Windows of Vulnerability in Embryo Development: Loss of Multidrug Efflux in Sea Urchin Pluripotent CellsEPA Grant Number: FP917116
Title: Windows of Vulnerability in Embryo Development: Loss of Multidrug Efflux in Sea Urchin Pluripotent Cells
Investigators: Campanale, Joseph Paul
Institution: University of California - San Diego
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Human Health: Risk Assessment and Decision Making
The large number of chemicals in the environment could represent a significant emerging risk to the health of most embryos. Recent research by the Environmental Working Group indicate 287 environmental chemicals, including pesticides, herbicides, heavy metals, DDT and dioxins could be detected in human umbilical cord blood (http://ewg.org/). These results show that human embryos are exposed to many chemicals in utero, as are embryos of most other species that develop in direct contact with the external environment. However, little is known about how embryos eliminate and/or detoxify chemicals or about specific windows of chemical vulnerability during development. Although embryos have potent defenses against environmental stress, many chemicals can act in stage, species and cell-type specific ways to induce teratology. The overall goal of this research project is to characterize the developmental changes in activity of these cellular defenses and their consequences for the vulnerability of multi-potent cells in embryos.
Embryonic cells have evolved mechanisms for protection against chemicals, including membrane transporters that efflux toxins. Anthropogenic compounds in the environment present new challenges for defenses and can adversely influence the health of adults or subsequent generations. Descriptions of chemical defenses in embryonic cells of the sea urchin can provide information about the role of efflux transporters in chemical protection and inform predictions of stage-specific risks to health.
Preliminary results indicate that multi-potent stem cells, the small micromeres, in the early sea urchin embryo experience a dramatic decrease in a key chemical defense, ATP-binding cassette (ABC) efflux transport, during development. To understand the causes and consequences for the loss of protective efflux activity from critical cell types, embryos from the purple sea urchin, Strongylocentrotus purpuratus, will be exposed to fluorescent substrates of these transporters and then imaged by confocal microscopy. In order to understand the regulation of defensive strategies, this research will quantitatively describe the amount and types of efflux transporter activity for a variety of cell types and the developmental timeline for these events. Second, assessments of whether the loss of ABC-transporter activity sensitizes the small micromeres to known environmental contaminants will indicate the relative vulnerability of these cells to environmental chemicals. Finally, this research will examine whether loss of ABC-transporter activity is part of a conserved developmental signaling pathway that drives cellular migration by sensitizing different cells to different developmental chemicals in the embryo.
Qualitative and quantitative estimates of ABC-efflux in critical cell types, including multi-potent stem cells, in embryos will provide important information regarding the relative sensitivity of these cells to environmental chemicals. The results of exposure experiments will accurately describe the timing and magnitude of any reduction in ABC-transporter activity for cells destined to become different tissue types. Experiments using ABC-transporter inhibitors will provide a correlation of reduced ABC-efflux and the vulnerability of critical cells to toxicants. Critical evaluations of the loss of cellular defenses, including in chemical efflux, will uncover information about windows of susceptibility for specific cells during embryogenesis and may provide links between defense against the environment and the developmental program in embryos.
Potential to Further Environmental/Human Health Protection:
Describing losses in the key chemical defenses provided by ABC-transporter mediated efflux of chemicals from cells in sea urchin embryos will provide information about the role of efflux transporters in protection in general and insights into developmental processes that underlie windows of chemical sensitivity in early embryos. This basic information would inform predictions of stage-specific risks to health and also expand our understanding of cellular regulation of key chemical defenses during the execution of the developmental program.