Non-Technical Paragraph Reprogramming somatic or differentiated cells into embryonic-like stem cells represents a major technical breakthrough in stem cell biology. Overexpression of four-defined factors in fibroblasts revealed that lineage-committed cells can revert to an embryonic-like ground state. These reprogrammed cells or induced pluripotent stem cells (iPSCs) have attributes similar to naturally-occurring embryonic stem cells (ESCs); and therefore, have the remarkable capacity to produce all tissue-types in the embryo and self-renew. However, cells with an even greater developmental potential exists during a narrow time window between fertilization and ESC formation. These cells are termed totipotent for their capacity to generate both embryonic and non-embryonic tissues, such as the placenta. Currently, the totipotent state can be achieved by natural fertilization, cloning, or genetic manipulation of ESCs or iPSCs. These approaches are impeded by low efficiency rates and a host of molecular barriers that have yet be identified. Furthermore, totipotent cells are unable to self-renew and propagate; thus, limiting large scale applications. This EAGER grant will test a simple, single-gene manipulation strategy to transform iPSCs or somatic cells entirely into totipotent cells that are capable of self-renewing. Success of the research plan will provide a novel reprogramming strategy that can pave the way to understand a molecular hierarchy regulating the totipotent state and the potential to generate the entire mammalian organism. Capitalizing on this novel technical innovation, freshmen and sophomore students will be recruited from introductory biology courses to learn basic techniques in stem cell biology. This hands-on-student training exercise is part of larger strategy to ultimately enhance retention and graduation rates at a minority-serving institution aspiring for tier-one research status.
Technical Paragraph Totipotent cells have the remarkable capacity to generate both embryonic and extraembryonic tissues, such as the placenta. Totipotent cells are therefore a defining feature that contributed to the propagation of the nearly 4,000 placental mammals. During preimplantation embryonic development, totipotent cells are present transiently between fertilization and prior to formation of the inner cell mass (ICM) of the blastocyst. In addition to natural fertilization, totipotent cells can be acquired artificially by somatic nuclear transfer (cloning) or by eliminating epigenetic regulators in ICM-derived embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs). However, the efficiency of these approaches is relatively low, and require the presence and/or elimination of a myriad of factors that establish barriers to the totipotent state. Strategies to fully-reprogram pluripotent stem or somatic cells to the totipotent state with defined factors therefore remain a challenge. This EAGER grant addresses this challenge, and will test a single-gene manipulation strategy that fully-reprograms iPSCs or somatic cells into totipotent cells. Specifically, totipotent cells acquired by this approach will be challenged with the mouse chimera assay. This rigorous approach will determine whether newly-acquired totipotent cells have the potential to generate both embryonic and extraembryonic tissues. Successful completion of this research program will profoundly impact the scientific community by providing an alternative reprogramming strategy, insight into a molecular hierarchy regulating totipotency and preimplantation embryonic development. As part of the Broader Impacts of this grant, undergraduate students will be recruited to the lab to engage in basic methodologies in stem cell biology. Targeting freshmen and sophomores is part of a larger strategy to help retain and enhance graduate rates at a minority-serving institution striving for tier-one research status.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
