Activation of Embryonic/germ Cell-like Axis Links Poor Outcomes of Gliomas

It is unclear which core events drive the malignant progression of gliomas. Earlier studies have revealed that the embryonic stem (ES) cell/early PGC state is associated with tumourigenicity. Here, our findings showed that germ cell-like cells were present in human gliomas and cultured glioma cells and that the formation of germ cell-like cells was essential for glioma tumours. Bioinformatic analysis showed that the mRNA levels of genes related to embryonic/germ cell development could be detected in most gliomas. Our findings showed that the activation of genes related to reprogramming or the germ cell-like state alone seemed to be insufficient to lead to a malignant prognosis, whereas increased mRNA levels of genes related to the activation of the embryonic/germ cell-like cycle (somatic PGC-EGC-like cycle and somatic parthenogenetic embryo-like cycle) were positively correlated with malignant prognoses and poor clinical outcomes of gliomas. Genes related to the embryonic/germ cell cycle alone or in combination with the WHO grade or 1p19q codeletion status could be used to subdivide gliomas with distinct clinical behaviours. Together, our findings indicated that a crucial role of germ cell-like cell formation in glioma initiation as well as activation of genes related with the parthenogenetic embryo-like cycle and PGC-EGC-like cycle link to the malignant prognosis and poor outcomes of gliomas, which might provide a novel way to better understand the nature of and develop targeted therapies for gliomas as well as important markers for predicting clinical outcomes in gliomas.

Loss of WTAP Impairs Early Parthenogenetic Embryo Development

m6A is one of the most common and abundant modifications of RNA molecules present in eukaryotes. The methyltransferase complex, consisting of methyltransferase-like 3 (METTL3), METTL14, and WTAP, is responsible for the m6A modification of RNA. WTAP was identified as an mRNA splicing regulator. Its role as a regulatory subunit of the m6A methyltransferase complex in embryonic development remains largely unknown. To investigate the role of WTAP in porcine early embryonic development, si-WTAP was microinjected into porcine parthenogenetic zygotes. WTAP knockdown significantly reduced the blastocyst rate and global m6A levels, but did not affect the cleavage rate. Betaine was supplemented into the in vitro culture (IVC) to increase the m6A levels. Betaine significantly increased the global m6A levels but did not affect the blastocyst rate. Furthermore, the pluripotency genes, including OCT4, SOX2, and NANOG, were downregulated following WTAP knockdown. The apoptotic genes BAX and CASPASE 3 were upregulated, while the anti-apoptotic gene BCL2 was downregulated in WTAP knockdown blastocysts. TUNEL staining revealed that the number of apoptotic cells was significantly increased following WTAP knockdown. Our study indicated that WTAP has an indispensable role in porcine early embryonic development.

Production and Characterization of Mouse Diploid Parthenogenetic Blastocyst Developed in Phosphate-Free Medium

Parthenogenesis is an artificial oocytes activation process without paternal contribution. Blastocyst, derived from parthenogenesis, is one of potential source for pluripotent stem cell propagation. Unfortunately, previous studies reported that parthenogenetic embryo did not achieve exhilarating blastocyst rate. One of the component that predicted inhibit parthenogenetic embryo development is phosphate. Therefore, we try to modify culture medium in order to overcome that problem. The aim of this research was to produce and analyze the characteristics of parthenogenetic blastocyst developed in phosphate-free medium. Mouse oocytes obtained from adult female DDY by superovulation. The activator was strontium chloride 10 mM and diploidization with cytochalasin B 5 μg/ml. Medium for activation and culture medium were modified rat 1 cell embryo medium (MR1ECM) which is phosphate free. The results showed that parthenotes that were cultured in phosphate free medium reached higher blastocyst rate compared to the other groups. The increase of phosphate in culture medium lead to impaired parthenogenetic embryos development. Further experiment was made to analyze the differences between fertilized and parthenogenetic embryo in this medium. The experiment showed that diploid parthenogenetic could achieve high blastocyst rate (30.9±1.3%). The quality of diploid parthenogenetic blastocyst, based on cells number, viability, and ICM ratio, was lower than fertilized blastocyst.

Induction of autophagy promotes porcine parthenogenetic embryo development under low oxygen conditions

Autophagy plays an important role in embryo development; however, only limited information is available on how autophagy specifically regulates embryo development, especially under low oxygen culture conditions. In this study we used parthenogenetic activation (PA) of porcine embryos to test the hypothesis that a low oxygen concentration (5%) could promote porcine embryo development by activating autophagy. Immunofluorescence staining revealed that low oxygen tension activated autophagy and alleviated oxidative stress in porcine PA embryos. Development was significantly affected when autophagy was blocked by 3-methyladenine, even under low oxygen culture conditions, with increased reactive oxygen species levels and malondialdehyde content. Furthermore, the decreased expression of pluripotency-associated genes induced by autophagy inhibition could be recovered by treatment with the antioxidant vitamin C. Together, these results demonstrate that low oxygen-induced autophagy regulates embryo development through antioxidant mechanisms in the pig.

Ascorbic acid improves parthenogenetic embryo development through TET proteins in mice

The TET (Ten-Eleven Translocation) proteins catalyze the oxidation of 5mC (5-methylcytosine) to 5hmC (5-hydroxymethylcytosine) and play crucial roles in embryonic development. Ascorbic acid (Vc, Vitamin C) stimulates the expression of TET proteins, whereas DMOG (dimethyloxallyl glycine) inhibits TET expression. To investigate the role of TET1, TET2, and TET3 in PA (parthenogenetic) embryonic development, Vc and DMOG treatments were administered during early embryonic development. The results showed that Vc treatment increased the blastocyst rate (20.73 ± 0.46 compared with 26.57 ± 0.53%). By contrast, DMOG reduced the blastocyst rate (20.73 ± 0.46 compared with 11.18 ± 0.13%) in PA embryos. qRT-PCR (quantitative real-time PCR) and IF (immunofluorescence) staining results revealed that TET1, TET2, and TET3 expressions were significantly lower in PA embryos compared with normal fertilized (Con) embryos. Our results revealed that Vc stimulated the expression of TET proteins in PA embryos. However, treatment with DMOG significantly inhibited the expression of TET proteins. In addition, 5hmC was increased following treatment with Vc and suppressed by DMOG in PA embryos. Taken together, these results indicate that the expression of TET proteins plays crucial roles mediated by 5hmC in PA embryonic development.

Peculiarities of in vitro parthenogenesis of unpollinated maize ovaries

The maize line AT-1 is characterized by a hereditary predisposition to parthenogenesis. The aim of this investigation is to study parthenogenetic embryo development in the culture of unpollinated ovaries in vitro . The unpollinated ovaries were explanted in 1, 3, 5, 7, 10, 15 days after the appearance of stigmas from ears. The nutrient medium included mineral components of MS, vitamins, sucrose (9,0%), 2,4-D (2,0 mg/l), agar-agar. The structure of megagametophytes at the time of inoculation of the ovaries and on the 3rd, 7th, 14th, 21th, 28th day of cultivation was studied. The first divisions of unfertilized egg cells were observed on the 5th-7th day after appearance of stigmas from ears, independently from whether all this time the ovaries were on the mother plant or they were inoculated into the nutrient medium. The formation of the autonomous abnormal endosperm in some cultivated ovaries was detected. The abnormal endosperm disturbed normal development of the proembryo. As a rule, the ovaries with embryo and endosperm degenerated. In the absence of endosperm, the morphogenesis of parthenogenetic proembryos was carried out in one of two directions in vitro : 1) development of plants by direct embryogenesis; 2) regeneration of plants from numerous embryoids, raised on the surface of globular proembryos. The second direction was prevailed. The culture of unpollinated ovaries can be a promising method of mass haploid regenerants not only in maize, but also in other types of agricultural plants.