Cell Biology Symposium
The Effects of Fetal Programming on Offspring Pancreas DNA Methylation – Dr. Maria Peterson, University of Rhode Island
The 2021 ASAS Cell Biology Symposium that took place on Friday, July 16th, focused on the role of epigenetics in production and health. Dr. Peterson started off the symposium by discussing the role epigenetics has in maternal and fetal programming specifically looking at the pancreas. The pancreas has an integral role in regulating metabolism as well as having both endocrine and exocrine functions. If the development of the pancreas or pancreas function overall is compromised, that can impact the metabolism and overall health of the animal. There is evidence that changes to the maternal environment during gestation can impact the overall growth and development of the offspring. When investigating the pancreas specifically, it was found that poor nutrition during gestation lead to an increase in islet size, reduction of islet number, and reduction in beta cell proliferation. The mechanisms by which this fetal programming occurs are not well understood.
Epigenetics is one of the potential mechanisms that may have a role in this fetal programming and further mediating the multigenerational effects observed. DNA methylation is one epigenetic modification that can result in changes to DNA availability ultimately altering expression of genes. It is needed for proper development and aberrant changes can result in various disease conditions. Dr. Peterson tied everything together by discussing her findings that maternal under and overnutrition during gestation alters the DNA methylation patterns of the offspring pancreas tissue, which is both diet dependent and sex specific in sheep. Her next goal is to further tease out this data in various models to see what is conserved across different species and if it is conserved into adult life, either transiently or permanently.
The Epigenetics and Plasticity of CD4+ T Cells in Poultry Health – Dr. Jiuzhou Song, University of Maryland
Dr. Song continued the symposium by further discussing the role of epigenetics in health, but specifically looking at Marek’s disease (MD) in poultry. Diseases in general are one of the major constraints for livestock productivity and profitability. There are a range of disease-control options that exist such as chemical and biological treatments, vaccination, various preventive strategies, but there are other options such as utilizing genetic approaches that may help complement or even substitute other disease-control strategies. MD is a contagious, lymphomatous disease of chickens caused by MD virus (MDV), a herpesvirus. There has been successful vaccine development that has led to an increased virulence of MDV and the ability to selectively breed naturally resistant chickens, but more questions, such as about the epigenetic effects of infection and overall understanding of genetic resistance to the disease, need to be answered to help develop more disease-control options to hopefully defeat MD.
Dr. Song explained his hypothesis that after MDV infection, genes that are related to MD resistance or susceptibility may exhibit distinctive trends in transcriptional activity leading to a varying degree of resistance to MD. He then discussed data from a genome-wide temporal expression analysis in spleen tissues from an MD resistant line 63, susceptible line 72 and recombinant congenic strain M (RCS-M) that has an intermediate phenotype between the other two lines. Some of the findings included: gene expressions related to robust immune responses were enriched in line 63 chickens compared with line 72 chickens, distinct lincRNAs expression signatures were seen between resistant and susceptible chickens, and increased chromatin accessibility was associated with line 63 chicken CD4+ T cells up-regulated genes induced by MDV infection. More research still needs to be conducted to help with understanding the epigenetic effects of MDV infection to hopefully elucidate the functional implications of the data that have been collected so far.
Epigenetic Changes Due to Environmental Toxicants: An Animal Health Concern – Dr. Cheryl Rosenfeld, University of Missouri
Dr. Rosenfeld concluded the symposium by again discussing the role of epigenetic changes, but now in terms of environmental toxicants. Endocrine disrupting chemicals (EDC) imitate natural hormones in the body but are not controlled by normal homeostatic regulatory mechanisms. Bisphenol A (BPA) is a particularly important EDC in animal and human health as it is found in many common household items as well as the environment. Aside from impacting the host by binding to steroid and non-steroid receptors, EDCs may also induce epigenetic changes directly or may impact gut bacteria promoting changes seen in the host. Dr. Rosenfeld went on to discuss the objectives of a few studies she worked on including to determine if developmental exposure to BPA and/or genistein (a phytoestrogen) would induce epigenetic and transcriptomic changes in different brain regions and the placenta and if those chemicals could also alter gut microbiota to indirectly trigger epigenetic alterations. Some of the animal models used to examine these objectives were California mice, laboratory mice, and deer mice. Across the various studies, there was evidence that developmental exposure to BPA and genistein leads to multiple behavioral deficits such as social and cognitive impairments, reduced voluntary physical activity, and anxiogenic behaviors. Gut dysbiosis was also observed with exposure to BPA and other estrogens in California mice. BPA and genistein also transformed the epigenome and transcriptome profiles in various brain regions, including the hypothalamus and hippocampus, and the placenta. Overall, perinatal exposure to BPA and genistein seem to have a significant impact on the epigenome, which can ultimately lead to long-term health consequences that need to be studied further as this not only pertains to veterinary health but also human health.