Genomes and Genes
Analysis of epigenetic regulation in early mammalian embryos via RNA interference
Principal Investigator: Charles R Long
Abstract: In the United States, it is estimated that about 1% of all babies will be born using assisted reproductive technologies and these numbers continue to grow at a steady rate. The promise of assisting infertile couples to have a family has been realized, but not without a growing concern over the effects of these revolutionary technologies on the proper development and ultimately the health and fitness of the child. Failed epigenetic programming is a primary suspect in the search for causes of unexplained infertility, congenital abnormalities and increased susceptibility to disease associated with both human assisted reproductive techniques and spontaneous conception. Epigenetic refers to differential patterns of gene expression based solely on the physical and biochemical properties of chromatin, without a change in DNA sequence. Two major mechanisms appear to be responsible for establishing and maintaining the epigenome, DNA methylation and histone modifications. Mammalian epigenetic marks are first erased and subsequently re-established during early embryonic development, concomitant with the period of embryo culture following IVF in fertility clinics. The long-term goal of our research is to develop a working model of epigenetic regulation during mammalian oocyte maturation, fertilization and pre-implantation embryonic development, so that in vitro embryo handling systems can be modified to improve the outcomes following ART. Our hypothesis states that subtle alterations of histone and DNA methyltransferases during the critical period of in vitro embryo culture manifest in aberrant embryo development. We will test our hypothesis by using RNA interference to study the functional genomics of epigenetic reprogramming in an established model of in vitro embryo development. The goal is to evaluate the molecular and biological effects of silencing a select group of epigenetic regulators on the establishment of epigenetic marks, maintenance of markers of pluripotency and initiation of differentiation. This Aim will investigate the role individual genes in epigenetic reprogramming and normal embryonic development by employing RNA interference (RNAi) techniques to silence the expression of genes regulating the epigenome during pre-implantation development. Global chromatin methylation patterns and quantitative gene expression during pre-implantation development will be assayed to observe the response to gene silencing. The successful completion of this innovative project will result in the identification of the proteins involved with maintaining and re-establishing the epigenetic program during the period of epigenetic reprogramming in the early embryo. These experiments will provide the first evidence of the functional genes controlling the embryonic epigenome and their effects on cell differentiation in a mammalian species other than the mouse. PUBLIC HEALTH RELEVANCE: Treatment of infertility using assisted reproductive technologies such as in vitro fertilization is at an all time high and growing rapidly in the United States. Numerous studies show a significantly increased risk of serious congenital abnormalities and disease associated with these procedures. Failed epigenetic abnormalities and disease associated with these procedures. Failed epigenetic programming is likely to blame and thus understanding the role of epigenetic gene regulation during embryonic development is critical for formulating infertility treatment options that reduce the possibility of adverse outcomes.
Funding Period: ----------------2010 - ---------------2011-
more information: NIH RePORT
- Reshaping the transcriptional frontier: epigenetics and somatic cell nuclear transferCharles R Long
Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A and M University, College Station, Texas
Mol Reprod Dev 81:183-93. 2014..Interestingly, while resetting somatic transcription and associated epigenetic marks are absolutely required for development of SCNT embryos, life does not demand perfection...
- Examination of DNA methyltransferase expression in cloned embryos reveals an essential role for Dnmt1 in bovine developmentMichael C Golding
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A and M University, College Station, TX 77843 4466, USA
Mol Reprod Dev 78:306-17. 2011..Our results indicate an essential role for Dnmt1 during bovine preimplantation development, and suggest proper transcriptional reprogramming of this gene family in SCNT embryos...
- Production of transgenic calves expressing an shRNA targeting myostatinK Tessanne
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A and M University, College Station, Texas, USA
Mol Reprod Dev 79:176-85. 2012..This is the first report of transgenic livestock produced by direct injection of a recombinant lentivirus, and expressing transgenes encoding shRNAs targeting an endogenous gene (myostatin) for silencing...