MicroRNA changes throughout the maternal to zygotic transition in bovine in vitro fertilized embryos
Class
Article
Graduation Year
2018
College
College of Agriculture and Applied Sciences
Department
Animal, Dairy, and Veterinary Sciences Department
Faculty Mentor
Abby Benninghoff and Ken White
Presentation Type
Oral Presentation
Abstract
Micro-RNAs (miRNAs) are important for post-transcriptional regulation of gene expression, and they play vital roles in the establishment and maintenance of pluripotency in stem cells. However, the functional relevance of miRNAs in modulating gene expression in pre-implantation stage embryos is not understood. During the maternal to zygotic transition (MZT) the embryo is a highly useful biological system to study cellular regulatory mechanisms for programming the epigenome and establishing appropriate developmental pathways. MiRNAs have been implicated in the regulation of expression of proteins that direct DNA methylation and histone modifications, as well as pluripotency factors. However, the functional relevance of miRNAs and other small RNAs in modulating gene expression in pre-implantation stage embryos is not understood. The objective of this study was to examine dynamic changes in expression profiles for miRNAs during the maternal to zygotic transition (MZT) in in vitro fertilized (IVF) embryos. We hypothesized that some miRNAs would be more abundant at the eight-cell stage of development during the start of the MZT, a point at which maternally derived transcripts are degraded. Small RNA was isolated from bovine oocytes and 8-cell and blastocyst staged embryos and then subjected to Ion Torrent small RNAseq. The total number of miRNA reads was markedly higher in 8-cell embryos as compared to the oocyte or blastocyst stage of development. Of note, miRNA members of the miR-302 family were very abundant in 8-cell embryos, yet absent in oocytes and blastocysts; studies of induced pluripotent stem cells indicate that this miRNA family is essential for the acquisition of pluripotency. Also, expression of miR-196 was also significantly greater in 8-cell embryos; this miRNA targets NOBOX, a transcription factor that regulates the expression of zygotic transcripts during early MZT. In conclusion, miRNAs known to play roles in pluripotency and maternal transcript degradation were significantly up regulated during the MZT in bovine 8-cell IVF embryos, and these miRNAs may play a role in epigenetic programming and pluripotency during the pre-MZT period of development.
Location
Room 154
Start Date
4-13-2017 12:00 PM
End Date
4-13-2017 1:15 PM
MicroRNA changes throughout the maternal to zygotic transition in bovine in vitro fertilized embryos
Room 154
Micro-RNAs (miRNAs) are important for post-transcriptional regulation of gene expression, and they play vital roles in the establishment and maintenance of pluripotency in stem cells. However, the functional relevance of miRNAs in modulating gene expression in pre-implantation stage embryos is not understood. During the maternal to zygotic transition (MZT) the embryo is a highly useful biological system to study cellular regulatory mechanisms for programming the epigenome and establishing appropriate developmental pathways. MiRNAs have been implicated in the regulation of expression of proteins that direct DNA methylation and histone modifications, as well as pluripotency factors. However, the functional relevance of miRNAs and other small RNAs in modulating gene expression in pre-implantation stage embryos is not understood. The objective of this study was to examine dynamic changes in expression profiles for miRNAs during the maternal to zygotic transition (MZT) in in vitro fertilized (IVF) embryos. We hypothesized that some miRNAs would be more abundant at the eight-cell stage of development during the start of the MZT, a point at which maternally derived transcripts are degraded. Small RNA was isolated from bovine oocytes and 8-cell and blastocyst staged embryos and then subjected to Ion Torrent small RNAseq. The total number of miRNA reads was markedly higher in 8-cell embryos as compared to the oocyte or blastocyst stage of development. Of note, miRNA members of the miR-302 family were very abundant in 8-cell embryos, yet absent in oocytes and blastocysts; studies of induced pluripotent stem cells indicate that this miRNA family is essential for the acquisition of pluripotency. Also, expression of miR-196 was also significantly greater in 8-cell embryos; this miRNA targets NOBOX, a transcription factor that regulates the expression of zygotic transcripts during early MZT. In conclusion, miRNAs known to play roles in pluripotency and maternal transcript degradation were significantly up regulated during the MZT in bovine 8-cell IVF embryos, and these miRNAs may play a role in epigenetic programming and pluripotency during the pre-MZT period of development.