Environmental factor – June 2021: In conversation with Elizabeth Martin, independent researcher
In my opinion, the strength of the NIEHS research enterprise is reflected in the approximately 200 postdoctoral, undergraduate and post-baccalaureate scientists who help advance the institute’s vital mission, which is to promote healthier living by finding out how the environment affects people. I am proud that our interns receive the support, mentorship and professional development that paves the way for their professional success, whether at the NIEHS or beyond.
Recently, I interviewed one of these success stories. Elizabeth Martin, Ph.D., is a postdoctoral fellow in the Institute’s Laboratory of Epigenetics and Stem Cell Biology which is supervised by Paul Wade, Ph.D. Martin just received a National Institutes of Health Independent researcher grant, awarded to outstanding early-career scientists committed to improving the diversity of the workforce.
I was delighted to speak with her about the scholarship, her research interests and what she hopes to accomplish in the future. I can say with pleasure that with individuals like Martin in the ascendant, the future of environmental health science research is indeed in good hands.
Pregnancy as a window of susceptibility
Rick woychik: Can you tell us a bit about your independent researcher grant?
Elisabeth martin: I was fortunate to win this award because it gives me a three-year, non-permanent Principal Investigator position at the NIEHS, and it aims to improve diversity in scientific research. I will continue to work with my mentor, Dr Wade, but I will also continue research independent of his work on how eukaryotic cells regulate gene expression.
I plan to view pregnancy as a window of susceptibility to environmental toxicants for moms. We often think of the infant as the most vulnerable during pregnancy. However, I am really interested in whether there is an epigenetic reprogramming event that occurs in the mother and if this increases her sensitivity to environmental agents, potentially leading to negative health consequences later in life.
Understanding individual risk
RW: Epigenetics refers to the chemical changes in DNA or proteins associated with DNA that affect the way genes are turned on and off. Understanding how environmental exposures influence such epigenetic changes is one of the key goals outlined in the NIEHS 2018-2023 Strategic Plan, so I think it’s great that you are continuing this line of research.
Prior to joining the institute, you received your PhD from the University of North Carolina at Chapel Hill, under the guidance of NIEHS Superfund research program recipient Rebecca Fry, Ph.D. You studied how the exhibition prenatal arsenic and other metals may affect individuals differently, depending on how they metabolize these substances, for example.
This work aligns with the concept of precision environmental health, which I touched on in a recent Directors’ Corner conversation with Cheryl Walker, Ph.D., Baylor College of Medicine. Can you tell us about this research, which was the basis of your thesis project?
EM: Absolutely. The motivation for my previous and current research comes from the idea of precision environmental health, which involves expanding knowledge about individual risks and working to prevent disease. I was strongly influenced by a 2014 Commentary through [former NIEHS and National Toxicology Program Director] Dr Ken Olden. He explained how scientists might integrate epigenetic data into risk assessment and what that data might tell us about how chemical and non-chemical stressors can worsen health disparities.
Accounting for complexity
One challenge is to take into account the complexity and variety of these stressors. Take arsenic as an example. If we look at different parts of the world, we find that there is no universal exposure because we are dealing with mixtures involving not only arsenic but nutrition, various types of pollution, psychosocial stress, etc. Then there is the question of timing – whether the exposure took place before birth, during puberty, or in adulthood.
Dr Fry and I have found inconsistent epigenetic changes between populations, making it difficult to determine which changes are true indicators of individual vulnerability. We hypothesized that the exposures act on what is called transcription factors – proteins that turn genes on or off by binding to DNA – rather than directly to DNA. This research was one of the reasons I wanted to join Dr. Wade’s lab, which is looking at how transcription factors affect the epigenetic landscape.
In the future, I hope to build on my work at Chapel Hill and the NIEHS in the context of pregnancy. I want to identify the consistent biological changes that can result from a given exposure, with the aim of improving understanding of the risk of disease later in mothers’ lives.
Maternal health and phthalates
RW: You collaborated with 14 other NIEHS scientists on a special issue of the Journal of Women’s Health devoted to maternal health, published in February. Can you tell us about your involvement in this project?
EM: I worked on the breast cancer section of this publication with Dr Sue Fenton, from the NIEHS division of the National Toxicology Program. Through this project, I realized that pregnancy on the maternal side is under-studied, especially in regards to how certain environmental exposures can lead to complications that turn into problems later in life such as diabetes. or cardiovascular disease.
Thinking about chemicals that could affect pregnancy, I landed on DEHP [Di(2-ethylhexyl) phthalate], which is one of the most common and toxic phthalates. These are synthetic chemicals used to make a variety of plastics, solvents, and personal care products. Almost all women are exposed to DEHP. Additionally, DEHP is believed to interfere with progesterone signaling, which is essential during pregnancy. Imbalances in this signaling can lead to preterm labor and prolonged labor.
Olden K, Lin YS, Gruber D, Sonawane B. 2014. Epigenome: biosensor of cumulative exposure to chemical and non-chemical stressors related to environmental justice. Am J Public Health 104 (10): 1816–21.
Martin EM, Fry RC. 2016. A cross-analysis of prenatal exposures to environmental contaminants and to the epigenome: support for the occupation of the stress-sensitive transcription factor as a mediator of gene-specific CpG methylation. About Epigenet 2 (1): dvv011.
Boyles AL, Beverly BE, Fenton SE, Jackson CL, Jukic AMZ, Sutherland VL, Baird DD, Collman GW, Dixon D, Ferguson KK, Hall JE, Martin EM, Schug TT, White AJ, Chandler KJ. 2021. Environmental factors involved in maternal morbidity and mortality. J Women’s Health (Larchmt) 30 (2): 245-252.
(Rick Woychik, Ph.D., heads the NIEHS and the National Toxicology Program.)