burlingame, CA, USA). Negative controls contained no primary antibody. Mounted cells/embryos were viewed by epifluorescence microscopy. MBD4 was found to be expressed in both murine and bovine oocytes and pre-implantation embryos. In the cow, faint nuclear expression was detected at the 2-cell stage, followed by exclusion of the protein from the nucleus until the blastocyst stage of development. At this stage, staining was primarily nuclear and quite intense. In the mouse, staining was cytoplasmic at the 2 pronuclear stage, but was then concentrated in the nucleus from the 2-cell stage onward. It will be interesting to determine if this is due to the different timing of embryonic genome activation between the two species, hence implying a role for MBD4 in this important biological process. Further investigations are underway to compare the subcellular localization of the other MBD proteins in both species during preimplantation development and to identify a role for MBD4 in embryonic genome activation.

Effect of increasing progesterone concentration from Day 3 of pregnancy on subsequent embryo survival and development in beef heifers

2008 ◽  
Vol 20 (3) ◽  
pp. 368 ◽  
Author(s):  
F. Carter ◽  
N. Forde ◽  
P. Duffy ◽  
M. Wade ◽  
T. Fair ◽  
...  
Keyword(s):  
Oestrous Cycle ◽  
Progesterone Concentration ◽  
Phenotypic Effect ◽  
Interferon Tau ◽  
Cell Stage ◽  
Embryo Survival ◽  
Serum Progesterone ◽  
Stage Of Development ◽  
Survival And Development ◽  
Chi Square Analysis

Higher systemic progesterone in the immediate post-conception period is associated with an increase in embryonic growth rate, interferon-tau production and pregnancy rate in cattle. The objective of this study was to examine the effect of increasing progesterone concentration on Day 3 on subsequent embryo survival and development. Oestrus (Day 0) was synchronised in beef-cross heifers (n = 210) and approximately two-thirds of the heifers were inseminated with semen from a proven sire, while the remainder were not inseminated. In order to produce animals with divergent progesterone concentrations, half of the animals received a progesterone-releasing intravaginal device (PRID) on Day 3 of the oestrous cycle, which was left in situ until slaughter. The four treatment groups were: (i) pregnant, high progesterone; (ii) pregnant, normal progesterone; (iii) non-pregnant, high progesterone; and (iv) non-pregnant, normal progesterone. Animals were blood-sampled twice daily from Days 0 to 8 and once daily thereafter until slaughter on Days 5, 7, 13 or 16, corresponding to the 16-cell stage, the blastocyst stage, the beginning of elongation and the day of maternal recognition of pregnancy, respectively. Embryos were recovered by flushing the tract with phosphate-buffered saline and characterised by stage of development and, in the case of Days 13 and 16, measured. Data were analysed by mixed models ANOVA, Chi-square analysis and Student’s t-test where appropriate. Insertion of a PRID on Day 3 increased (P < 0.05) progesterone concentrations from Day 3.5 onwards. There was no difference between treatments in the proportion of embryos at the expected stage of development on Days 5 or 7 (P > 0.05). While not significantly different, the proportion of viable embryos recovered was numerically greater in the high progesterone group on both Day 13 (58 v. 43%) and Day 16 (90 v. 50%). Elevation of progesterone significantly increased embryonic length on Day 13 (2.24 ± 0.51 mm v. 1.15 ± 0.16 mm, P = 0.034) and Day 16 (14.06 ± 1.18 cm v. 5.97 ± 1.18 cm, P = 0.012). In conclusion, insertion of a PRID on Day 3 of the oestrous cycle increased serum progesterone concentrations on subsequent days, which, while having no phenotypic effect on embryonic development on Days 5 or 7, was associated with an increase in embryonic size on Days 13 and 16.

scholarly journals Regulated nuclear accumulation of a histone methyltransferase times the onset of heterochromatin formation in C. elegans embryos

2018 ◽  
Author(s):  
Beste Mutlu ◽  
Huei-Mei Chen ◽  
James J. Moresco ◽  
Barbara D. Orelo ◽  
Bing Yang ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Histone Methyltransferase ◽  
Early Embryogenesis ◽  
Nuclear Accumulation ◽  
Heterochromatin Formation ◽  
C Elegans ◽  
Two Factors ◽  
Stable Association ◽  
And Function

ONE SENTENCE SUMMARYMET-2/SETDB1 and interactors (LIN-65/ATF7IP and ARLE-14/ARL14EP) initiate heterochromatin formation during embryogenesis.ABSTRACTHeterochromatin formation during early embryogenesis is timed precisely, but it has been elusive how this process is regulated. Here we report the discovery of a histone methyltransferase complex whose nuclear accumulation determines the onset of heterochromatin formation in C. elegans embryos. We find that the inception of heterochromatin generation coincides with the nuclear accumulation of the methyltransferase MET-2 (SETDB). The absence of MET-2 results in delayed and disturbed heterochromatin formation, whereas accelerated nuclear localization of the methyltransferase leads to precocious heterochromatin. We identify two factors that bind to and function with MET-2: LIN-65, which resembles ATF7IP, localizes MET-2 into nuclear hubs, and ARLE-14, orthologous to ARL14EP, promotes stable association of MET-2 with chromatin. These data reveal that nuclear accumulation of MET-2 in conjunction with LIN-65 and ARLE-14 regulates timing of heterochromatin domains during embryogenesis.

156 OVIDUCTAL FLUID SUPPLEMENTATION DURING MATURATION AND FERTILIZATION IMPROVES IN VITRO EMBRYONIC DEVELOPMENT IN PIGS

2017 ◽  
Vol 29 (1) ◽  
pp. 187
Author(s):  
A. Goldacker ◽  
E. Winn ◽  
J. Z. Current ◽  
B. D. Whitaker
Keyword(s):  
Embryonic Development ◽  
Developmental Stages ◽  
Blastocyst Stage ◽  
Success Rates ◽  
Blastocyst Development ◽  
Cell Stage ◽  
Stage Of Development ◽  
Fluid Supplementation ◽  
Chi Square Analysis

Oviducal fluid has a major role in the maturation of gametes and the process of fertilization. The objective of this study was to determine the effects of oviducal fluid supplementation in vitro, during oocyte maturation and IVF on fertilization characteristics and early embryonic development rates. Oocytes from aspired aspirated mature follicles (3–6 mm diameter) were obtained from a local abattoir. During the last 24 h of maturation, oocytes (n = 1303) were placed into maturation media supplemented either 1% (vol/vol) or 5% (vol/vol) thawed snap-frozen oviducal fluid. Fertilization was performed using pooled frozen-thawed semen from 3 different boars. During IVF, the fertilization medium was supplemented with 1% (vol/vol) or 5% (vol/vol) oviducal fluid. Fertilization characteristics were evaluated 12 h after IVF and rates of embryonic cleavage and blastocyst development were observed at 48 and 144 h after IVF, respectively. Data were analysed using ANOVA with the main effects including treatment, well, and replicate. Chi-square analysis was used to determine percentages of embryos reaching the different developmental stages for each treatment. There were no significant differences in the percentages of oocytes that reached metaphase II by the end of maturation or in sperm penetration rates after IVF. However, oocytes treated with 1% (vol/vol) oviducal fluid during the end of maturation and IVF (33.33 ± 2.61) and 5% (vol/vol) oviducal fluid during maturation (33.33 ± 2.66) or IVF (39.53 ± 3.78) had significantly less (P < 0.05) incidence of polyspermic penetrations and a significantly higher (P < 0.05) incidence of male pronuclear formation (87.50 ± 4.01; 86.67 ± 4.83; 86.05 ± 3.19, respectively) compared with no oviducal fluid supplementation. Oocytes supplemented with 5% (vol/vol) oviducal fluid during maturation and IVF had significantly lower (P < 0.05) incidences of polyspermic penetration (27.91 ± 2.50) and significantly higher (P < 0.05) percentages of embryos reaching the 2-cell stage (81.76 ± 3.72) and blastocyst stage of development (37.74 ± 1.09) by 48 and 144 h, respectively, compared with all other groups. The results of this study suggest that supplementing 5% (vol/vol) oviducal fluid during maturation and IVF improves the success rates of in vitro embryo development in pigs.

Effect of GnRH injection timing in the production of pronuclear-stage zygotes used for DNA microinjection

Zygote ◽  
2004 ◽  
Vol 12 (3) ◽  
pp. 257-261 ◽  
Author(s):  
Hernan Baldassarre ◽  
Bin Wang ◽  
Melanie Gauthier ◽  
Nathalie Neveu ◽  
Anthoula Lazaris ◽  
...  
Keyword(s):  
Medroxyprogesterone Acetate ◽  
Treatment Protocol ◽  
Hormonal Treatment ◽  
Injection Timing ◽  
Chi Square ◽  
Cell Stage ◽  
Embryo Recovery ◽  
Stage Of Development ◽  
Production Programme ◽  
Dna Microinjection

This study was aimed at developing a hormonal treatment protocol in order to optimize the proportion of pronuclear-stage embryos to be used for DNA microinjection in a goat transgenic founder production programme. A total of 46 adult BELE® and 47 adult standard goats (1–5 years old) were used as donors and recipients, respectively. They were heat-synchronized using intravaginal sponges containing 60 mg medroxyprogesterone acetate for 10 days with an injection of 125 μg cloprostenol on the morning of the eighth day. Recipients were injected with 400 IU eCG at the time of sponge removal while donors received a total of 133 mg NIH-FSH-P1 (Folltropin-V) given twice daily in decreasing doses over 3 days starting 48 h before sponge removal. Ovulation was induced in donors by injecting 100 μg of GnRH at 24 h (GnRH24) or 36 h (GnRH36) after sponge removal. Embryo recovery was performed by oviduct flushing following a standard mid-ventral laparotomy procedure. The proportion of embryos in the pronuclear stage of development was higher in the GnRH36 group (90% vs 34%, p<0.01). Embryos were microinjected with a DNA expression cassette followed by transfer to the oviduct of synchronized recipients. A higher, yet not statistically significant, pregnancy rate was found in the recipients transferred with pronuclear-stage embryos compared with those transferred with 2-cell-stage embryos (64% vs 37%, chi-square p=0.06). One transgenic female founder was produced from the group of recipients transferred with pronuclear-stage microinjected embryos.

scholarly journals Spatiotemporal dynamics of OCT4 protein localization during preimplantation development in mice

Reproduction ◽  
2016 ◽  
Vol 152 (5) ◽  
pp. 417-430 ◽  
Author(s):  
Atsushi Fukuda ◽  
Atsushi Mitani ◽  
Toshiyuki Miyashita ◽  
Hisato Kobayashi ◽  
Akihiro Umezawa ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Splice Variants ◽  
Protein Localization ◽  
Preimplantation Development ◽  
Preimplantation Embryos ◽  
Sequencing Analysis ◽  
Dependent Manner ◽  
Cell Stage ◽  
Protein Levels ◽  
Oct4 Protein

Spatiotemporal expression of transcription factors is crucial for genomic reprogramming. Pou5f1 (Oct4) is an essential transcription factor for reprogramming. A recent study reported that OCT4A, which is crucial for establishment and maintenance of pluripotent cells, is expressed in oocytes, but maternal OCT4A is dispensable for totipotency induction. Whereas another study reported that OCT4B, which is not related to pluripotency, is predominantly expressed instead of OCT4A during early preimplantation phases in mice. To determine the expression states of OCT4 in murine preimplantation embryos, we conducted in-depth expression and functional analyses. We found that pluripotency-related OCT4 mainly localizes to the cytoplasm in early preimplantation phases, with no major nuclear localization until the 8–16-cell stage despite high expression in both oocytes and early embryos. RNA-sequencing analysis using oocytes and early preimplantation embryos could not identify the splice variants creating alternative forms of OCT4 protein. Forced expression of OCT4 in zygotes by the injection of polyadenylated mRNA clearly showed nuclear localization of OCT4 protein around 3–5-fold greater than physiological levels and impaired developmental competency in a dose-dependent manner. Embryos with modest overexpression of OCT4 could develop to the 16-cell stage; however, more than 50% of the embryos were arrested at this stage, similar to the results for OCT4 depletion. In contrast, extensive overexpression of OCT4 resulted in complete arrest at the 2-cell stage accompanied by downregulation of zygotically activated genes and repetitive elements related to the totipotent state. These results demonstrated that OCT4 protein localization was spatiotemporally altered during preimplantation development, and strict control of Oct4 protein levels was essential for proper totipotential reprogramming.

The early development of haploid and aneuploid parthenogenetic embryos

Development ◽  
1975 ◽  
Vol 34 (3) ◽  
pp. 645-655
Author(s):  
Matthew H. Kaufman ◽  
Leo Sachs
Keyword(s):  
Early Development ◽  
Polar Body ◽  
Chromosome Counts ◽  
Cell Stage ◽  
Haploid Chromosome Number ◽  
Stage Of Development ◽  
Morula Stage ◽  
Second Polar Body ◽  
Similar Development ◽  
Parthenogenetic Embryos

The early development of parthenogenetically activated oocytes has been studied in C57BL × CBA-T6T6 (F1T6) translocation heterozygote mice and C57BL × CBA-LAC (F1LAC) mice. All F1T6 oocytes had either a quadrivalent or a univalent-trivalent configuration at meiosis I; no such chromosome configurations were observed in the F1LAC oocytes. At ovulation 36·5 % of the F1T6 oocytes had 19 or 21 chromosomes, whereas 97 % of the F1LAC had the normal haploid chromosome number of 20. After parthenogenetic activation, chromosome counts at metaphase of the first cleavage mitosis were made of the eggs with a single pronucleus following extrusion of the second polar body. These activated eggs had similar frequencies of 19, 20 and 21 chromosomes as had the oocytes at ovulation. The activated 1-cell eggs were transferred to the oviducts of pseudopregnant recipients and the embryos recovered 3 days later. At this stage of development, most of the F1T6 embryos with 19 chromosomes were no longer found, but the frequency of 21-chromosome embryos was similar to the frequency of 21-chromosome oocytes and activated eggs. There was a similar mean number of cells in the embryos with 20 and 21 chromosomes. The results indicate that nearly all the embryos with 19 chromosomes failed to develop, probably beyond the 2-cell stage, whereas oocytes with 21 chromosomes had a similar development to oocytes with 20 chromosomes up to the morula stage.

Early embryonic expression ofFGF4/6/9gene and its role in the induction of mesenchyme and notochord inCiona savignyiembryos

Development ◽  
2002 ◽  
Vol 129 (7) ◽  
pp. 1729-1738 ◽  
Author(s):  
Kaoru S. Imai ◽  
Nori Satoh ◽  
Yutaka Satou
Keyword(s):  
Cell Differentiation ◽  
Nuclear Localization ◽  
Target Genes ◽  
Muscle Cells ◽  
Cell Stage ◽  
Ciona Savignyi ◽  
Mesenchyme Cell ◽  
Notochord Cells ◽  
Mesenchyme Cells ◽  
Endodermal Cells

In early Ciona savignyi embryos, nuclear localization of β-catenin is the first step of endodermal cell specification, and triggers the activation of various target genes. A cDNA for Cs-FGF4/6/9, a gene activated downstream of β-catenin signaling, was isolated and shown to encode an FGF protein with features of both FGF4/6 and FGF9/20. The early embryonic expression of Cs-FGF4/6/9 was transient and the transcript was seen in endodermal cells at the 16- and 32-cell stages, in notochord and muscle cells at the 64-cell stage, and in nerve cord and muscle cells at the 110-cell stage; the gene was then expressed again in cells of the nervous system after neurulation. When the gene function was suppressed with a specific antisense morpholino oligo, the differentiation of mesenchyme cells was completely blocked, and the fate of presumptive mesenchyme cells appeared to change into that of muscle cells. The inhibition of mesenchyme differentiation was abrogated by coinjection of the morpholino oligo and synthetic Cs-FGF4/6/9 mRNA. Downregulation of β-catenin nuclear localization resulted in the absence of mesenchyme cell differentiation due to failure of the formation of signal-producing endodermal cells. Injection of synthetic Cs-FGF4/6/9 mRNA in β-catenin-downregulated embryos evoked mesenchyme cell differentiation. These results strongly suggest that Cs-FGF4/6/9 produced by endodermal cells acts an inductive signal for the differentiation of mesenchyme cells. On the other hand, the role of Cs-FGF4/6/9 in the induction of notochord cells is partial; the initial process of the induction was inhibited by Cs-FGF4/6/9 morpholino oligo, but notochord-specific genes were expressed later to form a partial notochord.

TRIM28 maintains genome imprints and regulates development of porcine SCNT embryos

Reproduction ◽  
2021 ◽  
Vol 161 (4) ◽  
pp. 411-424
Author(s):  
Yanhui Zhai ◽  
Meng Zhang ◽  
Xinglan An ◽  
Sheng Zhang ◽  
Xiangjie Kong ◽  
...  
Keyword(s):  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Transcript Abundance ◽  
Dna Demethylation ◽  
Epigenetic Variability ◽  
Promoter Regions ◽  
Cell Stage ◽  
Genome Wide ◽  
Developmental Progression ◽  
Imprinting Gene

Pre-implantation embryos undergo genome-wide DNA demethylation, however certain regions, like imprinted loci remain methylated. Further, the mechanisms ensuring demethylation resistance by TRIM28 in epigenetic reprogramming remain poorly understood. Here, TRIM28 was knocked down in oocytes, and its effects on porcine somatic cell nuclear transfer (SCNT) embryo development was examined. Our results showed that SCNT embryos constructed from TRIM28 knockdown oocytes had significantly lower cleavage (53.9 ± 3.4% vs 64.8 ± 2.7%) and blastocyst rates (12.1 ± 4.3% vs 19.8 ± 1.9%) than control-SCNT embryos. The DNA methylation levels at the promoter regions of the imprinting gene IGF2 and H19 were significantly decreased in the 4-cell stage, and the transcript abundance of other imprinting gene was substantially increased. We also identified an aberrant two-fold decrease in the expression of CXXC1and H3K4me3 methyltransferase (ASH2L and MLL2), and the signal intensity of H3K4me3 had a transient drop in SCNT 2-cell embryos. Our results indicated that maternal TRIM28 knockdown disrupted the genome imprints and caused epigenetic variability in H3K4me3 levels, which blocked the transcription activity of zygote genes and affected the normal developmental progression of porcine SCNT embryos.

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