Project description:Recent success in the derivation of mouse haploid embryonic stem cells from androgenetic blastocysts (ahESCs) has provided new avenues for the generation of genetically modified animals. However, the efficiency to produce viable transgenic mice via intracytoplasmic ahESCs injection (ICAI) was very low, which may correlate with the aberrant regulation of imprinted genes. Here we designed to delete the paternal imprinted gene H19 by CRSPR-Cas9 system combined with homologous recombination. The H19 deleted (H19Δ) ahESCs maintained haploidy and genome integrity, expressed pluripotency markers, differentiated into embryoid bodies (EBs), and contributed to chimeras after blastocyst injection. These cells exhibited similar imprinting features with sperm cells, and can produce fertile progenies after ICAI at a high efficiency. More importantly, it is feasible to perform genetic manipulations in H19Δ ahESCs, and the genomic modifications can be properly transmitted to offspring. Our study will benefit the reproductive medicine in curing the hereditary genetic diseases and infertility in the future.
Project description:Recent success in the derivation of mouse haploid embryonic stem cells from androgenetic blastocysts (ahESCs) has provided new avenues for the generation of genetically modified animals. However, the efficiency to produce viable transgenic mice via intracytoplasmic ahESCs injection (ICAI) was very low, which may correlate with the aberrant regulation of imprinted genes. Here we designed to delete the paternal imprinted gene H19 by CRSPR-Cas9 system combined with homologous recombination. The H19 deleted (H19Î) ahESCs maintained haploidy and genome integrity, expressed pluripotency markers, differentiated into embryoid bodies (EBs), and contributed to chimeras after blastocyst injection. These cells exhibited similar imprinting features with sperm cells, and can produce fertile progenies after ICAI at a high efficiency. More importantly, it is feasible to perform genetic manipulations in H19Î ahESCs, and the genomic modifications can be properly transmitted to offspring. Our study will benefit the reproductive medicine in curing the hereditary genetic diseases and infertility in the future. The copy number variations of the two H19Î ahESC lines were analyzed by the SurePrint G3 Mouse CGH 4Ã180 K microarrays (Agilent). Wild-type OG-3 ahESCs were used as reference.
Project description:Our lab first derived mouse androgenetic haploid embryonic stem cells (AG-haESCs) and demonstrated that AG-haESCs can be used as an “artificial spermatids” to generate gene-edited semi-cloned (SC) mice through intracytoplasmic injection (ICAHCI) into mature oocyte, even though the birth efficiency is very low. Further we proved that H19-DMR and IG-DMR were the main barrier to generate viable mice through androgenetic and parthenogenetic haESCs. More importantly, AG-haESCs mediated SC technology combined with CRISPR-Cas9 is a powerful tool to generate gene-modified mouse models and carry out genetic screening at organismal level. However, it is still not clear how the H19-DMR and IG-DMR coordinately regulate SC embryo development. Here, we found that the H19-DMR and IG-DMR regulate the development of SC embryos in spatio-temporal scales. Firstly, we found that the H19-DMR and IG-DMR are not indispensable for the development of preimplantation of SC embryos. Secondly, H19-DMR is essential for the development of SC embryos in mid-gestation and IG-DMR takes effect in late-gestation. Further, the maintenance of paternal H19-DMR methylation status and deletion of paternal H19 transcription unit play a key role in the structures and transport functions of SC embryo placenta. Importantly, AG-haESCs carrying triple deletions, including H19, H19-DMR and IG-DMR, can further improve the efficiency in generation of viable, normal-size, and fertile mice.
Project description:This SuperSeries is composed of the SubSeries listed below. Abstract Among all mammalian cell types, sperm cells exhibit one of the highest levels of DNA methylation, with ~80% of CpG sites being methylated. The role of this sperm hypermethylation in offspring development, aside from the methylation at the well-characterized H19-DMR and Dlk1-Dio3 intergenic germline DMR (IG-DMR) loci, remains largely unexplored. In mouse germ cells, removal of DNA methylation by deleting methyltransferase (Dnmt) genes causes meiotic catastrophe and infertility. To circumvent this limitation, we inactivated them instead in androgenetic haploid embryonic stem cells (AG-haESCs) lacking H19-DMR and IG-DMR to remove methylation prior to oocyte injection, and subsequently reactivated them in the resulting embryos during cleavage, to ensure Dnmt sufficiency. This strategy enabled the generation of viable offspring from unmethylated paternally-derived haploid cells. In the resulting embryos, the paternal genome rapidly reacquired methylation and was comparable to wild-type in post-implantation embryos. These semi-cloned embryos could develop to term and survived to adulthood, exhibiting near-normal morphological and physiological parameters. These findings indicate that the essential hereditary function of the paternal genome methylation is mainly restricted to the imprinted loci Igf2-H19 and Dlk1-Dio3, while methylation elsewhere appears dispensable for subsequent development, as de novo methylation activity intrinsic to the early embryo ensures epigenetic reprogramming for offspring development.
Project description:Among all mammalian cell types, sperm exhibit the highest level of DNA methylation, with approximately 70–80% of CpG sites being methylated. The role of this paternal hypermethylation in embryonic developmental competence, aside from the well-characterized H19-DMR and Dlk1-Dio3 intergenic germline DMR (IG-DMR) loci, remains largely unexplored. In mouse male germ cells, the lack of DNA methyltransferase (Dnmt) causes a loss of methylation, leading to meiotic catastrophe and infertility. To circumvent this limitation, we used sperm-like androgenetic haploid embryonic stem cells (AG-haESCs) for oocyte injection to produce offspring. Using CRISPR/Cas9, we effectively inactivated Dnmt1, Dnmt3a and Dnmt3b in AG-haESCs and later reactivated them in the resulting embryos, overcoming Dnmt haploinsufficiency and enabling the generation of viable offspring from methylation-deficient haploid cells. In the offspring embryos, the paternal genome derived from Dnmt-inactivated AG-haESCs rapidly reacquired methylation and restored a methylome in post-implantation embryos comparable to that of wild-type AG-haESC counterparts. These semi-cloned embryos could develop to term and survived to adulthood, exhibiting near-normal morphological and physiological parameters. These findings indicate that the functional significance of paternal genome methylation is mainly restricted to the imprinted loci Igf2-H19 and Dlk1-Dio3, while methylation of the paternal genome elsewhere appears dispensable for normal development.
Project description:Among all mammalian cell types, sperm exhibit the highest level of DNA methylation, with approximately 70–80% of CpG sites being methylated. The role of this paternal hypermethylation in embryonic developmental competence, aside from the well-characterized H19-DMR and Dlk1-Dio3 intergenic germline DMR (IG-DMR) loci, remains largely unexplored. In mouse male germ cells, the lack of DNA methyltransferase (Dnmt) causes a loss of methylation, leading to meiotic catastrophe and infertility. To circumvent this limitation, we used sperm-like androgenetic haploid embryonic stem cells (AG-haESCs) for oocyte injection to produce offspring. Using CRISPR/Cas9, we effectively inactivated Dnmt1, Dnmt3a and Dnmt3b in AG-haESCs and later reactivated them in the resulting embryos, overcoming Dnmt haploinsufficiency and enabling the generation of viable offspring from methylation-deficient haploid cells. In the offspring embryos, the paternal genome derived from Dnmt-inactivated AG-haESCs rapidly reacquired methylation and restored a methylome in post-implantation embryos comparable to that of wild-type AG-haESC counterparts. These semi-cloned embryos could develop to term and survived to adulthood, exhibiting near-normal morphological and physiological parameters. These findings indicate that the functional significance of paternal genome methylation is mainly restricted to the imprinted loci Igf2-H19 and Dlk1-Dio3, while methylation of the paternal genome elsewhere appears dispensable for normal development.
Project description:Among all mammalian cell types, sperm exhibit the highest level of DNA methylation, with approximately 70–80% of CpG sites being methylated. The role of this paternal hypermethylation in embryonic developmental competence, aside from the well-characterized H19-DMR and Dlk1-Dio3 intergenic germline DMR (IG-DMR) loci, remains largely unexplored. In mouse male germ cells, the lack of DNA methyltransferase (Dnmt) causes a loss of methylation, leading to meiotic catastrophe and infertility. To circumvent this limitation, we used sperm-like androgenetic haploid embryonic stem cells (AG-haESCs) for oocyte injection to produce offspring. Using CRISPR/Cas9, we effectively inactivated Dnmt1, Dnmt3a and Dnmt3b in AG-haESCs and later reactivated them in the resulting embryos, overcoming Dnmt haploinsufficiency and enabling the generation of viable offspring from methylation-deficient haploid cells. In the offspring embryos, the paternal genome derived from Dnmt-inactivated AG-haESCs rapidly reacquired methylation and restored a methylome in post-implantation embryos comparable to that of wild-type AG-haESC counterparts. These semi-cloned embryos could develop to term and survived to adulthood, exhibiting near-normal morphological and physiological parameters. These findings indicate that the functional significance of paternal genome methylation is mainly restricted to the imprinted loci Igf2-H19 and Dlk1-Dio3, while methylation of the paternal genome elsewhere appears dispensable for normal development.
Project description:Haploid stem cells offer an easy-to-manipulate genetic system and therefore have great values for studies of recessive phenotypes. Here, we show that mouse androgenetic haploid ES (ahES) cell lines can be established by transferring sperm into enucleated oocyte. The ahES cells maintain haploidy and stable growth over 30 passages, express pluripotent markers, possess the ability to differentiate into all three germ-layers in vitro and in vivo, and contribute to germline of chimeras when injected into blastocysts. Although epigenetically distinct from sperm cells, the ahES cells can produce viable and fertile progenies after intracytoplasmic injection into mature oocytes. The oocyte injection procedure can also produce viable transgenic mice from genetically engineered ahES cells. We used microarrays to compare the global programme of gene expression among ahES cells, normal diploid ES cells, MEF cells and round sperm cells and found that gene expression pattern of ahES cells was highly similar with ES cells but was distinct from MEF cells and round sperms. Androgenetic haploid ES cells were FACS sorted to harvest the G0/G1 phase haploid cells. Total RNA were extracted from three ahES cell lines (AH129-5, AH129-N1, AH129-NC1, all 129Sv genetic background), two ES cell lines ( CS1-1, R1, 129Sv background), MEF cells and round sperm and hybridized with Affymetrix GeneChip 430 2.0 array. Data were collected and analyzed to compare their gene expression pattern.
Project description:Haploid stem cells offer an easy-to-manipulate genetic system and therefore have great values for studies of recessive phenotypes. Here, we show that mouse androgenetic haploid ES (ahES) cell lines can be established by transferring sperm into enucleated oocyte. The ahES cells maintain haploidy and stable growth over 30 passages, express pluripotent markers, possess the ability to differentiate into all three germ-layers in vitro and in vivo, and contribute to germline of chimeras when injected into blastocysts. Although epigenetically distinct from sperm cells, the ahES cells can produce viable and fertile progenies after intracytoplasmic injection into mature oocytes. The oocyte injection procedure can also produce viable transgenic mice from genetically engineered ahES cells. We used microarrays to compare the global programme of gene expression among ahES cells, normal diploid ES cells, MEF cells and round sperm cells and found that gene expression pattern of ahES cells was highly similar with ES cells but was distinct from MEF cells and round sperms.